Commit 9b58b985 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: SVM: Convert feature updates from CPUID to KVM cpu caps 



Use the recently introduced KVM CPU caps to propagate SVM-only (kernel)
settings to supported CPUID flags.

Note, there are a few subtleties:

  - Setting a flag based on a *different* feature is effectively
    emulation, and must be done at runtime via ->set_supported_cpuid().

  - CPUID 0x8000000A.EDX is a feature leaf that was previously not
    adjusted by kvm_cpu_cap_mask() because all features are hidden by
    default.

Opportunistically add a technically unnecessary break and fix an
indentation issue in svm_set_supported_cpuid().

No functional change intended.

Reviewed-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 66a6950f

arch/x86/kvm/cpuid.c

+6 −0
Original line number Diff line number Diff line
@@ -370,6 +370,12 @@ void kvm_set_cpu_caps(void) 
		F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON)

	);



	/*

	 * Hide all SVM features by default, SVM will set the cap bits for

	 * features it emulates and/or exposes for L1.

	 */

	kvm_cpu_cap_mask(CPUID_8000_000A_EDX, 0);



	kvm_cpu_cap_mask(CPUID_C000_0001_EDX,

		F(XSTORE) | F(XSTORE_EN) | F(XCRYPT) | F(XCRYPT_EN) |

		F(ACE2) | F(ACE2_EN) | F(PHE) | F(PHE_EN) |

arch/x86/kvm/svm.c

+30 −16
Original line number Diff line number Diff line
@@ -1367,6 +1367,23 @@ static void svm_hardware_teardown(void) 
	iopm_base = 0;

}



static __init void svm_set_cpu_caps(void)

{

	kvm_set_cpu_caps();



	/* CPUID 0x80000001 */

	if (nested)

		kvm_cpu_cap_set(X86_FEATURE_SVM);



	/* CPUID 0x8000000A */

	/* Support next_rip if host supports it */

	if (boot_cpu_has(X86_FEATURE_NRIPS))

		kvm_cpu_cap_set(X86_FEATURE_NRIPS);



	if (npt_enabled)

		kvm_cpu_cap_set(X86_FEATURE_NPT);

}



static __init int svm_hardware_setup(void)

{

	int cpu;
@@ -1479,7 +1496,7 @@ static __init int svm_hardware_setup(void) 
			pr_info("Virtual GIF supported\n");

	}



	kvm_set_cpu_caps();

	svm_set_cpu_caps();



	return 0;
@@ -6035,13 +6052,17 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu) 
					 APICV_INHIBIT_REASON_NESTED);

}



/*

 * Vendor specific emulation must be handled via ->set_supported_cpuid(), not

 * svm_set_cpu_caps(), as capabilities configured during hardware_setup() are

 * masked against hardware/kernel support, i.e. they'd be lost.

 *

 * Note, setting a flag based on a *different* feature, e.g. setting VIRT_SSBD

 * if LS_CFG_SSBD or AMD_SSBD is supported, is effectively emulation.

 */

static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry)

{

	switch (entry->function) {

	case 0x80000001:

		if (nested)

			cpuid_entry_set(entry, X86_FEATURE_SVM);

		break;

	case 0x80000008:

		if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||

		    boot_cpu_has(X86_FEATURE_AMD_SSBD))
@@ -6052,16 +6073,9 @@ static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry) 
		entry->ebx = 8; /* Lets support 8 ASIDs in case we add proper

				   ASID emulation to nested SVM */

		entry->ecx = 0; /* Reserved */

		entry->edx = 0; /* Per default do not support any

				   additional features */



		/* Support next_rip if host supports it */

		if (boot_cpu_has(X86_FEATURE_NRIPS))

			cpuid_entry_set(entry, X86_FEATURE_NRIPS);



		/* Support NPT for the guest if enabled */

		if (npt_enabled)

			cpuid_entry_set(entry, X86_FEATURE_NPT);

		/* Note, 0x8000000A.EDX is managed via kvm_cpu_caps. */;

		cpuid_entry_mask(entry, CPUID_8000_000A_EDX);

		break;

	}

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE