Commit 0cf9135b authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86: Emulate MSR_IA32_ARCH_CAPABILITIES on AMD hosts 



The CPUID flag ARCH_CAPABILITIES is unconditioinally exposed to host
userspace for all x86 hosts, i.e. KVM advertises ARCH_CAPABILITIES
regardless of hardware support under the pretense that KVM fully
emulates MSR_IA32_ARCH_CAPABILITIES.  Unfortunately, only VMX hosts
handle accesses to MSR_IA32_ARCH_CAPABILITIES (despite KVM_GET_MSRS
also reporting MSR_IA32_ARCH_CAPABILITIES for all hosts).

Move the MSR_IA32_ARCH_CAPABILITIES handling to common x86 code so
that it's emulated on AMD hosts.

Fixes: 1eaafe91 ("kvm: x86: IA32_ARCH_CAPABILITIES is always supported")
Cc: stable@vger.kernel.org
Reported-by: default avatarXiaoyao Li <xiaoyao.li@linux.intel.com>
Cc: Jim Mattson <jmattson@google.com>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent ca0488aa

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -568,6 +568,7 @@ struct kvm_vcpu_arch { 
	bool tpr_access_reporting;

	u64 ia32_xss;

	u64 microcode_version;

	u64 arch_capabilities;



	/*

	 * Paging state of the vcpu

arch/x86/kvm/vmx/vmx.c

+0 −13
Original line number Diff line number Diff line
@@ -1683,12 +1683,6 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 


		msr_info->data = to_vmx(vcpu)->spec_ctrl;

		break;

	case MSR_IA32_ARCH_CAPABILITIES:

		if (!msr_info->host_initiated &&

		    !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES))

			return 1;

		msr_info->data = to_vmx(vcpu)->arch_capabilities;

		break;

	case MSR_IA32_SYSENTER_CS:

		msr_info->data = vmcs_read32(GUEST_SYSENTER_CS);

		break;
@@ -1895,11 +1889,6 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
		vmx_disable_intercept_for_msr(vmx->vmcs01.msr_bitmap, MSR_IA32_PRED_CMD,

					      MSR_TYPE_W);

		break;

	case MSR_IA32_ARCH_CAPABILITIES:

		if (!msr_info->host_initiated)

			return 1;

		vmx->arch_capabilities = data;

		break;

	case MSR_IA32_CR_PAT:

		if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {

			if (!kvm_mtrr_valid(vcpu, MSR_IA32_CR_PAT, data))
@@ -4088,8 +4077,6 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx) 
		++vmx->nmsrs;

	}



	vmx->arch_capabilities = kvm_get_arch_capabilities();



	vm_exit_controls_init(vmx, vmx_vmexit_ctrl());



	/* 22.2.1, 20.8.1 */

arch/x86/kvm/vmx/vmx.h

+0 −1
Original line number Diff line number Diff line
@@ -190,7 +190,6 @@ struct vcpu_vmx { 
	u64		      msr_guest_kernel_gs_base;

#endif



	u64		      arch_capabilities;

	u64		      spec_ctrl;



	u32 vm_entry_controls_shadow;

arch/x86/kvm/x86.c

+12 −0
Original line number Diff line number Diff line
@@ -2443,6 +2443,11 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
		if (msr_info->host_initiated)

			vcpu->arch.microcode_version = data;

		break;

	case MSR_IA32_ARCH_CAPABILITIES:

		if (!msr_info->host_initiated)

			return 1;

		vcpu->arch.arch_capabilities = data;

		break;

	case MSR_EFER:

		return set_efer(vcpu, data);

	case MSR_K7_HWCR:
@@ -2747,6 +2752,12 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
	case MSR_IA32_UCODE_REV:

		msr_info->data = vcpu->arch.microcode_version;

		break;

	case MSR_IA32_ARCH_CAPABILITIES:

		if (!msr_info->host_initiated &&

		    !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES))

			return 1;

		msr_info->data = vcpu->arch.arch_capabilities;

		break;

	case MSR_IA32_TSC:

		msr_info->data = kvm_scale_tsc(vcpu, rdtsc()) + vcpu->arch.tsc_offset;

		break;
@@ -8733,6 +8744,7 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, 


int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)

{

	vcpu->arch.arch_capabilities = kvm_get_arch_capabilities();

	vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT;

	kvm_vcpu_mtrr_init(vcpu);

	vcpu_load(vcpu);

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