On Tue, Dec 19, 2023 at 3:19 PM Changyuan Lyu <changyuanl@xxxxxxxxxx> wrote:
>
> As per virtio spec 1.2 section 5.19.5.2, if the feature
> VIRTIO_PMEM_F_SHMEM_REGION has been negotiated, the driver MUST query
> shared memory ID 0 for the physical address ranges.
>
> Signed-off-by: Changyuan Lyu <changyuanl@xxxxxxxxxx>
> ---
> drivers/nvdimm/virtio_pmem.c | 29 +++++++++++++++++++++++++----
> include/uapi/linux/virtio_pmem.h | 8 ++++++++
> 2 files changed, 33 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c
> index a92eb172f0e7..5b28d543728b 100644
> --- a/drivers/nvdimm/virtio_pmem.c
> +++ b/drivers/nvdimm/virtio_pmem.c
> @@ -35,6 +35,8 @@ static int virtio_pmem_probe(struct virtio_device *vdev)
> struct nd_region *nd_region;
> struct virtio_pmem *vpmem;
> struct resource res;
> + struct virtio_shm_region shm_reg;
> + bool have_shm;
> int err = 0;
>
> if (!vdev->config->get) {
> @@ -57,10 +59,23 @@ static int virtio_pmem_probe(struct virtio_device *vdev)
> goto out_err;
> }
>
> - virtio_cread_le(vpmem->vdev, struct virtio_pmem_config,
> - start, &vpmem->start);
> - virtio_cread_le(vpmem->vdev, struct virtio_pmem_config,
> - size, &vpmem->size);
> + if (virtio_has_feature(vdev, VIRTIO_PMEM_F_SHMEM_REGION)) {
> + have_shm = virtio_get_shm_region(vdev, &shm_reg,
> + (u8)VIRTIO_PMEM_SHMCAP_ID);
> + if (!have_shm) {
> + dev_err(&vdev->dev, "failed to get shared memory region %d\n",
> + VIRTIO_PMEM_SHMCAP_ID);
> + return -EINVAL;
> + }
> + vpmem->start = shm_reg.addr;
> + vpmem->size = shm_reg.len;
> + } else {
> + virtio_cread_le(vpmem->vdev, struct virtio_pmem_config,
> + start, &vpmem->start);
> + virtio_cread_le(vpmem->vdev, struct virtio_pmem_config,
> + size, &vpmem->size);
> + }
> +
>
> res.start = vpmem->start;
> res.end = vpmem->start + vpmem->size - 1;
> @@ -122,7 +137,13 @@ static void virtio_pmem_remove(struct virtio_device *vdev)
> virtio_reset_device(vdev);
> }
>
> +static unsigned int features[] = {
> + VIRTIO_PMEM_F_SHMEM_REGION,
> +};
> +
> static struct virtio_driver virtio_pmem_driver = {
> + .feature_table = features,
> + .feature_table_size = ARRAY_SIZE(features),
> .driver.name = KBUILD_MODNAME,
> .driver.owner = THIS_MODULE,
> .id_table = id_table,
> diff --git a/include/uapi/linux/virtio_pmem.h b/include/uapi/linux/virtio_pmem.h
> index d676b3620383..025174f6eacf 100644
> --- a/include/uapi/linux/virtio_pmem.h
> +++ b/include/uapi/linux/virtio_pmem.h
> @@ -14,6 +14,14 @@
> #include <linux/virtio_ids.h>
> #include <linux/virtio_config.h>
>
> +/* Feature bits */
> +#define VIRTIO_PMEM_F_SHMEM_REGION 0 /* guest physical address range will be
> + * indicated as shared memory region 0
> + */
> +
> +/* shmid of the shared memory region corresponding to the pmem */
> +#define VIRTIO_PMEM_SHMCAP_ID 0
NIT: not a native speaker, but any reason for "CAP" here? Would it be
better to use SHMMEM_REGION_ID?
Thanks
> +
> struct virtio_pmem_config {
> __le64 start;
> __le64 size;
> --
> 2.43.0.472.g3155946c3a-goog
>
