[PATCH v1 22/28] x86/hvm: avic: ensure SVM AVIC supports xAPIC operation only

[dmukhin@xxxxxxxx]

From: Denis Mukhin <dmukhin@xxxxxxxx>

xAVIC does not support x2APIC operation (yet).

Until x2APIC mode is supported, don't advertise x2APIC to HVM
guests when SVM AVIC is enabled.

Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
---
 xen/arch/x86/cpu-policy.c          |  3 ++-
 xen/arch/x86/hvm/svm/svm.c         | 12 ++++++++++++
 xen/arch/x86/hvm/vmx/vmx.c         |  4 ++++
 xen/arch/x86/include/asm/hvm/hvm.h | 15 ++++++++++++++-
 4 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/cpu-policy.c b/xen/arch/x86/cpu-policy.c
index 48a3185eed8d..ca9b1a523570 100644
--- a/xen/arch/x86/cpu-policy.c
+++ b/xen/arch/x86/cpu-policy.c
@@ -764,7 +764,8 @@ static void __init calculate_hvm_max_policy(void)
      * (x2)APIC isn't enabled.
      */
     __set_bit(X86_FEATURE_APIC, fs);
-    __set_bit(X86_FEATURE_X2APIC, fs);
+    if ( hvm_x2apic_supported() )
+        __set_bit(X86_FEATURE_X2APIC, fs);
 
     /*
      * We don't support EFER.LMSLE at all.  AMD has dropped the feature from
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index f2eb01799c63..667e8b05eecc 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -2478,6 +2478,10 @@ static struct hvm_function_table __initdata_cf_clobber 
svm_function_table = {
     .tsc_scaling = {
         .max_ratio = ~TSC_RATIO_RSVD_BITS,
     },
+
+    .caps = {
+        .x2apic = true,
+    },
 };
 
 static void __init print_svm_features(void)
@@ -2523,6 +2527,14 @@ static void __init svm_avic_start(void)
     svm_function_table.debug_posted_intr = svm_avic_hvm_debug_posted_intr;
 
     svm_function_table.caps.virtual_intr_delivery = true;
+
+    /*
+     * xAVIC does not support x2APIC operation.
+     *
+     * Until x2AVIC/hybrid AVIC support is implemented, don't expose
+     * x2APIC to guests when SVM AVIC is enabled.
+     */
+    svm_function_table.caps.x2apic = false;
 }
 
 const struct hvm_function_table * __init start_svm(void)
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 3c7374a9ff42..bad43b38efea 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2916,6 +2916,10 @@ static struct hvm_function_table __initdata_cf_clobber 
vmx_function_table = {
     .tsc_scaling = {
         .max_ratio = VMX_TSC_MULTIPLIER_MAX,
     },
+
+    .caps = {
+        .x2apic = true,
+    },
 };
 
 /* Handle VT-d posted-interrupt when VCPU is blocked. */
diff --git a/xen/arch/x86/include/asm/hvm/hvm.h 
b/xen/arch/x86/include/asm/hvm/hvm.h
index d44f136fae8f..b701fc003ced 100644
--- a/xen/arch/x86/include/asm/hvm/hvm.h
+++ b/xen/arch/x86/include/asm/hvm/hvm.h
@@ -119,7 +119,9 @@ struct hvm_function_table {
              virtual_intr_delivery:1,
 
              /* Nested virt capabilities */
-             nested_virt:1;
+             nested_virt:1,
+
+             x2apic:1;
     } caps;
 
     /*
@@ -716,6 +718,11 @@ static inline bool hvm_nested_virt_supported(void)
     return hvm_funcs.caps.nested_virt;
 }
 
+static inline bool hvm_x2apic_supported(void)
+{
+    return hvm_funcs.caps.x2apic;
+}
+
 #ifdef CONFIG_ALTP2M
 /* updates the current hardware p2m */
 static inline void altp2m_vcpu_update_p2m(struct vcpu *v)
@@ -905,6 +912,12 @@ static inline bool hvm_nested_virt_supported(void)
     return false;
 }
 
+static inline bool hvm_x2apic_supported(void)
+{
+    ASSERT_UNREACHABLE();
+    return false;
+}
+
 static inline bool nhvm_vmcx_hap_enabled(const struct vcpu *v)
 {
     ASSERT_UNREACHABLE();
-- 
2.55.0