KVM: Introduce kvm_get_arch_capabilities()

Extracted from commit 5b76a3cff011 "KVM: VMX: Tell the nested
hypervisor to skip L1D flush on vmentry".  We will need this to let a
nested hypervisor know that we have applied the mitigation for TAA.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 39f2024..dc60648 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1226,6 +1226,7 @@ void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu);
 void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
                                           unsigned long address);
 
+u64 kvm_get_arch_capabilities(void);
 void kvm_define_shared_msr(unsigned index, u32 msr);
 int kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
 

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f8f9d1b..f6d79f4 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5079,8 +5079,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
                ++vmx->nmsrs;
        }
 
-       if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES))
-               rdmsrl(MSR_IA32_ARCH_CAPABILITIES, vmx->arch_capabilities);
+       vmx->arch_capabilities = kvm_get_arch_capabilities();
 
        vm_exit_controls_init(vmx, vmcs_config.vmexit_ctrl);
 

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ad8e19f..9df5bc3 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -995,6 +995,16 @@ static u32 emulated_msrs[] = {
 
 static unsigned num_emulated_msrs;
 
+u64 kvm_get_arch_capabilities(void)
+{
+       u64 data;
+
+       rdmsrl_safe(MSR_IA32_ARCH_CAPABILITIES, &data);
+
+       return data;
+}
+EXPORT_SYMBOL_GPL(kvm_get_arch_capabilities);
+
 static bool __kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
 {
        if (efer & EFER_FFXSR) {