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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull Intel software guard extension (SGX) updates from Dave Hansen:
"A couple of x86/sgx changes.
The first one is a no-brainer to use the (simple) SHA-256 library.
For the second one, some folks doing testing noticed that SGX systems
under memory pressure were inducing fatal machine checks at pretty
unnerving rates, despite the SGX code having _some_ awareness of
memory poison.
It turns out that the SGX reclaim path was not checking for poison
_and_ it always accesses memory to copy it around. Make sure that
poisoned pages are not reclaimed"
* tag 'x86_sgx_for_6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/sgx: Prevent attempts to reclaim poisoned pages
x86/sgx: Use SHA-256 library API instead of crypto_shash API
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TL;DR: SGX page reclaim touches the page to copy its contents to
secondary storage. SGX instructions do not gracefully handle machine
checks. Despite this, the existing SGX code will try to reclaim pages
that it _knows_ are poisoned. Avoid even trying to reclaim poisoned pages.
The longer story:
Pages used by an enclave only get epc_page->poison set in
arch_memory_failure() but they currently stay on sgx_active_page_list until
sgx_encl_release(), with the SGX_EPC_PAGE_RECLAIMER_TRACKED flag untouched.
epc_page->poison is not checked in the reclaimer logic meaning that, if other
conditions are met, an attempt will be made to reclaim an EPC page that was
poisoned. This is bad because 1. we don't want that page to end up added
to another enclave and 2. it is likely to cause one core to shut down
and the kernel to panic.
Specifically, reclaiming uses microcode operations including "EWB" which
accesses the EPC page contents to encrypt and write them out to non-SGX
memory. Those operations cannot handle MCEs in their accesses other than
by putting the executing core into a special shutdown state (affecting
both threads with HT.) The kernel will subsequently panic on the
remaining cores seeing the core didn't enter MCE handler(s) in time.
Call sgx_unmark_page_reclaimable() to remove the affected EPC page from
sgx_active_page_list on memory error to stop it being considered for
reclaiming.
Testing epc_page->poison in sgx_reclaim_pages() would also work but I assume
it's better to add code in the less likely paths.
The affected EPC page is not added to &node->sgx_poison_page_list until
later in sgx_encl_release()->sgx_free_epc_page() when it is EREMOVEd.
Membership on other lists doesn't change to avoid changing any of the
lists' semantics except for sgx_active_page_list. There's a "TBD" comment
in arch_memory_failure() about pre-emptive actions, the goal here is not
to address everything that it may imply.
This also doesn't completely close the time window when a memory error
notification will be fatal (for a not previously poisoned EPC page) --
the MCE can happen after sgx_reclaim_pages() has selected its candidates
or even *inside* a microcode operation (actually easy to trigger due to
the amount of time spent in them.)
The spinlock in sgx_unmark_page_reclaimable() is safe because
memory_failure() runs in process context and no spinlocks are held,
explicitly noted in a mm/memory-failure.c comment.
Signed-off-by: Andrew Zaborowski <andrew.zaborowski@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: balrogg@gmail.com
Cc: linux-sgx@vger.kernel.org
Link: https://lore.kernel.org/r/20250508230429.456271-1-andrew.zaborowski@intel.com
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For historic reasons there are some TSC-related functions in the
<asm/msr.h> header, even though there's an <asm/tsc.h> header.
To facilitate the relocation of rdtsc{,_ordered}() from <asm/msr.h>
to <asm/tsc.h> and to eventually eliminate the inclusion of
<asm/msr.h> in <asm/tsc.h>, add an explicit <asm/msr.h> dependency
to the source files that reference definitions from <asm/msr.h>.
[ mingo: Clarified the changelog. ]
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Uros Bizjak <ubizjak@gmail.com>
Link: https://lore.kernel.org/r/20250501054241.1245648-1-xin@zytor.com
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Suggested-by: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Xin Li <xin@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull sgx update from Dave Hansen:
- Use vmalloc_array() instead of vmalloc()
* tag 'x86_sgx_for_6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/sgx: Use vmalloc_array() instead of vmalloc()
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Use vmalloc_array() instead of vmalloc() to calculate the number of
bytes to allocate.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/all/20241112182633.172944-2-thorsten.blum%40linux.dev
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fdget() is the first thing done in scope, all matching fdput() are
immediately followed by leaving the scope.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull 'struct fd' updates from Al Viro:
"Just the 'struct fd' layout change, with conversion to accessor
helpers"
* tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
add struct fd constructors, get rid of __to_fd()
struct fd: representation change
introduce fd_file(), convert all accessors to it.
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cleanups from Thomas Gleixner:
"A set of cleanups across x86:
- Use memremap() for the EISA probe instead of ioremap(). EISA is
strictly memory and not MMIO
- Cleanups and enhancement all over the place"
* tag 'x86-cleanups-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/EISA: Dereference memory directly instead of using readl()
x86/extable: Remove unused declaration fixup_bug()
x86/boot/64: Strip percpu address space when setting up GDT descriptors
x86/cpu: Clarify the error message when BIOS does not support SGX
x86/kexec: Add comments around swap_pages() assembly to improve readability
x86/kexec: Fix a comment of swap_pages() assembly
x86/sgx: Fix a W=1 build warning in function comment
x86/EISA: Use memremap() to probe for the EISA BIOS signature
x86/mtrr: Remove obsolete declaration for mtrr_bp_restore()
x86/cpu_entry_area: Annotate percpu_setup_exception_stacks() as __init
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For optimized performance, firmware typically distributes EPC sections
evenly across different NUMA nodes. However, there are scenarios where
a node may have both CPUs and memory but no EPC section configured. For
example, in an 8-socket system with a Sub-Numa-Cluster=2 setup, there
are a total of 16 nodes. Given that the maximum number of supported EPC
sections is 8, it is simply not feasible to assign one EPC section to
each node. This configuration is not incorrect - SGX will still operate
correctly; it is just not optimized from a NUMA standpoint.
For this reason, log a message when a node with both CPUs and memory
lacks an EPC section. This will provide users with a hint as to why they
might be experiencing less-than-ideal performance when running SGX
enclaves.
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/all/20240905080855.1699814-3-aaron.lu%40intel.com
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When the current node doesn't have an EPC section configured by firmware
and all other EPC sections are used up, CPU can get stuck inside the
while loop that looks for an available EPC page from remote nodes
indefinitely, leading to a soft lockup. Note how nid_of_current will
never be equal to nid in that while loop because nid_of_current is not
set in sgx_numa_mask.
Also worth mentioning is that it's perfectly fine for the firmware not
to setup an EPC section on a node. While setting up an EPC section on
each node can enhance performance, it is not a requirement for
functionality.
Rework the loop to start and end on *a* node that has SGX memory. This
avoids the deadlock looking for the current SGX-lacking node to show up
in the loop when it never will.
Fixes: 901ddbb9ecf5 ("x86/sgx: Add a basic NUMA allocation scheme to sgx_alloc_epc_page()")
Reported-by: "Molina Sabido, Gerardo" <gerardo.molina.sabido@intel.com>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Zhimin Luo <zhimin.luo@intel.com>
Link: https://lore.kernel.org/all/20240905080855.1699814-2-aaron.lu%40intel.com
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Building the SGX code with W=1 generates below warning:
arch/x86/kernel/cpu/sgx/main.c:741: warning: Function parameter or
struct member 'low' not described in 'sgx_calc_section_metric'
arch/x86/kernel/cpu/sgx/main.c:741: warning: Function parameter or
struct member 'high' not described in 'sgx_calc_section_metric'
...
The function sgx_calc_section_metric() is a simple helper which is only
used in sgx/main.c. There's no need to use kernel-doc style comment for
it.
Downgrade to a normal comment.
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240825080649.145250-1-kai.huang@intel.com
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For any changes of struct fd representation we need to
turn existing accesses to fields into calls of wrappers.
Accesses to struct fd::flags are very few (3 in linux/file.h,
1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in
explicit initializers).
Those can be dealt with in the commit converting to
new layout; accesses to struct fd::file are too many for that.
This commit converts (almost) all of f.file to
fd_file(f). It's not entirely mechanical ('file' is used as
a member name more than just in struct fd) and it does not
even attempt to distinguish the uses in pointer context from
those in boolean context; the latter will be eventually turned
into a separate helper (fd_empty()).
NOTE: mass conversion to fd_empty(), tempting as it
might be, is a bad idea; better do that piecewise in commit
that convert from fdget...() to CLASS(...).
[conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c
caught by git; fs/stat.c one got caught by git grep]
[fs/xattr.c conflict]
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Patch series "Memory allocation profiling", v6.
Overview:
Low overhead [1] per-callsite memory allocation profiling. Not just for
debug kernels, overhead low enough to be deployed in production.
Example output:
root@moria-kvm:~# sort -rn /proc/allocinfo
127664128 31168 mm/page_ext.c:270 func:alloc_page_ext
56373248 4737 mm/slub.c:2259 func:alloc_slab_page
14880768 3633 mm/readahead.c:247 func:page_cache_ra_unbounded
14417920 3520 mm/mm_init.c:2530 func:alloc_large_system_hash
13377536 234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs
11718656 2861 mm/filemap.c:1919 func:__filemap_get_folio
9192960 2800 kernel/fork.c:307 func:alloc_thread_stack_node
4206592 4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable
4136960 1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start
3940352 962 mm/memory.c:4214 func:alloc_anon_folio
2894464 22613 fs/kernfs/dir.c:615 func:__kernfs_new_node
...
Usage:
kconfig options:
- CONFIG_MEM_ALLOC_PROFILING
- CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
- CONFIG_MEM_ALLOC_PROFILING_DEBUG
adds warnings for allocations that weren't accounted because of a
missing annotation
sysctl:
/proc/sys/vm/mem_profiling
Runtime info:
/proc/allocinfo
Notes:
[1]: Overhead
To measure the overhead we are comparing the following configurations:
(1) Baseline with CONFIG_MEMCG_KMEM=n
(2) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n)
(3) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y)
(4) Enabled at runtime (CONFIG_MEM_ALLOC_PROFILING=y &&
CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n && /proc/sys/vm/mem_profiling=1)
(5) Baseline with CONFIG_MEMCG_KMEM=y && allocating with __GFP_ACCOUNT
(6) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n) && CONFIG_MEMCG_KMEM=y
(7) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y) && CONFIG_MEMCG_KMEM=y
Performance overhead:
To evaluate performance we implemented an in-kernel test executing
multiple get_free_page/free_page and kmalloc/kfree calls with allocation
sizes growing from 8 to 240 bytes with CPU frequency set to max and CPU
affinity set to a specific CPU to minimize the noise. Below are results
from running the test on Ubuntu 22.04.2 LTS with 6.8.0-rc1 kernel on
56 core Intel Xeon:
kmalloc pgalloc
(1 baseline) 6.764s 16.902s
(2 default disabled) 6.793s (+0.43%) 17.007s (+0.62%)
(3 default enabled) 7.197s (+6.40%) 23.666s (+40.02%)
(4 runtime enabled) 7.405s (+9.48%) 23.901s (+41.41%)
(5 memcg) 13.388s (+97.94%) 48.460s (+186.71%)
(6 def disabled+memcg) 13.332s (+97.10%) 48.105s (+184.61%)
(7 def enabled+memcg) 13.446s (+98.78%) 54.963s (+225.18%)
Memory overhead:
Kernel size:
text data bss dec diff
(1) 26515311 18890222 17018880 62424413
(2) 26524728 19423818 16740352 62688898 264485
(3) 26524724 19423818 16740352 62688894 264481
(4) 26524728 19423818 16740352 62688898 264485
(5) 26541782 18964374 16957440 62463596 39183
Memory consumption on a 56 core Intel CPU with 125GB of memory:
Code tags: 192 kB
PageExts: 262144 kB (256MB)
SlabExts: 9876 kB (9.6MB)
PcpuExts: 512 kB (0.5MB)
Total overhead is 0.2% of total memory.
Benchmarks:
Hackbench tests run 100 times:
hackbench -s 512 -l 200 -g 15 -f 25 -P
baseline disabled profiling enabled profiling
avg 0.3543 0.3559 (+0.0016) 0.3566 (+0.0023)
stdev 0.0137 0.0188 0.0077
hackbench -l 10000
baseline disabled profiling enabled profiling
avg 6.4218 6.4306 (+0.0088) 6.5077 (+0.0859)
stdev 0.0933 0.0286 0.0489
stress-ng tests:
stress-ng --class memory --seq 4 -t 60
stress-ng --class cpu --seq 4 -t 60
Results posted at: https://evilpiepirate.org/~kent/memalloc_prof_v4_stress-ng/
[2] https://lore.kernel.org/all/20240306182440.2003814-1-surenb@google.com/
This patch (of 37):
The next patch drops vmalloc.h from a system header in order to fix a
circular dependency; this adds it to all the files that were pulling it in
implicitly.
[kent.overstreet@linux.dev: fix arch/alpha/lib/memcpy.c]
Link: https://lkml.kernel.org/r/20240327002152.3339937-1-kent.overstreet@linux.dev
[surenb@google.com: fix arch/x86/mm/numa_32.c]
Link: https://lkml.kernel.org/r/20240402180933.1663992-1-surenb@google.com
[kent.overstreet@linux.dev: a few places were depending on sizes.h]
Link: https://lkml.kernel.org/r/20240404034744.1664840-1-kent.overstreet@linux.dev
[arnd@arndb.de: fix mm/kasan/hw_tags.c]
Link: https://lkml.kernel.org/r/20240404124435.3121534-1-arnd@kernel.org
[surenb@google.com: fix arc build]
Link: https://lkml.kernel.org/r/20240405225115.431056-1-surenb@google.com
Link: https://lkml.kernel.org/r/20240321163705.3067592-1-surenb@google.com
Link: https://lkml.kernel.org/r/20240321163705.3067592-2-surenb@google.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@samsung.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Gary Guo <gary@garyguo.net>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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kmap_local_page() is the preferred way to create temporary mappings when it
is feasible, because the mappings are thread-local and CPU-local.
kmap_local_page() uses per-task maps rather than per-CPU maps. This in
effect removes the need to disable preemption on the local CPU while the
mapping is active, and thus vastly reduces overall system latency. It is
also valid to take pagefaults within the mapped region.
The use of kmap_atomic() in the SGX code was not an explicit design choice
to disable page faults or preemption, and there is no compelling design
reason to using kmap_atomic() vs. kmap_local_page().
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/linux-sgx/Y0biN3%2FJsZMa0yUr@kernel.org/
Link: https://lore.kernel.org/r/20221115161627.4169428-1-kristen@linux.intel.com
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Unsanitized pages trigger WARN_ON() unconditionally, which can panic the
whole computer, if /proc/sys/kernel/panic_on_warn is set.
In sgx_init(), if misc_register() fails or misc_register() succeeds but
neither sgx_drv_init() nor sgx_vepc_init() succeeds, then ksgxd will be
prematurely stopped. This may leave unsanitized pages, which will result a
false warning.
Refine __sgx_sanitize_pages() to return:
1. Zero when the sanitization process is complete or ksgxd has been
requested to stop.
2. The number of unsanitized pages otherwise.
Fixes: 51ab30eb2ad4 ("x86/sgx: Replace section->init_laundry_list with sgx_dirty_page_list")
Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/linux-sgx/20220825051827.246698-1-jarkko@kernel.org/T/#u
Link: https://lkml.kernel.org/r/20220906000221.34286-2-jarkko@kernel.org
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 SGX updates from Dave Hansen:
"A set of x86/sgx changes focused on implementing the "SGX2" features,
plus a minor cleanup:
- SGX2 ISA support which makes enclave memory management much more
dynamic. For instance, enclaves can now change enclave page
permissions on the fly.
- Removal of an unused structure member"
* tag 'x86_sgx_for_v6.0-2022-08-03.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
x86/sgx: Drop 'page_index' from sgx_backing
selftests/sgx: Page removal stress test
selftests/sgx: Test reclaiming of untouched page
selftests/sgx: Test invalid access to removed enclave page
selftests/sgx: Test faulty enclave behavior
selftests/sgx: Test complete changing of page type flow
selftests/sgx: Introduce TCS initialization enclave operation
selftests/sgx: Introduce dynamic entry point
selftests/sgx: Test two different SGX2 EAUG flows
selftests/sgx: Add test for TCS page permission changes
selftests/sgx: Add test for EPCM permission changes
Documentation/x86: Introduce enclave runtime management section
x86/sgx: Free up EPC pages directly to support large page ranges
x86/sgx: Support complete page removal
x86/sgx: Support modifying SGX page type
x86/sgx: Tighten accessible memory range after enclave initialization
x86/sgx: Support adding of pages to an initialized enclave
x86/sgx: Support restricting of enclave page permissions
x86/sgx: Support VA page allocation without reclaiming
x86/sgx: Export sgx_encl_page_alloc()
...
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The page reclaimer ensures availability of EPC pages across all
enclaves. In support of this it runs independently from the
individual enclaves in order to take locks from the different
enclaves as it writes pages to swap.
When needing to load a page from swap an EPC page needs to be
available for its contents to be loaded into. Loading an existing
enclave page from swap does not reclaim EPC pages directly if
none are available, instead the reclaimer is woken when the
available EPC pages are found to be below a watermark.
When iterating over a large number of pages in an oversubscribed
environment there is a race between the reclaimer woken up and
EPC pages reclaimed fast enough for the page operations to proceed.
Ensure there are EPC pages available before attempting to load
a page that may potentially be pulled from swap into an available
EPC page.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/a0d8f037c4a075d56bf79f432438412985f7ff7a.1652137848.git.reinette.chatre@intel.com
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The ETRACK function followed by an IPI to all CPUs within an enclave
is a common pattern with more frequent use in support of SGX2.
Make the (empty) IPI callback function available internally in
preparation for usage by SGX2.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/1179ed4a9c3c1c2abf49d51bfcf2c30b493181cc.1652137848.git.reinette.chatre@intel.com
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The SGX reclaimer removes page table entries pointing to pages that are
moved to swap.
SGX2 enables changes to pages belonging to an initialized enclave, thus
enclave pages may have their permission or type changed while the page
is being accessed by an enclave. Supporting SGX2 requires page table
entries to be removed so that any cached mappings to changed pages
are removed. For example, with the ability to change enclave page types
a regular enclave page may be changed to a Thread Control Structure
(TCS) page that may not be accessed by an enclave.
Factor out the code removing page table entries to a separate function
sgx_zap_enclave_ptes(), fixing accuracy of comments in the process,
and make it available to the upcoming SGX2 code.
Place sgx_zap_enclave_ptes() with the rest of the enclave code in
encl.c interacting with the page table since this code is no longer
unique to the reclaimer.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/b010cdf01d7ce55dd0f00e883b7ccbd9db57160a.1652137848.git.reinette.chatre@intel.com
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sgx_encl_ewb_cpumask() is no longer unique to the reclaimer where it
is used during the EWB ENCLS leaf function when EPC pages are written
out to main memory and sgx_encl_ewb_cpumask() is used to learn which
CPUs might have executed the enclave to ensure that TLBs are cleared.
Upcoming SGX2 enabling will use sgx_encl_ewb_cpumask() during the
EMODPR and EMODT ENCLS leaf functions that make changes to enclave
pages. The function is needed for the same reason it is used now: to
learn which CPUs might have executed the enclave to ensure that TLBs
no longer point to the changed pages.
Rename sgx_encl_ewb_cpumask() to sgx_encl_cpumask() to reflect the
broader usage.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/d4d08c449450a13d8dd3bb6c2b1af03895586d4f.1652137848.git.reinette.chatre@intel.com
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Using sgx_encl_ewb_cpumask() to learn which CPUs might have executed
an enclave is useful to ensure that TLBs are cleared when changes are
made to enclave pages.
sgx_encl_ewb_cpumask() is used within the reclaimer when an enclave
page is evicted. The upcoming SGX2 support enables changes to be
made to enclave pages and will require TLBs to not refer to the
changed pages and thus will be needing sgx_encl_ewb_cpumask().
Relocate sgx_encl_ewb_cpumask() to be with the rest of the enclave
code in encl.c now that it is no longer unique to the reclaimer.
Take care to ensure that any future usage maintains the
current context requirement that ETRACK has been called first.
Expand the existing comments to highlight this while moving them
to a more prominent location before the function.
No functional change.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/05b60747fd45130cf9fc6edb1c373a69a18a22c5.1652137848.git.reinette.chatre@intel.com
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When the system runs out of enclave memory, SGX can reclaim EPC pages
by swapping to normal RAM. These backing pages are allocated via a
per-enclave shared memory area. Since SGX allows unlimited over
commit on EPC memory, the reclaimer thread can allocate a large
number of backing RAM pages in response to EPC memory pressure.
When the shared memory backing RAM allocation occurs during
the reclaimer thread context, the shared memory is charged to
the root memory control group, and the shmem usage of the enclave
is not properly accounted for, making cgroups ineffective at
limiting the amount of RAM an enclave can consume.
For example, when using a cgroup to launch a set of test
enclaves, the kernel does not properly account for 50% - 75% of
shmem page allocations on average. In the worst case, when
nearly all allocations occur during the reclaimer thread, the
kernel accounts less than a percent of the amount of shmem used
by the enclave's cgroup to the correct cgroup.
SGX stores a list of mm_structs that are associated with
an enclave. Pick one of them during reclaim and charge that
mm's memcg with the shmem allocation. The one that gets picked
is arbitrary, but this list almost always only has one mm. The
cases where there is more than one mm with different memcg's
are not worth considering.
Create a new function - sgx_encl_alloc_backing(). This function
is used whenever a new backing storage page needs to be
allocated. Previously the same function was used for page
allocation as well as retrieving a previously allocated page.
Prior to backing page allocation, if there is a mm_struct associated
with the enclave that is requesting the allocation, it is set
as the active memory control group.
[ dhansen: - fix merge conflict with ELDU fixes
- check against actual ksgxd_tsk, not ->mm ]
Cc: stable@vger.kernel.org
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Link: https://lkml.kernel.org/r/20220520174248.4918-1-kristen@linux.intel.com
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Haitao reported encountering a WARN triggered by the ENCLS[ELDU]
instruction faulting with a #GP.
The WARN is encountered when the reclaimer evicts a range of
pages from the enclave when the same pages are faulted back
right away.
The SGX backing storage is accessed on two paths: when there
are insufficient free pages in the EPC the reclaimer works
to move enclave pages to the backing storage and as enclaves
access pages that have been moved to the backing storage
they are retrieved from there as part of page fault handling.
An oversubscribed SGX system will often run the reclaimer and
page fault handler concurrently and needs to ensure that the
backing store is accessed safely between the reclaimer and
the page fault handler. This is not the case because the
reclaimer accesses the backing store without the enclave mutex
while the page fault handler accesses the backing store with
the enclave mutex.
Consider the scenario where a page is faulted while a page sharing
a PCMD page with the faulted page is being reclaimed. The
consequence is a race between the reclaimer and page fault
handler, the reclaimer attempting to access a PCMD at the
same time it is truncated by the page fault handler. This
could result in lost PCMD data. Data may still be
lost if the reclaimer wins the race, this is addressed in
the following patch.
The reclaimer accesses pages from the backing storage without
holding the enclave mutex and runs the risk of concurrently
accessing the backing storage with the page fault handler that
does access the backing storage with the enclave mutex held.
In the scenario below a PCMD page is truncated from the backing
store after all its pages have been loaded in to the enclave
at the same time the PCMD page is loaded from the backing store
when one of its pages are reclaimed:
sgx_reclaim_pages() { sgx_vma_fault() {
...
mutex_lock(&encl->lock);
...
__sgx_encl_eldu() {
...
if (pcmd_page_empty) {
/*
* EPC page being reclaimed /*
* shares a PCMD page with an * PCMD page truncated
* enclave page that is being * while requested from
* faulted in. * reclaimer.
*/ */
sgx_encl_get_backing() <----------> sgx_encl_truncate_backing_page()
}
mutex_unlock(&encl->lock);
} }
In this scenario there is a race between the reclaimer and the page fault
handler when the reclaimer attempts to get access to the same PCMD page
that is being truncated. This could result in the reclaimer writing to
the PCMD page that is then truncated, causing the PCMD data to be lost,
or in a new PCMD page being allocated. The lost PCMD data may still occur
after protecting the backing store access with the mutex - this is fixed
in the next patch. By ensuring the backing store is accessed with the mutex
held the enclave page state can be made accurate with the
SGX_ENCL_PAGE_BEING_RECLAIMED flag accurately reflecting that a page
is in the process of being reclaimed.
Consistently protect the reclaimer's backing store access with the
enclave's mutex to ensure that it can safely run concurrently with the
page fault handler.
Cc: stable@vger.kernel.org
Fixes: 1728ab54b4be ("x86/sgx: Add a page reclaimer")
Reported-by: Haitao Huang <haitao.huang@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Haitao Huang <haitao.huang@intel.com>
Link: https://lkml.kernel.org/r/fa2e04c561a8555bfe1f4e7adc37d60efc77387b.1652389823.git.reinette.chatre@intel.com
|
|
SGX uses shmem backing storage to store encrypted enclave pages
and their crypto metadata when enclave pages are moved out of
enclave memory. Two shmem backing storage pages are associated with
each enclave page - one backing page to contain the encrypted
enclave page data and one backing page (shared by a few
enclave pages) to contain the crypto metadata used by the
processor to verify the enclave page when it is loaded back into
the enclave.
sgx_encl_put_backing() is used to release references to the
backing storage and, optionally, mark both backing store pages
as dirty.
Managing references and dirty status together in this way results
in both backing store pages marked as dirty, even if only one of
the backing store pages are changed.
Additionally, waiting until the page reference is dropped to set
the page dirty risks a race with the page fault handler that
may load outdated data into the enclave when a page is faulted
right after it is reclaimed.
Consider what happens if the reclaimer writes a page to the backing
store and the page is immediately faulted back, before the reclaimer
is able to set the dirty bit of the page:
sgx_reclaim_pages() { sgx_vma_fault() {
...
sgx_encl_get_backing();
... ...
sgx_reclaimer_write() {
mutex_lock(&encl->lock);
/* Write data to backing store */
mutex_unlock(&encl->lock);
}
mutex_lock(&encl->lock);
__sgx_encl_eldu() {
...
/*
* Enclave backing store
* page not released
* nor marked dirty -
* contents may not be
* up to date.
*/
sgx_encl_get_backing();
...
/*
* Enclave data restored
* from backing store
* and PCMD pages that
* are not up to date.
* ENCLS[ELDU] faults
* because of MAC or PCMD
* checking failure.
*/
sgx_encl_put_backing();
}
...
/* set page dirty */
sgx_encl_put_backing();
...
mutex_unlock(&encl->lock);
} }
Remove the option to sgx_encl_put_backing() to set the backing
pages as dirty and set the needed pages as dirty right after
receiving important data while enclave mutex is held. This ensures that
the page fault handler can get up to date data from a page and prepares
the code for a following change where only one of the backing pages
need to be marked as dirty.
Cc: stable@vger.kernel.org
Fixes: 1728ab54b4be ("x86/sgx: Add a page reclaimer")
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Haitao Huang <haitao.huang@intel.com>
Link: https://lore.kernel.org/linux-sgx/8922e48f-6646-c7cc-6393-7c78dcf23d23@intel.com/
Link: https://lkml.kernel.org/r/fa9f98986923f43e72ef4c6702a50b2a0b3c42e3.1652389823.git.reinette.chatre@intel.com
|
|
The SGX reclaimer code lacks page poison handling in its main
free path. This can lead to avoidable machine checks if a
poisoned page is freed and reallocated instead of being
isolated.
A troublesome scenario is:
1. Machine check (#MC) occurs (asynchronous, !MF_ACTION_REQUIRED)
2. arch_memory_failure() is eventually called
3. (SGX) page->poison set to 1
4. Page is reclaimed
5. Page added to normal free lists by sgx_reclaim_pages()
^ This is the bug (poison pages should be isolated on the
sgx_poison_page_list instead)
6. Page is reallocated by some innocent enclave, a second (synchronous)
in-kernel #MC is induced, probably during EADD instruction.
^ This is the fallout from the bug
(6) is unfortunate and can be avoided by replacing the open coded
enclave page freeing code in the reclaimer with sgx_free_epc_page()
to obtain support for poison page handling that includes placing the
poisoned page on the correct list.
Fixes: d6d261bded8a ("x86/sgx: Add new sgx_epc_page flag bit to mark free pages")
Fixes: 992801ae9243 ("x86/sgx: Initial poison handling for dirty and free pages")
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/dcc95eb2aaefb042527ac50d0a50738c7c160dac.1643830353.git.reinette.chatre@intel.com
|
|
== Problem ==
Nathan Chancellor reported an oops when aceessing the
'sgx_total_bytes' sysfs file:
https://lore.kernel.org/all/YbzhBrimHGGpddDM@archlinux-ax161/
The sysfs output code accesses the sgx_numa_nodes[] array
unconditionally. However, this array is allocated during SGX
initialization, which only occurs on systems where SGX is
supported.
If the sysfs file is accessed on systems without SGX support,
sgx_numa_nodes[] is NULL and an oops occurs.
== Solution ==
To fix this, hide the entire nodeX/x86/ attribute group on
systems without SGX support using the ->is_visible attribute
group callback.
Unfortunately, SGX is initialized via a device_initcall() which
occurs _after_ the ->is_visible() callback. Instead of moving
SGX initialization earlier, call sysfs_update_group() during
SGX initialization to update the group visiblility.
This update requires moving the SGX sysfs code earlier in
sgx/main.c. There are no code changes other than the addition of
arch_update_sysfs_visibility() and a minor whitespace fixup to
arch_node_attr_is_visible() which checkpatch caught.
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-sgx@vger.kernel.org
Cc: x86@kernel.org
Fixes: 50468e431335 ("x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/20220104171527.5E8416A8@davehans-spike.ostc.intel.com
|
|
== Problem ==
The amount of SGX memory on a system is determined by the BIOS and it
varies wildly between systems. It can be as small as dozens of MB's
and as large as many GB's on servers. Just like how applications need
to know how much regular RAM is available, enclave builders need to
know how much SGX memory an enclave can consume.
== Solution ==
Introduce a new sysfs file:
/sys/devices/system/node/nodeX/x86/sgx_total_bytes
to enumerate the amount of SGX memory available in each NUMA node.
This serves the same function for SGX as /proc/meminfo or
/sys/devices/system/node/nodeX/meminfo does for normal RAM.
'sgx_total_bytes' is needed today to help drive the SGX selftests.
SGX-specific swap code is exercised by creating overcommitted enclaves
which are larger than the physical SGX memory on the system. They
currently use a CPUID-based approach which can diverge from the actual
amount of SGX memory available. 'sgx_total_bytes' ensures that the
selftests can work efficiently and do not attempt stupid things like
creating a 100,000 MB enclave on a system with 128 MB of SGX memory.
== Implementation Details ==
Introduce CONFIG_HAVE_ARCH_NODE_DEV_GROUP opt-in flag to expose an
arch specific attribute group, and add an attribute for the amount of
SGX memory in bytes to each NUMA node:
== ABI Design Discussion ==
As opposed to the per-node ABI, a single, global ABI was considered.
However, this would prevent enclaves from being able to size
themselves so that they fit on a single NUMA node. Essentially, a
single value would rule out NUMA optimizations for enclaves.
Create a new "x86/" directory inside each "nodeX/" sysfs directory.
'sgx_total_bytes' is expected to be the first of at least a few
sgx-specific files to be placed in the new directory. Just scanning
/proc/meminfo, these are the no-brainers that we have for RAM, but we
need for SGX:
MemTotal: xxxx kB // sgx_total_bytes (implemented here)
MemFree: yyyy kB // sgx_free_bytes
SwapTotal: zzzz kB // sgx_swapped_bytes
So, at *least* three. I think we will eventually end up needing
something more along the lines of a dozen. A new directory (as
opposed to being in the nodeX/ "root") directory avoids cluttering the
root with several "sgx_*" files.
Place the new file in a new "nodeX/x86/" directory because SGX is
highly x86-specific. It is very unlikely that any other architecture
(or even non-Intel x86 vendor) will ever implement SGX. Using "sgx/"
as opposed to "x86/" was also considered. But, there is a real chance
this can get used for other arch-specific purposes.
[ dhansen: rewrite changelog ]
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211116162116.93081-2-jarkko@kernel.org
|
|
Conflicts:
arch/x86/kernel/cpu/sgx/main.c
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
The SGX driver maintains a single global free page counter,
sgx_nr_free_pages, that reflects the number of free pages available
across all NUMA nodes. Correspondingly, a list of free pages is
associated with each NUMA node and sgx_nr_free_pages is updated
every time a page is added or removed from any of the free page
lists. The main usage of sgx_nr_free_pages is by the reclaimer
that runs when it (sgx_nr_free_pages) goes below a watermark
to ensure that there are always some free pages available to, for
example, support efficient page faults.
With sgx_nr_free_pages accessed and modified from a few places
it is essential to ensure that these accesses are done safely but
this is not the case. sgx_nr_free_pages is read without any
protection and updated with inconsistent protection by any one
of the spin locks associated with the individual NUMA nodes.
For example:
CPU_A CPU_B
----- -----
spin_lock(&nodeA->lock); spin_lock(&nodeB->lock);
... ...
sgx_nr_free_pages--; /* NOT SAFE */ sgx_nr_free_pages--;
spin_unlock(&nodeA->lock); spin_unlock(&nodeB->lock);
Since sgx_nr_free_pages may be protected by different spin locks
while being modified from different CPUs, the following scenario
is possible:
CPU_A CPU_B
----- -----
{sgx_nr_free_pages = 100}
spin_lock(&nodeA->lock); spin_lock(&nodeB->lock);
sgx_nr_free_pages--; sgx_nr_free_pages--;
/* LOAD sgx_nr_free_pages = 100 */ /* LOAD sgx_nr_free_pages = 100 */
/* sgx_nr_free_pages-- */ /* sgx_nr_free_pages-- */
/* STORE sgx_nr_free_pages = 99 */ /* STORE sgx_nr_free_pages = 99 */
spin_unlock(&nodeA->lock); spin_unlock(&nodeB->lock);
In the above scenario, sgx_nr_free_pages is decremented from two CPUs
but instead of sgx_nr_free_pages ending with a value that is two less
than it started with, it was only decremented by one while the number
of free pages were actually reduced by two. The consequence of
sgx_nr_free_pages not being protected is that its value may not
accurately reflect the actual number of free pages on the system,
impacting the availability of free pages in support of many flows.
The problematic scenario is when the reclaimer does not run because it
believes there to be sufficient free pages while any attempt to allocate
a page fails because there are no free pages available. In the SGX driver
the reclaimer's watermark is only 32 pages so after encountering the
above example scenario 32 times a user space hang is possible when there
are no more free pages because of repeated page faults caused by no
free pages made available.
The following flow was encountered:
asm_exc_page_fault
...
sgx_vma_fault()
sgx_encl_load_page()
sgx_encl_eldu() // Encrypted page needs to be loaded from backing
// storage into newly allocated SGX memory page
sgx_alloc_epc_page() // Allocate a page of SGX memory
__sgx_alloc_epc_page() // Fails, no free SGX memory
...
if (sgx_should_reclaim(SGX_NR_LOW_PAGES)) // Wake reclaimer
wake_up(&ksgxd_waitq);
return -EBUSY; // Return -EBUSY giving reclaimer time to run
return -EBUSY;
return -EBUSY;
return VM_FAULT_NOPAGE;
The reclaimer is triggered in above flow with the following code:
static bool sgx_should_reclaim(unsigned long watermark)
{
return sgx_nr_free_pages < watermark &&
!list_empty(&sgx_active_page_list);
}
In the problematic scenario there were no free pages available yet the
value of sgx_nr_free_pages was above the watermark. The allocation of
SGX memory thus always failed because of a lack of free pages while no
free pages were made available because the reclaimer is never started
because of sgx_nr_free_pages' incorrect value. The consequence was that
user space kept encountering VM_FAULT_NOPAGE that caused the same
address to be accessed repeatedly with the same result.
Change the global free page counter to an atomic type that
ensures simultaneous updates are done safely. While doing so, move
the updating of the variable outside of the spin lock critical
section to which it does not belong.
Cc: stable@vger.kernel.org
Fixes: 901ddbb9ecf5 ("x86/sgx: Add a basic NUMA allocation scheme to sgx_alloc_epc_page()")
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/a95a40743bbd3f795b465f30922dde7f1ea9e0eb.1637004094.git.reinette.chatre@intel.com
|
|
Provide a recovery function sgx_memory_failure(). If the poison was
consumed synchronously then send a SIGBUS. Note that the virtual
address of the access is not included with the SIGBUS as is the case
for poison outside of SGX enclaves. This doesn't matter as addresses
of code/data inside an enclave is of little to no use to code executing
outside the (now dead) enclave.
Poison found in a free page results in the page being moved from the
free list to the per-node poison page list.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20211026220050.697075-5-tony.luck@intel.com
|
|
A memory controller patrol scrubber can report poison in a page
that isn't currently being used.
Add "poison" field in the sgx_epc_page that can be set for an
sgx_epc_page. Check for it:
1) When sanitizing dirty pages
2) When freeing epc pages
Poison is a new field separated from flags to avoid having to make all
updates to flags atomic, or integrate poison state changes into some
other locking scheme to protect flags (Currently just sgx_reclaimer_lock
which protects the SGX_EPC_PAGE_RECLAIMER_TRACKED bit in page->flags).
In both cases place the poisoned page on a per-node list of poisoned
epc pages to make sure it will not be reallocated.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20211026220050.697075-4-tony.luck@intel.com
|
|
X86 machine check architecture reports a physical address when there
is a memory error. Handling that error requires a method to determine
whether the physical address reported is in any of the areas reserved
for EPC pages by BIOS.
SGX EPC pages do not have Linux "struct page" associated with them.
Keep track of the mapping from ranges of EPC pages to the sections
that contain them using an xarray. N.B. adds CONFIG_XARRAY_MULTI to
the SGX dependecies. So "select" that in arch/x86/Kconfig for X86/SGX.
Create a function arch_is_platform_page() that simply reports whether an
address is an EPC page for use elsewhere in the kernel. The ACPI error
injection code needs this function and is typically built as a module,
so export it.
Note that arch_is_platform_page() will be slower than other similar
"what type is this page" functions that can simply check bits in the
"struct page". If there is some future performance critical user of
this function it may need to be implemented in a more efficient way.
Note also that the current implementation of xarray allocates a few
hundred kilobytes for this usage on a system with 4GB of SGX EPC memory
configured. This isn't ideal, but worth it for the code simplicity.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20211026220050.697075-3-tony.luck@intel.com
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SGX EPC pages go through the following life cycle:
DIRTY ---> FREE ---> IN-USE --\
^ |
\-----------------/
Recovery action for poison for a DIRTY or FREE page is simple. Just
make sure never to allocate the page. IN-USE pages need some extra
handling.
Add a new flag bit SGX_EPC_PAGE_IS_FREE that is set when a page
is added to a free list and cleared when the page is allocated.
Notes:
1) These transitions are made while holding the node->lock so that
future code that checks the flags while holding the node->lock
can be sure that if the SGX_EPC_PAGE_IS_FREE bit is set, then the
page is on the free list.
2) Initially while the pages are on the dirty list the
SGX_EPC_PAGE_IS_FREE bit is cleared.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20211026220050.697075-2-tony.luck@intel.com
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc x86 cleanups from Borislav Petkov:
"Trivial cleanups and fixes all over the place"
* tag 'x86_cleanups_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
MAINTAINERS: Remove me from IDE/ATAPI section
x86/pat: Do not compile stubbed functions when X86_PAT is off
x86/asm: Ensure asm/proto.h can be included stand-alone
x86/platform/intel/quark: Fix incorrect kernel-doc comment syntax in files
x86/msr: Make locally used functions static
x86/cacheinfo: Remove unneeded dead-store initialization
x86/process/64: Move cpu_current_top_of_stack out of TSS
tools/turbostat: Unmark non-kernel-doc comment
x86/syscalls: Fix -Wmissing-prototypes warnings from COND_SYSCALL()
x86/fpu/math-emu: Fix function cast warning
x86/msr: Fix wr/rdmsr_safe_regs_on_cpu() prototypes
x86: Fix various typos in comments, take #2
x86: Remove unusual Unicode characters from comments
x86/kaslr: Return boolean values from a function returning bool
x86: Fix various typos in comments
x86/setup: Remove unused RESERVE_BRK_ARRAY()
stacktrace: Move documentation for arch_stack_walk_reliable() to header
x86: Remove duplicate TSC DEADLINE MSR definitions
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The commit in Fixes: changed the SGX EPC page sanitization to end up in
sgx_free_epc_page() which puts clean and sanitized pages on the free
list.
This was done for the reason that it is best to keep the logic to assign
available-for-use EPC pages to the correct NUMA lists in a single
location.
sgx_nr_free_pages is also incremented by sgx_free_epc_pages() but those
pages which are being added there per EPC section do not belong to the
free list yet because they haven't been sanitized yet - they land on the
dirty list first and the sanitization happens later when ksgxd starts
massaging them.
So remove that addition there and have sgx_free_epc_page() do that
solely.
[ bp: Sanitize commit message too. ]
Fixes: 51ab30eb2ad4 ("x86/sgx: Replace section->init_laundry_list with sgx_dirty_page_list")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210408092924.7032-1-jarkko@kernel.org
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And extract sgx_set_attribute() out of sgx_ioc_enclave_provision() and
export it as symbol for KVM to use.
The provisioning key is sensitive. The SGX driver only allows to create
an enclave which can access the provisioning key when the enclave
creator has permission to open /dev/sgx_provision. It should apply to
a VM as well, as the provisioning key is platform-specific, thus an
unrestricted VM can also potentially compromise the provisioning key.
Move the provisioning device creation out of sgx_drv_init() to
sgx_init() as a preparation for adding SGX virtualization support,
so that even if the SGX driver is not enabled due to flexible launch
control not being available, SGX virtualization can still be enabled,
and use it to restrict a VM's capability of being able to access the
provisioning key.
[ bp: Massage commit message. ]
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Link: https://lkml.kernel.org/r/0f4d044d621561f26d5f4ef73e8dc6cd18cc7e79.1616136308.git.kai.huang@intel.com
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Add a helper to update SGX_LEPUBKEYHASHn MSRs. SGX virtualization also
needs to update those MSRs based on guest's "virtual" SGX_LEPUBKEYHASHn
before EINIT from guest.
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/dfb7cd39d4dd62ea27703b64afdd8bccb579f623.1616136308.git.kai.huang@intel.com
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Modify sgx_init() to always try to initialize the virtual EPC driver,
even if the SGX driver is disabled. The SGX driver might be disabled
if SGX Launch Control is in locked mode, or not supported in the
hardware at all. This allows (non-Linux) guests that support non-LC
configurations to use SGX.
[ bp: De-silli-fy the test. ]
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Link: https://lkml.kernel.org/r/d35d17a02bbf8feef83a536cec8b43746d4ea557.1616136308.git.kai.huang@intel.com
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EREMOVE takes a page and removes any association between that page and
an enclave. It must be run on a page before it can be added into another
enclave. Currently, EREMOVE is run as part of pages being freed into the
SGX page allocator. It is not expected to fail, as it would indicate a
use-after-free of EPC pages. Rather than add the page back to the pool
of available EPC pages, the kernel intentionally leaks the page to avoid
additional errors in the future.
However, KVM does not track how guest pages are used, which means that
SGX virtualization use of EREMOVE might fail. Specifically, it is
legitimate that EREMOVE returns SGX_CHILD_PRESENT for EPC assigned to
KVM guest, because KVM/kernel doesn't track SECS pages.
To allow SGX/KVM to introduce a more permissive EREMOVE helper and
to let the SGX virtualization code use the allocator directly, break
out the EREMOVE call from the SGX page allocator. Rename the original
sgx_free_epc_page() to sgx_encl_free_epc_page(), indicating that
it is used to free an EPC page assigned to a host enclave. Replace
sgx_free_epc_page() with sgx_encl_free_epc_page() in all call sites so
there's no functional change.
At the same time, improve the error message when EREMOVE fails, and
add documentation to explain to the user what that failure means and
to suggest to the user what to do when this bug happens in the case it
happens.
[ bp: Massage commit message, fix typos and sanitize text, simplify. ]
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/20210325093057.122834-1-kai.huang@intel.com
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Background
==========
SGX enclave memory is enumerated by the processor in contiguous physical
ranges called Enclave Page Cache (EPC) sections. Currently, there is a
free list per section, but allocations simply target the lowest-numbered
sections. This is functional, but has no NUMA awareness.
Fortunately, EPC sections are covered by entries in the ACPI SRAT table.
These entries allow each EPC section to be associated with a NUMA node,
just like normal RAM.
Solution
========
Implement a NUMA-aware enclave page allocator. Mirror the buddy allocator
and maintain a list of enclave pages for each NUMA node. Attempt to
allocate enclave memory first from local nodes, then fall back to other
nodes.
Note that the fallback is not as sophisticated as the buddy allocator
and is itself not aware of NUMA distances. When a node's free list is
empty, it searches for the next-highest node with enclave pages (and
will wrap if necessary). This could be improved in the future.
Other
=====
NUMA_KEEP_MEMINFO dependency is required for phys_to_target_node().
[ Kai Huang: Do not return NULL from __sgx_alloc_epc_page() because
callers do not expect that and that leads to a NULL ptr deref. ]
[ dhansen: Fix an uninitialized 'nid' variable in
__sgx_alloc_epc_page() as
Reported-by: kernel test robot <lkp@intel.com>
to avoid any potential allocations from the wrong NUMA node or even
premature allocation failures. ]
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/lkml/158188326978.894464.217282995221175417.stgit@dwillia2-desk3.amr.corp.intel.com/
Link: https://lkml.kernel.org/r/20210319040602.178558-1-kai.huang@intel.com
Link: https://lkml.kernel.org/r/20210318214933.29341-1-dave.hansen@intel.com
Link: https://lkml.kernel.org/r/20210317235332.362001-2-jarkko.sakkinen@intel.com
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During normal runtime, the "ksgxd" daemon behaves like a version of
kswapd just for SGX. But, before it starts acting like kswapd, its first
job is to initialize enclave memory.
Currently, the SGX boot code places each enclave page on a
epc_section->init_laundry_list. Once it starts up, the ksgxd code walks
over that list and populates the actual SGX page allocator.
However, the per-section structures are going away to make way for the
SGX NUMA allocator. There's also little need to have a per-section
structure; the enclave pages are all treated identically, and they can
be placed on the correct allocator list from metadata stored in the
enclave page (struct sgx_epc_page) itself.
Modify sgx_sanitize_section() to take a single page list instead of
taking a section and deriving the list from there.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/20210317235332.362001-1-jarkko.sakkinen@intel.com
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Fix ~144 single-word typos in arch/x86/ code comments.
Doing this in a single commit should reduce the churn.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-kernel@vger.kernel.org
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device_initcall() expects a function of type initcall_t, which returns
an integer. Change the signature of sgx_init() to match.
Fixes: e7e0545299d8c ("x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections")
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/20210113232311.277302-1-samitolvanen@google.com
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Short Version:
The SGX section->laundry_list structure is effectively thread-local, but
declared next to some shared structures. Its semantics are clear as mud.
Fix that. No functional changes. Compile tested only.
Long Version:
The SGX hardware keeps per-page metadata. This can provide things like
permissions, integrity and replay protection. It also prevents things
like having an enclave page mapped multiple times or shared between
enclaves.
But, that presents a problem for kexec()'d kernels (or any other kernel
that does not run immediately after a hardware reset). This is because
the last kernel may have been rude and forgotten to reset pages, which
would trigger the "shared page" sanity check.
To fix this, the SGX code "launders" the pages by running the EREMOVE
instruction on all pages at boot. This is slow and can take a long
time, so it is performed off in the SGX-specific ksgxd instead of being
synchronous at boot. The init code hands the list of pages to launder in
a per-SGX-section list: ->laundry_list. The only code to touch this list
is the init code and ksgxd. This means that no locking is necessary for
->laundry_list.
However, a lock is required for section->page_list, which is accessed
while creating enclaves and by ksgxd. This lock (section->lock) is
acquired by ksgxd while also processing ->laundry_list. It is easy to
confuse the purpose of the locking as being for ->laundry_list and
->page_list.
Rename ->laundry_list to ->init_laundry_list to make it clear that this
is not normally used at runtime. Also add some comments clarifying the
locking, and reorganize 'sgx_epc_section' to put 'lock' near the things
it protects.
Note: init_laundry_list is 128 bytes of wasted space at runtime. It
could theoretically be dynamically allocated and then freed after
the laundering process. But it would take nearly 128 bytes of extra
instructions to do that.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20201116222531.4834-1-dave.hansen@intel.com
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Just like normal RAM, there is a limited amount of enclave memory available
and overcommitting it is a very valuable tool to reduce resource use.
Introduce a simple reclaim mechanism for enclave pages.
In contrast to normal page reclaim, the kernel cannot directly access
enclave memory. To get around this, the SGX architecture provides a set of
functions to help. Among other things, these functions copy enclave memory
to and from normal memory, encrypting it and protecting its integrity in
the process.
Implement a page reclaimer by using these functions. Picks victim pages in
LRU fashion from all the enclaves running in the system. A new kernel
thread (ksgxswapd) reclaims pages in the background based on watermarks,
similar to normal kswapd.
All enclave pages can be reclaimed, architecturally. But, there are some
limits to this, such as the special SECS metadata page which must be
reclaimed last. The page version array (used to mitigate replaying old
reclaimed pages) is also architecturally reclaimable, but not yet
implemented. The end result is that the vast majority of enclave pages are
currently reclaimable.
Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Jethro Beekman <jethro@fortanix.com>
Link: https://lkml.kernel.org/r/20201112220135.165028-22-jarkko@kernel.org
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Intel(R) SGX is a new hardware functionality that can be used by
applications to set aside private regions of code and data called
enclaves. New hardware protects enclave code and data from outside
access and modification.
Add a driver that presents a device file and ioctl API to build and
manage enclaves.
[ bp: Small touchups, remove unused encl variable in sgx_encl_find() as
Reported-by: kernel test robot <lkp@intel.com> ]
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Jethro Beekman <jethro@fortanix.com>
Link: https://lkml.kernel.org/r/20201112220135.165028-12-jarkko@kernel.org
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Add functions for runtime allocation and free.
This allocator and its algorithms are as simple as it gets. They do a
linear search across all EPC sections and find the first free page. They
are not NUMA-aware and only hand out individual pages. The SGX hardware
does not support large pages, so something more complicated like a buddy
allocator is unwarranted.
The free function (sgx_free_epc_page()) implicitly calls ENCLS[EREMOVE],
which returns the page to the uninitialized state. This ensures that the
page is ready for use at the next allocation.
Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Jethro Beekman <jethro@fortanix.com>
Link: https://lkml.kernel.org/r/20201112220135.165028-10-jarkko@kernel.org
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Although carved out of normal DRAM, enclave memory is marked in the
system memory map as reserved and is not managed by the core mm. There
may be several regions spread across the system. Each contiguous region
is called an Enclave Page Cache (EPC) section. EPC sections are
enumerated via CPUID
Enclave pages can only be accessed when they are mapped as part of an
enclave, by a hardware thread running inside the enclave.
Parse CPUID data, create metadata for EPC pages and populate a simple
EPC page allocator. Although much smaller, ‘struct sgx_epc_page’
metadata is the SGX analog of the core mm ‘struct page’.
Similar to how the core mm’s page->flags encode zone and NUMA
information, embed the EPC section index to the first eight bits of
sgx_epc_page->desc. This allows a quick reverse lookup from EPC page to
EPC section. Existing client hardware supports only a single section,
while upcoming server hardware will support at most eight sections.
Thus, eight bits should be enough for long term needs.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Co-developed-by: Serge Ayoun <serge.ayoun@intel.com>
Signed-off-by: Serge Ayoun <serge.ayoun@intel.com>
Co-developed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Jethro Beekman <jethro@fortanix.com>
Link: https://lkml.kernel.org/r/20201112220135.165028-6-jarkko@kernel.org
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