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SubjectRe: [PATCH 0/2] KVM: X86: Don't reset mmu context when changing PGE or PCID
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On 14/10/21 18:03, Lai Jiangshan wrote:
> Ping
>
> On 2021/9/19 10:42, Lai Jiangshan wrote:
>> From: Lai Jiangshan <laijs@linux.alibaba.com>
>>
>> This patchset uses kvm_vcpu_flush_tlb_guest() instead of
>> kvm_mmu_reset_context()
>> when X86_CR4_PGE is changed or X86_CR4_PCIDE is changed 1->0.
>>
>> Neither X86_CR4_PGE nor X86_CR4_PCIDE participates in kvm_mmu_role, so
>> kvm_mmu_reset_context() is not required to be invoked.  Only flushing tlb
>> is required as SDM says.
>>
>> The patchset has nothing to do with performance, because the overheads of
>> kvm_mmu_reset_context() and kvm_vcpu_flush_tlb_guest() are the same.  And
>> even in the [near] future, kvm_vcpu_flush_tlb_guest() will be optimized,
>> the code is not in the hot path.
>>
>> This patchset makes the code more clear when to reset the mmu context.
>> And it makes KVM_MMU_CR4_ROLE_BITS consistent with kvm_mmu_role.
>>
>> Lai Jiangshan (2):
>>    KVM: X86: Don't reset mmu context when X86_CR4_PCIDE 1->0
>>    KVM: X86: Don't reset mmu context when toggling X86_CR4_PGE
>>
>>   arch/x86/kvm/mmu.h | 5 ++---
>>   arch/x86/kvm/x86.c | 7 +++++--
>>   2 files changed, 7 insertions(+), 5 deletions(-)
>>
>

Queued with kvm_make_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu) replacement,
thanks.

Paolo

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