[Qemu-devel] [PATCH] Return amount of ASIDs

[Qemu-devel] [PATCH] Return amount of ASIDs

[Alexander Graf]

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Return amount of ASIDs

With SVM the TLB supports tagging to distinguish TLB entries from 
different virtual CPUs. This tag is called an ASID. The amount of ASIDs 
is given in EBX of the SVM-CPUID-leaf. Currently we return 0, which 
might break hypervisors. Let's better return something >0 here, say 0x10.
Since we're flushing the complete TLB on every VM entry and exit we're 
not making use of the ASID information anyways.

Signed-off-by: Alexander Graf <agraf@suse.de>



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Index: target-i386/op_helper.c
===================================================================
--- target-i386/op_helper.c	(revision 5494)
+++ target-i386/op_helper.c	(working copy)
@@ -2037,10 +2037,10 @@
         EDX = 0;
         break;
     case 0x8000000A:
-        EAX = 0x00000001;
-        EBX = 0;
+        EAX = 0x00000001; /* SVM Revision */
+        EBX = 0x00000010; /* nr of ASIDs */
         ECX = 0;
-        EDX = 0;
+        EDX = 0; /* optional features */
         break;
     default:
         /* reserved values: zero */

Re: [Qemu-devel] [PATCH] Return amount of ASIDs

[Aurelien Jarno]

On Wed, Oct 15, 2008 at 08:17:23PM +0200, Alexander Graf wrote:
> Return amount of ASIDs
>
> With SVM the TLB supports tagging to distinguish TLB entries from  
> different virtual CPUs. This tag is called an ASID. The amount of ASIDs  
> is given in EBX of the SVM-CPUID-leaf. Currently we return 0, which  
> might break hypervisors. Let's better return something >0 here, say 0x10.
> Since we're flushing the complete TLB on every VM entry and exit we're  
> not making use of the ASID information anyways.
>
> Signed-off-by: Alexander Graf <agraf@suse.de>
>

Applied, thanks.

> Index: target-i386/op_helper.c
> ===================================================================
> --- target-i386/op_helper.c	(revision 5494)
> +++ target-i386/op_helper.c	(working copy)
> @@ -2037,10 +2037,10 @@
>          EDX = 0;
>          break;
>      case 0x8000000A:
> -        EAX = 0x00000001;
> -        EBX = 0;
> +        EAX = 0x00000001; /* SVM Revision */
> +        EBX = 0x00000010; /* nr of ASIDs */
>          ECX = 0;
> -        EDX = 0;
> +        EDX = 0; /* optional features */
>          break;
>      default:
>          /* reserved values: zero */


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