From nobody Mon Feb 9 05:58:22 2026 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (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 2FDE321ABB9 for ; Fri, 31 Oct 2025 00:30:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761870657; cv=none; b=nr7GRd4jBg+R4m1gDfdhEoA7FVzlAlseTj8tu/QIngWNULfH3zM65H/VBdeYVxwSoXOV2oyvV1X0BtD7cfLfNVTm3kELwhqSmiEo+jpeB+hqnRjW/GFsnBM21fWxSsWs5mRCSxMD9zYCDZdnfhUX6H01mltcpYBYhP6q7eAdUNc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761870657; c=relaxed/simple; bh=CKcaOTjItVz4WLo4iTzMHZzjSrJXPFSfhk1I27YzRz8=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=PSoLSNqZouwgHAICihJbAvgsmNg+PA6MdN6ADI6sp/XwMo41YE2773wf9Ps1rwW5al/l57JvfQcoTNxHFDb4v/RVgTsKGs/oBfz0BT+u0phCMDwRoOW8RGVfnih6hfQ9MtlQutcJ8uQC8F9eN5aheA03NAx8mPRC7HK1fg2KMq4= 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=UyN/0dBI; arc=none smtp.client-ip=209.85.215.202 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="UyN/0dBI" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-b62b7af4fddso1204562a12.2 for ; Thu, 30 Oct 2025 17:30:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1761870655; x=1762475455; 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=plvc6sr/HSiAC52HAJ4IaJ4vyv8ZKviRrYeEAUlJ9Xc=; b=UyN/0dBIOtL71t37zvUkgh4S0/e/HronxyDumSllbzwO6S3qzY8iR7/vWMLFGI7ZE3 KFp1KcvQQcXL7Iomgx/ip+IjYR/Ep28rjJjbHCgoxk87b+QOsBTafGIwD74XBGStJq4g DAnR+JOZ23bksw46fHUT/VKGDuqevGjyJ6lGfxaG3z2mG3wbSJDg3ojPeTBC45ZgfDkt u2/0ATBizzVyNGaM1gzLkehQUeJco+pSq2Ur7u2VaSlCgJQsOg7vyTS77REeFb6ntEfa cEQxp+aOoI/eVo5GweOg8Uzmy0BHWttot8aiBNdAn/bjOb93vZCp6+5GX/LMdvagf17h K7wQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761870655; x=1762475455; 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=plvc6sr/HSiAC52HAJ4IaJ4vyv8ZKviRrYeEAUlJ9Xc=; b=ku15Nrs9/Z/X0jlGv6883GD9PkyuJa/bqyWm4XN5hx+Ky2o+L9cBgKcfJYH7/CSgaI /6tWXdOzXjm9fy1LRUGmg/vr4owhwDJCxJCIuAUt72SWbsSnVmEPfDRXZhrJ6U7/lexP CY999rUQuuTgoH7jM23D0pce8fIxJ8s0VtBTe7hm/D3xgVUzxlNaltjFaHEFvN4Z8Hhw fswJuzbmT7riqSaupkV77AWXEOol5T+kZAc52wkH36Ldt5BWJ7czGJoh7HQnQunlpEw5 1kHZiWDdqwQ5O3+NdfgfUd0X/V0yUPQCnqKxa1jgndc3odDgq0x4KKxgAyoELj5oZcbA E44w== X-Forwarded-Encrypted: i=1; AJvYcCWb+RieOuL9tjRDAuOOTGG0yfbFj5oyYvNEfqOAWpS0R92JZWPc/0fXZW1/MOhxMc9Y0O87+x979/ItVi4=@vger.kernel.org X-Gm-Message-State: AOJu0YymSp63ESuUEAjM2eKeQA2bgH6omOxHABmv7EyjTRwc4PffWj6M pG0Tn5krC2D3fiffU+TwVfjb6Lt0gllBF+T1Jec62RGm7IAKwkWJ2o9xXVJF6kZf2B9Cf82DRgn RZ6HRHQ== X-Google-Smtp-Source: AGHT+IFIzJ7ZEinVQ37x8dGUbzHaunbWA0l4ceoWMJoW0i44376UHeVDoVTVqIoOKauus5lpArxJCTtPusU= X-Received: from pjbcf5.prod.google.com ([2002:a17:90a:ebc5:b0:32d:a4d4:bb17]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:e212:b0:340:fce2:a152 with SMTP id adf61e73a8af0-348cca00f0bmr2183966637.55.1761870655555; Thu, 30 Oct 2025 17:30:55 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 30 Oct 2025 17:30:37 -0700 In-Reply-To: <20251031003040.3491385-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251031003040.3491385-1-seanjc@google.com> X-Mailer: git-send-email 2.51.1.930.gacf6e81ea2-goog Message-ID: <20251031003040.3491385-6-seanjc@google.com> Subject: [PATCH v4 5/8] 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 sequency 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. Signed-off-by: Sean Christopherson Acked-by: Borislav Petkov (AMD) Reviewed-by: Brendan Jackman --- 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 b29df45b1edb..88fe40d6949a 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -323,9 +323,6 @@ #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 235c4af6b692..da5f481cb17e 100644 --- a/arch/x86/kvm/svm/vmenter.S +++ b/arch/x86/kvm/svm/vmenter.S @@ -92,6 +92,8 @@ 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 @@ -170,7 +172,7 @@ 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 @@ -339,7 +341,7 @@ 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 2.51.1.930.gacf6e81ea2-goog