[Qemu-devel] [PATCH] kvm: Use KVM_GET_MSR_INDEX_LIST for MSR_IA32_ARCH_CAPABILITIES support

[Bandan Das <bsd@redhat.com>]

When writing to guest's MSR_IA32_ARCH_CAPABILITIES, check whether it's
supported in the guest using the KVM_GET_MSR_INDEX_LIST ioctl.

Fixes: d86f963694df27f11b3681ffd225c9362de1b634
Suggested-by: Eduardo Habkost <ehabkost@redhat.com>
Tested-by: balducci@units.it
Signed-off-by: Bandan Das <bsd@redhat.com>
---
 target/i386/kvm.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index f524e7d929..3d6739a2b2 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -95,6 +95,7 @@ static bool has_msr_xss;
 static bool has_msr_spec_ctrl;
 static bool has_msr_virt_ssbd;
 static bool has_msr_smi_count;
+static bool has_msr_arch_capabs;
 
 static uint32_t has_architectural_pmu_version;
 static uint32_t num_architectural_pmu_gp_counters;
@@ -1481,6 +1482,9 @@ static int kvm_get_supported_msrs(KVMState *s)
                 case MSR_VIRT_SSBD:
                     has_msr_virt_ssbd = true;
                     break;
+                case MSR_IA32_ARCH_CAPABILITIES:
+                    has_msr_arch_capabs = true;
+                    break;
                 }
             }
         }
@@ -2002,14 +2006,9 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
 #endif
 
     /* If host supports feature MSR, write down. */
-    if (kvm_feature_msrs) {
-        int i;
-        for (i = 0; i < kvm_feature_msrs->nmsrs; i++)
-            if (kvm_feature_msrs->indices[i] == MSR_IA32_ARCH_CAPABILITIES) {
-                kvm_msr_entry_add(cpu, MSR_IA32_ARCH_CAPABILITIES,
-                              env->features[FEAT_ARCH_CAPABILITIES]);
-                break;
-            }
+    if (has_msr_arch_capabs) {
+        kvm_msr_entry_add(cpu, MSR_IA32_ARCH_CAPABILITIES,
+                          env->features[FEAT_ARCH_CAPABILITIES]);
     }
 
     /*
-- 
2.14.5