[PATCH 8/9] kvm: vmx: add MSR logic for XSAVES

Paolo Bonzini
2014-12-04T15:57:13Z

From: Wanpeng Li <wanpeng.li@linux.intel.com>

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

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/vmx.c | 29 ++++++++++++++++++++++++++++-
2 files changed, 29 insertions(+), 1 deletion(-)

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;
}

--
1.8.3.1