On Wed, 2011-05-11 at 08:37 +0300, Pekka Enberg wrote:
> On Wed, May 11, 2011 at 12:05 AM, Sasha Levin <levinsasha928@xxxxxxxxx> wrote:
> > + if (kvm->ram_size < 0xe0000000) {
>
> Please use the ULL postfix for constants to ensure the types are sane.
> Also, please come up with a sane name for these.
>
> > @@ -60,7 +60,14 @@ static inline u32 segment_to_flat(u16 selector, u16 offset)
> >
> > static inline void *guest_flat_to_host(struct kvm *self, unsigned long offset)
> > {
> > - return self->ram_start + offset;
> > + /*
> > + * We have a gap between 0xe0000000 and 0x100000000.
> > + * Consider it when translating an address above 0x100000000.
> > + */
> > + if (offset < 0xe0000000)
> > + return self->ram_start + offset;
> > + else
> > + return self->ram_start + 0xe0000000 + (offset - 0x100000000);
> > }
>
> Would it not be simpler to mmap() a "ram_size + gap_size" contiguous
> region and mprotect(PROT_NONE) the gap? We'd still tell KVM and E820
> maps about two separate regions but guest_flat_to_host() would
> work-as-is.
I've wanted to avoid actually allocating that gap (which is currently
512MB) and instead take the hit in guest_flat_to_host().
If you feel the 512MB vs guest_flat_to_host() trade-off is worth it,
I'll change it to work that way.
--
Sasha.
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