linux-kernel - [PATCH v4 13/21] kvm: x86: Emulate IA32_XFD

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Message-Id: <20211229131328.12283-14-yang.zhong@intel.com>
Date:   Wed, 29 Dec 2021 05:13:20 -0800
From:   Yang Zhong <yang.zhong@...el.com>
To:     x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, pbonzini@...hat.com, corbet@....net,
        shuah@...nel.org
Cc:     seanjc@...gle.com, jun.nakajima@...el.com, kevin.tian@...el.com,
        jing2.liu@...ux.intel.com, jing2.liu@...el.com,
        guang.zeng@...el.com, wei.w.wang@...el.com, yang.zhong@...el.com
Subject: [PATCH v4 13/21] kvm: x86: Emulate IA32_XFD_ERR for guest

From: Jing Liu <jing2.liu@...el.com>

Emulate read/write to IA32_XFD_ERR MSR.

Only the saved value in the guest_fpu container is touched in the
emulation handler. Actual MSR update is handled right before entering
the guest (with preemption disabled)

Signed-off-by: Zeng Guang <guang.zeng@...el.com>
Signed-off-by: Wei Wang <wei.w.wang@...el.com>
Signed-off-by: Jing Liu <jing2.liu@...el.com>
Signed-off-by: Yang Zhong <yang.zhong@...el.com>
---
 arch/x86/kvm/x86.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b22defad5cab..a48a89f73027 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1359,7 +1359,7 @@ static const u32 msrs_to_save_all[] = {
 	MSR_F15H_PERF_CTL3, MSR_F15H_PERF_CTL4, MSR_F15H_PERF_CTL5,
 	MSR_F15H_PERF_CTR0, MSR_F15H_PERF_CTR1, MSR_F15H_PERF_CTR2,
 	MSR_F15H_PERF_CTR3, MSR_F15H_PERF_CTR4, MSR_F15H_PERF_CTR5,
-	MSR_IA32_XFD,
+	MSR_IA32_XFD, MSR_IA32_XFD_ERR,
 };
 
 static u32 msrs_to_save[ARRAY_SIZE(msrs_to_save_all)];
@@ -3682,6 +3682,17 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 
 		fpu_update_guest_xfd(&vcpu->arch.guest_fpu, data);
 		break;
+	case MSR_IA32_XFD_ERR:
+		if (!msr_info->host_initiated &&
+		    !guest_cpuid_has(vcpu, X86_FEATURE_XFD))
+			return 1;
+
+		if (data & ~(XFEATURE_MASK_USER_DYNAMIC &
+			     vcpu->arch.guest_supported_xcr0))
+			return 1;
+
+		vcpu->arch.guest_fpu.xfd_err = data;
+		break;
 #endif
 	default:
 		if (kvm_pmu_is_valid_msr(vcpu, msr))
@@ -4011,6 +4022,13 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 
 		msr_info->data = vcpu->arch.guest_fpu.fpstate->xfd;
 		break;
+	case MSR_IA32_XFD_ERR:
+		if (!msr_info->host_initiated &&
+		    !guest_cpuid_has(vcpu, X86_FEATURE_XFD))
+			return 1;
+
+		msr_info->data = vcpu->arch.guest_fpu.xfd_err;
+		break;
 #endif
 	default:
 		if (kvm_pmu_is_valid_msr(vcpu, msr_info->index))
@@ -6446,6 +6464,7 @@ static void kvm_init_msr_list(void)
 				continue;
 			break;
 		case MSR_IA32_XFD:
+		case MSR_IA32_XFD_ERR:
 			if (!kvm_cpu_cap_has(X86_FEATURE_XFD))
 				continue;
 			break;