[PATCH v5 26/32] x86, drm, fbdev: Do not specify encrypted memory for video mappings

[Tom Lendacky]

On 5/16/2017 12:35 PM, Borislav Petkov wrote:
> On Tue, Apr 18, 2017 at 04:20:56PM -0500, Tom Lendacky wrote:
>> Since video memory needs to be accessed decrypted, be sure that the
>> memory encryption mask is not set for the video ranges.
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky at amd.com>
>> ---
>>   arch/x86/include/asm/vga.h       |   13 +++++++++++++
>>   arch/x86/mm/pageattr.c           |    2 ++
>>   drivers/gpu/drm/drm_gem.c        |    2 ++
>>   drivers/gpu/drm/drm_vm.c         |    4 ++++
>>   drivers/gpu/drm/ttm/ttm_bo_vm.c  |    7 +++++--
>>   drivers/gpu/drm/udl/udl_fb.c     |    4 ++++
>>   drivers/video/fbdev/core/fbmem.c |   12 ++++++++++++
>>   7 files changed, 42 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/vga.h b/arch/x86/include/asm/vga.h
>> index c4b9dc2..5c7567a 100644
>> --- a/arch/x86/include/asm/vga.h
>> +++ b/arch/x86/include/asm/vga.h
>> @@ -7,12 +7,25 @@
>>   #ifndef _ASM_X86_VGA_H
>>   #define _ASM_X86_VGA_H
>>   
>> +#include <asm/cacheflush.h>
>> +
>>   /*
>>    *	On the PC, we can just recalculate addresses and then
>>    *	access the videoram directly without any black magic.
>> + *	To support memory encryption however, we need to access
>> + *	the videoram as decrypted memory.
>>    */
>>   
>> +#ifdef CONFIG_AMD_MEM_ENCRYPT
>> +#define VGA_MAP_MEM(x, s)					\
>> +({								\
>> +	unsigned long start = (unsigned long)phys_to_virt(x);	\
>> +	set_memory_decrypted(start, (s) >> PAGE_SHIFT);		\
>> +	start;							\
>> +})
>> +#else
>>   #define VGA_MAP_MEM(x, s) (unsigned long)phys_to_virt(x)
>> +#endif
> 
> Can we push the check in and save us the ifdeffery?
> 
> #define VGA_MAP_MEM(x, s)                                       \
> ({                                                              \
>          unsigned long start = (unsigned long)phys_to_virt(x);   \
>                                                                  \
>          if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT))                 \
>                  set_memory_decrypted(start, (s) >> PAGE_SHIFT); \
>                                                                  \
>          start;                                                  \
> })
> 
> It does build here. :)
> 

That works for me and it's a lot cleaner.  I'll make the change.

Thanks,
Tom