[Qemu-devel] [PULL 5/9] valgrind/i386: avoid false positives on KVM_SET_MSRS ioctl

[Christian Borntraeger]

struct kvm_msrs contains padding bytes. Let's use a designated
initializer on the info part to avoid false positives from
valgrind/memcheck. Do the same for generic MSRS, the TSC and
feature control.

We also need to zero out the reserved fields in the entries.
We do this in kvm_msr_entry_set as suggested by Paolo. This
avoids a big memset that a designated initializer on the
full structure would do.

Signed-off-by: Christian Borntraeger <borntrae...@de.ibm.com>
---
 target-i386/kvm.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index f42b4bf..8b4a9e9 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -1152,6 +1152,7 @@ static void kvm_msr_entry_set(struct kvm_msr_entry *entry,
                               uint32_t index, uint64_t value)
 {
     entry->index = index;
+    entry->reserved = 0;
     entry->data = value;
 }
 
@@ -1170,7 +1171,9 @@ static int kvm_put_tscdeadline_msr(X86CPU *cpu)
 
     kvm_msr_entry_set(&msrs[0], MSR_IA32_TSCDEADLINE, env->tsc_deadline);
 
-    msr_data.info.nmsrs = 1;
+    msr_data.info = (struct kvm_msrs) {
+        .nmsrs = 1,
+    };
 
     return kvm_vcpu_ioctl(CPU(cpu), KVM_SET_MSRS, &msr_data);
 }
@@ -1190,7 +1193,11 @@ static int kvm_put_msr_feature_control(X86CPU *cpu)
 
     kvm_msr_entry_set(&msr_data.entry, MSR_IA32_FEATURE_CONTROL,
                       cpu->env.msr_ia32_feature_control);
-    msr_data.info.nmsrs = 1;
+
+    msr_data.info = (struct kvm_msrs) {
+        .nmsrs = 1,
+    };
+
     return kvm_vcpu_ioctl(CPU(cpu), KVM_SET_MSRS, &msr_data);
 }
 
@@ -1339,7 +1346,9 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
         }
     }
 
-    msr_data.info.nmsrs = n;
+    msr_data.info = (struct kvm_msrs) {
+        .nmsrs = n,
+    };
 
     return kvm_vcpu_ioctl(CPU(cpu), KVM_SET_MSRS, &msr_data);
 
-- 
1.9.3