On Fri, Aug 07, 2020 at 03:55:11PM -0400, Vivek Goyal wrote:
> From: Sebastien Boeuf <sebastien.boeuf@xxxxxxxxx>
>
> On MMIO a new set of registers is defined for finding SHM
> regions. Add their definitions and use them to find the region.
>
> Signed-off-by: Sebastien Boeuf <sebastien.boeuf@xxxxxxxxx>
> Cc: kvm@xxxxxxxxxxxxxxx
> Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
> drivers/virtio/virtio_mmio.c | 32 ++++++++++++++++++++++++++++++++
> include/uapi/linux/virtio_mmio.h | 11 +++++++++++
> 2 files changed, 43 insertions(+)
>
> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> index 627ac0487494..2697c492cf78 100644
> --- a/drivers/virtio/virtio_mmio.c
> +++ b/drivers/virtio/virtio_mmio.c
> @@ -498,6 +498,37 @@ static const char *vm_bus_name(struct virtio_device *vdev)
> return vm_dev->pdev->name;
> }
>
> +static bool vm_get_shm_region(struct virtio_device *vdev,
> + struct virtio_shm_region *region, u8 id)
> +{
> + struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
> + u64 len, addr;
> +
> + /* Select the region we're interested in */
> + writel(id, vm_dev->base + VIRTIO_MMIO_SHM_SEL);
> +
> + /* Read the region size */
> + len = (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_LEN_LOW);
> + len |= (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_LEN_HIGH) << 32;
> +
> + region->len = len;
> +
> + /* Check if region length is -1. If that's the case, the shared memory
> + * region does not exist and there is no need to proceed further.
> + */
> + if (len == ~(u64)0) {
> + return false;
> + }
> +
It might make sense to validate that addr/len do not overlap.
Will be useful for PCI too.
Can be a patch on top.
> + /* Read the region base address */
> + addr = (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_BASE_LOW);
> + addr |= (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_BASE_HIGH) << 32;
> +
> + region->addr = addr;
> +
> + return true;
> +}
> +
> static const struct virtio_config_ops virtio_mmio_config_ops = {
> .get = vm_get,
> .set = vm_set,
> @@ -510,6 +541,7 @@ static const struct virtio_config_ops virtio_mmio_config_ops = {
> .get_features = vm_get_features,
> .finalize_features = vm_finalize_features,
> .bus_name = vm_bus_name,
> + .get_shm_region = vm_get_shm_region,
> };
>
>
> diff --git a/include/uapi/linux/virtio_mmio.h b/include/uapi/linux/virtio_mmio.h
> index c4b09689ab64..0650f91bea6c 100644
> --- a/include/uapi/linux/virtio_mmio.h
> +++ b/include/uapi/linux/virtio_mmio.h
> @@ -122,6 +122,17 @@
> #define VIRTIO_MMIO_QUEUE_USED_LOW 0x0a0
> #define VIRTIO_MMIO_QUEUE_USED_HIGH 0x0a4
>
> +/* Shared memory region id */
> +#define VIRTIO_MMIO_SHM_SEL 0x0ac
> +
> +/* Shared memory region length, 64 bits in two halves */
> +#define VIRTIO_MMIO_SHM_LEN_LOW 0x0b0
> +#define VIRTIO_MMIO_SHM_LEN_HIGH 0x0b4
> +
> +/* Shared memory region base address, 64 bits in two halves */
> +#define VIRTIO_MMIO_SHM_BASE_LOW 0x0b8
> +#define VIRTIO_MMIO_SHM_BASE_HIGH 0x0bc
> +
> /* Configuration atomicity value */
> #define VIRTIO_MMIO_CONFIG_GENERATION 0x0fc
>
> --
> 2.25.4
>
