From: Chao Gao <chao.gao@intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, <kvm@vger.kernel.org>,
<linux-kernel@vger.kernel.org>,
Alexander Potapenko <glider@google.com>
Subject: Re: [PATCH 2/2] KVM: x86: Harden KVM against imbalanced load/put of guest FPU state
Date: Tue, 4 Nov 2025 14:07:19 +0800 [thread overview]
Message-ID: <aQmYF8jDKlzecQ6A@intel.com> (raw)
In-Reply-To: <20251030185802.3375059-3-seanjc@google.com>
On Thu, Oct 30, 2025 at 11:58:02AM -0700, Sean Christopherson wrote:
>Assert, via KVM_BUG_ON(), that guest FPU state isn't/is in use when
>loading/putting the FPU to help detect KVM bugs without needing an assist
>from KASAN. If an imbalanced load/put is detected, skip the redundant
>load/put to avoid clobbering guest state and/or crashing the host.
>
>Note, kvm_access_xstate_msr() already provides a similar assertion.
>
>Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
next prev parent reply other threads:[~2025-11-04 6:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-30 18:58 [PATCH 0/2] KVM: x86: Fix an FPU+CET splat Sean Christopherson
2025-10-30 18:58 ` [PATCH 1/2] KVM: x86: Unload "FPU" state on INIT if and only if its currently in-use Sean Christopherson
2025-11-04 3:10 ` Chao Gao
2025-10-30 18:58 ` [PATCH 2/2] KVM: x86: Harden KVM against imbalanced load/put of guest FPU state Sean Christopherson
2025-11-04 6:07 ` Chao Gao [this message]
2025-10-31 6:28 ` [PATCH 0/2] KVM: x86: Fix an FPU+CET splat Yao Yuan
2025-11-04 17:45 ` Sean Christopherson
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