Re: [Xen-devel] [PATCH 6/7] x86/pagewalk: Consistently use guest_walk_*() helpers for translation

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 27/02/17 14:03, Andrew Cooper wrote:
> hap_p2m_ga_to_gfn() and sh_page_fault() currently use guest_l1e_get_gfn() to
> obtain the translation of a pagewalk.  This is conceptually wrong (the
> semantics of gw.l1e is an internal detail), and will actually be wrong when
> PSE36 superpage support is fixed.  Switch them to using guest_walk_to_gfn().
> 
> Take the opportunity to const-correct the walk_t parameter of the
> guest_walk_to_*() helpers, and implement guest_walk_to_gpa() in terms of
> guest_walk_to_gfn() to avoid duplicating the actual translation calculation.
> 
> While editing guest_walk_to_gpa(), fix a latent bug by causing it to return
> INVALID_PADDR rather than 0 for a failed translation, as 0 is also a valid
> successful result.  The sole caller, sh_page_fault(), has already confirmed
> that the translation is valid, so this doesn't cause a behavioural change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx>


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