Re: [Xen-devel] [PATCH] xc_map_foreign_pages(), a convenient alternative to xc_map_foreign_batch()

[Markus Armbruster <armbru@xxxxxxxxxx>]

Isaku Yamahata <yamahata@xxxxxxxxxxxxx> writes:

> On Wed, Sep 05, 2007 at 06:36:54PM +0200, Markus Armbruster wrote:
>> The patch converts only those uses of xc_map_foreign_batch() to
>> xc_map_foreign_pages() where I'm 100% sure it's safe.  For the others,
>> I'd rather have a second opinion from somebody familiar with the code.
>> 
>> Discussion of uses:
> ...
>> * main() in tools/ioemu/vl.c, in __ia64__ code
>> 
>>   Doesn't test for mapping failure.  Likely candidate for
>>   xc_map_foreign_pages().
>
> This can't be replaced because some pages, e.g. VGA area [0xA0000, 0xC0000),
> can't be mapped.

Is it okay not to check for success?

>> * copy_from_GFW_to_nvram() in tools/libxc/ia64/xc_ia64_hvm_build.c
>> 
>>   Doesn't test for mapping failure.  Likely candidate for
>>   xc_map_foreign_pages(), but I have no way to test it.
>
> This can be replaced with xc_map_foreign_pages()
> This change will go through xen-ia64-devel.hg.
> I'll send the patch to xen-ia64-devel.

Thanks!

>> * xc_core_arch_map_p2m() in tools/libxc/xc_core_x86.c
>> 
>>   This maps a two level page directory: first a a page of pfns for the
>>   page directory (live_p2m_frame_list_list), using that pages of pfns
>>   for the pages themselves (live_p2m_frame_list), and using that the
>>   actual pages.
>> 
>>   Doesn't test for mapping failure.  Likely candidate for
>>   xc_map_foreign_pages().
>
> This can be replaced with xc_map_foreign_pages().

Obvious patch for that:

diff -r 9071521d4864 tools/libxc/xc_core_x86.c
--- a/tools/libxc/xc_core_x86.c Fri Sep 07 11:39:10 2007 +0100
+++ b/tools/libxc/xc_core_x86.c Mon Sep 10 15:26:26 2007 +0200
@@ -86,7 +86,7 @@ xc_core_arch_map_p2m(int xc_handle, xc_d
     }
 
     live_p2m_frame_list =
-        xc_map_foreign_batch(xc_handle, dom, PROT_READ,
+        xc_map_foreign_pages(xc_handle, dom, PROT_READ,
                              live_p2m_frame_list_list,
                              P2M_FLL_ENTRIES);
 
@@ -96,7 +96,7 @@ xc_core_arch_map_p2m(int xc_handle, xc_d
         goto out;
     }
 
-    *live_p2m = xc_map_foreign_batch(xc_handle, dom, PROT_READ,
+    *live_p2m = xc_map_foreign_pages(xc_handle, dom, PROT_READ,
                                     live_p2m_frame_list,
                                     P2M_FL_ENTRIES);
 

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