Commit db574f2f authored by Tao Su's avatar Tao Su Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Don't save mmu_invalidate_seq after checking private attr 



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.

Fixes: f6adeae8 ("KVM: x86/mmu: Handle no-slot faults at the beginning of kvm_faultin_pfn()")
Signed-off-by: default avatarTao Su <tao1.su@linux.intel.com>
Message-ID: <20240528102234.2162763-1-tao1.su@linux.intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 45ce0314

arch/x86/kvm/mmu/mmu.c

+0 −3
Original line number Diff line number Diff line
@@ -4411,9 +4411,6 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, 
			return RET_PF_EMULATE;

	}



	fault->mmu_seq = vcpu->kvm->mmu_invalidate_seq;

	smp_rmb();



	/*

	 * Check for a relevant mmu_notifier invalidation event before getting

	 * the pfn from the primary MMU, and before acquiring mmu_lock.