[PATCH master/stable-0.12/stable-0.13] kvm: reset MSR_IA32_CR_PAT correctly

[PATCH master/stable-0.12/stable-0.13] kvm: reset MSR_IA32_CR_PAT correctly

[Avi Kivity]

The power-on value of MSR_IA32_CR_PAT is not 0 - that disables cacheing and
makes everything dog slow.

Fix to reset MSR_IA32_CR_PAT to the correct value.

Signed-off-by: Avi Kivity <avi@redhat.com>
---
 qemu-kvm-x86.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/qemu-kvm-x86.c b/qemu-kvm-x86.c
index 4c32771..e02e896 100644
--- a/qemu-kvm-x86.c
+++ b/qemu-kvm-x86.c
@@ -1289,12 +1289,21 @@ static int kvm_reset_msrs(CPUState *env)
     } msr_data;
     int n;
     struct kvm_msr_entry *msrs = msr_data.entries;
+    uint32_t index;
+    uint64_t data;
 
     if (!kvm_msr_list)
         return -1;
 
     for (n = 0; n < kvm_msr_list->nmsrs; n++) {
-        kvm_msr_entry_set(&msrs[n], kvm_msr_list->indices[n], 0);
+        index = kvm_msr_list->indices[n];
+        switch (index) {
+        case MSR_PAT:
+            data = 0x0007040600070406ULL;
+        default:
+            data = 0;
+        }
+        kvm_msr_entry_set(&msrs[n], index, data);
     }
 
     msr_data.info.nmsrs = n;
-- 
1.7.1

Re: [PATCH master/stable-0.12/stable-0.13] kvm: reset MSR_IA32_CR_PAT correctly

[Avi Kivity]

  On 09/07/2010 04:21 PM, Avi Kivity wrote:
> The power-on value of MSR_IA32_CR_PAT is not 0 - that disables cacheing and
> makes everything dog slow.
>
> Fix to reset MSR_IA32_CR_PAT to the correct value.
>
> Signed-off-by: Avi Kivity<avi@redhat.com>
> ---
>   qemu-kvm-x86.c |   11 ++++++++++-
>   1 files changed, 10 insertions(+), 1 deletions(-)
>
> diff --git a/qemu-kvm-x86.c b/qemu-kvm-x86.c
> index 4c32771..e02e896 100644
> --- a/qemu-kvm-x86.c
> +++ b/qemu-kvm-x86.c
> @@ -1289,12 +1289,21 @@ static int kvm_reset_msrs(CPUState *env)
>       } msr_data;
>       int n;
>       struct kvm_msr_entry *msrs = msr_data.entries;
> +    uint32_t index;
> +    uint64_t data;
>
>       if (!kvm_msr_list)
>           return -1;
>
>       for (n = 0; n<  kvm_msr_list->nmsrs; n++) {
> -        kvm_msr_entry_set(&msrs[n], kvm_msr_list->indices[n], 0);
> +        index = kvm_msr_list->indices[n];
> +        switch (index) {
> +        case MSR_PAT:
> +            data = 0x0007040600070406ULL;
> +        default:
> +            data = 0;
> +        }
> +        kvm_msr_entry_set(&msrs[n], index, data);
>       }

Note: a better fix is to read all msr values during vm creation, so we 
get the kernel reset values instead of making up our own.  This is more 
future proof wrt newer msrs.  But let's start with the simple fix first.

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

Re: [PATCH master/stable-0.12/stable-0.13] kvm: reset MSR_IA32_CR_PAT correctly

[Marcelo Tosatti]

On Tue, Sep 07, 2010 at 04:21:22PM +0300, Avi Kivity wrote:
> The power-on value of MSR_IA32_CR_PAT is not 0 - that disables cacheing and
> makes everything dog slow.
> 
> Fix to reset MSR_IA32_CR_PAT to the correct value.
> 
> Signed-off-by: Avi Kivity <avi@redhat.com>
> ---
>  qemu-kvm-x86.c |   11 ++++++++++-
>  1 files changed, 10 insertions(+), 1 deletions(-)

Applied, thanks.