From: Sean Christopherson <seanjc@google.com>
To: Sasha Levin <sashal@kernel.org>
Cc: stable@vger.kernel.org, Dapeng Mi <dapeng1.mi@linux.intel.com>
Subject: Re: [PATCH 6.12.y 1/3] KVM: VMX: Extract checking of guest's DEBUGCTL into helper
Date: Thu, 14 Aug 2025 09:17:08 -0700 [thread overview]
Message-ID: <aJ4MBBiDTewc6i06@google.com> (raw)
In-Reply-To: <20250814125614.2090890-1-sashal@kernel.org>
On Thu, Aug 14, 2025, Sasha Levin wrote:
> From: Sean Christopherson <seanjc@google.com>
>
> [ Upstream commit 8a4351ac302cd8c19729ba2636acfd0467c22ae8 ]
>
> Move VMX's logic to check DEBUGCTL values into a standalone helper so that
> the code can be used by nested VM-Enter to apply the same logic to the
> value being loaded from vmcs12.
>
> KVM needs to explicitly check vmcs12->guest_ia32_debugctl on nested
> VM-Enter, as hardware may support features that KVM does not, i.e. relying
> on hardware to detect invalid guest state will result in false negatives.
> Unfortunately, that means applying KVM's funky suppression of BTF and LBR
> to vmcs12 so as not to break existing guests.
>
> No functional change intended.
>
> Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
> Link: https://lore.kernel.org/r/20250610232010.162191-6-seanjc@google.com
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> Stable-dep-of: 7d0cce6cbe71 ("KVM: VMX: Wrap all accesses to IA32_DEBUGCTL with getter/setter APIs")
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
Acked-by: Sean Christopherson <seanjc@google.com>
prev parent reply other threads:[~2025-08-14 16:17 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-12 16:15 FAILED: patch "[PATCH] KVM: VMX: Wrap all accesses to IA32_DEBUGCTL with" failed to apply to 6.12-stable tree gregkh
2025-08-14 12:56 ` [PATCH 6.12.y 1/3] KVM: VMX: Extract checking of guest's DEBUGCTL into helper Sasha Levin
2025-08-14 12:56 ` [PATCH 6.12.y 2/3] KVM: nVMX: Check vmcs12->guest_ia32_debugctl on nested VM-Enter Sasha Levin
2025-08-14 16:17 ` Sean Christopherson
2025-08-14 12:56 ` [PATCH 6.12.y 3/3] KVM: VMX: Wrap all accesses to IA32_DEBUGCTL with getter/setter APIs Sasha Levin
2025-08-14 16:18 ` Sean Christopherson
2025-08-14 16:17 ` Sean Christopherson [this message]
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