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SubjectRe: [PATCH] KVM: x86/mmu: preserve pending TLB flush across calls to kvm_tdp_mmu_zap_sp
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On 06/04/21 20:25, Greg KH wrote:
> On Tue, Apr 06, 2021 at 12:25:50PM -0400, Paolo Bonzini wrote:
>> Right now, if a call to kvm_tdp_mmu_zap_sp returns false, the caller
>> will skip the TLB flush, which is wrong. There are two ways to fix
>> it:
>>
>> - since kvm_tdp_mmu_zap_sp will not yield and therefore will not flush
>> the TLB itself, we could change the call to kvm_tdp_mmu_zap_sp to
>> use "flush |= ..."
>>
>> - or we can chain the flush argument through kvm_tdp_mmu_zap_sp down
>> to __kvm_tdp_mmu_zap_gfn_range.
>>
>> This patch does the former to simplify application to stable kernels.
>>
>> Cc: seanjc@google.com
>> Fixes: 048f49809c526 ("KVM: x86/mmu: Ensure TLBs are flushed for TDP MMU during NX zapping")
>> Cc: <stable@vger.kernel.org> # 5.10.x: 048f49809c: KVM: x86/mmu: Ensure TLBs are flushed for TDP MMU during NX zapping
>> Cc: <stable@vger.kernel.org> # 5.10.x: 33a3164161: KVM: x86/mmu: Don't allow TDP MMU to yield when recovering NX pages
>> Cc: <stable@vger.kernel.org>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>> arch/x86/kvm/mmu/mmu.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Is this for only the stable kernels, or is it addressed toward upstream
> merges?
>
> Confused,

It's for upstream. I'll include it (with the expected "[ Upstream
commit abcd ]" header) when I post the complete backport. I'll send
this patch to Linus as soon as I get a review even if I don't have
anything else in the queue, so (as a general idea) the full backport
should be sent and tested on Thursday-Friday.

Paolo

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