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From: David Matlack <dmatlack@google.com>
To: Sean Christopherson <seanjc@google.com>
Cc: stable@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Pattara Teerapong <pteerapong@google.com>,
	David Stevens <stevensd@google.com>,
	Yiwei Zhang <zzyiwei@google.com>, Paul Hsia <paulhsia@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH] KVM: x86/mmu: Stop zapping invalidated TDP MMU roots asynchronously
Date: Fri, 20 Oct 2023 11:52:34 -0700	[thread overview]
Message-ID: <ZTLMcmj-ycWhZuTX@google.com> (raw)
In-Reply-To: <20231019201138.2076865-1-seanjc@google.com>

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@google.com>
> Cc: David Stevens <stevensd@google.com>
> Cc: Yiwei Zhang<zzyiwei@google.com>
> Cc: Paul Hsia <paulhsia@google.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> Message-Id: <20230916003916.2545000-4-seanjc@google.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Cc: David Matlack <dmatlack@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---

Reviewed-by: David Matlack <dmatlack@google.com>
Tested-by: David Matlack <dmatlack@google.com>

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

  parent reply	other threads:[~2023-10-20 18:52 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-19 20:11 [PATCH] KVM: x86/mmu: Stop zapping invalidated TDP MMU roots asynchronously Sean Christopherson
2023-10-19 21:55 ` Sean Christopherson
2023-10-20 18:52 ` David Matlack [this message]
2023-10-21  9:10   ` Greg Kroah-Hartman

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