Re: [PATCH] KVM: x86/mmu: Don't save mmu_invalidate_seq after checking private attr

[Sean Christopherson <seanjc@google.com>]

On Wed, Jun 05, 2024, Paolo Bonzini wrote:
> On 6/5/24 01:29, Sean Christopherson wrote:
> > On Tue, 28 May 2024 18:22:34 +0800, Tao Su wrote:
> > > Drop the second snapshot of mmu_invalidate_seq in kvm_faultin_pfn().
> > > Before checking the mismatch of private vs. shared, mmu_invalidate_seq is
> > > saved to fault->mmu_seq, which can be used to detect an invalidation
> > > related to the gfn occurred, i.e. KVM will not install a mapping in page
> > > table if fault->mmu_seq != mmu_invalidate_seq.
> > > 
> > > Currently there is a second snapshot of mmu_invalidate_seq, which may not
> > > be same as the first snapshot in kvm_faultin_pfn(), i.e. the gfn attribute
> > > may be changed between the two snapshots, but the gfn may be mapped in
> > > page table without hindrance. Therefore, drop the second snapshot as it
> > > has no obvious benefits.
> > > 
> > > [...]
> > 
> > Applied to kvm-x86 fixes, thanks!
> > 
> > [1/1] KVM: x86/mmu: Don't save mmu_invalidate_seq after checking private attr
> >        https://github.com/kvm-x86/linux/commit/f66e50ed09b3
> 
> Since I'm already sending a much larger pull request for -rc3, I guess you
> don't mind if I also queue this one. :)

Not at all, dropped from kvm-x86.