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SubjectRe: [PATCH] KVM: x86: Fix the intel_pt PMI handling wrongly considered from guest
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On 2022/5/16 21:58, Sean Christopherson wrote:
> On Mon, May 16, 2022, Yanfei Xu wrote:
>> When kernel handles the vm-exit caused by external interrupts and PMI,
>> it always set a type of kvm_intr_type to handling_intr_from_guest to
>> tell if it's dealing an IRQ or NMI.
>> However, the further type judgment is missing in kvm_arch_pmi_in_guest().
>> It could make the PMI of intel_pt wrongly considered it comes from a
>> guest once the PMI breaks the handling of vm-exit of external interrupts.
>>
>> Fixes: db215756ae59 ("KVM: x86: More precisely identify NMI from guest when handling PMI")
>> Signed-off-by: Yanfei Xu <yanfei.xu@intel.com>
>> ---
>> arch/x86/include/asm/kvm_host.h | 8 +++++++-
>> arch/x86/kvm/x86.h | 6 ------
>> 2 files changed, 7 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index 4ff36610af6a..308cf19f123d 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -1582,8 +1582,14 @@ static inline int kvm_arch_flush_remote_tlb(struct kvm *kvm)
>> return -ENOTSUPP;
>> }
>>
>> +enum kvm_intr_type {
>> + /* Values are arbitrary, but must be non-zero. */
>> + KVM_HANDLING_IRQ = 1,
>> + KVM_HANDLING_NMI,
>> +};
>> +
>> #define kvm_arch_pmi_in_guest(vcpu) \
>> - ((vcpu) && (vcpu)->arch.handling_intr_from_guest)
>> + ((vcpu) && (vcpu)->arch.handling_intr_from_guest == KVM_HANDLING_NMI)
> My understanding is that this isn't correct as a general change, as perf events
> can use regular IRQs in some cases. See commit dd60d217062f4 ("KVM: x86: Fix perf
> timer mode IP reporting").
>
> I assume there's got to be a way to know which mode perf is using, e.g. we should
> be able to make this look something like:
>
> ((vcpu) && (vcpu)->arch.handling_intr_from_guest == kvm_pmi_vector)

Thanks for your comments, I am going to understand these clearly and
then reply or give a next version.

Regards,
Yanfei

>
>> void kvm_mmu_x86_module_init(void);
>> int kvm_mmu_vendor_module_init(void);
>> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
>> index 588792f00334..3bdf1bc76863 100644
>> --- a/arch/x86/kvm/x86.h
>> +++ b/arch/x86/kvm/x86.h
>> @@ -344,12 +344,6 @@ static inline bool kvm_cstate_in_guest(struct kvm *kvm)
>> return kvm->arch.cstate_in_guest;
>> }
>>
>> -enum kvm_intr_type {
>> - /* Values are arbitrary, but must be non-zero. */
>> - KVM_HANDLING_IRQ = 1,
>> - KVM_HANDLING_NMI,
>> -};
>> -
>> static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu,
>> enum kvm_intr_type intr)
>> {
>> --
>> 2.32.0
>>

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