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

On Sun, Nov 25, 2018 at 11:17:28PM -0500, Bandan Das wrote:
> 
> 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>

Thanks!  Queued for 3.1.

-- 
Eduardo

Thanks for fixing. Sorry I missed the whole discussion for I hadn't checked my
linux.intel.com account for a long time.

Best Regards,
Robert Hoo

> -----Original Message-----
> From: Qemu-devel <qemu-devel-bounces+robert.hu=intel.com@nongnu.org>
> On Behalf Of Bandan Das
> Sent: Monday, November 26, 2018 12:17
> To: Eduardo Habkost <ehabkost@redhat.com>; Paolo Bonzini
> <pbonzini@redhat.com>
> Cc: balducci@units.it; Cole Robinson <crobinso@redhat.com>; qemu-
> devel@nongnu.org; Laine Stump <laine@redhat.com>; David Alan Gilbert
> <dgilbert@redhat.com>
> Subject: [Qemu-devel] [PATCH] kvm: Use KVM_GET_MSR_INDEX_LIST for
> MSR_IA32_ARCH_CAPABILITIES support
> 
> 
> 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) {

[Robert Hoo] 
Why not as your original "if (kvm_arch_get_supported_msr_feature(kvm_state, MSR_IA32_ARCH_CAPABILITIES))"?
checking if there is the MSR feature?

> +        kvm_msr_entry_add(cpu, MSR_IA32_ARCH_CAPABILITIES,
> +                          env->features[FEAT_ARCH_CAPABILITIES]);
>      }
> 
>      /*
> --
> 2.14.5
>