On Tue, 4 Feb 2014, Paolo Bonzini wrote:
> Il 04/02/2014 08:55, Alexander Graf ha scritto:
> >> With this change, the
> >> memory system is now refusing to allow an access of size
> >> 2 through, because it's greater than the region length. So
> >
> > Ouch. Yes, for ioport reads/writes we definitely have to only cap the port
> > range, not the length.
>
> We can do it in general for MMIO. Something like this?
>
> diff --git a/exec.c b/exec.c
> index 9ad0a4b..9a1eef3 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -325,7 +325,7 @@ address_space_translate_internal(AddressSpaceDispatch *d,
> hwaddr addr, hwaddr *x
> hwaddr *plen, bool resolve_subpage)
> {
> MemoryRegionSection *section;
> - Int128 diff, diff_page;
> + Int128 diff;
>
> section = address_space_lookup_region(d, addr, resolve_subpage);
> /* Compute offset within MemoryRegionSection */
> @@ -334,9 +334,7 @@ address_space_translate_internal(AddressSpaceDispatch *d,
> hwaddr addr, hwaddr *x
> /* Compute offset within MemoryRegion */
> *xlat = addr + section->offset_within_region;
>
> - diff_page = int128_make64(((addr & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE)
> - addr);
> diff = int128_sub(section->mr->size, int128_make64(addr));
> - diff = int128_min(diff, diff_page);
> *plen = int128_get64(int128_min(diff, int128_make64(*plen)));
> return section;
> }
> @@ -370,6 +368,11 @@ MemoryRegion *address_space_translate(AddressSpace *as,
> hwaddr addr,
> as = iotlb.target_as;
> }
>
> + if (memory_access_is_direct(mr, is_write)) {
> + hwaddr page = (addr & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE - addr;
> + len = MIN(page, len);
> + }
> +
> *plen = len;
> *xlat = addr;
> return mr;
>
>
> Stefano, Anthony, can you test it on Xen?
>
> I wouldn't mind sticking a "xen_enabled()" in there, and/or a comment to
> document
> why we do it.
The patch looks OK as it is, let's see how Anthony's tests turn out.
