[PART1 RFC v3 10/12] svm: Do not expose x2APIC when enable AVIC

[Suravee Suthikulpanit]

From: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com>

Since AVIC only virtualizes xAPIC hardware for the guest, we need to:
    * Intercept APIC BAR msr accesses to disable x2APIC
    * Intercept CPUID access to not advertise x2APIC support
    * Hide x2APIC support when checking via KVM ioctl

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com>
---
 arch/x86/kvm/svm.c | 49 ++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 42 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 6303147..ba84d57 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -209,6 +209,7 @@ static const struct svm_direct_access_msrs {
        { .index = MSR_IA32_LASTBRANCHTOIP,             .always = false },
        { .index = MSR_IA32_LASTINTFROMIP,              .always = false },
        { .index = MSR_IA32_LASTINTTOIP,                .always = false },
+       { .index = MSR_IA32_APICBASE,                   .always = false },
        { .index = MSR_INVALID,                         .always = false },
 };
 
@@ -841,7 +842,7 @@ static void set_msr_interception(u32 *msrpm, unsigned msr,
        msrpm[offset] = tmp;
 }
 
-static void svm_vcpu_init_msrpm(u32 *msrpm)
+static void svm_vcpu_init_msrpm(struct vcpu_svm *svm, u32 *msrpm)
 {
        int i;
 
@@ -853,6 +854,9 @@ static void svm_vcpu_init_msrpm(u32 *msrpm)
 
                set_msr_interception(msrpm, direct_access_msrs[i].index, 1, 1);
        }
+
+       if (svm_vcpu_avic_enabled(svm))
+               set_msr_interception(msrpm, MSR_IA32_APICBASE, 1, 1);
 }
 
 static void add_msr_offset(u32 offset)
@@ -1394,18 +1398,18 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm 
*kvm, unsigned int id)
 
        svm->nested.hsave = page_address(hsave_page);
 
-       svm->msrpm = page_address(msrpm_pages);
-       svm_vcpu_init_msrpm(svm->msrpm);
-
-       svm->nested.msrpm = page_address(nested_msrpm_pages);
-       svm_vcpu_init_msrpm(svm->nested.msrpm);
-
        svm->vmcb = page_address(page);
        clear_page(svm->vmcb);
        svm->vmcb_pa = page_to_pfn(page) << PAGE_SHIFT;
        svm->asid_generation = 0;
        init_vmcb(svm);
 
+       svm->msrpm = page_address(msrpm_pages);
+       svm_vcpu_init_msrpm(svm, svm->msrpm);
+
+       svm->nested.msrpm = page_address(nested_msrpm_pages);
+       svm_vcpu_init_msrpm(svm, svm->nested.msrpm);
+
        svm_init_osvw(&svm->vcpu);
 
        return &svm->vcpu;
@@ -3308,6 +3312,18 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct 
msr_data *msr_info)
                        msr_info->data = 0x1E;
                }
                break;
+       case MSR_IA32_APICBASE:
+               if (svm_vcpu_avic_enabled(svm)) {
+                       /* Note:
+                        * For AVIC, we need to disable X2APIC
+                        * and enable XAPIC
+                        */
+                       kvm_get_msr_common(vcpu, msr_info);
+                       msr_info->data &= ~X2APIC_ENABLE;
+                       msr_info->data |= XAPIC_ENABLE;
+                       break;
+               }
+               /* Follow through if not AVIC */
        default:
                return kvm_get_msr_common(vcpu, msr_info);
        }
@@ -3436,6 +3452,10 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct 
msr_data *msr)
        case MSR_VM_IGNNE:
                vcpu_unimpl(vcpu, "unimplemented wrmsr: 0x%x data 0x%llx\n", 
ecx, data);
                break;
+       case MSR_IA32_APICBASE:
+               if (svm_vcpu_avic_enabled(svm))
+                       avic_update_vapic_bar(to_svm(vcpu), data);
+               /* Follow through */
        default:
                return kvm_set_msr_common(vcpu, msr);
        }
@@ -4554,11 +4574,26 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu)
 
        /* Update nrips enabled cache */
        svm->nrips_enabled = !!guest_cpuid_has_nrips(&svm->vcpu);
+
+       /* Do not support X2APIC when enable AVIC */
+       if (svm_vcpu_avic_enabled(svm)) {
+               int i;
+
+               for (i = 0 ; i < vcpu->arch.cpuid_nent ; i++) {
+                       if (vcpu->arch.cpuid_entries[i].function == 1)
+                               vcpu->arch.cpuid_entries[i].ecx &= ~(1 << 21);
+               }
+       }
 }
 
 static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
 {
        switch (func) {
+       case 0x00000001:
+               /* Do not support X2APIC when enable AVIC */
+               if (avic)
+                       entry->ecx &= ~(1 << 21);
+               break;
        case 0x80000001:
                if (nested)
                        entry->ecx |= (1 << 2); /* Set SVM bit */
-- 
1.9.1