Commit 50896de4 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: x86: always expose VIRT_SSBD to guests 



Even though it is preferrable to use SPEC_CTRL (represented by
X86_FEATURE_AMD_SSBD) instead of VIRT_SPEC, VIRT_SPEC is always
supported anyway because otherwise it would be impossible to
migrate from old to new CPUs.  Make this apparent in the
result of KVM_GET_SUPPORTED_CPUID as well.

However, we need to hide the bit on Intel processors, so move
the setting to svm_set_supported_cpuid.

Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reported-by: default avatarEduardo Habkost <ehabkost@redhat.com>
Reviewed-by: default avatarJim Mattson <jmattson@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 4c6903a0

arch/x86/kvm/svm.c

+9 −4
Original line number Diff line number Diff line
@@ -68,10 +68,8 @@ MODULE_DEVICE_TABLE(x86cpu, svm_cpu_id); 
#define SEG_TYPE_LDT 2

#define SEG_TYPE_BUSY_TSS16 3



#define SVM_FEATURE_NPT            (1 <<  0)

#define SVM_FEATURE_LBRV           (1 <<  1)

#define SVM_FEATURE_SVML           (1 <<  2)

#define SVM_FEATURE_NRIP           (1 <<  3)

#define SVM_FEATURE_TSC_RATE       (1 <<  4)

#define SVM_FEATURE_VMCB_CLEAN     (1 <<  5)

#define SVM_FEATURE_FLUSH_ASID     (1 <<  6)
@@ -5933,6 +5931,8 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu) 
	guest_cpuid_clear(vcpu, X86_FEATURE_X2APIC);

}



#define F(x) bit(X86_FEATURE_##x)



static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)

{

	switch (func) {
@@ -5944,6 +5944,11 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry) 
		if (nested)

			entry->ecx |= (1 << 2); /* Set SVM bit */

		break;

	case 0x80000008:

		if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||

		     boot_cpu_has(X86_FEATURE_AMD_SSBD))

			entry->ebx |= F(VIRT_SSBD);

		break;

	case 0x8000000A:

		entry->eax = 1; /* SVM revision 1 */

		entry->ebx = 8; /* Lets support 8 ASIDs in case we add proper
@@ -5954,11 +5959,11 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry) 


		/* Support next_rip if host supports it */

		if (boot_cpu_has(X86_FEATURE_NRIPS))

			entry->edx |= SVM_FEATURE_NRIP;

			entry->edx |= F(NRIPS);



		/* Support NPT for the guest if enabled */

		if (npt_enabled)

			entry->edx |= SVM_FEATURE_NPT;

			entry->edx |= F(NPT);



		break;

	case 0x8000001F:

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