[PATCH v1 01/28] i386/kvm: avoid installing duplicate msr entries in msr_handlers

[Ani Sinha]

kvm_filter_msr() does not check if an msr entry is already present in the
msr_handlers table and installs a new handler unconditionally. If the function
is called again with the same MSR, it will result in duplicate entries in the
table and multiple such calls will fill up the table needlessly. Fix that.

Signed-off-by: Ani Sinha <anisi...@redhat.com>
---
 target/i386/kvm/kvm.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 60c7981138..02819de625 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -5925,27 +5925,33 @@ static int kvm_install_msr_filters(KVMState *s)
 static int kvm_filter_msr(KVMState *s, uint32_t msr, QEMURDMSRHandler *rdmsr,
                           QEMUWRMSRHandler *wrmsr)
 {
-    int i, ret;
+    int i, ret = 0;
 
     for (i = 0; i < ARRAY_SIZE(msr_handlers); i++) {
-        if (!msr_handlers[i].msr) {
+        if (msr_handlers[i].msr == msr) {
+            break;
+        } else if (!msr_handlers[i].msr) {
             msr_handlers[i] = (KVMMSRHandlers) {
                 .msr = msr,
                 .rdmsr = rdmsr,
                 .wrmsr = wrmsr,
             };
+            break;
+        }
+    }
 
-            ret = kvm_install_msr_filters(s);
-            if (ret) {
-                msr_handlers[i] = (KVMMSRHandlers) { };
-                return ret;
-            }
+    if (i == ARRAY_SIZE(msr_handlers)) {
+        ret = -EINVAL;
+        goto end;
+    }
 
-            return 0;
-        }
+    ret = kvm_install_msr_filters(s);
+    if (ret) {
+        msr_handlers[i] = (KVMMSRHandlers) { };
     }
 
-    return -EINVAL;
+ end:
+    return ret;
 }
 
 static int kvm_handle_rdmsr(X86CPU *cpu, struct kvm_run *run)
-- 
2.42.0