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 E123E3E6DCF; Tue, 17 Mar 2026 17:13:34 +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=1773767615; cv=none; b=OvQiTUTtfx09FQK1tquJvkOCQfSyQRzlQxh1Gcc2f3zDrTD4jJiRsBK+2zgsAZLk3C5Qpfyoy3xEeeeUbyZbM6AK6wTCc9VtfwLIUWP20xDs1zWmIFnYU3QOH/m4QnbXTlK1UWliVElVMSKenqZYq4VrcEtqwa/aHQ6dU+6ZbAw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773767615; c=relaxed/simple; bh=UjGoSxRSBMfaoXHVqT0kCXwG4kQdD3fuDAL8qaI4Oag=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WSUH1wPwCV8R5FphGb7Hc7yRkW+5/JqVsG59igIqgDgbNLVn0rmcTHYeyP0U5odf6SttUSy0V/Ri/Ppy03kzbTJHKZPynO/W9YhfwkICurAmQy83gXXFDcdzFqOC/FyN6oF3i0ngBpjushG++cb011pJsl6gldiqFD8Bj/B4PHs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=PPYcvNTC; 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="PPYcvNTC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 19A6CC4CEF7; Tue, 17 Mar 2026 17:13:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1773767614; bh=UjGoSxRSBMfaoXHVqT0kCXwG4kQdD3fuDAL8qaI4Oag=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PPYcvNTCtfETestaw0BwApxWiSaFi84LfqRzJ4LtaAwblaIRTUQm3MuRHApnXk0aj NYXyl8wMYNc51lVoH42hBQ+a+NQkZNuDoqry2Xizr583JfBZyIxY1OE0f7cG5hZuh6 AvsZftNXhmrSb604QpEglaS/9vdaN1/8ghGudZnI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jim Mattson , Sean Christopherson , Paolo Bonzini Subject: [PATCH 6.18 123/333] KVM: x86: Introduce KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM Date: Tue, 17 Mar 2026 17:32:32 +0100 Message-ID: <20260317163003.927182647@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260317162959.345812316@linuxfoundation.org> References: <20260317162959.345812316@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jim Mattson commit e2ffe85b6d2bb7780174b87aa4468a39be17eb81 upstream. Add KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM to allow L1 to set FREEZE_IN_SMM in vmcs12's GUEST_IA32_DEBUGCTL field, as permitted prior to commit 6b1dd26544d0 ("KVM: VMX: Preserve host's DEBUGCTLMSR_FREEZE_IN_SMM while running the guest"). Enable the quirk by default for backwards compatibility (like all quirks); userspace can disable it via KVM_CAP_DISABLE_QUIRKS2 for consistency with the constraints on WRMSR(IA32_DEBUGCTL). Note that the quirk only bypasses the consistency check. The vmcs02 bit is still owned by the host, and PMCs are not frozen during virtualized SMM. In particular, if a host administrator decides that PMCs should not be frozen during physical SMM, then L1 has no say in the matter. Fixes: 095686e6fcb4 ("KVM: nVMX: Check vmcs12->guest_ia32_debugctl on nested VM-Enter") Cc: stable@vger.kernel.org Signed-off-by: Jim Mattson Link: https://patch.msgid.link/20260205231537.1278753-1-jmattson@google.com [sean: tag for stable@, clean-up and fix goofs in the comment and docs] Signed-off-by: Sean Christopherson [Rename quirk. - Paolo] Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- Documentation/virt/kvm/api.rst | 8 ++++++++ arch/x86/include/asm/kvm_host.h | 3 ++- arch/x86/include/uapi/asm/kvm.h | 1 + arch/x86/kvm/vmx/nested.c | 22 ++++++++++++++++++---- 4 files changed, 29 insertions(+), 5 deletions(-) --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -8403,6 +8403,14 @@ KVM_X86_QUIRK_IGNORE_GUEST_PAT By d guest software, for example if it does not expose a bochs graphics device (which is known to have had a buggy driver). + +KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM By default, KVM relaxes the consistency + check for GUEST_IA32_DEBUGCTL in vmcs12 + to allow FREEZE_IN_SMM to be set. When + this quirk is disabled, KVM requires this + bit to be cleared. Note that the vmcs02 + bit is still completely controlled by the + host, regardless of the quirk setting. =================================== ============================================ 7.32 KVM_CAP_MAX_VCPU_ID --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -2473,7 +2473,8 @@ int memslot_rmap_alloc(struct kvm_memory KVM_X86_QUIRK_MWAIT_NEVER_UD_FAULTS | \ KVM_X86_QUIRK_SLOT_ZAP_ALL | \ KVM_X86_QUIRK_STUFF_FEATURE_MSRS | \ - KVM_X86_QUIRK_IGNORE_GUEST_PAT) + KVM_X86_QUIRK_IGNORE_GUEST_PAT | \ + KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM) #define KVM_X86_CONDITIONAL_QUIRKS \ (KVM_X86_QUIRK_CD_NW_CLEARED | \ --- a/arch/x86/include/uapi/asm/kvm.h +++ b/arch/x86/include/uapi/asm/kvm.h @@ -476,6 +476,7 @@ struct kvm_sync_regs { #define KVM_X86_QUIRK_SLOT_ZAP_ALL (1 << 7) #define KVM_X86_QUIRK_STUFF_FEATURE_MSRS (1 << 8) #define KVM_X86_QUIRK_IGNORE_GUEST_PAT (1 << 9) +#define KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM (1 << 10) #define KVM_STATE_NESTED_FORMAT_VMX 0 #define KVM_STATE_NESTED_FORMAT_SVM 1 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -3262,10 +3262,24 @@ static int nested_vmx_check_guest_state( if (CC(vmcs12->guest_cr4 & X86_CR4_CET && !(vmcs12->guest_cr0 & X86_CR0_WP))) return -EINVAL; - if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS) && - (CC(!kvm_dr7_valid(vmcs12->guest_dr7)) || - CC(!vmx_is_valid_debugctl(vcpu, vmcs12->guest_ia32_debugctl, false)))) - return -EINVAL; + if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS) { + u64 debugctl = vmcs12->guest_ia32_debugctl; + + /* + * FREEZE_IN_SMM is not virtualized, but allow L1 to set it in + * vmcs12's DEBUGCTL under a quirk for backwards compatibility. + * Note that the quirk only relaxes the consistency check. The + * vmcc02 bit is still under the control of the host. In + * particular, if a host administrator decides to clear the bit, + * then L1 has no say in the matter. + */ + if (kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM)) + debugctl &= ~DEBUGCTLMSR_FREEZE_IN_SMM; + + if (CC(!kvm_dr7_valid(vmcs12->guest_dr7)) || + CC(!vmx_is_valid_debugctl(vcpu, debugctl, false))) + return -EINVAL; + } if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PAT) && CC(!kvm_pat_valid(vmcs12->guest_ia32_pat)))