kvm: vmx: add MSR logic for XSAVES

Add logic to get/set the XSS model-specific register.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 29 insertions, 1 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0271f6bcf123..0c4c88c008ce 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -362,6 +362,7 @@ struct kvm_vcpu_arch {
         int mp_state;
         u64 ia32_misc_enable_msr;
         bool tpr_access_reporting;
+        u64 ia32_xss;
 
         /*
          * Paging state of the vcpu
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 88048c72b6b1..ad1153a725a2 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -99,6 +99,8 @@ module_param_named(enable_shadow_vmcs, enable_shadow_vmcs, bool, S_IRUGO);
 static bool __read_mostly nested = 0;
 module_param(nested, bool, S_IRUGO);
 
+static u64 __read_mostly host_xss;
+
 #define KVM_GUEST_CR0_MASK (X86_CR0_NW | X86_CR0_CD)
 #define KVM_VM_CR0_ALWAYS_ON_UNRESTRICTED_GUEST (X86_CR0_WP | X86_CR0_NE)
 #define KVM_VM_CR0_ALWAYS_ON                                            \
@@ -2570,6 +2572,11 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
                 if (!nested_vmx_allowed(vcpu))
                         return 1;
                 return vmx_get_vmx_msr(vcpu, msr_index, pdata);
+        case MSR_IA32_XSS:
+                if (!vmx_xsaves_supported())
+                        return 1;
+                data = vcpu->arch.ia32_xss;
+                break;
         case MSR_TSC_AUX:
                 if (!to_vmx(vcpu)->rdtscp_enabled)
                         return 1;
@@ -2661,6 +2668,22 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
                 break;
         case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC:
                 return 1; /* they are read-only */
+        case MSR_IA32_XSS:
+                if (!vmx_xsaves_supported())
+                        return 1;
+                /*
+                 * The only supported bit as of Skylake is bit 8, but
+                 * it is not supported on KVM.
+                 */
+                if (data != 0)
+                        return 1;
+                vcpu->arch.ia32_xss = data;
+                if (vcpu->arch.ia32_xss != host_xss)
+                        add_atomic_switch_msr(vmx, MSR_IA32_XSS,
+                                vcpu->arch.ia32_xss, host_xss);
+                else
+                        clear_atomic_switch_msr(vmx, MSR_IA32_XSS);
+                break;
         case MSR_TSC_AUX:
                 if (!vmx->rdtscp_enabled)
                         return 1;
@@ -2896,7 +2919,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
                         SECONDARY_EXEC_ENABLE_INVPCID |
                         SECONDARY_EXEC_APIC_REGISTER_VIRT |
                         SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
-                        SECONDARY_EXEC_SHADOW_VMCS;
+                        SECONDARY_EXEC_SHADOW_VMCS |
+                        SECONDARY_EXEC_XSAVES;
                 if (adjust_vmx_controls(min2, opt2,
                                         MSR_IA32_VMX_PROCBASED_CTLS2,
                                         &_cpu_based_2nd_exec_control) < 0)
@@ -3019,6 +3043,9 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
                 }
         }
 
+        if (cpu_has_xsaves)
+                rdmsrl(MSR_IA32_XSS, host_xss);
+
         return 0;
 }