KVM: SVM: Add a helper to look up the max physical ID for AVIC

To help with a future change, add a helper to look up the maximum
physical ID depending on the vCPU AVIC mode. No functional change
intended.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Naveen N Rao (AMD) <naveen@kernel.org>
Link: https://lore.kernel.org/r/0ab9bf5e20a3463a4aa3a5ea9bbbac66beedf1d1.1757009416.git.naveen@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 1a0573f5ff7ccbbc78c5172354545a7bf71cb43f..96bad58ee3b4953eb909279507e9a9805bbec432 100644 (file)
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -158,13 +158,31 @@ static void avic_set_x2apic_msr_interception(struct vcpu_svm *svm,
        svm->x2avic_msrs_intercepted = intercept;
 }
 
+static u32 avic_get_max_physical_id(struct kvm_vcpu *vcpu)
+{
+       u32 arch_max;
+
+       if (x2avic_enabled && apic_x2apic_mode(vcpu->arch.apic))
+               arch_max = X2AVIC_MAX_PHYSICAL_ID;
+       else
+               arch_max = AVIC_MAX_PHYSICAL_ID;
+
+       /*
+        * Despite its name, KVM_CAP_MAX_VCPU_ID represents the maximum APIC ID
+        * plus one, so the max possible APIC ID is one less than that.
+        */
+       return min(vcpu->kvm->arch.max_vcpu_ids - 1, arch_max);
+}
+
 static void avic_activate_vmcb(struct vcpu_svm *svm)
 {
        struct vmcb *vmcb = svm->vmcb01.ptr;
-       struct kvm *kvm = svm->vcpu.kvm;
+       struct kvm_vcpu *vcpu = &svm->vcpu;
 
        vmcb->control.int_ctl &= ~(AVIC_ENABLE_MASK | X2APIC_MODE_MASK);
+
        vmcb->control.avic_physical_id &= ~AVIC_PHYSICAL_MAX_INDEX_MASK;
+       vmcb->control.avic_physical_id |= avic_get_max_physical_id(vcpu);
 
        vmcb->control.int_ctl |= AVIC_ENABLE_MASK;
 
@@ -177,8 +195,7 @@ static void avic_activate_vmcb(struct vcpu_svm *svm)
         */
        if (x2avic_enabled && apic_x2apic_mode(svm->vcpu.arch.apic)) {
                vmcb->control.int_ctl |= X2APIC_MODE_MASK;
-               vmcb->control.avic_physical_id |= min(kvm->arch.max_vcpu_ids - 1,
-                                                     X2AVIC_MAX_PHYSICAL_ID);
+
                /* Disabling MSR intercept for x2APIC registers */
                avic_set_x2apic_msr_interception(svm, false);
        } else {
@@ -188,9 +205,6 @@ static void avic_activate_vmcb(struct vcpu_svm *svm)
                 */
                kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, &svm->vcpu);
 
-               /* For xAVIC and hybrid-xAVIC modes */
-               vmcb->control.avic_physical_id |= min(kvm->arch.max_vcpu_ids - 1,
-                                                     AVIC_MAX_PHYSICAL_ID);
                /* Enabling MSR intercept for x2APIC registers */
                avic_set_x2apic_msr_interception(svm, true);
        }