On Fri, Jun 02, 2017 at 07:50:53PM +0800, Peter Xu wrote:
> This patch let address_space_get_iotlb_entry() to use the newly
> introduced page_mask parameter in address_space_do_translate(). Then we
> will be sure the IOTLB can be aligned to page mask, also we should
> nicely support huge pages now when introducing a764040.
>
> Fixes: a764040 ("exec: abstract address_space_do_translate()")
> Signed-off-by: Peter Xu <pet...@redhat.com>
> ---
> exec.c | 29 ++++++++++-------------------
> 1 file changed, 10 insertions(+), 19 deletions(-)
>
> diff --git a/exec.c b/exec.c
> index 63a3ff0..1f86253 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -544,14 +544,14 @@ IOMMUTLBEntry
> address_space_get_iotlb_entry(AddressSpace *as, hwaddr addr,
> bool is_write)
> {
> MemoryRegionSection section;
> - hwaddr xlat, plen;
> + hwaddr xlat, page_mask;
>
> - /* Try to get maximum page mask during translation. */
> - plen = (hwaddr)-1;
> -
> - /* This can never be MMIO. */
> - section = address_space_do_translate(as, addr, &xlat, &plen,
> - NULL, is_write, false);
> + /*
> + * This can never be MMIO, and we don't really care about plen,
> + * but page mask.
> + */
> + section = address_space_do_translate(as, addr, &xlat, NULL,
> + &page_mask, is_write, false);
>
> /* Illegal translation */
> if (section.mr == &io_mem_unassigned) {
Can we just use section.size - xlat here?
> @@ -562,20 +562,11 @@ IOMMUTLBEntry
> address_space_get_iotlb_entry(AddressSpace *as, hwaddr addr,
> xlat += section.offset_within_address_space -
> section.offset_within_region;
>
> - if (plen == (hwaddr)-1) {
> - /* If not specified during translation, use default mask */
> - plen = TARGET_PAGE_MASK;
> - } else {
> - /* Make it a valid page mask */
> - assert(plen);
> - plen = pow2floor(plen) - 1;
> - }
> -
> return (IOMMUTLBEntry) {
> .target_as = section.address_space,
> - .iova = addr & ~plen,
> - .translated_addr = xlat & ~plen,
> - .addr_mask = plen,
> + .iova = addr & ~page_mask,
> + .translated_addr = xlat & ~page_mask,
> + .addr_mask = page_mask,
> /* IOTLBs are for DMAs, and DMA only allows on RAMs. */
BTW this comment is pretty confusing. What does it mean?
> .perm = IOMMU_RW,
> };
Looks like we should change IOMMUTLBEntry to pass size and not mask -
then we could simply pass info from section as is. iova would be
addr - xlat.
> --
> 2.7.4
