[Qemu-devel] [PATCH for-2.10 v2] kvm: Print MSR information if KVM_{GET, SET}_MSRS failed

[Eduardo Habkost]

When a KVM_{GET,SET}_MSRS ioctl() fails, it is difficult to find
out which MSR caused the problem. Print an error message for
debugging, before we trigger the (ret == cpu->kvm_msr_buf->nmsrs)
assert.

Suggested-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
Signed-off-by: Eduardo Habkost <ehabk...@redhat.com>
---
Changes v1 -> v2:
* Print error message on KVM_GET_MSRS too
  * Suggested-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
---
 target/i386/kvm.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 887a81268f..705e971a63 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -1807,6 +1807,12 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
         return ret;
     }
 
+    if (ret < cpu->kvm_msr_buf->nmsrs) {
+        struct kvm_msr_entry *e = &cpu->kvm_msr_buf->entries[ret];
+        error_report("error: failed to set MSR 0x%" PRIx32 " to 0x%" PRIx64,
+                     (uint32_t)e->index, (uint64_t)e->data);
+    }
+
     assert(ret == cpu->kvm_msr_buf->nmsrs);
     return 0;
 }
@@ -2172,6 +2178,12 @@ static int kvm_get_msrs(X86CPU *cpu)
         return ret;
     }
 
+    if (ret < cpu->kvm_msr_buf->nmsrs) {
+        struct kvm_msr_entry *e = &cpu->kvm_msr_buf->entries[ret];
+        error_report("error: failed to get MSR 0x%" PRIx32,
+                     (uint32_t)e->index);
+    }
+
     assert(ret == cpu->kvm_msr_buf->nmsrs);
     /*
      * MTRR masks: Each mask consists of 5 parts
-- 
2.11.0.259.g40922b1