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kvm_hypercall has to place the hypercall number in rax.
Trace events show that kvm_pv_test doesn't work properly:
kvm_pv_test-53132: kvm_hypercall: nr 0x0 a0 0x0 a1 0x0 a2 0x0 a3 0x0
kvm_pv_test-53132: kvm_hypercall: nr 0x0 a0 0x0 a1 0x0 a2 0x0 a3 0x0
kvm_pv_test-53132: kvm_hypercall: nr 0x0 a0 0x0 a1 0x0 a2 0x0 a3 0x0
With this change, it starts working as expected:
kvm_pv_test-54285: kvm_hypercall: nr 0x5 a0 0x0 a1 0x0 a2 0x0 a3 0x0
kvm_pv_test-54285: kvm_hypercall: nr 0xa a0 0x0 a1 0x0 a2 0x0 a3 0x0
kvm_pv_test-54285: kvm_hypercall: nr 0xb a0 0x0 a1 0x0 a2 0x0 a3 0x0
Signed-off-by: Andrei Vagin <avagin@google.com>
Message-Id: <20220722230241.1944655-5-avagin@google.com>
Fixes: ac4a4d6de22e ("selftests: kvm: test enforcement of paravirtual cpuid features")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The only sensible exponent for a boolean stat is 0. Add a test assertion
requiring all boolean statistics to have an exponent of 0.
Signed-off-by: Oliver Upton <oupton@google.com>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Message-Id: <20220719143134.3246798-4-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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As it turns out, tests sometimes fail. When that is the case, packing
the test assertion with as much relevant information helps track down
the problem more quickly.
Sharpen up the stat descriptor assertions in kvm_binary_stats_test to
more precisely describe the reason for the test assertion and which
stat is to blame.
Signed-off-by: Oliver Upton <oupton@google.com>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Message-Id: <20220719143134.3246798-3-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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In order to provide more useful test assertions that describe the broken
stats descriptor, perform sanity check on the stat name before any other
descriptor field. While at it, avoid dereferencing the name field if the
sanity check fails as it is more likely to contain garbage.
Signed-off-by: Oliver Upton <oupton@google.com>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Message-Id: <20220719143134.3246798-2-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The last use of 'pfn' went away with the same-named argument to
host_pfn_mapping_level; now that the hugepage level is obtained
exclusively from the host page tables, kvm_mmu_zap_collapsible_spte
does not need to know host pfns at all.
Fixes: a8ac499bb6ab ("KVM: x86/mmu: Don't require refcounted "struct page" to create huge SPTEs")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm64 updates for 5.20:
- Unwinder implementations for both nVHE modes (classic and
protected), complete with an overflow stack
- Rework of the sysreg access from userspace, with a complete
rewrite of the vgic-v3 view to allign with the rest of the
infrastructure
- Disagregation of the vcpu flags in separate sets to better track
their use model.
- A fix for the GICv2-on-v3 selftest
- A small set of cosmetic fixes
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KVM/s390, KVM/x86 and common infrastructure changes for 5.20
x86:
* Permit guests to ignore single-bit ECC errors
* Fix races in gfn->pfn cache refresh; do not pin pages tracked by the cache
* Intel IPI virtualization
* Allow getting/setting pending triple fault with KVM_GET/SET_VCPU_EVENTS
* PEBS virtualization
* Simplify PMU emulation by just using PERF_TYPE_RAW events
* More accurate event reinjection on SVM (avoid retrying instructions)
* Allow getting/setting the state of the speaker port data bit
* Refuse starting the kvm-intel module if VM-Entry/VM-Exit controls are inconsistent
* "Notify" VM exit (detect microarchitectural hangs) for Intel
* Cleanups for MCE MSR emulation
s390:
* add an interface to provide a hypervisor dump for secure guests
* improve selftests to use TAP interface
* enable interpretive execution of zPCI instructions (for PCI passthrough)
* First part of deferred teardown
* CPU Topology
* PV attestation
* Minor fixes
Generic:
* new selftests API using struct kvm_vcpu instead of a (vm, id) tuple
x86:
* Use try_cmpxchg64 instead of cmpxchg64
* Bugfixes
* Ignore benign host accesses to PMU MSRs when PMU is disabled
* Allow disabling KVM's "MONITOR/MWAIT are NOPs!" behavior
* x86/MMU: Allow NX huge pages to be disabled on a per-vm basis
* Port eager page splitting to shadow MMU as well
* Enable CMCI capability by default and handle injected UCNA errors
* Expose pid of vcpu threads in debugfs
* x2AVIC support for AMD
* cleanup PIO emulation
* Fixes for LLDT/LTR emulation
* Don't require refcounted "struct page" to create huge SPTEs
x86 cleanups:
* Use separate namespaces for guest PTEs and shadow PTEs bitmasks
* PIO emulation
* Reorganize rmap API, mostly around rmap destruction
* Do not workaround very old KVM bugs for L0 that runs with nesting enabled
* new selftests API for CPUID
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KVM/riscv changes for 5.20
* Track ISA extensions used by Guest using bitmap
* Added system instruction emulation framework
* Added CSR emulation framework
* Added gfp_custom flag in struct kvm_mmu_memory_cache
* Added G-stage ioremap() and iounmap() functions
* Added support for Svpbmt inside Guest
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The Guest/VM can use Svpbmt in VS-stage page tables when allowed by the
Hypervisor using the henvcfg.PBMTE bit.
We add Svpbmt support for the KVM Guest/VM which can be enabled/disabled
by the KVM user-space (QEMU/KVMTOOL) using the ISA extension ONE_REG
interface.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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When the host has Svpbmt extension, we should use page based memory
type 2 (i.e. IO) for IO mappings in the G-stage page table.
To achieve this, we replace use of PAGE_KERNEL with PAGE_KERNEL_IO
in the kvm_riscv_gstage_ioremap().
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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The in-kernel AIA IMSIC support requires on-demand mapping / unmapping
of Guest IMSIC address to Host IMSIC guest files. To help achieve this,
we add kvm_riscv_stage2_ioremap() and kvm_riscv_stage2_iounmap() functions.
These new functions for updating G-stage page table mappings will be called
in atomic context so we have special "in_atomic" parameter for this purpose.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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The kvm_mmu_topup_memory_cache() always uses GFP_KERNEL_ACCOUNT for
memory allocation which prevents it's use in atomic context. To address
this limitation of kvm_mmu_topup_memory_cache(), we add gfp_custom flag
in struct kvm_mmu_memory_cache. When the gfp_custom flag is set to some
GFP_xyz flags, the kvm_mmu_topup_memory_cache() will use that instead of
GFP_KERNEL_ACCOUNT.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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We add an extensible CSR emulation framework which is based upon the
existing system instruction emulation. This will be useful to upcoming
AIA, PMU, Nested and other virtualization features.
The CSR emulation framework also has provision to emulate CSR in user
space but this will be used only in very specific cases such as AIA
IMSIC CSR emulation in user space or vendor specific CSR emulation
in user space.
By default, all CSRs not handled by KVM RISC-V will be redirected back
to Guest VCPU as illegal instruction trap.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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We will be emulating more system instructions in near future with
upcoming AIA, PMU, Nested and other virtualization features.
To accommodate above, we add an extensible system instruction emulation
framework in vcpu_insn.c.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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The instruction and CSR emulation for VCPU is going to grow over time
due to upcoming AIA, PMU, Nested and other virtualization features.
Let us factor-out VCPU instruction emulation from vcpu_exit.c to a
separate source dedicated for this purpose.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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local_irq_disable provides stronger guarantees than preempt_disable so
calling the latter is redundant when interrupts are disabled. Instead,
explicitly disable preemption right before interrupts are enabled/disabled
to ensure that the time accounted in guest_timing_exit_irqoff
includes time taken by the guest or interrupts.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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It can never fail so convey that fact explicitly by making the function
void. Also in kvm_arch_init_vm it makes it clear that there no need
to do any cleanup after kvm_riscv_gstage_vmid_init has been called.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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There is a spelling mistake in mmu.c and vcpu_exit.c. Fix it.
Signed-off-by: Zhang Jiaming <jiaming@nfschina.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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Currently, the every vcpu only stores the ISA extensions in a unsigned long
which is not scalable as number of extensions will continue to grow.
Using a bitmap allows the ISA extension to support any number of
extensions. The CONFIG one reg interface implementation is modified to
support the bitmap as well. But it is meant only for base extensions.
Thus, the first element of the bitmap array is sufficient for that
interface.
In the future, all the new multi-letter extensions must use the
ISA_EXT one reg interface that allows enabling/disabling any extension
now.
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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Now kvm_tdp_mmu_zap_leafs() only zaps leaf SPTEs but not any non-root
pages within that GFN range anymore, so the comment around it isn't
right.
Fix it by shifting the comment from tdp_mmu_zap_leafs() instead of
duplicating it, as tdp_mmu_zap_leafs() is static and is only called by
kvm_tdp_mmu_zap_leafs().
Opportunistically tweak the blurb about SPTEs being cleared to (a) say
"zapped" instead of "cleared" because "cleared" will be wrong if/when
KVM allows a non-zero value for non-present SPTE (i.e. for Intel TDX),
and (b) to clarify that a flush is needed if and only if a SPTE has been
zapped since MMU lock was last acquired.
Fixes: f47e5bbbc92f ("KVM: x86/mmu: Zap only TDP MMU leafs in zap range and mmu_notifier unmap")
Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Message-Id: <20220728030452.484261-1-kai.huang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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As Virtual Machine Save Area (VMSA) is essential in troubleshooting
attestation, dump it to the klog with the KERN_DEBUG level of priority.
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Suggested-by: Harald Hoyer <harald@profian.com>
Signed-off-by: Jarkko Sakkinen <jarkko@profian.com>
Message-Id: <20220728050919.24113-1-jarkko@profian.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Treat the NX bit as valid when using NPT, as KVM will set the NX bit when
the NX huge page mitigation is enabled (mindblowing) and trigger the WARN
that fires on reserved SPTE bits being set.
KVM has required NX support for SVM since commit b26a71a1a5b9 ("KVM: SVM:
Refuse to load kvm_amd if NX support is not available") for exactly this
reason, but apparently it never occurred to anyone to actually test NPT
with the mitigation enabled.
------------[ cut here ]------------
spte = 0x800000018a600ee7, level = 2, rsvd bits = 0x800f0000001fe000
WARNING: CPU: 152 PID: 15966 at arch/x86/kvm/mmu/spte.c:215 make_spte+0x327/0x340 [kvm]
Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 10.48.0 01/27/2022
RIP: 0010:make_spte+0x327/0x340 [kvm]
Call Trace:
<TASK>
tdp_mmu_map_handle_target_level+0xc3/0x230 [kvm]
kvm_tdp_mmu_map+0x343/0x3b0 [kvm]
direct_page_fault+0x1ae/0x2a0 [kvm]
kvm_tdp_page_fault+0x7d/0x90 [kvm]
kvm_mmu_page_fault+0xfb/0x2e0 [kvm]
npf_interception+0x55/0x90 [kvm_amd]
svm_invoke_exit_handler+0x31/0xf0 [kvm_amd]
svm_handle_exit+0xf6/0x1d0 [kvm_amd]
vcpu_enter_guest+0xb6d/0xee0 [kvm]
? kvm_pmu_trigger_event+0x6d/0x230 [kvm]
vcpu_run+0x65/0x2c0 [kvm]
kvm_arch_vcpu_ioctl_run+0x355/0x610 [kvm]
kvm_vcpu_ioctl+0x551/0x610 [kvm]
__se_sys_ioctl+0x77/0xc0
__x64_sys_ioctl+0x1d/0x20
do_syscall_64+0x44/0xa0
entry_SYSCALL_64_after_hwframe+0x46/0xb0
</TASK>
---[ end trace 0000000000000000 ]---
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220723013029.1753623-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The commit 5413bcba7ed5 ("KVM: x86: Add support for vICR APIC-write
VM-Exits in x2APIC mode") introduces logic to prevent APIC write
for offset other than ICR in kvm_apic_write_nodecode() function.
This breaks x2AVIC support, which requires KVM to trap and emulate
x2APIC MSR writes.
Therefore, removes the warning and modify to logic to allow MSR write.
Fixes: 5413bcba7ed5 ("KVM: x86: Add support for vICR APIC-write VM-Exits in x2APIC mode")
Cc: Zeng Guang <guang.zeng@intel.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <20220725053356.4275-1-suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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AMD does not support APIC TSC-deadline timer mode. AVIC hardware
will generate GP fault when guest kernel writes 1 to bits [18]
of the APIC LVTT register (offset 0x32) to set the timer mode.
(Note: bit 18 is reserved on AMD system).
Therefore, always intercept and let KVM emulate the MSR accesses.
Fixes: f3d7c8aa6882 ("KVM: SVM: Fix x2APIC MSRs interception")
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <20220725033428.3699-1-suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Verify that KVM allows toggling VMX MSR bits to be "more" restrictive,
and also allows restoring each MSR to KVM's original, less restrictive
value.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220607213604.3346000-16-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Make UMIP an "allowed-1" bit CR4_FIXED1 MSR when KVM is emulating UMIP.
KVM emulates UMIP for both L1 and L2, and so should enumerate that L2 is
allowed to have CR4.UMIP=1. Not setting the bit doesn't immediately
break nVMX, as KVM does set/clear the bit in CR4_FIXED1 in response to a
guest CPUID update, i.e. KVM will correctly (dis)allow nested VM-Entry
based on whether or not UMIP is exposed to L1. That said, KVM should
enumerate the bit as being allowed from time zero, e.g. userspace will
see the wrong value if the MSR is read before CPUID is written.
Fixes: 0367f205a3b7 ("KVM: vmx: add support for emulating UMIP")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220607213604.3346000-12-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This reverts commit 03a8871add95213827e2bea84c12133ae5df952e.
Since commit 03a8871add95 ("KVM: nVMX: Expose load IA32_PERF_GLOBAL_CTRL
VM-{Entry,Exit} control"), KVM has taken ownership of the "load
IA32_PERF_GLOBAL_CTRL" VMX entry/exit control bits, trying to set these
bits in the IA32_VMX_TRUE_{ENTRY,EXIT}_CTLS MSRs if the guest's CPUID
supports the architectural PMU (CPUID[EAX=0Ah].EAX[7:0]=1), and clear
otherwise.
This was a misguided attempt at mimicking what commit 5f76f6f5ff96
("KVM: nVMX: Do not expose MPX VMX controls when guest MPX disabled",
2018-10-01) did for MPX. However, that commit was a workaround for
another KVM bug and not something that should be imitated. Mucking with
the VMX MSRs creates a subtle, difficult to maintain ABI as KVM must
ensure that any internal changes, e.g. to how KVM handles _any_ guest
CPUID changes, yield the same functional result. Therefore, KVM's policy
is to let userspace have full control of the guest vCPU model so long
as the host kernel is not at risk.
Now that KVM really truly ensures kvm_set_msr() will succeed by loading
PERF_GLOBAL_CTRL if and only if it exists, revert KVM's misguided and
roundabout behavior.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[sean: make it a pure revert]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220722224409.1336532-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Attempt to load PERF_GLOBAL_CTRL during nested VM-Enter/VM-Exit if and
only if the MSR exists (according to the guest vCPU model). KVM has very
misguided handling of VM_{ENTRY,EXIT}_LOAD_IA32_PERF_GLOBAL_CTRL and
attempts to force the nVMX MSR settings to match the vPMU model, i.e. to
hide/expose the control based on whether or not the MSR exists from the
guest's perspective.
KVM's modifications fail to handle the scenario where the vPMU is hidden
from the guest _after_ being exposed to the guest, e.g. by userspace
doing multiple KVM_SET_CPUID2 calls, which is allowed if done before any
KVM_RUN. nested_vmx_pmu_refresh() is called if and only if there's a
recognized vPMU, i.e. KVM will leave the bits in the allow state and then
ultimately reject the MSR load and WARN.
KVM should not force the VMX MSRs in the first place. KVM taking control
of the MSRs was a misguided attempt at mimicking what commit 5f76f6f5ff96
("KVM: nVMX: Do not expose MPX VMX controls when guest MPX disabled",
2018-10-01) did for MPX. However, the MPX commit was a workaround for
another KVM bug and not something that should be imitated (and it should
never been done in the first place).
In other words, KVM's ABI _should_ be that userspace has full control
over the MSRs, at which point triggering the WARN that loading the MSR
must not fail is trivial.
The intent of the WARN is still valid; KVM has consistency checks to
ensure that vmcs12->{guest,host}_ia32_perf_global_ctrl is valid. The
problem is that '0' must be considered a valid value at all times, and so
the simple/obvious solution is to just not actually load the MSR when it
does not exist. It is userspace's responsibility to provide a sane vCPU
model, i.e. KVM is well within its ABI and Intel's VMX architecture to
skip the loads if the MSR does not exist.
Fixes: 03a8871add95 ("KVM: nVMX: Expose load IA32_PERF_GLOBAL_CTRL VM-{Entry,Exit} control")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220722224409.1336532-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add a helper to check of the guest PMU has PERF_GLOBAL_CTRL, which is
unintuitive _and_ diverges from Intel's architecturally defined behavior.
Even worse, KVM currently implements the check using two different (but
equivalent) checks, _and_ there has been at least one attempt to add a
_third_ flavor.
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220722224409.1336532-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Mark all MSR_CORE_PERF_GLOBAL_CTRL and MSR_CORE_PERF_GLOBAL_OVF_CTRL bits
as reserved if there is no guest vPMU. The nVMX VM-Entry consistency
checks do not check for a valid vPMU prior to consuming the masks via
kvm_valid_perf_global_ctrl(), i.e. may incorrectly allow a non-zero mask
to be loaded via VM-Enter or VM-Exit (well, attempted to be loaded, the
actual MSR load will be rejected by intel_is_valid_msr()).
Fixes: f5132b01386b ("KVM: Expose a version 2 architectural PMU to a guests")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220722224409.1336532-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Since commit 5f76f6f5ff96 ("KVM: nVMX: Do not expose MPX VMX controls
when guest MPX disabled"), KVM has taken ownership of the "load
IA32_BNDCFGS" and "clear IA32_BNDCFGS" VMX entry/exit controls,
trying to set these bits in the IA32_VMX_TRUE_{ENTRY,EXIT}_CTLS
MSRs if the guest's CPUID supports MPX, and clear otherwise.
The intent of the patch was to apply it to L0 in order to work around
L1 kernels that lack the fix in commit 691bd4340bef ("kvm: vmx: allow
host to access guest MSR_IA32_BNDCFGS", 2017-07-04): by hiding the
control bits from L0, L1 hides BNDCFGS from KVM_GET_MSR_INDEX_LIST,
and the L1 bug is neutralized even in the lack of commit 691bd4340bef.
This was perhaps a sensible kludge at the time, but a horrible
idea in the long term and in fact it has not been extended to
other CPUID bits like these:
X86_FEATURE_LM => VM_EXIT_HOST_ADDR_SPACE_SIZE, VM_ENTRY_IA32E_MODE,
VMX_MISC_SAVE_EFER_LMA
X86_FEATURE_TSC => CPU_BASED_RDTSC_EXITING, CPU_BASED_USE_TSC_OFFSETTING,
SECONDARY_EXEC_TSC_SCALING
X86_FEATURE_INVPCID_SINGLE => SECONDARY_EXEC_ENABLE_INVPCID
X86_FEATURE_MWAIT => CPU_BASED_MONITOR_EXITING, CPU_BASED_MWAIT_EXITING
X86_FEATURE_INTEL_PT => SECONDARY_EXEC_PT_CONCEAL_VMX, SECONDARY_EXEC_PT_USE_GPA,
VM_EXIT_CLEAR_IA32_RTIT_CTL, VM_ENTRY_LOAD_IA32_RTIT_CTL
X86_FEATURE_XSAVES => SECONDARY_EXEC_XSAVES
These days it's sort of common knowledge that any MSR in
KVM_GET_MSR_INDEX_LIST must allow *at least* setting it with KVM_SET_MSR
to a default value, so it is unlikely that something like commit
5f76f6f5ff96 will be needed again. So revert it, at the potential cost
of breaking L1s with a 6 year old kernel. While in principle the L0 owner
doesn't control what runs on L1, such an old hypervisor would probably
have many other bugs.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Restrict the nVMX MSRs based on KVM's config, not based on the guest's
current config. Using the guest's config to audit the new config
prevents userspace from restoring the original config (KVM's config) if
at any point in the past the guest's config was restricted in any way.
Fixes: 62cc6b9dc61e ("KVM: nVMX: support restore of VMX capability MSRs")
Cc: stable@vger.kernel.org
Cc: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220607213604.3346000-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Rename the exit handlers for VMXON and VMXOFF to match the instruction
names, the terms "vmon" and "vmoff" are not used anywhere in Intel's
documentation, nor are they used elsehwere in KVM.
Sadly, the exit reasons are exposed to userspace and so cannot be renamed
without breaking userspace. :-(
Fixes: ec378aeef9df ("KVM: nVMX: Implement VMXON and VMXOFF")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220607213604.3346000-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Inject a #UD if L1 attempts VMXON with a CR0 or CR4 that is disallowed
per the associated nested VMX MSRs' fixed0/1 settings. KVM cannot rely
on hardware to perform the checks, even for the few checks that have
higher priority than VM-Exit, as (a) KVM may have forced CR0/CR4 bits in
hardware while running the guest, (b) there may incompatible CR0/CR4 bits
that have lower priority than VM-Exit, e.g. CR0.NE, and (c) userspace may
have further restricted the allowed CR0/CR4 values by manipulating the
guest's nested VMX MSRs.
Note, despite a very strong desire to throw shade at Jim, commit
70f3aac964ae ("kvm: nVMX: Remove superfluous VMX instruction fault checks")
is not to blame for the buggy behavior (though the comment...). That
commit only removed the CR0.PE, EFLAGS.VM, and COMPATIBILITY mode checks
(though it did erroneously drop the CPL check, but that has already been
remedied). KVM may force CR0.PE=1, but will do so only when also
forcing EFLAGS.VM=1 to emulate Real Mode, i.e. hardware will still #UD.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216033
Fixes: ec378aeef9df ("KVM: nVMX: Implement VMXON and VMXOFF")
Reported-by: Eric Li <ercli@ucdavis.edu>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220607213604.3346000-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Check that the guest (L2) and host (L1) CR4 values that would be loaded
by nested VM-Enter and VM-Exit respectively are valid with respect to
KVM's (L0 host) allowed CR4 bits. Failure to check KVM reserved bits
would allow L1 to load an illegal CR4 (or trigger hardware VM-Fail or
failed VM-Entry) by massaging guest CPUID to allow features that are not
supported by KVM. Amusingly, KVM itself is an accomplice in its doom, as
KVM adjusts L1's MSR_IA32_VMX_CR4_FIXED1 to allow L1 to enable bits for
L2 based on L1's CPUID model.
Note, although nested_{guest,host}_cr4_valid() are _currently_ used if
and only if the vCPU is post-VMXON (nested.vmxon == true), that may not
be true in the future, e.g. emulating VMXON has a bug where it doesn't
check the allowed/required CR0/CR4 bits.
Cc: stable@vger.kernel.org
Fixes: 3899152ccbf4 ("KVM: nVMX: fix checks on CR{0,4} during virtual VMX operation")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220607213604.3346000-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Split the common x86 parts of kvm_is_valid_cr4(), i.e. the reserved bits
checks, into a separate helper, __kvm_is_valid_cr4(), and export only the
inner helper to vendor code in order to prevent nested VMX from calling
back into vmx_is_valid_cr4() via kvm_is_valid_cr4().
On SVM, this is a nop as SVM doesn't place any additional restrictions on
CR4.
On VMX, this is also currently a nop, but only because nested VMX is
missing checks on reserved CR4 bits for nested VM-Enter. That bug will
be fixed in a future patch, and could simply use kvm_is_valid_cr4() as-is,
but nVMX has _another_ bug where VMXON emulation doesn't enforce VMX's
restrictions on CR0/CR4. The cleanest and most intuitive way to fix the
VMXON bug is to use nested_host_cr{0,4}_valid(). If the CR4 variant
routes through kvm_is_valid_cr4(), using nested_host_cr4_valid() won't do
the right thing for the VMXON case as vmx_is_valid_cr4() enforces VMX's
restrictions if and only if the vCPU is post-VMXON.
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220607213604.3346000-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add a command line option to dirty_log_perf_test to run vCPUs for the
entire duration of disabling dirty logging. By default, the test stops
running runs vCPUs before disabling dirty logging, which is faster but
less interesting as it doesn't stress KVM's handling of contention
between page faults and the zapping of collapsible SPTEs. Enabling the
flag also lets the user verify that KVM is indeed rebuilding zapped SPTEs
as huge pages by checking KVM's pages_{1g,2m,4k} stats. Without vCPUs to
fault in the zapped SPTEs, the stats will show that KVM is zapping pages,
but they never show whether or not KVM actually allows huge pages to be
recreated.
Note! Enabling the flag can _significantly_ increase runtime, especially
if the thread that's disabling dirty logging doesn't have a dedicated
pCPU, e.g. if all pCPUs are used to run vCPUs.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220715232107.3775620-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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When zapping collapsible SPTEs in the TDP MMU, don't bottom out on a leaf
SPTE now that KVM doesn't require a PFN to compute the host mapping level,
i.e. now that there's no need to first find a leaf SPTE and then step
back up.
Drop the now unused tdp_iter_step_up(), as it is not the safest of
helpers (using any of the low level iterators requires some understanding
of the various side effects).
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220715232107.3775620-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add a comment to document how host_pfn_mapping_level() can be used safely,
as the line between safe and dangerous is quite thin. E.g. if KVM were
to ever support in-place promotion to create huge pages, consuming the
level is safe if the caller holds mmu_lock and checks that there's an
existing _leaf_ SPTE, but unsafe if the caller only checks that there's a
non-leaf SPTE.
Opportunistically tweak the existing comments to explicitly document why
KVM needs to use READ_ONCE().
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220715232107.3775620-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Drop the requirement that a pfn be backed by a refcounted, compound or
or ZONE_DEVICE, struct page, and instead rely solely on the host page
tables to identify huge pages. The PageCompound() check is a remnant of
an old implementation that identified (well, attempt to identify) huge
pages without walking the host page tables. The ZONE_DEVICE check was
added as an exception to the PageCompound() requirement. In other words,
neither check is actually a hard requirement, if the primary has a pfn
backed with a huge page, then KVM can back the pfn with a huge page
regardless of the backing store.
Dropping the @pfn parameter will also allow KVM to query the max host
mapping level without having to first get the pfn, which is advantageous
for use outside of the page fault path where KVM wants to take action if
and only if a page can be mapped huge, i.e. avoids the pfn lookup for
gfns that can't be backed with a huge page.
Cc: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Message-Id: <20220715232107.3775620-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Restrict the mapping level for SPTEs based on the guest MTRRs if and only
if KVM may actually use the guest MTRRs to compute the "real" memtype.
For all forms of paging, guest MTRRs are purely virtual in the sense that
they are completely ignored by hardware, i.e. they affect the memtype
only if software manually consumes them. The only scenario where KVM
consumes the guest MTRRs is when shadow_memtype_mask is non-zero and the
guest has non-coherent DMA, in all other cases KVM simply leaves the PAT
field in SPTEs as '0' to encode WB memtype.
Note, KVM may still ultimately ignore guest MTRRs, e.g. if the backing
pfn is host MMIO, but false positives are ok as they only cause a slight
performance blip (unless the guest is doing weird things with its MTRRs,
which is extremely unlikely).
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220715230016.3762909-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add shadow_memtype_mask to capture that EPT needs a non-zero memtype mask
instead of relying on TDP being enabled, as NPT doesn't need a non-zero
mask. This is a glorified nop as kvm_x86_ops.get_mt_mask() returns zero
for NPT anyways.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220715230016.3762909-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Return directly if kvm_arch_init() detects an error before doing any real
work, jumping through a label obfuscates what's happening and carries the
unnecessary risk of leaving 'r' uninitialized.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220715230016.3762909-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Reject KVM if entry '0' in the host's IA32_PAT MSR is not programmed to
writeback (WB) memtype. KVM subtly relies on IA32_PAT entry '0' to be
programmed to WB by leaving the PAT bits in shadow paging and NPT SPTEs
as '0'. If something other than WB is in PAT[0], at _best_ guests will
suffer very poor performance, and at worst KVM will crash the system by
breaking cache-coherency expecations (e.g. using WC for guest memory).
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220715230016.3762909-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The index for svm_direct_access_msrs was incorrectly initialized with
the APIC MMIO register macros. Fix by introducing a macro for calculating
x2APIC MSRs.
Fixes: 5c127c85472c ("KVM: SVM: Adding support for configuring x2APIC MSRs interception")
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <20220718083833.222117-1-suravee.suthikulpanit@amd.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Remove the underscores from __pte_list_remove(), the function formerly
known as pte_list_remove() is now named kvm_zap_one_rmap_spte() to show
that it zaps rmaps/PTEs, i.e. doesn't just remove an entry from a list.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220715224226.3749507-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Rename pte_list_remove() and pte_list_destroy() to kvm_zap_one_rmap_spte()
and kvm_zap_all_rmap_sptes() respectively to document that (a) they zap
SPTEs and (b) to better document how they differ (remove vs. destroy does
not exactly scream "one vs. all").
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220715224226.3749507-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Rename kvm_unmap_rmap() and kvm_zap_rmap() to kvm_zap_rmap() and
__kvm_zap_rmap() respectively to show that what was the "unmap" helper is
just a wrapper for the "zap" helper, i.e. that they do the exact same
thing, one just exists to deal with its caller passing in more params.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220715224226.3749507-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Rename __kvm_zap_rmaps() to kvm_rmap_zap_gfn_range() to avoid future
confusion with a soon-to-be-introduced __kvm_zap_rmap(). Using a plural
"rmaps" is somewhat ambiguous without additional context, as it's not
obvious whether it's referring to multiple rmap lists, versus multiple
rmap entries within a single list.
Use kvm_rmap_zap_gfn_range() to align with the pattern established by
kvm_rmap_zap_collapsible_sptes(), without losing the information that it
zaps only rmap-based MMUs, i.e. don't rename it to __kvm_zap_gfn_range().
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220715224226.3749507-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Drop the trailing "p" from rmap helpers, i.e. rename functions to simply
be kvm_<action>_rmap(). Declaring that a function takes a pointer is
completely unnecessary and goes against kernel style.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220715224226.3749507-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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