Re: [Xen-devel] [PATCH] xen/arm: define PAGE_HYPERVISOR as BUFFERABLE

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 10 May 2013, Stefano Stabellini wrote:
> Use stage 1 attribute indexes for PAGE_HYPERVISOR, the appriopriate one
> for normal memory hypervisor mappings would be BUFFERABLE.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>
> diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
> index fd6946e..13f76fc 100644
> --- a/xen/include/asm-arm/page.h
> +++ b/xen/include/asm-arm/page.h
> @@ -58,7 +58,7 @@
>  #define DEV_WC        BUFFERABLE
>  #define DEV_CACHED    WRITEBACK
>  
> -#define PAGE_HYPERVISOR         (MATTR_MEM)
> +#define PAGE_HYPERVISOR         (BUFFERABLE)
>  #define MAP_SMALL_PAGES         PAGE_HYPERVISOR
>  
>  /*
 
This patch is completely wrong, fortunately it hasn't been applied.

Despite the name, BUFFERABLE means non-cacheable. Mapping a guest page
non-cacheable in the hypervisor would cause mismatch in memory
attributes.

We should map the guest page as "normal memory", that is WRITEBACK.

diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
index fd6946e..13f76fc 100644
--- a/xen/include/asm-arm/page.h
+++ b/xen/include/asm-arm/page.h
@@ -58,7 +58,7 @@
 #define DEV_WC        BUFFERABLE
 #define DEV_CACHED    WRITEBACK
 
-#define PAGE_HYPERVISOR         (MATTR_MEM)
+#define PAGE_HYPERVISOR         (WRITEBACK)
 #define MAP_SMALL_PAGES         PAGE_HYPERVISOR
 
 /*

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel