[PATCH v2 1/3] KVM: SVM: Configure ALLOW_LARGER_RAP in svm_vcpu_after_set_cpuid()

[Jim Mattson <jmattson@google.com>]

On initial vCPU creation, init_vmcb() is called before userspace configures
guest CPUID via KVM_SET_CPUID2. Consequently, ERAP_CONTROL_ALLOW_LARGER_RAP
is never set during initial vCPU creation. If an AP later receives an INIT
signal after CPUID has been set, init_vmcb() would set the bit for that AP,
but the BSP would be left with ALLOW_LARGER_RAP clear.

Configure ALLOW_LARGER_RAP in svm_vcpu_after_set_cpuid() to handle the BSP.

Keep the code in init_vmcb() to restore ALLOW_LARGER_RAP after the VMCB has
been cleared on the VCPU triple-fault reset path.

Fixes: db5e82496492 ("KVM: SVM: Virtualize and advertise support for ERAPS")
Assisted-by: Gemini:Gemini-Next
Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kvm/svm/svm.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 4d2bacd00ec4..bf868da14cd2 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4736,6 +4736,11 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 	if (guest_cpuid_is_intel_compatible(vcpu))
 		guest_cpu_cap_clear(vcpu, X86_FEATURE_V_VMSAVE_VMLOAD);
 
+	if (guest_cpu_cap_has(vcpu, X86_FEATURE_ERAPS))
+		svm->vmcb01.ptr->control.erap_ctl |= ERAP_CONTROL_ALLOW_LARGER_RAP;
+	else
+		svm->vmcb01.ptr->control.erap_ctl &= ~ERAP_CONTROL_ALLOW_LARGER_RAP;
+
 	if (is_sev_guest(vcpu))
 		sev_vcpu_after_set_cpuid(svm);
 }
-- 
2.55.0.229.g6434b31f56-goog