linux-kernel - Re: [PATCH MANUALSEL 5.15 1/8] KVM: X86: Fix tlb flush for tdp in kvm_invalidate

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Message-ID: <8b3b34a6-3aba-8471-453b-f15935edf438@redhat.com>
Date:   Wed, 24 Nov 2021 19:20:09 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Cc:     Lai Jiangshan <laijs@...ux.alibaba.com>, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, kvm@...r.kernel.org
Subject: Re: [PATCH MANUALSEL 5.15 1/8] KVM: X86: Fix tlb flush for tdp in
 kvm_invalidate_pcid()

On 11/23/21 17:36, Sasha Levin wrote:
> From: Lai Jiangshan <laijs@...ux.alibaba.com>
> 
> [ Upstream commit e45e9e3998f0001079b09555db5bb3b4257f6746 ]
> 
> The KVM doesn't know whether any TLB for a specific pcid is cached in
> the CPU when tdp is enabled.  So it is better to flush all the guest
> TLB when invalidating any single PCID context.
> 
> The case is very rare or even impossible since KVM generally doesn't
> intercept CR3 write or INVPCID instructions when tdp is enabled, so the
> fix is mostly for the sake of overall robustness.
> 
> Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
> Message-Id: <20211019110154.4091-2-jiangshanlai@...il.com>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> Signed-off-by: Sasha Levin <sashal@...nel.org>

Acked-by: Paolo Bonzini <pbonzini@...hat.com>

for this patch, but not to all the others.

Paolo