[Qemu-devel] [PATCH] kvm: fill in padding to help valgrind

[Qemu-devel] [PATCH] kvm: fill in padding to help valgrind

[Michael S. Tsirkin]

valgrind warns about padding fields which are passed
to vcpu ioctls uninitialized.
This is not an error in practice because kvm ignored padding.
Since the ioctls in question are off data path and
the cost is zero anyway, initialize padding to 0
to suppress these errors.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

---
 kvm-all.c         |    2 ++
 target-i386/kvm.c |    6 ++++++
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/kvm-all.c b/kvm-all.c
index c58c77b..3bc0eb3 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -447,6 +447,7 @@ int kvm_coalesce_mmio_region(target_phys_addr_t start, ram_addr_t size)
 
         zone.addr = start;
         zone.size = size;
+        zone.pad = 0;
 
         ret = kvm_vm_ioctl(s, KVM_REGISTER_COALESCED_MMIO, &zone);
     }
@@ -464,6 +465,7 @@ int kvm_uncoalesce_mmio_region(target_phys_addr_t start, ram_addr_t size)
 
         zone.addr = start;
         zone.size = size;
+        zone.pad = 0;
 
         ret = kvm_vm_ioctl(s, KVM_UNREGISTER_COALESCED_MMIO, &zone);
     }
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 981192d..285cf55 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -555,6 +555,7 @@ int kvm_arch_init_vcpu(CPUState *env)
 
     qemu_add_vm_change_state_handler(cpu_update_state, env);
 
+    cpuid_data.cpuid.padding = 0;
     r = kvm_vcpu_ioctl(env, KVM_SET_CPUID2, &cpuid_data);
     if (r) {
         return r;
@@ -740,6 +741,7 @@ static void set_seg(struct kvm_segment *lhs, const SegmentCache *rhs)
     lhs->g = (flags & DESC_G_MASK) != 0;
     lhs->avl = (flags & DESC_AVL_MASK) != 0;
     lhs->unusable = 0;
+    lhs->padding = 0;
 }
 
 static void get_seg(SegmentCache *lhs, const struct kvm_segment *rhs)
@@ -919,8 +921,10 @@ static int kvm_put_sregs(CPUState *env)
 
     sregs.idt.limit = env->idt.limit;
     sregs.idt.base = env->idt.base;
+    memset(sregs.idt.padding, 0, sizeof sregs.idt.padding);
     sregs.gdt.limit = env->gdt.limit;
     sregs.gdt.base = env->gdt.base;
+    memset(sregs.gdt.padding, 0, sizeof sregs.gdt.padding);
 
     sregs.cr0 = env->cr[0];
     sregs.cr2 = env->cr[2];
@@ -1392,6 +1396,7 @@ static int kvm_put_vcpu_events(CPUState *env, int level)
     events.exception.nr = env->exception_injected;
     events.exception.has_error_code = env->has_error_code;
     events.exception.error_code = env->error_code;
+    events.exception.pad = 0;
 
     events.interrupt.injected = (env->interrupt_injected >= 0);
     events.interrupt.nr = env->interrupt_injected;
@@ -1400,6 +1405,7 @@ static int kvm_put_vcpu_events(CPUState *env, int level)
     events.nmi.injected = env->nmi_injected;
     events.nmi.pending = env->nmi_pending;
     events.nmi.masked = !!(env->hflags2 & HF2_NMI_MASK);
+    events.nmi.pad = 0;
 
     events.sipi_vector = env->sipi_vector;
 
-- 
1.7.9.111.gf3fb0

Re: [Qemu-devel] [PATCH] kvm: fill in padding to help valgrind

[Avi Kivity]

On 02/29/2012 05:54 PM, Michael S. Tsirkin wrote:
> valgrind warns about padding fields which are passed
> to vcpu ioctls uninitialized.
> This is not an error in practice because kvm ignored padding.
> Since the ioctls in question are off data path and
> the cost is zero anyway, initialize padding to 0
> to suppress these errors.
>

Applied to uq/master, thanks.

-- 
error compiling committee.c: too many arguments to function