Messages in this thread | | | Date | Mon, 06 Sep 2010 21:05:35 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH 10/27] KVM: MMU: Add infrastructure for two-level page walker |
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On 09/06/2010 06:55 PM, Joerg Roedel wrote: > This patch introduces a mmu-callback to translate gpa > addresses in the walk_addr code. This is later used to > translate l2_gpa addresses into l1_gpa addresses.
> @@ -534,6 +534,11 @@ static inline gpa_t gfn_to_gpa(gfn_t gfn) > return (gpa_t)gfn<< PAGE_SHIFT; > } > > +static inline gfn_t gpa_to_gfn(gpa_t gpa) > +{ > + return (gfn_t)gpa>> PAGE_SHIFT; > +} > +
That's a bug - gfn_t may be smaller than gpa_t, so you're truncating just before the shift. Note the casts in the surrounding functions are widening, not narrowing.
However, gfn_t is u64 so the bug is only theoretical.
-- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.
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