On Tue, Dec 19, 2023 at 11:32:27PM -0800, Changyuan Lyu wrote: > On Tue, Dec 19, 2023 at 11:01 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > > > This is not a great description. Please describe what the patch does. > > Thanks for the feedback! Please see the v3 patch below. > > ---8<--- > > This patch adds the support for feature VIRTIO_PMEM_F_SHMEM_REGION > (virtio spec v1.2 section 5.19.5.2 [1]). Feature bit > VIRTIO_PMEM_F_SHMEM_REGION is added to the driver feature > table. > > If the driver feature bit VIRTIO_PMEM_F_SHMEM_REGION is found, > during probe, virtio pmem ignores the `start` and `size` fields in > device config and looks for a shared memory region of id 0. The > physical address range of the pmem is then determined by the physical > address range of shared memory region 0. > > [1] https://docs.oasis-open.org/virtio/virtio/v1.2/csd01/virtio-v1.2-csd01.html#x1-6480002 > > Signed-off-by: Changyuan Lyu <changyuanl@xxxxxxxxxx> > > --- > v3: > * updated the patch description. > V2: > * renamed VIRTIO_PMEM_SHMCAP_ID to VIRTIO_PMEM_SHMEM_REGION_ID > * fixed the error handling when region 0 does not exist > --- > drivers/nvdimm/virtio_pmem.c | 30 ++++++++++++++++++++++++++---- > include/uapi/linux/virtio_pmem.h | 8 ++++++++ > 2 files changed, 34 insertions(+), 4 deletions(-) > > diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c > index a92eb172f0e7..8e447c7558cb 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 +59,24 @@ 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_SHMEM_REGION_ID); > + if (!have_shm) { > + dev_err(&vdev->dev, "failed to get shared memory region %d\n", > + VIRTIO_PMEM_SHMEM_REGION_ID); > + err = -ENXIO; > + goto out_vq; Maybe additionally, add a validate callback and clear VIRTIO_PMEM_F_SHMEM_REGION if VIRTIO_PMEM_SHMEM_REGION_ID is not there. > + } > + 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 +138,13 @@ 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..c5e49b6e58b1 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 > + */ Either make this comment shorter to fit in one line, or put the multi-line comment before the define. > + > +/* shmid of the shared memory region corresponding to the pmem */ > +#define VIRTIO_PMEM_SHMEM_REGION_ID 0 > + > struct virtio_pmem_config { > __le64 start; > __le64 size; > -- > 2.43.0.472.g3155946c3a-goog
