>>> On 03.07.15 at 18:25, <paul.durr...@citrix.com> wrote:
> @@ -635,13 +605,41 @@ static int hvmemul_phys_mmio_access(
> return rc;
> }
>
> +static struct hvm_mmio_cache *hvmemul_find_mmio_cache(
> + struct hvm_vcpu_io *vio, unsigned long gla, uint8_t dir)
> +{
> + unsigned int i;
> + struct hvm_mmio_cache *cache;
> +
> + for ( i = 0; i < vio->mmio_cache_count; i ++ )
> + {
> + cache = &vio->mmio_cache[i];
> +
> + if ( gla == cache->gla &&
> + dir == cache->dir )
> + return cache;
> + }
> +
> + i = vio->mmio_cache_count++;
> + BUG_ON(i == ARRAY_SIZE(vio->mmio_cache));
> +
> + cache = &vio->mmio_cache[i];
> + memset(cache, 0, sizeof (*cache));
> +
> + cache->gla = gla;
> + cache->dir = dir;
> +
> + return cache;
> +}
There's still a weakness here (but that also applies if you used physical
addresses): Multiple reads to the same address may not return the
same result. I don't think this needs to be addressed here, but adding
a comment clarifying that this case isn't handled correctly would help
future readers easier understand the state of affairs.
As to the BUG_ON() - I think this would better be a domain_crash(),
just in case we overlooked an exotic instruction accessing more than
3 memory locations.
Jan
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