Re: [PATCH] KVM: x86/mmu: Stop zapping invalidated TDP MMU roots asynchronously

[David Matlack]

On 2023-10-19 01:11 PM, Sean Christopherson wrote:
> [ Upstream commit 0df9dab891ff0d9b646d82e4fe038229e4c02451 ]
> 
> Stop zapping invalidate TDP MMU roots via work queue now that KVM
> preserves TDP MMU roots until they are explicitly invalidated.  Zapping
> roots asynchronously was effectively a workaround to avoid stalling a vCPU
> for an extended during if a vCPU unloaded a root, which at the time
> happened whenever the guest toggled CR0.WP (a frequent operation for some
> guest kernels).
> 
[...]
> 
> Reported-by: Pattara Teerapong <pteerapong@xxxxxxxxxx>
> Cc: David Stevens <stevensd@xxxxxxxxxx>
> Cc: Yiwei Zhang<zzyiwei@xxxxxxxxxx>
> Cc: Paul Hsia <paulhsia@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> Message-Id: <20230916003916.2545000-4-seanjc@xxxxxxxxxx>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: David Matlack <dmatlack@xxxxxxxxxx>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> ---

Reviewed-by: David Matlack <dmatlack@xxxxxxxxxx>
Tested-by: David Matlack <dmatlack@xxxxxxxxxx>

(Ran all KVM selftests and kvm-unit-tests with lockdep enabled.)