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KVM x86 misc changes for 6.14:
- Overhaul KVM's CPUID feature infrastructure to track all vCPU capabilities
instead of just those where KVM needs to manage state and/or explicitly
enable the feature in hardware. Along the way, refactor the code to make
it easier to add features, and to make it more self-documenting how KVM
is handling each feature.
- Rework KVM's handling of VM-Exits during event vectoring; this plugs holes
where KVM unintentionally puts the vCPU into infinite loops in some scenarios
(e.g. if emulation is triggered by the exit), and brings parity between VMX
and SVM.
- Add pending request and interrupt injection information to the kvm_exit and
kvm_entry tracepoints respectively.
- Fix a relatively benign flaw where KVM would end up redoing RDPKRU when
loading guest/host PKRU, due to a refactoring of the kernel helpers that
didn't account for KVM's pre-checking of the need to do WRPKRU.
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Rename PML_ENTITY_NUM to PML_LOG_NR_ENTRIES
Add PML_HEAD_INDEX to specify the first entry that CPU writes.
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20241219221034.903927-2-mlevitsk@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Remove the redundant .hwapic_irr_update() ops.
If a vCPU has APICv enabled, KVM updates its RVI before VM-enter to L1
in vmx_sync_pir_to_irr(). This guarantees RVI is up-to-date and aligned
with the vIRR in the virtual APIC. So, no need to update RVI every time
the vIRR changes.
Note that KVM never updates vmcs02 RVI in .hwapic_irr_update() or
vmx_sync_pir_to_irr(). So, removing .hwapic_irr_update() has no
impact to the nested case.
Signed-off-by: Chao Gao <chao.gao@intel.com>
Link: https://lore.kernel.org/r/20241111085947.432645-1-chao.gao@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Add VMX/SVM specific interrupt injection info the kvm_entry tracepoint.
As is done with kvm_exit, gather the information via a kvm_x86_ops hook
to avoid the moderately costly VMREADs on VMX when the tracepoint isn't
enabled.
Opportunistically rename the parameters in the get_exit_info()
declaration to match the names used by both SVM and VMX.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20240910200350.264245-2-mlevitsk@redhat.com
[sean: drop is_guest_mode() change, use intr_info/error_code for names]
Signed-off-by: Sean Christopherson <seanjc@google.com>
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When querying guest CPL to determine if a vCPU was preempted while in
kernel mode, bypass the register cache, i.e. always read SS.AR_BYTES from
the VMCS on Intel CPUs. If the kernel is running with full preemption
enabled, using the register cache in the preemption path can result in
stale and/or uninitialized data being cached in the segment cache.
In particular the following scenario is currently possible:
- vCPU is just created, and the vCPU thread is preempted before
SS.AR_BYTES is written in vmx_vcpu_reset().
- When scheduling out the vCPU task, kvm_arch_vcpu_in_kernel() =>
vmx_get_cpl() reads and caches '0' for SS.AR_BYTES.
- vmx_vcpu_reset() => seg_setup() configures SS.AR_BYTES, but doesn't
invoke vmx_segment_cache_clear() to invalidate the cache.
As a result, KVM retains a stale value in the cache, which can be read,
e.g. via KVM_GET_SREGS. Usually this is not a problem because the VMX
segment cache is reset on each VM-Exit, but if the userspace VMM (e.g KVM
selftests) reads and writes system registers just after the vCPU was
created, _without_ modifying SS.AR_BYTES, userspace will write back the
stale '0' value and ultimately will trigger a VM-Entry failure due to
incorrect SS segment type.
Note, the VM-Enter failure can also be avoided by moving the call to
vmx_segment_cache_clear() until after the vmx_vcpu_reset() initializes all
segments. However, while that change is correct and desirable (and will
come along shortly), it does not address the underlying problem that
accessing KVM's register caches from !task context is generally unsafe.
In addition to fixing the immediate bug, bypassing the cache for this
particular case will allow hardening KVM register caching log to assert
that the caches are accessed only when KVM _knows_ it is safe to do so.
Fixes: de63ad4cf497 ("KVM: X86: implement the logic for spinlock optimization")
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Closes: https://lore.kernel.org/all/20240716022014.240960-3-mlevitsk@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20241009175002.1118178-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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KVM x86 misc changes for 6.12
- Advertise AVX10.1 to userspace (effectively prep work for the "real" AVX10
functionality that is on the horizon).
- Rework common MSR handling code to suppress errors on userspace accesses to
unsupported-but-advertised MSRs. This will allow removing (almost?) all of
KVM's exemptions for userspace access to MSRs that shouldn't exist based on
the vCPU model (the actual cleanup is non-trivial future work).
- Rework KVM's handling of x2APIC ICR, again, because AMD (x2AVIC) splits the
64-bit value into the legacy ICR and ICR2 storage, whereas Intel (APICv)
stores the entire 64-bit value a the ICR offset.
- Fix a bug where KVM would fail to exit to userspace if one was triggered by
a fastpath exit handler.
- Add fastpath handling of HLT VM-Exit to expedite re-entering the guest when
there's already a pending wake event at the time of the exit.
- Finally fix the RSM vs. nested VM-Enter WARN by forcing the vCPU out of
guest mode prior to signalling SHUTDOWN (architecturally, the SHUTDOWN is
supposed to hit L1, not L2).
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Register the "disable virtualization in an emergency" callback just
before KVM enables virtualization in hardware, as there is no functional
need to keep the callbacks registered while KVM happens to be loaded, but
is inactive, i.e. if KVM hasn't enabled virtualization.
Note, unregistering the callback every time the last VM is destroyed could
have measurable latency due to the synchronize_rcu() needed to ensure all
references to the callback are dropped before KVM is unloaded. But the
latency should be a small fraction of the total latency of disabling
virtualization across all CPUs, and userspace can set enable_virt_at_load
to completely eliminate the runtime overhead.
Add a pointer in kvm_x86_ops to allow vendor code to provide its callback.
There is no reason to force vendor code to do the registration, and either
way KVM would need a new kvm_x86_ops hook.
Suggested-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Acked-by: Kai Huang <kai.huang@intel.com>
Tested-by: Farrah Chen <farrah.chen@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20240830043600.127750-11-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Rename x86's the per-CPU vendor hooks used to enable virtualization in
hardware to align with the recently renamed arch hooks.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Message-ID: <20240830043600.127750-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Re-introduce the "split" x2APIC ICR storage that KVM used prior to Intel's
IPI virtualization support, but only for AMD. While not stated anywhere
in the APM, despite stating the ICR is a single 64-bit register, AMD CPUs
store the 64-bit ICR as two separate 32-bit values in ICR and ICR2. When
IPI virtualization (IPIv on Intel, all AVIC flavors on AMD) is enabled,
KVM needs to match CPU behavior as some ICR ICR writes will be handled by
the CPU, not by KVM.
Add a kvm_x86_ops knob to control the underlying format used by the CPU to
store the x2APIC ICR, and tune it to AMD vs. Intel regardless of whether
or not x2AVIC is enabled. If KVM is handling all ICR writes, the storage
format for x2APIC mode doesn't matter, and having the behavior follow AMD
versus Intel will provide better test coverage and ease debugging.
Fixes: 4d1d7942e36a ("KVM: SVM: Introduce logic to (de)activate x2AVIC mode")
Cc: stable@vger.kernel.org
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Link: https://lore.kernel.org/r/20240719235107.3023592-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Rename all APIs related to feature MSRs from get_msr_feature() to
get_feature_msr(). The APIs get "feature MSRs", not "MSR features".
And unlike kvm_{g,s}et_msr_common(), the "feature" adjective doesn't
describe the helper itself.
No functional change intended.
Link: https://lore.kernel.org/r/20240802181935.292540-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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KVM VMX changes for 6.11
- Remove an unnecessary EPT TLB flush when enabling hardware.
- Fix a series of bugs that cause KVM to fail to detect nested pending posted
interrupts as valid wake eents for a vCPU executing HLT in L2 (with
HLT-exiting disable by L1).
- Misc cleanups
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KVM x86 misc changes for 6.11
- Add a global struct to consolidate tracking of host values, e.g. EFER, and
move "shadow_phys_bits" into the structure as "maxphyaddr".
- Add KVM_CAP_X86_APIC_BUS_CYCLES_NS to allow configuring the effective APIC
bus frequency, because TDX.
- Print the name of the APICv/AVIC inhibits in the relevant tracepoint.
- Clean up KVM's handling of vendor specific emulation to consistently act on
"compatible with Intel/AMD", versus checking for a specific vendor.
- Misc cleanups
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Check for a Requested Virtual Interrupt, i.e. a virtual interrupt that is
pending delivery, in vmx_has_nested_events() and drop the one-off
kvm_x86_ops.guest_apic_has_interrupt() hook.
In addition to dropping a superfluous hook, this fixes a bug where KVM
would incorrectly treat virtual interrupts _for L2_ as always enabled due
to kvm_arch_interrupt_allowed(), by way of vmx_interrupt_blocked(),
treating IRQs as enabled if L2 is active and vmcs12 is configured to exit
on IRQs, i.e. KVM would treat a virtual interrupt for L2 as a valid wake
event based on L1's IRQ blocking status.
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240607172609.3205077-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Fold the guts of kvm_arch_sched_in() into kvm_arch_vcpu_load(), keying
off the recently added kvm_vcpu.scheduled_out as appropriate.
Note, there is a very slight functional change, as PLE shrink updates will
now happen after blasting WBINVD, but that is quite uninteresting as the
two operations do not interact in any way.
Acked-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20240522014013.1672962-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Keep kvm_apicv_inhibit enum naming consistent with the current pattern by
renaming the reason/enumerator defined as APICV_INHIBIT_REASON_DISABLE to
APICV_INHIBIT_REASON_DISABLED.
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Link: https://lore.kernel.org/r/20240506225321.3440701-3-alejandro.j.jimenez@oracle.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Pull KVM updates from Paolo Bonzini:
"ARM:
- Move a lot of state that was previously stored on a per vcpu basis
into a per-CPU area, because it is only pertinent to the host while
the vcpu is loaded. This results in better state tracking, and a
smaller vcpu structure.
- Add full handling of the ERET/ERETAA/ERETAB instructions in nested
virtualisation. The last two instructions also require emulating
part of the pointer authentication extension. As a result, the trap
handling of pointer authentication has been greatly simplified.
- Turn the global (and not very scalable) LPI translation cache into
a per-ITS, scalable cache, making non directly injected LPIs much
cheaper to make visible to the vcpu.
- A batch of pKVM patches, mostly fixes and cleanups, as the
upstreaming process seems to be resuming. Fingers crossed!
- Allocate PPIs and SGIs outside of the vcpu structure, allowing for
smaller EL2 mapping and some flexibility in implementing more or
less than 32 private IRQs.
- Purge stale mpidr_data if a vcpu is created after the MPIDR map has
been created.
- Preserve vcpu-specific ID registers across a vcpu reset.
- Various minor cleanups and improvements.
LoongArch:
- Add ParaVirt IPI support
- Add software breakpoint support
- Add mmio trace events support
RISC-V:
- Support guest breakpoints using ebreak
- Introduce per-VCPU mp_state_lock and reset_cntx_lock
- Virtualize SBI PMU snapshot and counter overflow interrupts
- New selftests for SBI PMU and Guest ebreak
- Some preparatory work for both TDX and SNP page fault handling.
This also cleans up the page fault path, so that the priorities of
various kinds of fauls (private page, no memory, write to read-only
slot, etc.) are easier to follow.
x86:
- Minimize amount of time that shadow PTEs remain in the special
REMOVED_SPTE state.
This is a state where the mmu_lock is held for reading but
concurrent accesses to the PTE have to spin; shortening its use
allows other vCPUs to repopulate the zapped region while the zapper
finishes tearing down the old, defunct page tables.
- Advertise the max mappable GPA in the "guest MAXPHYADDR" CPUID
field, which is defined by hardware but left for software use.
This lets KVM communicate its inability to map GPAs that set bits
51:48 on hosts without 5-level nested page tables. Guest firmware
is expected to use the information when mapping BARs; this avoids
that they end up at a legal, but unmappable, GPA.
- Fixed a bug where KVM would not reject accesses to MSR that aren't
supposed to exist given the vCPU model and/or KVM configuration.
- As usual, a bunch of code cleanups.
x86 (AMD):
- Implement a new and improved API to initialize SEV and SEV-ES VMs,
which will also be extendable to SEV-SNP.
The new API specifies the desired encryption in KVM_CREATE_VM and
then separately initializes the VM. The new API also allows
customizing the desired set of VMSA features; the features affect
the measurement of the VM's initial state, and therefore enabling
them cannot be done tout court by the hypervisor.
While at it, the new API includes two bugfixes that couldn't be
applied to the old one without a flag day in userspace or without
affecting the initial measurement. When a SEV-ES VM is created with
the new VM type, KVM_GET_REGS/KVM_SET_REGS and friends are rejected
once the VMSA has been encrypted. Also, the FPU and AVX state will
be synchronized and encrypted too.
- Support for GHCB version 2 as applicable to SEV-ES guests.
This, once more, is only accessible when using the new
KVM_SEV_INIT2 flow for initialization of SEV-ES VMs.
x86 (Intel):
- An initial bunch of prerequisite patches for Intel TDX were merged.
They generally don't do anything interesting. The only somewhat
user visible change is a new debugging mode that checks that KVM's
MMU never triggers a #VE virtualization exception in the guest.
- Clear vmcs.EXIT_QUALIFICATION when synthesizing an EPT Misconfig
VM-Exit to L1, as per the SDM.
Generic:
- Use vfree() instead of kvfree() for allocations that always use
vcalloc() or __vcalloc().
- Remove .change_pte() MMU notifier - the changes to non-KVM code are
small and Andrew Morton asked that I also take those through the
KVM tree.
The callback was only ever implemented by KVM (which was also the
original user of MMU notifiers) but it had been nonfunctional ever
since calls to set_pte_at_notify were wrapped with
invalidate_range_start and invalidate_range_end... in 2012.
Selftests:
- Enhance the demand paging test to allow for better reporting and
stressing of UFFD performance.
- Convert the steal time test to generate TAP-friendly output.
- Fix a flaky false positive in the xen_shinfo_test due to comparing
elapsed time across two different clock domains.
- Skip the MONITOR/MWAIT test if the host doesn't actually support
MWAIT.
- Avoid unnecessary use of "sudo" in the NX hugepage test wrapper
shell script, to play nice with running in a minimal userspace
environment.
- Allow skipping the RSEQ test's sanity check that the vCPU was able
to complete a reasonable number of KVM_RUNs, as the assert can fail
on a completely valid setup.
If the test is run on a large-ish system that is otherwise idle,
and the test isn't affined to a low-ish number of CPUs, the vCPU
task can be repeatedly migrated to CPUs that are in deep sleep
states, which results in the vCPU having very little net runtime
before the next migration due to high wakeup latencies.
- Define _GNU_SOURCE for all selftests to fix a warning that was
introduced by a change to kselftest_harness.h late in the 6.9
cycle, and because forcing every test to #define _GNU_SOURCE is
painful.
- Provide a global pseudo-RNG instance for all tests, so that library
code can generate random, but determinstic numbers.
- Use the global pRNG to randomly force emulation of select writes
from guest code on x86, e.g. to help validate KVM's emulation of
locked accesses.
- Allocate and initialize x86's GDT, IDT, TSS, segments, and default
exception handlers at VM creation, instead of forcing tests to
manually trigger the related setup.
Documentation:
- Fix a goof in the KVM_CREATE_GUEST_MEMFD documentation"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (225 commits)
selftests/kvm: remove dead file
KVM: selftests: arm64: Test vCPU-scoped feature ID registers
KVM: selftests: arm64: Test that feature ID regs survive a reset
KVM: selftests: arm64: Store expected register value in set_id_regs
KVM: selftests: arm64: Rename helper in set_id_regs to imply VM scope
KVM: arm64: Only reset vCPU-scoped feature ID regs once
KVM: arm64: Reset VM feature ID regs from kvm_reset_sys_regs()
KVM: arm64: Rename is_id_reg() to imply VM scope
KVM: arm64: Destroy mpidr_data for 'late' vCPU creation
KVM: arm64: Use hVHE in pKVM by default on CPUs with VHE support
KVM: arm64: Fix hvhe/nvhe early alias parsing
KVM: SEV: Allow per-guest configuration of GHCB protocol version
KVM: SEV: Add GHCB handling for termination requests
KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests
KVM: SEV: Add support to handle AP reset MSR protocol
KVM: x86: Explicitly zero kvm_caps during vendor module load
KVM: x86: Fully re-initialize supported_mce_cap on vendor module load
KVM: x86: Fully re-initialize supported_vm_types on vendor module load
KVM: x86/mmu: Sanity check that __kvm_faultin_pfn() doesn't create noslot pfns
KVM: x86/mmu: Initialize kvm_page_fault's pfn and hva to error values
...
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KVM accesses Virtual Machine Control Structure (VMCS) with VMX instructions
to operate on VM. TDX doesn't allow VMM to operate VMCS directly.
Instead, TDX has its own data structures, and TDX SEAMCALL APIs for VMM to
indirectly operate those data structures. This means we must have a TDX
version of kvm_x86_ops.
The existing global struct kvm_x86_ops already defines an interface which
can be adapted to TDX, but kvm_x86_ops is a system-wide, not per-VM
structure. To allow VMX to coexist with TDs, the kvm_x86_ops callbacks
will have wrappers "if (tdx) tdx_op() else vmx_op()" to pick VMX or
TDX at run time.
To split the runtime switch, the VMX implementation, and the TDX
implementation, add main.c, and move out the vmx_x86_ops hooks in
preparation for adding TDX. Use 'vt' for the naming scheme as a nod to
VT-x and as a concatenation of VmxTdx.
The eventually converted code will look like this:
vmx.c:
vmx_op() { ... }
VMX initialization
tdx.c:
tdx_op() { ... }
TDX initialization
x86_ops.h:
vmx_op();
tdx_op();
main.c:
static vt_op() { if (tdx) tdx_op() else vmx_op() }
static struct kvm_x86_ops vt_x86_ops = {
.op = vt_op,
initialization functions call both VMX and TDX initialization
Opportunistically, fix the name inconsistency from vmx_create_vcpu() and
vmx_free_vcpu() to vmx_vcpu_create() and vmx_vcpu_free().
Co-developed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Yuan Yao <yuan.yao@intel.com>
Message-Id: <e603c317587f933a9d1bee8728c84e4935849c16.1705965634.git.isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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