[Qemu-devel] [PATCH 2/3] target-i386: kvm: Use env->mcg_cap when setting up MCE

[Eduardo Habkost <ehabkost@redhat.com>]

When setting up MCE, instead of using the MCE_*_DEF macros
directly, just filter the existing env->mcg_cap value.

As env->mcg_cap is already initialized as
MCE_CAP_DEF|MCE_BANKS_DEF at target-i386/cpu.c:mce_init(), this
doesn't change any behavior. But it will allow us to change
mce_init() in the future, to implement different defaults
depending on CPU model, machine-type or command-line parameters.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/cpu.h |  2 ++
 target-i386/kvm.c | 11 ++++-------
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index fc4a605..84edfd0 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -286,6 +286,8 @@
 #define MCE_CAP_DEF     (MCG_CTL_P|MCG_SER_P)
 #define MCE_BANKS_DEF   10
 
+#define MCG_CAP_BANKS_MASK 0xff
+
 #define MCG_STATUS_RIPV (1ULL<<0)   /* restart ip valid */
 #define MCG_STATUS_EIPV (1ULL<<1)   /* ip points to correct instruction */
 #define MCG_STATUS_MCIP (1ULL<<2)   /* machine check in progress */
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index ee7bc69..d63a85b 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -784,21 +784,18 @@ int kvm_arch_init_vcpu(CPUState *cs)
             return ret;
         }
 
-        if (MCE_BANKS_DEF > banks) {
+        if ((env->mcg_cap & MCG_CAP_BANKS_MASK) > banks) {
             error_report("kvm: Unsupported MCE bank count: %d > %d\n",
-                         MCE_BANKS_DEF, banks);
+                         (int)(env->mcg_cap & MCG_CAP_BANKS_MASK), banks);
             return -ENOTSUP;
         }
 
-        mcg_cap &= MCE_CAP_DEF;
-        mcg_cap |= MCE_BANKS_DEF;
-        ret = kvm_vcpu_ioctl(cs, KVM_X86_SETUP_MCE, &mcg_cap);
+        env->mcg_cap &= mcg_cap | MCG_CAP_BANKS_MASK;
+        ret = kvm_vcpu_ioctl(cs, KVM_X86_SETUP_MCE, &env->mcg_cap);
         if (ret < 0) {
             fprintf(stderr, "KVM_X86_SETUP_MCE: %s", strerror(-ret));
             return ret;
         }
-
-        env->mcg_cap = mcg_cap;
     }
 
     qemu_add_vm_change_state_handler(cpu_update_state, env);
-- 
2.1.0