From mboxrd@z Thu Jan 1 00:00:00 1970 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 D4E4044DB9D for ; Wed, 27 May 2026 17:44:06 +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=1779903849; cv=none; b=AlM8qvSrOpOvaebePOHXjzmAq7ZTZiWviVqDSFZ0AZ62m/Ry/2gPQnCmAtqccRhlYEUVV1e2z+ddtwH9S6JoubXp7frlcYASwDnBni0TIb0ejR9w1saKL1neFwbwE3yii2UGxs24Zj6e3VqbQh86xklUKfwgzXZwNC9EVz9r7po= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779903849; c=relaxed/simple; bh=g92puMUS5q4qjw4cCB0B3jIHADA2n8iUKrYZu5tW+Vs=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=hvIrVbujxr6dej/TDdh/kP+RkVk99NrHb6WjOErZV9jBVflFK1ayRN1fmk8dI55mFe6sHwdxRR8MXl/S0e1EOs/wW4QUo8C/X0HxT0MnFSilhyoCetbk+qiNjueqBbwwUlxEG7V6RkPfrx+SeCAK8v2sET51wtVfA0wXIeNzd5w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jmattson.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=czn7fz4L; 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--jmattson.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="czn7fz4L" Received: by mail-pf1-f201.google.com with SMTP id d2e1a72fcca58-841d02525b5so2095708b3a.0 for ; Wed, 27 May 2026 10:44:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1779903846; x=1780508646; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=k3wATNCkoFXn3WUzHEjzhnXj8xnV0EDTL1EvmQz7WMw=; b=czn7fz4L9v1GLjG5p1O7OX+5XbP14kY/kHZ48DoZ//vtbR/7lN6KRp1crQ42GiyBX4 ipLIAkNEon6Bv41gRCMhJtwDFRpOIS/809c0nwRkkQmqd5lVXoueRkY0O246NE5LrNdh 3/otNJMmeNUBlNqEnvVDFz4F+pDJAXi2W0Z4BVXkD0isnXw0H+6KtRxKVM98wZLFGbgW PW1WyodesY96RHJV51hBUvJNXJh3W7d7VkIqm8cVlR9mEYl16qIdLkrmFZX3P00vXcqC GEC/ZOzkw1Ghtzo8suJjYpwQ5jg/tUp/TWq9FwK81Qii7zadyBAK+2fT0e/vmzi1QgEL 5wSg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779903846; x=1780508646; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=k3wATNCkoFXn3WUzHEjzhnXj8xnV0EDTL1EvmQz7WMw=; b=XYBcvbkSsfHWIFPGzbeQVNlq1ye9rucuxk8QQLYWqa4MvT51q1JYPyjgr7oeRtxG4f tzyG0wSbIhCRuJcoSgu650TYX7R2zNwzDp2mCXXswvAuaAVUdo58QyajG5pEXJ4cDppS cnHxUKxX+3v7PSr3tCh5PrPVXGqnUZRhl24RuLHNl8GsafkEAqv0dX41cSS4+b8DLQKQ 1p+WV+keJWMxVIt5cjCuOlEaM9MmTzKjS8mVayGr5Pfgb7ONxXnmJj9RMQ7e0CrVpBnl EhZwi44TjdUQ1o9V+BO/6kqE6U06os1oW/net5ReQZd42ovva2i1c7JrJahP5LYS8dbd E1CQ== X-Forwarded-Encrypted: i=1; AFNElJ+5RoGJgkkORT5JvDLxMdlukF4u1PybUi3GM+hBfg3BfOOk2dNG6oSCBpzQE/ebVNF/eOf7jU/o3QsKCzc=@vger.kernel.org X-Gm-Message-State: AOJu0Yxnqt8Y+BBX+dy2/BcFPu4I5R5rmaiT+ZX9jDkRyAe+gv5Bme3+ EMZTJr67QnSMb885A17COg7vGLTd4jc5RFQi7wPYfIfzEZ3BxBIntyvHeZmoRZWpaKXBW0ihXCN IoCx/KCMHAMXLzA== X-Received: from pfuj10.prod.google.com ([2002:a05:6a00:130a:b0:836:6e32:7280]) (user=jmattson job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:715:b0:841:69e4:f21b with SMTP id d2e1a72fcca58-84169e4f7f5mr15277392b3a.39.1779903845550; Wed, 27 May 2026 10:44:05 -0700 (PDT) Date: Wed, 27 May 2026 10:43:46 -0700 In-Reply-To: <20260527174347.2356165-1-jmattson@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260527174347.2356165-1-jmattson@google.com> X-Mailer: git-send-email 2.54.0.794.g4f17f83d09-goog Message-ID: <20260527174347.2356165-5-jmattson@google.com> Subject: [PATCH v4 4/5] KVM: x86: Virtualize AMD CPUID faulting From: Jim Mattson To: seanjc@google.com, pbonzini@redhat.com, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, shuah@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, ctpence@google.com, David.Kaplan@amd.com, binbin.wu@linux.intel.com Cc: Jim Mattson Content-Type: text/plain; charset="UTF-8" On AMD CPUs, CPUID faulting support is advertised via CPUID.80000021H:EAX.CpuidUserDis[bit 17] and enabled by setting HWCR.CpuidUserDis[bit 35]. Advertise the feature to userspace regardless of host CPU support. Allow writes to HWCR to set bit 35 when the guest CPUID advertises CpuidUserDis. Update cpuid_fault_enabled() to check HWCR.CpuidUserDis as well as MSR_FEATURE_ENABLES.CPUID_GP_ON_CPL_GT_0. Unlike VMX, SVM prioritizes the CPUID intercept over the #GP induced by CPUID faulting.[1] This behavior has been confirmed on a Turin CPU (F/M/S 1AH/2/1). Link: https://lore.kernel.org/r/DS7PR12MB82011943131DF5415365E19E940B2@DS7PR12MB8201.namprd12.prod.outlook.com [1] Signed-off-by: Jim Mattson --- arch/x86/include/asm/msr-index.h | 1 + arch/x86/kvm/cpuid.c | 2 +- arch/x86/kvm/cpuid.h | 5 +++-- arch/x86/kvm/x86.c | 18 ++++++++++++------ 4 files changed, 17 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index a14a0f43e04a..f534f150d1c5 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -898,6 +898,7 @@ #define MSR_K7_HWCR_IRPERF_EN_BIT 30 #define MSR_K7_HWCR_IRPERF_EN BIT_ULL(MSR_K7_HWCR_IRPERF_EN_BIT) #define MSR_K7_HWCR_CPUID_USER_DIS_BIT 35 +#define MSR_K7_HWCR_CPUID_USER_DIS BIT_ULL(MSR_K7_HWCR_CPUID_USER_DIS_BIT) #define MSR_K7_FID_VID_CTL 0xc0010041 #define MSR_K7_FID_VID_STATUS 0xc0010042 #define MSR_K7_HWCR_CPB_DIS_BIT 25 diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 1c95d1fa3ead..8e5340dd2621 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -1248,7 +1248,7 @@ void kvm_initialize_cpu_caps(void) F(AUTOIBRS), EMULATED_F(NO_SMM_CTL_MSR), /* PrefetchCtlMsr */ - /* GpOnUserCpuid */ + EMULATED_F(GP_ON_USER_CPUID), /* EPSF */ F(PREFETCHI), F(AVX512_BMM), diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index 95d09ccbf951..fc96ba86c644 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -185,8 +185,9 @@ static inline int guest_cpuid_stepping(struct kvm_vcpu *vcpu) static inline bool cpuid_fault_enabled(struct kvm_vcpu *vcpu) { - return vcpu->arch.msr_misc_features_enables & - MSR_MISC_FEATURES_ENABLES_CPUID_FAULT; + return (vcpu->arch.msr_misc_features_enables & + MSR_MISC_FEATURES_ENABLES_CPUID_FAULT) || + (vcpu->arch.msr_hwcr & MSR_K7_HWCR_CPUID_USER_DIS); } static inline bool kvm_is_cpuid_allowed(struct kvm_vcpu *vcpu) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d5a2d794c3c9..54c552efb59e 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4002,22 +4002,28 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) break; case MSR_EFER: return set_efer(vcpu, msr_info); - case MSR_K7_HWCR: - data &= ~(u64)0x40; /* ignore flush filter disable */ - data &= ~(u64)0x100; /* ignore ignne emulation enable */ - data &= ~(u64)0x8; /* ignore TLB cache disable */ - + case MSR_K7_HWCR: { /* * Allow McStatusWrEn and TscFreqSel. (Linux guests from v3.2 * through at least v6.6 whine if TscFreqSel is clear, * depending on F/M/S. */ - if (data & ~(BIT_ULL(18) | BIT_ULL(24))) { + u64 valid = BIT_ULL(18) | BIT_ULL(24); + + data &= ~(u64)0x40; /* ignore flush filter disable */ + data &= ~(u64)0x100; /* ignore ignne emulation enable */ + data &= ~(u64)0x8; /* ignore TLB cache disable */ + + if (guest_cpu_cap_has(vcpu, X86_FEATURE_GP_ON_USER_CPUID)) + valid |= MSR_K7_HWCR_CPUID_USER_DIS; + + if (data & ~valid) { kvm_pr_unimpl_wrmsr(vcpu, msr, data); return 1; } vcpu->arch.msr_hwcr = data; break; + } case MSR_FAM10H_MMIO_CONF_BASE: if (data != 0) { kvm_pr_unimpl_wrmsr(vcpu, msr, data); -- 2.54.0.794.g4f17f83d09-goog