On 13/03/2015 09:11, Greg Kurz wrote:
> The data argument is a host entity. It is not related to the target
> endianness. Let's introduce a HOST_WORDS_BIGENDIAN based helper for
> that.
>
> This patch fixes ioeventfd and vhost for a ppc64le host running a ppc64le
> guest (only virtqueue 0 was handled, all others being byteswapped because
> of TARGET_WORDS_BIGENDIAN). It doesn't change functionnality for fixed
> endian architectures (i.e. doesn't break x86).
>
> Reported-by: Cédric Le Goater <c...@fr.ibm.com>
> Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com>
> ---
> memory.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/memory.c b/memory.c
> index 6291cc0..1e29d40 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1549,6 +1549,15 @@ void memory_region_clear_flush_coalesced(MemoryRegion
> *mr)
> }
> }
>
> +static bool eventfd_wrong_endianness(MemoryRegion *mr)
> +{
> +#ifdef HOST_WORDS_BIGENDIAN
> + return mr->ops->endianness == DEVICE_LITTLE_ENDIAN;
> +#else
> + return mr->ops->endianness == DEVICE_BIG_ENDIAN;
> +#endif
> +}
> +
> void memory_region_add_eventfd(MemoryRegion *mr,
> hwaddr addr,
> unsigned size,
> @@ -1565,7 +1574,7 @@ void memory_region_add_eventfd(MemoryRegion *mr,
> };
> unsigned i;
>
> - adjust_endianness(&mrfd.data, size, memory_region_wrong_endianness(mr));
> + adjust_endianness(&mrfd.data, size, eventfd_wrong_endianness(mr));
Strictly speaking, the place to do this would be kvm_set_ioeventfd_mmio.
A hypothetical userspace ioeventfd emulation would not need the swap.
I can accept the patch, but it's better to add a comment.
Paolo
> memory_region_transaction_begin();
> for (i = 0; i < mr->ioeventfd_nb; ++i) {
> if (memory_region_ioeventfd_before(mrfd, mr->ioeventfds[i])) {
> @@ -1598,7 +1607,7 @@ void memory_region_del_eventfd(MemoryRegion *mr,
> };
> unsigned i;
>
> - adjust_endianness(&mrfd.data, size, memory_region_wrong_endianness(mr));
> + adjust_endianness(&mrfd.data, size, eventfd_wrong_endianness(mr));
> memory_region_transaction_begin();
> for (i = 0; i < mr->ioeventfd_nb; ++i) {
> if (memory_region_ioeventfd_equal(mrfd, mr->ioeventfds[i])) {
>
