From nobody Sat Feb 7 14:39:22 2026 Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) (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 643FA42883F for ; Fri, 6 Feb 2026 19:09:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.188 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770404951; cv=none; b=algog17TzKECtk9kXuxVgtWSzZ4W0Ner6eQhbjTs/4oqnq1eXy/iqETQQ/NkqNZ+GIVX9OaNwrj30mXjNCRrPaPfP10GK2KRWZNNirxTsT8Y4ekaYX7TZEP4tsB5dxVpvNWlKJx3Mz2d5xcef9y0uJR3ib4Hmc3LjtpguxzeJNQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770404951; c=relaxed/simple; bh=Kmr1cFOljWw2hgaMq50BmZqyywx7sk43KBMKDj7eJu4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=k356Me+4YMn9b0K/YMIttviY5yOVm362D6PgUYB1m/2Te8dVWtQszxtBDLdb4KwzT0mqJmU9Ym3kXXyMerYa6T11KT6dOtNno33UuyUEZ91X5jjLCEnQyDokLdYGwf4kQYZdCwsc7saGuR6Zt3QY7V9gYfRzMV789HjCWtodWQ4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=b6CxSVCo; arc=none smtp.client-ip=91.218.175.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="b6CxSVCo" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1770404949; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=aWtD9FCS1AgrEOXeXG6aQzMP8BhNwBCqOc4fqV1JL44=; b=b6CxSVCojNDocHy3aD1EJ7m7RUHzPNwC70DmUS2Ncu9Ekl6oCKFKBCWllkgQUD9yBMg3mB oIbLHstgrX63A8rWFCmCNbBoNfheup5Oq/X1Pi//qgV0AeM0vE1j1wVOn7U0cH/THAFsJE Os2NP6gYEwMTE09DKM0sIiOjmE++N7w= From: Yosry Ahmed To: Sean Christopherson Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Yosry Ahmed , stable@vger.kernel.org Subject: [PATCH v5 01/26] KVM: nSVM: Avoid clearing VMCB_LBR in vmcb12 Date: Fri, 6 Feb 2026 19:08:26 +0000 Message-ID: <20260206190851.860662-2-yosry.ahmed@linux.dev> In-Reply-To: <20260206190851.860662-1-yosry.ahmed@linux.dev> References: <20260206190851.860662-1-yosry.ahmed@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" svm_copy_lbrs() always marks VMCB_LBR dirty in the destination VMCB. However, nested_svm_vmexit() uses it to copy LBRs to vmcb12, and clearing clean bits in vmcb12 is not architecturally defined. Move vmcb_mark_dirty() to callers and drop it for vmcb12. This also facilitates incoming refactoring that does not pass the entire VMCB to svm_copy_lbrs(). Fixes: d20c796ca370 ("KVM: x86: nSVM: implement nested LBR virtualization") Cc: stable@vger.kernel.org Signed-off-by: Yosry Ahmed --- arch/x86/kvm/svm/nested.c | 7 +++++-- arch/x86/kvm/svm/svm.c | 2 -- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index de90b104a0dd..a31f3be1e16e 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -714,6 +714,7 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm = *svm, struct vmcb *vmcb12 } else { svm_copy_lbrs(vmcb02, vmcb01); } + vmcb_mark_dirty(vmcb02, VMCB_LBR); svm_update_lbrv(&svm->vcpu); } =20 @@ -1232,10 +1233,12 @@ int nested_svm_vmexit(struct vcpu_svm *svm) kvm_make_request(KVM_REQ_EVENT, &svm->vcpu); =20 if (unlikely(guest_cpu_cap_has(vcpu, X86_FEATURE_LBRV) && - (svm->nested.ctl.virt_ext & LBR_CTL_ENABLE_MASK))) + (svm->nested.ctl.virt_ext & LBR_CTL_ENABLE_MASK))) { svm_copy_lbrs(vmcb12, vmcb02); - else + } else { svm_copy_lbrs(vmcb01, vmcb02); + vmcb_mark_dirty(vmcb01, VMCB_LBR); + } =20 svm_update_lbrv(vcpu); =20 diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 5f0136dbdde6..98cbd7c7beed 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -848,8 +848,6 @@ void svm_copy_lbrs(struct vmcb *to_vmcb, struct vmcb *f= rom_vmcb) to_vmcb->save.br_to =3D from_vmcb->save.br_to; to_vmcb->save.last_excp_from =3D from_vmcb->save.last_excp_from; to_vmcb->save.last_excp_to =3D from_vmcb->save.last_excp_to; - - vmcb_mark_dirty(to_vmcb, VMCB_LBR); } =20 static void __svm_enable_lbrv(struct kvm_vcpu *vcpu) --=20 2.53.0.rc2.204.g2597b5adb4-goog