Re: [PATCH] virtio_mmio: fix endian-ness for mmio

Michael S. Tsirkin
2015-03-09T08:39:52Z

On Thu, Mar 05, 2015 at 10:54:31PM +0100, Michael S. Tsirkin wrote:
> Going over the virtio mmio code, I noticed that it doesn't correctly
> return device config values in LE format when using virtio 1.0.
> Borrow code from virtio_pci_modern to do this correctly.
>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Pawel, could you review and ack please?
It'd be unfortunate if we released a version
with incorrect endian-ness.

> ---
>
> Note: untested: QEMU doesn't support virtio 1.0 for virtio-mmio.
> Pawel, could you please confirm this patch makes sense?
>
> drivers/virtio/virtio_mmio.c | 79 +++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 71 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> index cad5698..0375456 100644
> --- a/drivers/virtio/virtio_mmio.c
> +++ b/drivers/virtio/virtio_mmio.c
> @@ -156,22 +156,85 @@ static void vm_get(struct virtio_device *vdev, unsigned offset,
> void *buf, unsigned len)
> {
> struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
> - u8 *ptr = buf;
> - int i;
> + void __iomem *base = vm_dev->base + VIRTIO_MMIO_CONFIG;
> + u8 b;
> + __le16 w;
> + __le32 l;
>
> - for (i = 0; i < len; i++)
> - ptr[i] = readb(vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
> + if (vm_dev->version == 1) {
> + u8 *ptr = buf;
> + int i;
> +
> + for (i = 0; i < len; i++)
> + ptr[i] = readb(base + offset + i);
> + return;
> + }
> +
> + switch (len) {
> + case 1:
> + b = readb(base + offset);
> + memcpy(buf, &b, sizeof b);
> + break;
> + case 2:
> + w = cpu_to_le16(readw(base + offset));
> + memcpy(buf, &w, sizeof w);
> + break;
> + case 4:
> + l = cpu_to_le32(readl(base + offset));
> + memcpy(buf, &l, sizeof l);
> + break;
> + case 8:
> + l = cpu_to_le32(readl(base + offset));
> + memcpy(buf, &l, sizeof l);
> + l = cpu_to_le32(ioread32(base + offset + sizeof l));
> + memcpy(buf + sizeof l, &l, sizeof l);
> + break;
> + default:
> + BUG();
> + }
> }
>
> static void vm_set(struct virtio_device *vdev, unsigned offset,
> const void *buf, unsigned len)
> {
> struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
> - const u8 *ptr = buf;
> - int i;
> + void __iomem *base = vm_dev->base + VIRTIO_MMIO_CONFIG;
> + u8 b;
> + __le16 w;
> + __le32 l;
>
> - for (i = 0; i < len; i++)
> - writeb(ptr[i], vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
> + if (vm_dev->version == 1) {
> + const u8 *ptr = buf;
> + int i;
> +
> + for (i = 0; i < len; i++)
> + writeb(ptr[i], base + offset + i);
> +
> + return;
> + }
> +
> + switch (len) {
> + case 1:
> + memcpy(&b, buf, sizeof b);
> + writeb(b, base + offset);
> + break;
> + case 2:
> + memcpy(&w, buf, sizeof w);
> + writew(le16_to_cpu(w), base + offset);
> + break;
> + case 4:
> + memcpy(&l, buf, sizeof l);
> + writel(le32_to_cpu(l), base + offset);
> + break;
> + case 8:
> + memcpy(&l, buf, sizeof l);
> + writel(le32_to_cpu(l), base + offset);
> + memcpy(&l, buf + sizeof l, sizeof l);
> + writel(le32_to_cpu(l), base + offset + sizeof l);
> + break;
> + default:
> + BUG();
> + }
> }
>
> static u8 vm_get_status(struct virtio_device *vdev)
> --
> MST