From nobody Mon Feb 9 02:13:24 2026 Received: from mail-pf1-f201.google.com (mail-pf1-f201.google.com [209.85.210.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 795EB329E77 for ; Thu, 13 Nov 2025 23:37:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763077082; cv=none; b=B5O1VES7hBcLDEjziqtPvX4SunWZBp5pa29PYEmMO79e2i/kU2Gyw76XvpAtcb+o3ju/AXATL3fmPbijRYnKEf6Y31kzSkfRQvVzEgFts+H4F1GSkRsRR2itFBStkDNESQCdDdhIPXQI2mX4JCvRJSOblt35Dweni96kAPR6Org= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763077082; c=relaxed/simple; bh=0snOzrDQ95f27zuaBEn47BWb8Pruz/6zOIKlPuSWTV4=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=HAeQZPkso0ovpTG/iSfznRJhnufb0anb0JMN9tFv0AP+ANQSDZF7lIIGwKdRW+hS67R1ELWzl8c7Kra02wFC6QHId5PJe/txP4tSv7ZnnUkx+qsYG8y31E+/wWt2bEOQOcc6FQo+P8WqyelxnMNiTlodVUpcXDQ6MuYzVLFU0j8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=3RSY+WCH; arc=none smtp.client-ip=209.85.210.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="3RSY+WCH" Received: by mail-pf1-f201.google.com with SMTP id d2e1a72fcca58-7aac981b333so1278532b3a.2 for ; Thu, 13 Nov 2025 15:37:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1763077079; x=1763681879; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=Wv5BfAollS99XFhIeOpKfkgpNs04gEhUuvVsDJUAfOk=; b=3RSY+WCH9/WGLFURTJaEXlSc22WizYLQ+UxZEugQWcgtdrM5AA9hkxj6N6LZSwMaHK Vpoecu0wavw/nmsfqI3i+mOEH5mPEryRmxi7fER8mgiEqOmWPyyYzCD7kLTwQ39z0cNt RzHBq67XuBUyN6ZV8cvmlCmOuUEK7RCH+SmmdHY72Aqlg0nlZIPxcVOEy/HmDv7qVlmV ShGWy5wzSG7kUYQpr0cnVukoLE6ApU66VfxGomozsHvrAxelWtGtWwUQaIcxWUjXG7Dc E+0lfgSpZJuZKYISg/VN6mkEQkDK3PMbN4qlVLbe3XSeIJxwyQKOWtwN/UiRk5C9BKrs AEew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763077079; x=1763681879; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Wv5BfAollS99XFhIeOpKfkgpNs04gEhUuvVsDJUAfOk=; b=IR9ui9fp8ve6+bBQgsolRWgPxnj+oFjIrCpKwqPbzt7RAwQgUAKQZzb97ZHTP2OPE8 /3YjKy3wYlUWqWVPgcNomHKGuDb7DZbwLYKi+qzyeOJqHNtxFqWVtS+5yePElP/NUezM iJDE51xH2dvopRYv2oXSf9NDlhdop44XCBA62lotiVLvMg2SJ0tI4licLmfK0IBCWKt9 JPwnWmFTRdmKGQbiAAfqqAz1MQX3SNb6UbzXTzDDBvIUGck1lIQNcb0Npjic6GFFyN7Z jYUMfL7/p2+F+pgg0ULTS/SNzDQSqXLOlCPEyP1wjyxzyKkQkDtIytsfASp7ZlRFIVh/ ZE5g== X-Forwarded-Encrypted: i=1; AJvYcCXP326hJAeIVWNJ3dncTPCCpwIIiwLrzNwhA8M49D8iOxtbFwAOcVJ0+4AwgtrUQ0c5dXLUY+Igyt8UcU0=@vger.kernel.org X-Gm-Message-State: AOJu0YyurvIXtvLpPS0c6ulqVDTfIFR/nlcQWkIxCLGCLygeU1N+IJ9h Hvu/JSefbfA1yIafT6W6Fh6Vix8Ia6Hk8M7nKe1XNhqGvUhIQtV7lpzDcOn7j9t2l0Cy0aG/HR1 IJtYpug== X-Google-Smtp-Source: AGHT+IEbtSUSfVPD1OTBTXG3h1YJ+Su4Df2wRMJHldoJY/HJ5rz+ppkYTp4GcI5dxuBKeGbAnXDLEg3pOLQ= X-Received: from pgbfe16.prod.google.com ([2002:a05:6a02:2890:b0:bac:a20:5f0a]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:12d2:b0:348:9a99:6253 with SMTP id adf61e73a8af0-35ba2796ff5mr1438155637.57.1763077078702; Thu, 13 Nov 2025 15:37:58 -0800 (PST) Reply-To: Sean Christopherson Date: Thu, 13 Nov 2025 15:37:43 -0800 In-Reply-To: <20251113233746.1703361-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251113233746.1703361-1-seanjc@google.com> X-Mailer: git-send-email 2.52.0.rc1.455.g30608eb744-goog Message-ID: <20251113233746.1703361-7-seanjc@google.com> Subject: [PATCH v5 6/9] x86/bugs: KVM: Move VM_CLEAR_CPU_BUFFERS into SVM as SVM_CLEAR_CPU_BUFFERS From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Borislav Petkov , Peter Zijlstra , Josh Poimboeuf Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Pawan Gupta , Brendan Jackman Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Now that VMX encodes its own sequence for clearing CPU buffers, move VM_CLEAR_CPU_BUFFERS into SVM to minimize the chances of KVM botching a mitigation in the future, e.g. using VM_CLEAR_CPU_BUFFERS instead of checking multiple mitigation flags. No functional change intended. Reviewed-by: Brendan Jackman Acked-by: Borislav Petkov (AMD) Signed-off-by: Sean Christopherson --- arch/x86/include/asm/nospec-branch.h | 3 --- arch/x86/kvm/svm/vmenter.S | 6 ++++-- 2 files changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/no= spec-branch.h index b1b1811216c5..3a5ac39877a0 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -324,9 +324,6 @@ #define CLEAR_CPU_BUFFERS \ ALTERNATIVE "", __CLEAR_CPU_BUFFERS, X86_FEATURE_CLEAR_CPU_BUF =20 -#define VM_CLEAR_CPU_BUFFERS \ - ALTERNATIVE "", __CLEAR_CPU_BUFFERS, X86_FEATURE_CLEAR_CPU_BUF_VM - #ifdef CONFIG_X86_64 .macro CLEAR_BRANCH_HISTORY ALTERNATIVE "", "call clear_bhb_loop", X86_FEATURE_CLEAR_BHB_LOOP diff --git a/arch/x86/kvm/svm/vmenter.S b/arch/x86/kvm/svm/vmenter.S index 98bfa2e00d88..3392bcadfb89 100644 --- a/arch/x86/kvm/svm/vmenter.S +++ b/arch/x86/kvm/svm/vmenter.S @@ -116,6 +116,8 @@ jmp 901b .endm =20 +#define SVM_CLEAR_CPU_BUFFERS \ + ALTERNATIVE "", __CLEAR_CPU_BUFFERS, X86_FEATURE_CLEAR_CPU_BUF_VM =20 /** * __svm_vcpu_run - Run a vCPU via a transition to SVM guest mode @@ -194,7 +196,7 @@ SYM_FUNC_START(__svm_vcpu_run) mov VCPU_RDI(%_ASM_DI), %_ASM_DI =20 /* Clobbers EFLAGS.ZF */ - VM_CLEAR_CPU_BUFFERS + SVM_CLEAR_CPU_BUFFERS =20 /* Enter guest mode */ 3: vmrun %_ASM_AX @@ -366,7 +368,7 @@ SYM_FUNC_START(__svm_sev_es_vcpu_run) mov KVM_VMCB_pa(%rax), %rax =20 /* Clobbers EFLAGS.ZF */ - VM_CLEAR_CPU_BUFFERS + SVM_CLEAR_CPU_BUFFERS =20 /* Enter guest mode */ 1: vmrun %rax --=20 2.52.0.rc1.455.g30608eb744-goog