On 07/24/2013 04:39:59 AM, Alexander Graf wrote:
On 24.07.2013, at 11:35, Gleb Natapov wrote:
> On Wed, Jul 24, 2013 at 11:21:11AM +0200, Alexander Graf wrote:
>>> Are not we going to use page_is_ram() from
e500_shadow_mas2_attrib() as Scott commented?
>>
>> rWhy aren't we using page_is_ram() in kvm_is_mmio_pfn()?
>>
>>
> Because it is much slower and, IIRC, actually used to build pfn map
that allow
> us to check quickly for valid pfn.
Then why should we use page_is_ram()? :)
I really don't want the e500 code to diverge too much from what the
rest of the kvm code is doing.
I don't understand "actually used to build pfn map...". What code is
this? I don't see any calls to page_is_ram() in the KVM code, or in
generic mm code. Is this a statement about what x86 does?
On PPC page_is_ram() is only called (AFAICT) for determining what
attributes to set on mmaps. We want to be sure that KVM always makes
the same decision. While pfn_valid() seems like it should be
equivalent, it's not obvious from the PPC code that it is.
If pfn_valid() is better, why is that not used for mmap? Why are there
two different names for the same thing?
-Scott
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