From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1644C31A077; Wed, 3 Dec 2025 16:39:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764779976; cv=none; b=Kvfql1v8s3LBvLyFFpSt6Q0NdZjvlNF+cl/AldVesZRKPjbMj7ZHkVim2SJq0uHdCTG6I8JCsg0bUo8TXdZ4KzjIyevsejtjUXvInb0gzzTlnj5XTEbuMmrqhVSnlbr9VCSCYy5hoBf4qYT9gTJBKuPr1Qdfef9GxYakV5ke+X8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764779976; c=relaxed/simple; bh=M0dvR6WmuFRPqCtcxsST9z9oLau2zmj0a7Ut+OVWBBE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=O7ISileT+XOMUOpAak9t1O67Gt8NflhNsgEOs3o3SPr/xd3zs04ToB92qTPqEzPTbBsVjHKaXs7nYE245ma9u7XeF0lhaSxowCcqof8P3SZjmFqV6K9bmm8Wj6BDqCHIhPkgm+1Q0IS7qfPengKXbRO2K7VdeLfIknU6VD730bU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cKDXVObA; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="cKDXVObA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 78DD1C4CEF5; Wed, 3 Dec 2025 16:39:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1764779976; bh=M0dvR6WmuFRPqCtcxsST9z9oLau2zmj0a7Ut+OVWBBE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cKDXVObANcYdSLBzgEFP78KESShX2p9g94dbss9m25zAdtvbFEWbjrv9gs/fGWV8G JqkjPxU3vJqY6ADN4BlSvi+rDzPEkvXidcG3t0tXdAA97hxYC6tfP/yG8XnAQap8jn YIt+xBHGFy3+L0whv0pFip7Yyk2RNtev9tr3QJqM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Matteo Rizzo , evn@google.com, Jim Mattson , Yosry Ahmed , Paolo Bonzini , Sasha Levin Subject: [PATCH 6.1 417/568] KVM: SVM: Mark VMCB_LBR dirty when MSR_IA32_DEBUGCTLMSR is updated Date: Wed, 3 Dec 2025 16:26:59 +0100 Message-ID: <20251203152455.968090987@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251203152440.645416925@linuxfoundation.org> References: <20251203152440.645416925@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yosry Ahmed [ Upstream commit dc55b3c3f61246e483e50c85d8d5366f9567e188 ] The APM lists the DbgCtlMsr field as being tracked by the VMCB_LBR clean bit. Always clear the bit when MSR_IA32_DEBUGCTLMSR is updated. The history is complicated, it was correctly cleared for L1 before commit 1d5a1b5860ed ("KVM: x86: nSVM: correctly virtualize LBR msrs when L2 is running"). At that point svm_set_msr() started to rely on svm_update_lbrv() to clear the bit, but when nested virtualization is enabled the latter does not always clear it even if MSR_IA32_DEBUGCTLMSR changed. Go back to clearing it directly in svm_set_msr(). Fixes: 1d5a1b5860ed ("KVM: x86: nSVM: correctly virtualize LBR msrs when L2 is running") Reported-by: Matteo Rizzo Reported-by: evn@google.com Co-developed-by: Jim Mattson Signed-off-by: Jim Mattson Signed-off-by: Yosry Ahmed Link: https://patch.msgid.link/20251108004524.1600006-2-yosry.ahmed@linux.dev Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini [ Open coded svm_get_lbr_vmcb() call ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/svm/svm.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -3053,11 +3053,17 @@ static int svm_set_msr(struct kvm_vcpu * if (data & DEBUGCTL_RESERVED_BITS) return 1; - if (svm->vmcb->control.virt_ext & LBR_CTL_ENABLE_MASK) + if (svm->vmcb->control.virt_ext & LBR_CTL_ENABLE_MASK) { + if (svm->vmcb->save.dbgctl == data) + break; svm->vmcb->save.dbgctl = data; - else + } else { + if (svm->vmcb01.ptr->save.dbgctl == data) + break; svm->vmcb01.ptr->save.dbgctl = data; + } + vmcb_mark_dirty(svm->vmcb, VMCB_LBR); svm_update_lbrv(vcpu); break;