[Qemu-devel] [PATCH] Use msr list to load and save msrs

[Qemu-devel] [PATCH] Use msr list to load and save msrs

[Glauber Costa]

Since there is an ioctl that tells us which msrs are available,
use it. This saves us from the need of functions like has_star(),
lm_capable(), etc.

Signed-off-by: Glauber Costa <glommer@redhat.com>
CC: Marcelo Tosatti <mtosatti@redhat.com>
CC: Avi Kivity <avi@redhat.com>
---
 target-i386/kvm.c |  200 ++++++++++++++++++++++++++---------------------------
 1 files changed, 98 insertions(+), 102 deletions(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 7010999..488a3f5 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -221,49 +221,41 @@ int kvm_arch_init_vcpu(CPUState *env)
     return kvm_vcpu_ioctl(env, KVM_SET_CPUID2, &cpuid_data);
 }
 
-static int kvm_has_msr_star(CPUState *env)
+static struct kvm_msr_list *kvm_get_msr_list(CPUState *env)
 {
-    static int has_msr_star;
+    struct kvm_msr_list msr_list;
+    static struct kvm_msr_list *kvm_msr_list;
     int ret;
 
-    /* first time */
-    if (has_msr_star == 0) {        
-        struct kvm_msr_list msr_list, *kvm_msr_list;
+    if (kvm_msr_list)
+        return kvm_msr_list;
 
-        has_msr_star = -1;
+    /* Obtain MSR list from KVM.  These are the MSRs that we must
+     * save/restore */
+    msr_list.nmsrs = 0;
+    ret = kvm_ioctl(env->kvm_state, KVM_GET_MSR_INDEX_LIST, &msr_list);
+    if ((ret < 0) && (ret != -E2BIG)) {
+        printf("FAIL1 %d\n", ret);
+        return NULL;
+    }
 
-        /* Obtain MSR list from KVM.  These are the MSRs that we must
-         * save/restore */
-        msr_list.nmsrs = 0;
-        ret = kvm_ioctl(env->kvm_state, KVM_GET_MSR_INDEX_LIST, &msr_list);
-        if (ret < 0)
-            return 0;
-
-        /* Old kernel modules had a bug and could write beyond the provided
-           memory. Allocate at least a safe amount of 1K. */
-        kvm_msr_list = qemu_mallocz(MAX(1024, sizeof(msr_list) +
-                                              msr_list.nmsrs *
-                                              sizeof(msr_list.indices[0])));
-
-        kvm_msr_list->nmsrs = msr_list.nmsrs;
-        ret = kvm_ioctl(env->kvm_state, KVM_GET_MSR_INDEX_LIST, kvm_msr_list);
-        if (ret >= 0) {
-            int i;
-
-            for (i = 0; i < kvm_msr_list->nmsrs; i++) {
-                if (kvm_msr_list->indices[i] == MSR_STAR) {
-                    has_msr_star = 1;
-                    break;
-                }
-            }
-        }
+    /* Old kernel modules had a bug and could write beyond the provided
+       memory. Allocate at least a safe amount of 1K. */
+    kvm_msr_list = qemu_mallocz(MAX(1024, sizeof(msr_list) +
+                                          msr_list.nmsrs *
+                                          sizeof(msr_list.indices[0])));
+
+    kvm_msr_list->nmsrs = msr_list.nmsrs;
+    ret = kvm_ioctl(env->kvm_state, KVM_GET_MSR_INDEX_LIST, kvm_msr_list);
 
-        free(kvm_msr_list);
+    if (ret < 0) {
+        printf("FAIL2\n");
+        qemu_free(kvm_msr_list);
+        return NULL;
     }
 
-    if (has_msr_star == 1)
-        return 1;
-    return 0;
+    return kvm_msr_list;
+
 }
 
 int kvm_arch_init(KVMState *s, int smp_cpus)
@@ -455,13 +447,47 @@ static int kvm_put_sregs(CPUState *env)
     return kvm_vcpu_ioctl(env, KVM_SET_SREGS, &sregs);
 }
 
-static void kvm_msr_entry_set(struct kvm_msr_entry *entry,
-                              uint32_t index, uint64_t value)
+static uint64_t *kvm_get_msr_data_addr(CPUState *env, int index)
 {
-    entry->index = index;
-    entry->data = value;
+    uint64_t *addr;
+
+    switch (index) {
+    case MSR_IA32_SYSENTER_CS:
+        addr = (uint64_t *)&env->sysenter_cs;
+        break;
+    case MSR_IA32_SYSENTER_ESP:
+        addr = (uint64_t *)&env->sysenter_esp;
+        break;
+    case MSR_IA32_SYSENTER_EIP:
+        addr = (uint64_t *)&env->sysenter_eip;
+        break;
+    case MSR_STAR:
+        addr = &env->star;
+        break;
+#ifdef TARGET_X86_64
+    case MSR_CSTAR:
+        addr = &env->cstar;
+        break;
+    case MSR_KERNELGSBASE:
+        addr = &env->kernelgsbase;
+        break;
+    case MSR_FMASK:
+        addr = &env->fmask;
+        break;
+    case MSR_LSTAR:
+        addr = &env->lstar;
+        break;
+#endif
+    case MSR_IA32_TSC:
+        addr = &env->tsc;
+        break;
+    default:
+        addr = NULL;
+    }
+    return addr;
 }
 
+
 static int kvm_put_msrs(CPUState *env)
 {
     struct {
@@ -469,22 +495,24 @@ static int kvm_put_msrs(CPUState *env)
         struct kvm_msr_entry entries[100];
     } msr_data;
     struct kvm_msr_entry *msrs = msr_data.entries;
-    int n = 0;
-
-    kvm_msr_entry_set(&msrs[n++], MSR_IA32_SYSENTER_CS, env->sysenter_cs);
-    kvm_msr_entry_set(&msrs[n++], MSR_IA32_SYSENTER_ESP, env->sysenter_esp);
-    kvm_msr_entry_set(&msrs[n++], MSR_IA32_SYSENTER_EIP, env->sysenter_eip);
-    if (kvm_has_msr_star(env))
-	kvm_msr_entry_set(&msrs[n++], MSR_STAR, env->star);
-    kvm_msr_entry_set(&msrs[n++], MSR_IA32_TSC, env->tsc);
-#ifdef TARGET_X86_64
-    /* FIXME if lm capable */
-    kvm_msr_entry_set(&msrs[n++], MSR_CSTAR, env->cstar);
-    kvm_msr_entry_set(&msrs[n++], MSR_KERNELGSBASE, env->kernelgsbase);
-    kvm_msr_entry_set(&msrs[n++], MSR_FMASK, env->fmask);
-    kvm_msr_entry_set(&msrs[n++], MSR_LSTAR, env->lstar);
-#endif
-    msr_data.info.nmsrs = n;
+    struct kvm_msr_list *kvm_msr_list;
+    int i;
+
+    kvm_msr_list = kvm_get_msr_list(env);
+    if (!kvm_msr_list) {
+        printf("FAILED\n");
+        return -1;
+    }
+
+    msr_data.info.nmsrs = kvm_msr_list->nmsrs;
+
+    for (i = 0; i < kvm_msr_list->nmsrs; i++) {
+        uint64_t *data = kvm_get_msr_data_addr(env, kvm_msr_list->indices[i]);
+        msrs[i].index = kvm_msr_list->indices[i];
+        if (data != NULL) {
+            msrs[i].data = *data;
+        }
+    }
 
     return kvm_vcpu_ioctl(env, KVM_SET_MSRS, &msr_data);
 
@@ -601,58 +629,26 @@ static int kvm_get_msrs(CPUState *env)
         struct kvm_msr_entry entries[100];
     } msr_data;
     struct kvm_msr_entry *msrs = msr_data.entries;
-    int ret, i, n;
-
-    n = 0;
-    msrs[n++].index = MSR_IA32_SYSENTER_CS;
-    msrs[n++].index = MSR_IA32_SYSENTER_ESP;
-    msrs[n++].index = MSR_IA32_SYSENTER_EIP;
-    if (kvm_has_msr_star(env))
-	msrs[n++].index = MSR_STAR;
-    msrs[n++].index = MSR_IA32_TSC;
-#ifdef TARGET_X86_64
-    /* FIXME lm_capable_kernel */
-    msrs[n++].index = MSR_CSTAR;
-    msrs[n++].index = MSR_KERNELGSBASE;
-    msrs[n++].index = MSR_FMASK;
-    msrs[n++].index = MSR_LSTAR;
-#endif
-    msr_data.info.nmsrs = n;
+    int ret, i;
+    struct kvm_msr_list *kvm_msr_list;
+
+    kvm_msr_list = kvm_get_msr_list(env);
+    if (!kvm_msr_list)
+        return -1;
+
+    msr_data.info.nmsrs = kvm_msr_list->nmsrs;
+    for (i = 0; i < kvm_msr_list->nmsrs; i++) {
+        msrs[i].index = kvm_msr_list->indices[i];
+    }
+
     ret = kvm_vcpu_ioctl(env, KVM_GET_MSRS, &msr_data);
     if (ret < 0)
         return ret;
 
     for (i = 0; i < ret; i++) {
-        switch (msrs[i].index) {
-        case MSR_IA32_SYSENTER_CS:
-            env->sysenter_cs = msrs[i].data;
-            break;
-        case MSR_IA32_SYSENTER_ESP:
-            env->sysenter_esp = msrs[i].data;
-            break;
-        case MSR_IA32_SYSENTER_EIP:
-            env->sysenter_eip = msrs[i].data;
-            break;
-        case MSR_STAR:
-            env->star = msrs[i].data;
-            break;
-#ifdef TARGET_X86_64
-        case MSR_CSTAR:
-            env->cstar = msrs[i].data;
-            break;
-        case MSR_KERNELGSBASE:
-            env->kernelgsbase = msrs[i].data;
-            break;
-        case MSR_FMASK:
-            env->fmask = msrs[i].data;
-            break;
-        case MSR_LSTAR:
-            env->lstar = msrs[i].data;
-            break;
-#endif
-        case MSR_IA32_TSC:
-            env->tsc = msrs[i].data;
-            break;
+        uint64_t *data = kvm_get_msr_data_addr(env, msrs[i].index);
+        if (data) {
+            *data = msrs[i].data;
         }
     }
 
-- 
1.6.2.5

[Qemu-devel] Re: [PATCH] Use msr list to load and save msrs

[Avi Kivity]

On 10/26/2009 08:26 PM, Glauber Costa wrote:
> +
> +    kvm_msr_list = kvm_get_msr_list(env);
> +    if (!kvm_msr_list) {
> +        printf("FAILED\n");
> +        return -1;
> +    }
> +
> +    msr_data.info.nmsrs = kvm_msr_list->nmsrs;
> +
> +    for (i = 0; i<  kvm_msr_list->nmsrs; i++) {
> +        uint64_t *data = kvm_get_msr_data_addr(env, kvm_msr_list->indices[i]);
> +        msrs[i].index = kvm_msr_list->indices[i];
> +        if (data != NULL) {
> +            msrs[i].data = *data;
> +        }
> +    }
>
>       return kvm_vcpu_ioctl(env, KVM_SET_MSRS,&msr_data);
>
>    

Aren't you leaking the msr list structure?

Best to get it once during setup and reuse it later.

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

[Qemu-devel] Re: [PATCH] Use msr list to load and save msrs

[Glauber Costa]

On Tue, Oct 27, 2009 at 12:01:59PM +0200, Avi Kivity wrote:
> On 10/26/2009 08:26 PM, Glauber Costa wrote:
>> +
>> +    kvm_msr_list = kvm_get_msr_list(env);
>> +    if (!kvm_msr_list) {
>> +        printf("FAILED\n");
>> +        return -1;
>> +    }
>> +
>> +    msr_data.info.nmsrs = kvm_msr_list->nmsrs;
>> +
>> +    for (i = 0; i<  kvm_msr_list->nmsrs; i++) {
>> +        uint64_t *data = kvm_get_msr_data_addr(env, kvm_msr_list->indices[i]);
>> +        msrs[i].index = kvm_msr_list->indices[i];
>> +        if (data != NULL) {
>> +            msrs[i].data = *data;
>> +        }
>> +    }
>>
>>       return kvm_vcpu_ioctl(env, KVM_SET_MSRS,&msr_data);
>>
>>    
>
> Aren't you leaking the msr list structure?
>
> Best to get it once during setup and reuse it later.

That's exactly what the function kvm_get_msr_list() does.
it allocs the structure the first time we use, and in subsequent
times, just return it.

[Qemu-devel] Re: [PATCH] Use msr list to load and save msrs

[Avi Kivity]

On 10/27/2009 12:19 PM, Glauber Costa wrote:
> On Tue, Oct 27, 2009 at 12:01:59PM +0200, Avi Kivity wrote:
>    
>> On 10/26/2009 08:26 PM, Glauber Costa wrote:
>>      
>>> +
>>> +    kvm_msr_list = kvm_get_msr_list(env);
>>> +    if (!kvm_msr_list) {
>>> +        printf("FAILED\n");
>>> +        return -1;
>>> +    }
>>> +
>>> +    msr_data.info.nmsrs = kvm_msr_list->nmsrs;
>>> +
>>> +    for (i = 0; i<   kvm_msr_list->nmsrs; i++) {
>>> +        uint64_t *data = kvm_get_msr_data_addr(env, kvm_msr_list->indices[i]);
>>> +        msrs[i].index = kvm_msr_list->indices[i];
>>> +        if (data != NULL) {
>>> +            msrs[i].data = *data;
>>> +        }
>>> +    }
>>>
>>>        return kvm_vcpu_ioctl(env, KVM_SET_MSRS,&msr_data);
>>>
>>>
>>>        
>> Aren't you leaking the msr list structure?
>>
>> Best to get it once during setup and reuse it later.
>>      
> That's exactly what the function kvm_get_msr_list() does.
> it allocs the structure the first time we use, and in subsequent
> times, just return it.
>    

Oh, somehow I missed that.

(it's still better form to allocate on initialization, but that's not 
really a problem)

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

[Qemu-devel] Re: [PATCH] Use msr list to load and save msrs

[Glauber Costa]

On Tue, Oct 27, 2009 at 12:25:41PM +0200, Avi Kivity wrote:
> On 10/27/2009 12:19 PM, Glauber Costa wrote:
>> On Tue, Oct 27, 2009 at 12:01:59PM +0200, Avi Kivity wrote:
>>    
>>> On 10/26/2009 08:26 PM, Glauber Costa wrote:
>>>      
>>>> +
>>>> +    kvm_msr_list = kvm_get_msr_list(env);
>>>> +    if (!kvm_msr_list) {
>>>> +        printf("FAILED\n");
>>>> +        return -1;
>>>> +    }
>>>> +
>>>> +    msr_data.info.nmsrs = kvm_msr_list->nmsrs;
>>>> +
>>>> +    for (i = 0; i<   kvm_msr_list->nmsrs; i++) {
>>>> +        uint64_t *data = kvm_get_msr_data_addr(env, kvm_msr_list->indices[i]);
>>>> +        msrs[i].index = kvm_msr_list->indices[i];
>>>> +        if (data != NULL) {
>>>> +            msrs[i].data = *data;
>>>> +        }
>>>> +    }
>>>>
>>>>        return kvm_vcpu_ioctl(env, KVM_SET_MSRS,&msr_data);
>>>>
>>>>
>>>>        
>>> Aren't you leaking the msr list structure?
>>>
>>> Best to get it once during setup and reuse it later.
>>>      
>> That's exactly what the function kvm_get_msr_list() does.
>> it allocs the structure the first time we use, and in subsequent
>> times, just return it.
>>    
>
> Oh, somehow I missed that.
>
> (it's still better form to allocate on initialization, but that's not  
> really a problem)
Yeah... there's no scenarion in which we don't need to allocate it, so it
is less confusing, indeed. I'll send that in v2 after people send in (hopefully)
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