linux-kernel - [PATCH v6 13/21] kvm: x86: Emulate IA32_XFD

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Date:   Fri,  7 Jan 2022 13:55:04 -0500
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     guang.zeng@...el.com, jing2.liu@...el.com, kevin.tian@...el.com,
        seanjc@...gle.com, tglx@...utronix.de, wei.w.wang@...el.com,
        yang.zhong@...el.com
Subject: [PATCH v6 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>
Message-Id: <20220105123532.12586-14-yang.zhong@...el.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.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 bb9534590a3a..2475b64cb762 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1377,7 +1377,7 @@ 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)];
@@ -3699,6 +3699,17 @@ 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))
@@ -4028,6 +4039,13 @@ 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))
@@ -6465,6 +6483,7 @@ 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;
-- 
2.31.1