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Re: [Qemu-devel] [PATCH 2/2] memory: fix the eventfd data endianness acc
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] memory: fix the eventfd data endianness according to the host |
Date: |
Fri, 13 Mar 2015 12:06:06 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
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 <address@hidden>
> Signed-off-by: Greg Kurz <address@hidden>
> ---
> 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])) {
>
- Re: [Qemu-devel] [PATCH] virtio-pci: fix host notifiers on bi-endian architectures, (continued)
- Re: [Qemu-devel] [PATCH] virtio-pci: fix host notifiers on bi-endian architectures, Michael S. Tsirkin, 2015/03/11
- Re: [Qemu-devel] [PATCH] virtio-pci: fix host notifiers on bi-endian architectures, Michael S. Tsirkin, 2015/03/12
- Re: [Qemu-devel] [PATCH] virtio-pci: fix host notifiers on bi-endian architectures, Paolo Bonzini, 2015/03/12
- Re: [Qemu-devel] [PATCH] virtio-pci: fix host notifiers on bi-endian architectures, Greg Kurz, 2015/03/13
- [Qemu-devel] [PATCH 1/2] memory: make adjust_endianness() generic, Greg Kurz, 2015/03/13
- [Qemu-devel] [PATCH 2/2] memory: fix the eventfd data endianness according to the host, Greg Kurz, 2015/03/13
- Re: [Qemu-devel] [PATCH 2/2] memory: fix the eventfd data endianness according to the host,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 2/2] memory: fix the eventfd data endianness according to the host, Greg Kurz, 2015/03/13
- Re: [Qemu-devel] [PATCH 2/2] memory: fix the eventfd data endianness according to the host, Paolo Bonzini, 2015/03/13
- Re: [Qemu-devel] [PATCH 2/2] memory: fix the eventfd data endianness according to the host, Michael S. Tsirkin, 2015/03/13
- Re: [Qemu-devel] [PATCH 2/2] memory: fix the eventfd data endianness according to the host, Michael S. Tsirkin, 2015/03/13