Re: [PATCH 1/5] mmu: mark spte present if the x bit is set

Paolo Bonzini
2016-06-28T20:18:14Z

On 28/06/2016 19:33, Bandan Das wrote:
>>> >> static int is_shadow_present_pte(u64 pte)
>>> >> {
>>> >> - return pte & PT_PRESENT_MASK && !is_mmio_spte(pte);
>>> >> + return pte & (PT_PRESENT_MASK | shadow_x_mask) &&
>>> >> + !is_mmio_spte(pte);
>> >
>> > This should really be pte & 7 when using EPT. But this is okay as an
>> > alternative to a new shadow_present_mask.
> I could revive shadow_xonly_valid probably... Anyway, for now I will
> add a TODO comment here.

It's okay to it like this, because the only invalid PTEs reaching this
point are those that is_mmio_spte filters away. Hence you'll never get
-W- PTEs here, and pte & 7 is really the same as how you wrote it. It's
pretty clever, and doesn't need a TODO at all. :)

Paolo