| Message ID | 20190510155202.14737-3-pagupta@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | virtio pmem driver | expand |
On Fri, May 10, 2019 at 09:21:58PM +0530, Pankaj Gupta wrote: > This patch adds virtio-pmem driver for KVM guest. > > Guest reads the persistent memory range information from > Qemu over VIRTIO and registers it on nvdimm_bus. It also > creates a nd_region object with the persistent memory > range information so that existing 'nvdimm/pmem' driver > can reserve this into system memory map. This way > 'virtio-pmem' driver uses existing functionality of pmem > driver to register persistent memory compatible for DAX > capable filesystems. > > This also provides function to perform guest flush over > VIRTIO from 'pmem' driver when userspace performs flush > on DAX memory range. > > Signed-off-by: Pankaj Gupta <pagupta@redhat.com> > Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> > --- > drivers/nvdimm/Makefile | 1 + > drivers/nvdimm/nd_virtio.c | 129 +++++++++++++++++++++++++++++++ > drivers/nvdimm/virtio_pmem.c | 117 ++++++++++++++++++++++++++++ > drivers/virtio/Kconfig | 10 +++ > include/linux/virtio_pmem.h | 60 ++++++++++++++ > include/uapi/linux/virtio_ids.h | 1 + > include/uapi/linux/virtio_pmem.h | 10 +++ > 7 files changed, 328 insertions(+) > create mode 100644 drivers/nvdimm/nd_virtio.c > create mode 100644 drivers/nvdimm/virtio_pmem.c > create mode 100644 include/linux/virtio_pmem.h > create mode 100644 include/uapi/linux/virtio_pmem.h > > diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile > index 6f2a088afad6..cefe233e0b52 100644 > --- a/drivers/nvdimm/Makefile > +++ b/drivers/nvdimm/Makefile > @@ -5,6 +5,7 @@ obj-$(CONFIG_ND_BTT) += nd_btt.o > obj-$(CONFIG_ND_BLK) += nd_blk.o > obj-$(CONFIG_X86_PMEM_LEGACY) += nd_e820.o > obj-$(CONFIG_OF_PMEM) += of_pmem.o > +obj-$(CONFIG_VIRTIO_PMEM) += virtio_pmem.o nd_virtio.o > > nd_pmem-y := pmem.o > > diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c > new file mode 100644 > index 000000000000..ed7ddcc5a62c > --- /dev/null > +++ b/drivers/nvdimm/nd_virtio.c > @@ -0,0 +1,129 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * virtio_pmem.c: Virtio pmem Driver > + * > + * Discovers persistent memory range information > + * from host and provides a virtio based flushing > + * interface. > + */ > +#include <linux/virtio_pmem.h> > +#include "nd.h" > + > + /* The interrupt handler */ > +void host_ack(struct virtqueue *vq) > +{ > + unsigned int len; > + unsigned long flags; > + struct virtio_pmem_request *req, *req_buf; > + struct virtio_pmem *vpmem = vq->vdev->priv; > + > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > + while ((req = virtqueue_get_buf(vq, &len)) != NULL) { > + req->done = true; > + wake_up(&req->host_acked); > + > + if (!list_empty(&vpmem->req_list)) { > + req_buf = list_first_entry(&vpmem->req_list, > + struct virtio_pmem_request, list); > + req_buf->wq_buf_avail = true; > + wake_up(&req_buf->wq_buf); > + list_del(&req_buf->list); > + } > + } > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > +} > +EXPORT_SYMBOL_GPL(host_ack); > + > + /* The request submission function */ > +int virtio_pmem_flush(struct nd_region *nd_region) > +{ > + int err, err1; > + unsigned long flags; > + struct scatterlist *sgs[2], sg, ret; > + struct virtio_device *vdev = nd_region->provider_data; > + struct virtio_pmem *vpmem = vdev->priv; > + struct virtio_pmem_request *req; > + > + might_sleep(); > + req = kmalloc(sizeof(*req), GFP_KERNEL); > + if (!req) > + return -ENOMEM; > + > + req->done = false; > + strcpy(req->name, "FLUSH"); > + init_waitqueue_head(&req->host_acked); > + init_waitqueue_head(&req->wq_buf); > + INIT_LIST_HEAD(&req->list); > + sg_init_one(&sg, req->name, strlen(req->name)); > + sgs[0] = &sg; > + sg_init_one(&ret, &req->ret, sizeof(req->ret)); > + sgs[1] = &ret; > + > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > + /* > + * If virtqueue_add_sgs returns -ENOSPC then req_vq virtual > + * queue does not have free descriptor. We add the request > + * to req_list and wait for host_ack to wake us up when free > + * slots are available. > + */ > + while ((err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req, > + GFP_ATOMIC)) == -ENOSPC) { > + > + dev_err(&vdev->dev, "failed to send command to virtio pmem"\ > + "device, no free slots in the virtqueue\n"); > + req->wq_buf_avail = false; > + list_add_tail(&req->list, &vpmem->req_list); > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > + > + /* When host has read buffer, this completes via host_ack */ > + wait_event(req->wq_buf, req->wq_buf_avail); > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > + } > + err1 = virtqueue_kick(vpmem->req_vq); > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > + > + /* > + * virtqueue_add_sgs failed with error different than -ENOSPC, we can't > + * do anything about that. > + */ > + if (err || !err1) { > + dev_info(&vdev->dev, "failed to send command to virtio pmem device\n"); > + err = -EIO; > + goto ret; > + } > + > + /* When host has read buffer, this completes via host_ack */ > + wait_event(req->host_acked, req->done); > + err = req->ret; > +ret: > + kfree(req); > + return err; > +}; > + > +/* The asynchronous flush callback function */ > +int async_pmem_flush(struct nd_region *nd_region, struct bio *bio) > +{ > + int rc = 0; > + > + /* Create child bio for asynchronous flush and chain with > + * parent bio. Otherwise directly call nd_region flush. > + */ > + if (bio && bio->bi_iter.bi_sector != -1) { > + struct bio *child = bio_alloc(GFP_ATOMIC, 0); > + > + if (!child) > + return -ENOMEM; > + bio_copy_dev(child, bio); > + child->bi_opf = REQ_PREFLUSH; > + child->bi_iter.bi_sector = -1; > + bio_chain(child, bio); > + submit_bio(child); > + } else { > + if (virtio_pmem_flush(nd_region)) > + rc = -EIO; > + } > + > + return rc; > +}; > +EXPORT_SYMBOL_GPL(async_pmem_flush); > +MODULE_LICENSE("GPL"); > diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c > new file mode 100644 > index 000000000000..cfc6381c4e5d > --- /dev/null > +++ b/drivers/nvdimm/virtio_pmem.c > @@ -0,0 +1,117 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * virtio_pmem.c: Virtio pmem Driver > + * > + * Discovers persistent memory range information > + * from host and registers the virtual pmem device > + * with libnvdimm core. > + */ > +#include <linux/virtio_pmem.h> > +#include "nd.h" > + > +static struct virtio_device_id id_table[] = { > + { VIRTIO_ID_PMEM, VIRTIO_DEV_ANY_ID }, > + { 0 }, > +}; > + > + /* Initialize virt queue */ > +static int init_vq(struct virtio_pmem *vpmem) > +{ > + /* single vq */ > + vpmem->req_vq = virtio_find_single_vq(vpmem->vdev, > + host_ack, "flush_queue"); > + if (IS_ERR(vpmem->req_vq)) > + return PTR_ERR(vpmem->req_vq); > + > + spin_lock_init(&vpmem->pmem_lock); > + INIT_LIST_HEAD(&vpmem->req_list); > + > + return 0; > +}; > + > +static int virtio_pmem_probe(struct virtio_device *vdev) > +{ > + int err = 0; > + struct resource res; > + struct virtio_pmem *vpmem; > + struct nd_region_desc ndr_desc = {}; > + int nid = dev_to_node(&vdev->dev); > + struct nd_region *nd_region; > + > + if (!vdev->config->get) { > + dev_err(&vdev->dev, "%s failure: config access disabled\n", > + __func__); > + return -EINVAL; > + } > + > + vpmem = devm_kzalloc(&vdev->dev, sizeof(*vpmem), GFP_KERNEL); > + if (!vpmem) { > + err = -ENOMEM; > + goto out_err; > + } > + > + vpmem->vdev = vdev; > + vdev->priv = vpmem; > + err = init_vq(vpmem); > + if (err) > + goto out_err; > + > + virtio_cread(vpmem->vdev, struct virtio_pmem_config, > + start, &vpmem->start); > + virtio_cread(vpmem->vdev, struct virtio_pmem_config, > + size, &vpmem->size); > + > + res.start = vpmem->start; > + res.end = vpmem->start + vpmem->size-1; > + vpmem->nd_desc.provider_name = "virtio-pmem"; > + vpmem->nd_desc.module = THIS_MODULE; > + > + vpmem->nvdimm_bus = nvdimm_bus_register(&vdev->dev, > + &vpmem->nd_desc); > + if (!vpmem->nvdimm_bus) > + goto out_vq; > + > + dev_set_drvdata(&vdev->dev, vpmem->nvdimm_bus); > + > + ndr_desc.res = &res; > + ndr_desc.numa_node = nid; > + ndr_desc.flush = async_pmem_flush; > + set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags); > + set_bit(ND_REGION_ASYNC, &ndr_desc.flags); > + nd_region = nvdimm_pmem_region_create(vpmem->nvdimm_bus, &ndr_desc); > + > + if (!nd_region) > + goto out_nd; > + nd_region->provider_data = dev_to_virtio(nd_region->dev.parent->parent); > + return 0; > +out_nd: > + err = -ENXIO; > + nvdimm_bus_unregister(vpmem->nvdimm_bus); > +out_vq: > + vdev->config->del_vqs(vdev); > +out_err: > + dev_err(&vdev->dev, "failed to register virtio pmem memory\n"); > + return err; > +} > + > +static void virtio_pmem_remove(struct virtio_device *vdev) > +{ > + struct nvdimm_bus *nvdimm_bus = dev_get_drvdata(&vdev->dev); > + > + nvdimm_bus_unregister(nvdimm_bus); > + vdev->config->del_vqs(vdev); > + vdev->config->reset(vdev); > +} > + > +static struct virtio_driver virtio_pmem_driver = { > + .driver.name = KBUILD_MODNAME, > + .driver.owner = THIS_MODULE, > + .id_table = id_table, > + .probe = virtio_pmem_probe, > + .remove = virtio_pmem_remove, > +}; > + > +module_virtio_driver(virtio_pmem_driver); > +MODULE_DEVICE_TABLE(virtio, id_table); > +MODULE_DESCRIPTION("Virtio pmem driver"); > +MODULE_LICENSE("GPL"); > diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig > index 35897649c24f..9f634a2ed638 100644 > --- a/drivers/virtio/Kconfig > +++ b/drivers/virtio/Kconfig > @@ -42,6 +42,16 @@ config VIRTIO_PCI_LEGACY > > If unsure, say Y. > > +config VIRTIO_PMEM > + tristate "Support for virtio pmem driver" > + depends on VIRTIO > + depends on LIBNVDIMM > + help > + This driver provides support for virtio based flushing interface > + for persistent memory range. > + > + If unsure, say M. > + > config VIRTIO_BALLOON > tristate "Virtio balloon driver" > depends on VIRTIO > diff --git a/include/linux/virtio_pmem.h b/include/linux/virtio_pmem.h > new file mode 100644 > index 000000000000..ab1da877575d > --- /dev/null > +++ b/include/linux/virtio_pmem.h > @@ -0,0 +1,60 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * virtio_pmem.h: virtio pmem Driver > + * > + * Discovers persistent memory range information > + * from host and provides a virtio based flushing > + * interface. > + **/ > + > +#ifndef _LINUX_VIRTIO_PMEM_H > +#define _LINUX_VIRTIO_PMEM_H > + > +#include <linux/virtio_ids.h> > +#include <linux/module.h> > +#include <linux/virtio_config.h> > +#include <uapi/linux/virtio_pmem.h> > +#include <linux/libnvdimm.h> > +#include <linux/spinlock.h> > + > +struct virtio_pmem_request { > + /* Host return status corresponding to flush request */ > + int ret; > + > + /* command name*/ > + char name[16]; > + > + /* Wait queue to process deferred work after ack from host */ > + wait_queue_head_t host_acked; > + bool done; > + > + /* Wait queue to process deferred work after virt queue buffer avail */ > + wait_queue_head_t wq_buf; > + bool wq_buf_avail; > + struct list_head list; > +}; > + > +struct virtio_pmem { > + struct virtio_device *vdev; > + > + /* Virtio pmem request queue */ > + struct virtqueue *req_vq; > + > + /* nvdimm bus registers virtio pmem device */ > + struct nvdimm_bus *nvdimm_bus; > + struct nvdimm_bus_descriptor nd_desc; > + > + /* List to store deferred work if virtqueue is full */ > + struct list_head req_list; > + > + /* Synchronize virtqueue data */ > + spinlock_t pmem_lock; > + > + /* Memory region information */ > + uint64_t start; > + uint64_t size; > +}; > + > +void host_ack(struct virtqueue *vq); > +int async_pmem_flush(struct nd_region *nd_region, struct bio *bio); > +#endif > diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h > index 6d5c3b2d4f4d..32b2f94d1f58 100644 > --- a/include/uapi/linux/virtio_ids.h > +++ b/include/uapi/linux/virtio_ids.h > @@ -43,5 +43,6 @@ > #define VIRTIO_ID_INPUT 18 /* virtio input */ > #define VIRTIO_ID_VSOCK 19 /* virtio vsock transport */ > #define VIRTIO_ID_CRYPTO 20 /* virtio crypto */ > +#define VIRTIO_ID_PMEM 27 /* virtio pmem */ > > #endif /* _LINUX_VIRTIO_IDS_H */ > diff --git a/include/uapi/linux/virtio_pmem.h b/include/uapi/linux/virtio_pmem.h > new file mode 100644 > index 000000000000..fa3f7d52717a > --- /dev/null > +++ b/include/uapi/linux/virtio_pmem.h > @@ -0,0 +1,10 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > + > +#ifndef _UAPI_LINUX_VIRTIO_PMEM_H > +#define _UAPI_LINUX_VIRTIO_PMEM_H > + > +struct virtio_pmem_config { > + __le64 start; > + __le64 size; > +}; > +#endif > -- > 2.20.1
> > Guest reads the persistent memory range information from > > Qemu over VIRTIO and registers it on nvdimm_bus. It also > > creates a nd_region object with the persistent memory > > range information so that existing 'nvdimm/pmem' driver > > can reserve this into system memory map. This way > > 'virtio-pmem' driver uses existing functionality of pmem > > driver to register persistent memory compatible for DAX > > capable filesystems. > > > > This also provides function to perform guest flush over > > VIRTIO from 'pmem' driver when userspace performs flush > > on DAX memory range. > > > > Signed-off-by: Pankaj Gupta <pagupta@redhat.com> > > Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com> > > Acked-by: Michael S. Tsirkin <mst@redhat.com> Thank you, Michael. Best regards, Pankaj > > > --- > > drivers/nvdimm/Makefile | 1 + > > drivers/nvdimm/nd_virtio.c | 129 +++++++++++++++++++++++++++++++ > > drivers/nvdimm/virtio_pmem.c | 117 ++++++++++++++++++++++++++++ > > drivers/virtio/Kconfig | 10 +++ > > include/linux/virtio_pmem.h | 60 ++++++++++++++ > > include/uapi/linux/virtio_ids.h | 1 + > > include/uapi/linux/virtio_pmem.h | 10 +++ > > 7 files changed, 328 insertions(+) > > create mode 100644 drivers/nvdimm/nd_virtio.c > > create mode 100644 drivers/nvdimm/virtio_pmem.c > > create mode 100644 include/linux/virtio_pmem.h > > create mode 100644 include/uapi/linux/virtio_pmem.h > > > > diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile > > index 6f2a088afad6..cefe233e0b52 100644 > > --- a/drivers/nvdimm/Makefile > > +++ b/drivers/nvdimm/Makefile > > @@ -5,6 +5,7 @@ obj-$(CONFIG_ND_BTT) += nd_btt.o > > obj-$(CONFIG_ND_BLK) += nd_blk.o > > obj-$(CONFIG_X86_PMEM_LEGACY) += nd_e820.o > > obj-$(CONFIG_OF_PMEM) += of_pmem.o > > +obj-$(CONFIG_VIRTIO_PMEM) += virtio_pmem.o nd_virtio.o > > > > nd_pmem-y := pmem.o > > > > diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c > > new file mode 100644 > > index 000000000000..ed7ddcc5a62c > > --- /dev/null > > +++ b/drivers/nvdimm/nd_virtio.c > > @@ -0,0 +1,129 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * virtio_pmem.c: Virtio pmem Driver > > + * > > + * Discovers persistent memory range information > > + * from host and provides a virtio based flushing > > + * interface. > > + */ > > +#include <linux/virtio_pmem.h> > > +#include "nd.h" > > + > > + /* The interrupt handler */ > > +void host_ack(struct virtqueue *vq) > > +{ > > + unsigned int len; > > + unsigned long flags; > > + struct virtio_pmem_request *req, *req_buf; > > + struct virtio_pmem *vpmem = vq->vdev->priv; > > + > > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > > + while ((req = virtqueue_get_buf(vq, &len)) != NULL) { > > + req->done = true; > > + wake_up(&req->host_acked); > > + > > + if (!list_empty(&vpmem->req_list)) { > > + req_buf = list_first_entry(&vpmem->req_list, > > + struct virtio_pmem_request, list); > > + req_buf->wq_buf_avail = true; > > + wake_up(&req_buf->wq_buf); > > + list_del(&req_buf->list); > > + } > > + } > > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > > +} > > +EXPORT_SYMBOL_GPL(host_ack); > > + > > + /* The request submission function */ > > +int virtio_pmem_flush(struct nd_region *nd_region) > > +{ > > + int err, err1; > > + unsigned long flags; > > + struct scatterlist *sgs[2], sg, ret; > > + struct virtio_device *vdev = nd_region->provider_data; > > + struct virtio_pmem *vpmem = vdev->priv; > > + struct virtio_pmem_request *req; > > + > > + might_sleep(); > > + req = kmalloc(sizeof(*req), GFP_KERNEL); > > + if (!req) > > + return -ENOMEM; > > + > > + req->done = false; > > + strcpy(req->name, "FLUSH"); > > + init_waitqueue_head(&req->host_acked); > > + init_waitqueue_head(&req->wq_buf); > > + INIT_LIST_HEAD(&req->list); > > + sg_init_one(&sg, req->name, strlen(req->name)); > > + sgs[0] = &sg; > > + sg_init_one(&ret, &req->ret, sizeof(req->ret)); > > + sgs[1] = &ret; > > + > > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > > + /* > > + * If virtqueue_add_sgs returns -ENOSPC then req_vq virtual > > + * queue does not have free descriptor. We add the request > > + * to req_list and wait for host_ack to wake us up when free > > + * slots are available. > > + */ > > + while ((err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req, > > + GFP_ATOMIC)) == -ENOSPC) { > > + > > + dev_err(&vdev->dev, "failed to send command to virtio pmem"\ > > + "device, no free slots in the virtqueue\n"); > > + req->wq_buf_avail = false; > > + list_add_tail(&req->list, &vpmem->req_list); > > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > > + > > + /* When host has read buffer, this completes via host_ack */ > > + wait_event(req->wq_buf, req->wq_buf_avail); > > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > > + } > > + err1 = virtqueue_kick(vpmem->req_vq); > > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > > + > > + /* > > + * virtqueue_add_sgs failed with error different than -ENOSPC, we can't > > + * do anything about that. > > + */ > > + if (err || !err1) { > > + dev_info(&vdev->dev, "failed to send command to virtio pmem device\n"); > > + err = -EIO; > > + goto ret; > > + } > > + > > + /* When host has read buffer, this completes via host_ack */ > > + wait_event(req->host_acked, req->done); > > + err = req->ret; > > +ret: > > + kfree(req); > > + return err; > > +}; > > + > > +/* The asynchronous flush callback function */ > > +int async_pmem_flush(struct nd_region *nd_region, struct bio *bio) > > +{ > > + int rc = 0; > > + > > + /* Create child bio for asynchronous flush and chain with > > + * parent bio. Otherwise directly call nd_region flush. > > + */ > > + if (bio && bio->bi_iter.bi_sector != -1) { > > + struct bio *child = bio_alloc(GFP_ATOMIC, 0); > > + > > + if (!child) > > + return -ENOMEM; > > + bio_copy_dev(child, bio); > > + child->bi_opf = REQ_PREFLUSH; > > + child->bi_iter.bi_sector = -1; > > + bio_chain(child, bio); > > + submit_bio(child); > > + } else { > > + if (virtio_pmem_flush(nd_region)) > > + rc = -EIO; > > + } > > + > > + return rc; > > +}; > > +EXPORT_SYMBOL_GPL(async_pmem_flush); > > +MODULE_LICENSE("GPL"); > > diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c > > new file mode 100644 > > index 000000000000..cfc6381c4e5d > > --- /dev/null > > +++ b/drivers/nvdimm/virtio_pmem.c > > @@ -0,0 +1,117 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * virtio_pmem.c: Virtio pmem Driver > > + * > > + * Discovers persistent memory range information > > + * from host and registers the virtual pmem device > > + * with libnvdimm core. > > + */ > > +#include <linux/virtio_pmem.h> > > +#include "nd.h" > > + > > +static struct virtio_device_id id_table[] = { > > + { VIRTIO_ID_PMEM, VIRTIO_DEV_ANY_ID }, > > + { 0 }, > > +}; > > + > > + /* Initialize virt queue */ > > +static int init_vq(struct virtio_pmem *vpmem) > > +{ > > + /* single vq */ > > + vpmem->req_vq = virtio_find_single_vq(vpmem->vdev, > > + host_ack, "flush_queue"); > > + if (IS_ERR(vpmem->req_vq)) > > + return PTR_ERR(vpmem->req_vq); > > + > > + spin_lock_init(&vpmem->pmem_lock); > > + INIT_LIST_HEAD(&vpmem->req_list); > > + > > + return 0; > > +}; > > + > > +static int virtio_pmem_probe(struct virtio_device *vdev) > > +{ > > + int err = 0; > > + struct resource res; > > + struct virtio_pmem *vpmem; > > + struct nd_region_desc ndr_desc = {}; > > + int nid = dev_to_node(&vdev->dev); > > + struct nd_region *nd_region; > > + > > + if (!vdev->config->get) { > > + dev_err(&vdev->dev, "%s failure: config access disabled\n", > > + __func__); > > + return -EINVAL; > > + } > > + > > + vpmem = devm_kzalloc(&vdev->dev, sizeof(*vpmem), GFP_KERNEL); > > + if (!vpmem) { > > + err = -ENOMEM; > > + goto out_err; > > + } > > + > > + vpmem->vdev = vdev; > > + vdev->priv = vpmem; > > + err = init_vq(vpmem); > > + if (err) > > + goto out_err; > > + > > + virtio_cread(vpmem->vdev, struct virtio_pmem_config, > > + start, &vpmem->start); > > + virtio_cread(vpmem->vdev, struct virtio_pmem_config, > > + size, &vpmem->size); > > + > > + res.start = vpmem->start; > > + res.end = vpmem->start + vpmem->size-1; > > + vpmem->nd_desc.provider_name = "virtio-pmem"; > > + vpmem->nd_desc.module = THIS_MODULE; > > + > > + vpmem->nvdimm_bus = nvdimm_bus_register(&vdev->dev, > > + &vpmem->nd_desc); > > + if (!vpmem->nvdimm_bus) > > + goto out_vq; > > + > > + dev_set_drvdata(&vdev->dev, vpmem->nvdimm_bus); > > + > > + ndr_desc.res = &res; > > + ndr_desc.numa_node = nid; > > + ndr_desc.flush = async_pmem_flush; > > + set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags); > > + set_bit(ND_REGION_ASYNC, &ndr_desc.flags); > > + nd_region = nvdimm_pmem_region_create(vpmem->nvdimm_bus, &ndr_desc); > > + > > + if (!nd_region) > > + goto out_nd; > > + nd_region->provider_data = dev_to_virtio(nd_region->dev.parent->parent); > > + return 0; > > +out_nd: > > + err = -ENXIO; > > + nvdimm_bus_unregister(vpmem->nvdimm_bus); > > +out_vq: > > + vdev->config->del_vqs(vdev); > > +out_err: > > + dev_err(&vdev->dev, "failed to register virtio pmem memory\n"); > > + return err; > > +} > > + > > +static void virtio_pmem_remove(struct virtio_device *vdev) > > +{ > > + struct nvdimm_bus *nvdimm_bus = dev_get_drvdata(&vdev->dev); > > + > > + nvdimm_bus_unregister(nvdimm_bus); > > + vdev->config->del_vqs(vdev); > > + vdev->config->reset(vdev); > > +} > > + > > +static struct virtio_driver virtio_pmem_driver = { > > + .driver.name = KBUILD_MODNAME, > > + .driver.owner = THIS_MODULE, > > + .id_table = id_table, > > + .probe = virtio_pmem_probe, > > + .remove = virtio_pmem_remove, > > +}; > > + > > +module_virtio_driver(virtio_pmem_driver); > > +MODULE_DEVICE_TABLE(virtio, id_table); > > +MODULE_DESCRIPTION("Virtio pmem driver"); > > +MODULE_LICENSE("GPL"); > > diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig > > index 35897649c24f..9f634a2ed638 100644 > > --- a/drivers/virtio/Kconfig > > +++ b/drivers/virtio/Kconfig > > @@ -42,6 +42,16 @@ config VIRTIO_PCI_LEGACY > > > > If unsure, say Y. > > > > +config VIRTIO_PMEM > > + tristate "Support for virtio pmem driver" > > + depends on VIRTIO > > + depends on LIBNVDIMM > > + help > > + This driver provides support for virtio based flushing interface > > + for persistent memory range. > > + > > + If unsure, say M. > > + > > config VIRTIO_BALLOON > > tristate "Virtio balloon driver" > > depends on VIRTIO > > diff --git a/include/linux/virtio_pmem.h b/include/linux/virtio_pmem.h > > new file mode 100644 > > index 000000000000..ab1da877575d > > --- /dev/null > > +++ b/include/linux/virtio_pmem.h > > @@ -0,0 +1,60 @@ > > +/* SPDX-License-Identifier: GPL-2.0 */ > > +/* > > + * virtio_pmem.h: virtio pmem Driver > > + * > > + * Discovers persistent memory range information > > + * from host and provides a virtio based flushing > > + * interface. > > + **/ > > + > > +#ifndef _LINUX_VIRTIO_PMEM_H > > +#define _LINUX_VIRTIO_PMEM_H > > + > > +#include <linux/virtio_ids.h> > > +#include <linux/module.h> > > +#include <linux/virtio_config.h> > > +#include <uapi/linux/virtio_pmem.h> > > +#include <linux/libnvdimm.h> > > +#include <linux/spinlock.h> > > + > > +struct virtio_pmem_request { > > + /* Host return status corresponding to flush request */ > > + int ret; > > + > > + /* command name*/ > > + char name[16]; > > + > > + /* Wait queue to process deferred work after ack from host */ > > + wait_queue_head_t host_acked; > > + bool done; > > + > > + /* Wait queue to process deferred work after virt queue buffer avail */ > > + wait_queue_head_t wq_buf; > > + bool wq_buf_avail; > > + struct list_head list; > > +}; > > + > > +struct virtio_pmem { > > + struct virtio_device *vdev; > > + > > + /* Virtio pmem request queue */ > > + struct virtqueue *req_vq; > > + > > + /* nvdimm bus registers virtio pmem device */ > > + struct nvdimm_bus *nvdimm_bus; > > + struct nvdimm_bus_descriptor nd_desc; > > + > > + /* List to store deferred work if virtqueue is full */ > > + struct list_head req_list; > > + > > + /* Synchronize virtqueue data */ > > + spinlock_t pmem_lock; > > + > > + /* Memory region information */ > > + uint64_t start; > > + uint64_t size; > > +}; > > + > > +void host_ack(struct virtqueue *vq); > > +int async_pmem_flush(struct nd_region *nd_region, struct bio *bio); > > +#endif > > diff --git a/include/uapi/linux/virtio_ids.h > > b/include/uapi/linux/virtio_ids.h > > index 6d5c3b2d4f4d..32b2f94d1f58 100644 > > --- a/include/uapi/linux/virtio_ids.h > > +++ b/include/uapi/linux/virtio_ids.h > > @@ -43,5 +43,6 @@ > > #define VIRTIO_ID_INPUT 18 /* virtio input */ > > #define VIRTIO_ID_VSOCK 19 /* virtio vsock transport */ > > #define VIRTIO_ID_CRYPTO 20 /* virtio crypto */ > > +#define VIRTIO_ID_PMEM 27 /* virtio pmem */ > > > > #endif /* _LINUX_VIRTIO_IDS_H */ > > diff --git a/include/uapi/linux/virtio_pmem.h > > b/include/uapi/linux/virtio_pmem.h > > new file mode 100644 > > index 000000000000..fa3f7d52717a > > --- /dev/null > > +++ b/include/uapi/linux/virtio_pmem.h > > @@ -0,0 +1,10 @@ > > +/* SPDX-License-Identifier: GPL-2.0 */ > > + > > +#ifndef _UAPI_LINUX_VIRTIO_PMEM_H > > +#define _UAPI_LINUX_VIRTIO_PMEM_H > > + > > +struct virtio_pmem_config { > > + __le64 start; > > + __le64 size; > > +}; > > +#endif > > -- > > 2.20.1 > >
On 10.05.19 17:51, Pankaj Gupta wrote: > This patch adds virtio-pmem driver for KVM guest. > > Guest reads the persistent memory range information from > Qemu over VIRTIO and registers it on nvdimm_bus. It also > creates a nd_region object with the persistent memory > range information so that existing 'nvdimm/pmem' driver > can reserve this into system memory map. This way > 'virtio-pmem' driver uses existing functionality of pmem > driver to register persistent memory compatible for DAX > capable filesystems. > > This also provides function to perform guest flush over > VIRTIO from 'pmem' driver when userspace performs flush > on DAX memory range. > > Signed-off-by: Pankaj Gupta <pagupta@redhat.com> > Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com> > --- > drivers/nvdimm/Makefile | 1 + > drivers/nvdimm/nd_virtio.c | 129 +++++++++++++++++++++++++++++++ > drivers/nvdimm/virtio_pmem.c | 117 ++++++++++++++++++++++++++++ > drivers/virtio/Kconfig | 10 +++ > include/linux/virtio_pmem.h | 60 ++++++++++++++ > include/uapi/linux/virtio_ids.h | 1 + > include/uapi/linux/virtio_pmem.h | 10 +++ > 7 files changed, 328 insertions(+) > create mode 100644 drivers/nvdimm/nd_virtio.c > create mode 100644 drivers/nvdimm/virtio_pmem.c > create mode 100644 include/linux/virtio_pmem.h > create mode 100644 include/uapi/linux/virtio_pmem.h > > diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile > index 6f2a088afad6..cefe233e0b52 100644 > --- a/drivers/nvdimm/Makefile > +++ b/drivers/nvdimm/Makefile > @@ -5,6 +5,7 @@ obj-$(CONFIG_ND_BTT) += nd_btt.o > obj-$(CONFIG_ND_BLK) += nd_blk.o > obj-$(CONFIG_X86_PMEM_LEGACY) += nd_e820.o > obj-$(CONFIG_OF_PMEM) += of_pmem.o > +obj-$(CONFIG_VIRTIO_PMEM) += virtio_pmem.o nd_virtio.o > > nd_pmem-y := pmem.o > > diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c > new file mode 100644 > index 000000000000..ed7ddcc5a62c > --- /dev/null > +++ b/drivers/nvdimm/nd_virtio.c > @@ -0,0 +1,129 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * virtio_pmem.c: Virtio pmem Driver > + * > + * Discovers persistent memory range information > + * from host and provides a virtio based flushing > + * interface. > + */ > +#include <linux/virtio_pmem.h> > +#include "nd.h" > + > + /* The interrupt handler */ > +void host_ack(struct virtqueue *vq) > +{ > + unsigned int len; > + unsigned long flags; > + struct virtio_pmem_request *req, *req_buf; > + struct virtio_pmem *vpmem = vq->vdev->priv; Nit: use reverse Christmas tree layout :) > + > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > + while ((req = virtqueue_get_buf(vq, &len)) != NULL) { > + req->done = true; > + wake_up(&req->host_acked); > + > + if (!list_empty(&vpmem->req_list)) { > + req_buf = list_first_entry(&vpmem->req_list, > + struct virtio_pmem_request, list); > + req_buf->wq_buf_avail = true; > + wake_up(&req_buf->wq_buf); > + list_del(&req_buf->list); > + } > + } > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > +} > +EXPORT_SYMBOL_GPL(host_ack); > + > + /* The request submission function */ > +int virtio_pmem_flush(struct nd_region *nd_region) > +{ > + int err, err1; > + unsigned long flags; > + struct scatterlist *sgs[2], sg, ret; > + struct virtio_device *vdev = nd_region->provider_data; > + struct virtio_pmem *vpmem = vdev->priv; > + struct virtio_pmem_request *req; Nit: use reverse Christmas tree layout :) > + > + might_sleep(); > + req = kmalloc(sizeof(*req), GFP_KERNEL); > + if (!req) > + return -ENOMEM; > + > + req->done = false; > + strcpy(req->name, "FLUSH"); > + init_waitqueue_head(&req->host_acked); > + init_waitqueue_head(&req->wq_buf); > + INIT_LIST_HEAD(&req->list); > + sg_init_one(&sg, req->name, strlen(req->name)); > + sgs[0] = &sg; > + sg_init_one(&ret, &req->ret, sizeof(req->ret)); > + sgs[1] = &ret; > + > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > + /* > + * If virtqueue_add_sgs returns -ENOSPC then req_vq virtual > + * queue does not have free descriptor. We add the request > + * to req_list and wait for host_ack to wake us up when free > + * slots are available. > + */ > + while ((err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req, > + GFP_ATOMIC)) == -ENOSPC) { > + > + dev_err(&vdev->dev, "failed to send command to virtio pmem"\ > + "device, no free slots in the virtqueue\n"); > + req->wq_buf_avail = false; > + list_add_tail(&req->list, &vpmem->req_list); > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > + > + /* When host has read buffer, this completes via host_ack */ "A host repsonse results in "host_ack" getting called" ... ? > + wait_event(req->wq_buf, req->wq_buf_avail); > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > + } > + err1 = virtqueue_kick(vpmem->req_vq); > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > + > + /* > + * virtqueue_add_sgs failed with error different than -ENOSPC, we can't > + * do anything about that. > + */ > + if (err || !err1) { > + dev_info(&vdev->dev, "failed to send command to virtio pmem device\n"); > + err = -EIO; > + goto ret; Avoid the goto. Just move the following statements into an "else" case. > + } > + > + /* When host has read buffer, this completes via host_ack */ "A host repsonse results in "host_ack" getting called" ... ? > + wait_event(req->host_acked, req->done); > + err = req->ret; > +ret: > + kfree(req); > + return err; > +}; > + > +/* The asynchronous flush callback function */ > +int async_pmem_flush(struct nd_region *nd_region, struct bio *bio) > +{ > + int rc = 0; > + > + /* Create child bio for asynchronous flush and chain with > + * parent bio. Otherwise directly call nd_region flush. > + */ > + if (bio && bio->bi_iter.bi_sector != -1) { > + struct bio *child = bio_alloc(GFP_ATOMIC, 0); > + > + if (!child) > + return -ENOMEM; > + bio_copy_dev(child, bio); > + child->bi_opf = REQ_PREFLUSH; > + child->bi_iter.bi_sector = -1; > + bio_chain(child, bio); > + submit_bio(child); return 0; Then, drop the "else" case and "int rc" and do directly if (virtio_pmem_flush(nd_region)) return -EIO; > + } else { > + > + rc = -EIO; > + } > + > + return rc; > +}; > +EXPORT_SYMBOL_GPL(async_pmem_flush); > +MODULE_LICENSE("GPL"); > diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c > new file mode 100644 > index 000000000000..cfc6381c4e5d > --- /dev/null > +++ b/drivers/nvdimm/virtio_pmem.c > @@ -0,0 +1,117 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * virtio_pmem.c: Virtio pmem Driver > + * > + * Discovers persistent memory range information > + * from host and registers the virtual pmem device > + * with libnvdimm core. > + */ > +#include <linux/virtio_pmem.h> > +#include "nd.h" > + > +static struct virtio_device_id id_table[] = { > + { VIRTIO_ID_PMEM, VIRTIO_DEV_ANY_ID }, > + { 0 }, > +}; > + > + /* Initialize virt queue */ > +static int init_vq(struct virtio_pmem *vpmem) > +{ > + /* single vq */ > + vpmem->req_vq = virtio_find_single_vq(vpmem->vdev, > + host_ack, "flush_queue"); Nit: Wrong indentation of parameters. > + if (IS_ERR(vpmem->req_vq)) > + return PTR_ERR(vpmem->req_vq); > + > + spin_lock_init(&vpmem->pmem_lock); > + INIT_LIST_HEAD(&vpmem->req_list); I would initialize the locks in the virtio_pmem_probe() directly, earlier (directly after allocating vpmem). > + > + return 0; > +}; > + > +static int virtio_pmem_probe(struct virtio_device *vdev) > +{ > + int err = 0; > + struct resource res; > + struct virtio_pmem *vpmem; > + struct nd_region_desc ndr_desc = {}; > + int nid = dev_to_node(&vdev->dev); > + struct nd_region *nd_region; Nit: use reverse Christmas tree layout :) > + > + if (!vdev->config->get) { > + dev_err(&vdev->dev, "%s failure: config access disabled\n", > + __func__); > + return -EINVAL; > + } > + > + vpmem = devm_kzalloc(&vdev->dev, sizeof(*vpmem), GFP_KERNEL); > + if (!vpmem) { > + err = -ENOMEM; > + goto out_err; > + } > + > + vpmem->vdev = vdev; > + vdev->priv = vpmem; > + err = init_vq(vpmem); > + if (err) > + goto out_err; > + > + virtio_cread(vpmem->vdev, struct virtio_pmem_config, > + start, &vpmem->start); > + virtio_cread(vpmem->vdev, struct virtio_pmem_config, > + size, &vpmem->size); > + > + res.start = vpmem->start; > + res.end = vpmem->start + vpmem->size-1; > + vpmem->nd_desc.provider_name = "virtio-pmem"; > + vpmem->nd_desc.module = THIS_MODULE; > + > + vpmem->nvdimm_bus = nvdimm_bus_register(&vdev->dev, > + &vpmem->nd_desc); > + if (!vpmem->nvdimm_bus) > + goto out_vq; > + > + dev_set_drvdata(&vdev->dev, vpmem->nvdimm_bus); > + > + ndr_desc.res = &res; > + ndr_desc.numa_node = nid; > + ndr_desc.flush = async_pmem_flush; > + set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags); > + set_bit(ND_REGION_ASYNC, &ndr_desc.flags); > + nd_region = nvdimm_pmem_region_create(vpmem->nvdimm_bus, &ndr_desc); > + I'd drop this empty line. > + if (!nd_region) > + goto out_nd; > + nd_region->provider_data = dev_to_virtio(nd_region->dev.parent->parent); Does it make sense to move some parts into separate functions for readability? E.g., virtio_pmem_init_nvdimm_bus() > + return 0; > +out_nd: > + err = -ENXIO; I'd always initialize "err" along with the goto statement for readability, especially because ... > + nvdimm_bus_unregister(vpmem->nvdimm_bus); > +out_vq: ... you don't initialize err in this case. Err is here 0 if I am not wrong. > + vdev->config->del_vqs(vdev); > +out_err: > + dev_err(&vdev->dev, "failed to register virtio pmem memory\n"); Should we try to give more meaning full messages? I can think of scenarios like "memory region is not properly aligned" or "out of memory". > + return err; > +} > + > +static void virtio_pmem_remove(struct virtio_device *vdev) > +{ > + struct nvdimm_bus *nvdimm_bus = dev_get_drvdata(&vdev->dev); > + Is the nd_region implicitly cleaned up? You are not freeing "vdev->priv". > + nvdimm_bus_unregister(nvdimm_bus); > + vdev->config->del_vqs(vdev); > + vdev->config->reset(vdev); > +} > + > +static struct virtio_driver virtio_pmem_driver = { > + .driver.name = KBUILD_MODNAME, > + .driver.owner = THIS_MODULE, > + .id_table = id_table, > + .probe = virtio_pmem_probe, > + .remove = virtio_pmem_remove, > +}; > + > +module_virtio_driver(virtio_pmem_driver); > +MODULE_DEVICE_TABLE(virtio, id_table); > +MODULE_DESCRIPTION("Virtio pmem driver"); > +MODULE_LICENSE("GPL"); > diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig > index 35897649c24f..9f634a2ed638 100644 > --- a/drivers/virtio/Kconfig > +++ b/drivers/virtio/Kconfig > @@ -42,6 +42,16 @@ config VIRTIO_PCI_LEGACY > > If unsure, say Y. > > +config VIRTIO_PMEM > + tristate "Support for virtio pmem driver" > + depends on VIRTIO > + depends on LIBNVDIMM > + help > + This driver provides support for virtio based flushing interface > + for persistent memory range. "This driver provides access to virtio-pmem devices, storage devices that are mapped into the physical address space - similar to NVDIMMs - with a virtio-based flushing interface." ... ? > + > + If unsure, say M. > +
Hi David, Thank you for the review. > On 10.05.19 17:51, Pankaj Gupta wrote: > > This patch adds virtio-pmem driver for KVM guest. > > > > Guest reads the persistent memory range information from > > Qemu over VIRTIO and registers it on nvdimm_bus. It also > > creates a nd_region object with the persistent memory > > range information so that existing 'nvdimm/pmem' driver > > can reserve this into system memory map. This way > > 'virtio-pmem' driver uses existing functionality of pmem > > driver to register persistent memory compatible for DAX > > capable filesystems. > > > > This also provides function to perform guest flush over > > VIRTIO from 'pmem' driver when userspace performs flush > > on DAX memory range. > > > > Signed-off-by: Pankaj Gupta <pagupta@redhat.com> > > Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com> > > --- > > drivers/nvdimm/Makefile | 1 + > > drivers/nvdimm/nd_virtio.c | 129 +++++++++++++++++++++++++++++++ > > drivers/nvdimm/virtio_pmem.c | 117 ++++++++++++++++++++++++++++ > > drivers/virtio/Kconfig | 10 +++ > > include/linux/virtio_pmem.h | 60 ++++++++++++++ > > include/uapi/linux/virtio_ids.h | 1 + > > include/uapi/linux/virtio_pmem.h | 10 +++ > > 7 files changed, 328 insertions(+) > > create mode 100644 drivers/nvdimm/nd_virtio.c > > create mode 100644 drivers/nvdimm/virtio_pmem.c > > create mode 100644 include/linux/virtio_pmem.h > > create mode 100644 include/uapi/linux/virtio_pmem.h > > > > diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile > > index 6f2a088afad6..cefe233e0b52 100644 > > --- a/drivers/nvdimm/Makefile > > +++ b/drivers/nvdimm/Makefile > > @@ -5,6 +5,7 @@ obj-$(CONFIG_ND_BTT) += nd_btt.o > > obj-$(CONFIG_ND_BLK) += nd_blk.o > > obj-$(CONFIG_X86_PMEM_LEGACY) += nd_e820.o > > obj-$(CONFIG_OF_PMEM) += of_pmem.o > > +obj-$(CONFIG_VIRTIO_PMEM) += virtio_pmem.o nd_virtio.o > > > > nd_pmem-y := pmem.o > > > > diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c > > new file mode 100644 > > index 000000000000..ed7ddcc5a62c > > --- /dev/null > > +++ b/drivers/nvdimm/nd_virtio.c > > @@ -0,0 +1,129 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * virtio_pmem.c: Virtio pmem Driver > > + * > > + * Discovers persistent memory range information > > + * from host and provides a virtio based flushing > > + * interface. > > + */ > > +#include <linux/virtio_pmem.h> > > +#include "nd.h" > > + > > + /* The interrupt handler */ > > +void host_ack(struct virtqueue *vq) > > +{ > > + unsigned int len; > > + unsigned long flags; > > + struct virtio_pmem_request *req, *req_buf; > > + struct virtio_pmem *vpmem = vq->vdev->priv; > > Nit: use reverse Christmas tree layout :) o.k > > > + > > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > > + while ((req = virtqueue_get_buf(vq, &len)) != NULL) { > > + req->done = true; > > + wake_up(&req->host_acked); > > + > > + if (!list_empty(&vpmem->req_list)) { > > + req_buf = list_first_entry(&vpmem->req_list, > > + struct virtio_pmem_request, list); > > + req_buf->wq_buf_avail = true; > > + wake_up(&req_buf->wq_buf); > > + list_del(&req_buf->list); > > + } > > + } > > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > > +} > > +EXPORT_SYMBOL_GPL(host_ack); > > + > > + /* The request submission function */ > > +int virtio_pmem_flush(struct nd_region *nd_region) > > +{ > > + int err, err1; > > + unsigned long flags; > > + struct scatterlist *sgs[2], sg, ret; > > + struct virtio_device *vdev = nd_region->provider_data; > > + struct virtio_pmem *vpmem = vdev->priv; > > + struct virtio_pmem_request *req; > > Nit: use reverse Christmas tree layout :) o.k > > > + > > + might_sleep(); > > + req = kmalloc(sizeof(*req), GFP_KERNEL); > > + if (!req) > > + return -ENOMEM; > > + > > + req->done = false; > > + strcpy(req->name, "FLUSH"); > > + init_waitqueue_head(&req->host_acked); > > + init_waitqueue_head(&req->wq_buf); > > + INIT_LIST_HEAD(&req->list); > > + sg_init_one(&sg, req->name, strlen(req->name)); > > + sgs[0] = &sg; > > + sg_init_one(&ret, &req->ret, sizeof(req->ret)); > > + sgs[1] = &ret; > > + > > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > > + /* > > + * If virtqueue_add_sgs returns -ENOSPC then req_vq virtual > > + * queue does not have free descriptor. We add the request > > + * to req_list and wait for host_ack to wake us up when free > > + * slots are available. > > + */ > > + while ((err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req, > > + GFP_ATOMIC)) == -ENOSPC) { > > + > > + dev_err(&vdev->dev, "failed to send command to virtio pmem"\ > > + "device, no free slots in the virtqueue\n"); > > + req->wq_buf_avail = false; > > + list_add_tail(&req->list, &vpmem->req_list); > > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > > + > > + /* When host has read buffer, this completes via host_ack */ > > "A host repsonse results in "host_ack" getting called" ... ? o.k > > > + wait_event(req->wq_buf, req->wq_buf_avail); > > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > > + } > > + err1 = virtqueue_kick(vpmem->req_vq); > > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > > + > > + /* > > + * virtqueue_add_sgs failed with error different than -ENOSPC, we can't > > + * do anything about that. > > + */ > > + if (err || !err1) { > > + dev_info(&vdev->dev, "failed to send command to virtio pmem device\n"); > > + err = -EIO; > > + goto ret; > > Avoid the goto. Just move the following statements into an "else" case. o.k > > > + } > > + > > + /* When host has read buffer, this completes via host_ack */ > > "A host repsonse results in "host_ack" getting called" ... ? > > > + wait_event(req->host_acked, req->done); > > + err = req->ret; > > +ret: > > + kfree(req); > > + return err; > > +}; > > + > > +/* The asynchronous flush callback function */ > > +int async_pmem_flush(struct nd_region *nd_region, struct bio *bio) > > +{ > > + int rc = 0; > > + > > + /* Create child bio for asynchronous flush and chain with > > + * parent bio. Otherwise directly call nd_region flush. > > + */ > > + if (bio && bio->bi_iter.bi_sector != -1) { > > + struct bio *child = bio_alloc(GFP_ATOMIC, 0); > > + > > + if (!child) > > + return -ENOMEM; > > + bio_copy_dev(child, bio); > > + child->bi_opf = REQ_PREFLUSH; > > + child->bi_iter.bi_sector = -1; > > + bio_chain(child, bio); > > + submit_bio(child); > > return 0; > > Then, drop the "else" case and "int rc" and do directly > > if (virtio_pmem_flush(nd_region)) > return -EIO; and another 'return 0' here :) I don't like return from multiple places instead I prefer single exit point from function. > > > + } else { > > + > > + rc = -EIO; > > + } > > + > > + return rc; > > +}; > > +EXPORT_SYMBOL_GPL(async_pmem_flush); > > +MODULE_LICENSE("GPL"); > > diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c > > new file mode 100644 > > index 000000000000..cfc6381c4e5d > > --- /dev/null > > +++ b/drivers/nvdimm/virtio_pmem.c > > @@ -0,0 +1,117 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * virtio_pmem.c: Virtio pmem Driver > > + * > > + * Discovers persistent memory range information > > + * from host and registers the virtual pmem device > > + * with libnvdimm core. > > + */ > > +#include <linux/virtio_pmem.h> > > +#include "nd.h" > > + > > +static struct virtio_device_id id_table[] = { > > + { VIRTIO_ID_PMEM, VIRTIO_DEV_ANY_ID }, > > + { 0 }, > > +}; > > + > > + /* Initialize virt queue */ > > +static int init_vq(struct virtio_pmem *vpmem) > > +{ > > + /* single vq */ > > + vpmem->req_vq = virtio_find_single_vq(vpmem->vdev, > > + host_ack, "flush_queue"); > > Nit: Wrong indentation of parameters. o.k > > > + if (IS_ERR(vpmem->req_vq)) > > + return PTR_ERR(vpmem->req_vq); > > + > > + spin_lock_init(&vpmem->pmem_lock); > > + INIT_LIST_HEAD(&vpmem->req_list); > > I would initialize the locks in the virtio_pmem_probe() directly, > earlier (directly after allocating vpmem). Since the lock is to protect the vq so logically I put it in 'init_vq' which is eventually called by probe. > > > + > > + return 0; > > +}; > > + > > +static int virtio_pmem_probe(struct virtio_device *vdev) > > +{ > > + int err = 0; > > + struct resource res; > > + struct virtio_pmem *vpmem; > > + struct nd_region_desc ndr_desc = {}; > > + int nid = dev_to_node(&vdev->dev); > > + struct nd_region *nd_region; > > Nit: use reverse Christmas tree layout :) Done. > > > + > > + if (!vdev->config->get) { > > + dev_err(&vdev->dev, "%s failure: config access disabled\n", > > + __func__); > > + return -EINVAL; > > + } > > + > > + vpmem = devm_kzalloc(&vdev->dev, sizeof(*vpmem), GFP_KERNEL); > > + if (!vpmem) { > > + err = -ENOMEM; > > + goto out_err; > > + } > > + > > + vpmem->vdev = vdev; > > + vdev->priv = vpmem; > > + err = init_vq(vpmem); > > + if (err) > > + goto out_err; > > + > > + virtio_cread(vpmem->vdev, struct virtio_pmem_config, > > + start, &vpmem->start); > > + virtio_cread(vpmem->vdev, struct virtio_pmem_config, > > + size, &vpmem->size); > > + > > + res.start = vpmem->start; > > + res.end = vpmem->start + vpmem->size-1; > > + vpmem->nd_desc.provider_name = "virtio-pmem"; > > + vpmem->nd_desc.module = THIS_MODULE; > > + > > + vpmem->nvdimm_bus = nvdimm_bus_register(&vdev->dev, > > + &vpmem->nd_desc); > > + if (!vpmem->nvdimm_bus) > > + goto out_vq; > > + > > + dev_set_drvdata(&vdev->dev, vpmem->nvdimm_bus); > > + > > + ndr_desc.res = &res; > > + ndr_desc.numa_node = nid; > > + ndr_desc.flush = async_pmem_flush; > > + set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags); > > + set_bit(ND_REGION_ASYNC, &ndr_desc.flags); > > + nd_region = nvdimm_pmem_region_create(vpmem->nvdimm_bus, &ndr_desc); > > + > > I'd drop this empty line. hmm. > > > + if (!nd_region) > > + goto out_nd; > > + nd_region->provider_data = dev_to_virtio(nd_region->dev.parent->parent); > > Does it make sense to move some parts into separate functions for > readability? E.g., virtio_pmem_init_nvdimm_bus() I think this function only has initialization and don't have any complex logic. > > > + return 0; > > +out_nd: > > + err = -ENXIO; > > I'd always initialize "err" along with the goto statement for > readability, especially because ... > > > + nvdimm_bus_unregister(vpmem->nvdimm_bus); > > +out_vq: > > ... you don't initialize err in this case. Err is here 0 if I am not wrong. Right. Changed. > > > + vdev->config->del_vqs(vdev); > > +out_err: > > + dev_err(&vdev->dev, "failed to register virtio pmem memory\n"); > > Should we try to give more meaning full messages? I can think of > scenarios like "memory region is not properly aligned" or "out of memory". o.k > > > + return err; > > +} > > + > > +static void virtio_pmem_remove(struct virtio_device *vdev) > > +{ > > + struct nvdimm_bus *nvdimm_bus = dev_get_drvdata(&vdev->dev); > > + > > Is the nd_region implicitly cleaned up? yes. it will be. > > You are not freeing "vdev->priv". vdev->priv is vpmem which is allocated using devm API. > > > + nvdimm_bus_unregister(nvdimm_bus); > > + vdev->config->del_vqs(vdev); > > + vdev->config->reset(vdev); > > +} > > + > > +static struct virtio_driver virtio_pmem_driver = { > > + .driver.name = KBUILD_MODNAME, > > + .driver.owner = THIS_MODULE, > > + .id_table = id_table, > > + .probe = virtio_pmem_probe, > > + .remove = virtio_pmem_remove, > > +}; > > + > > +module_virtio_driver(virtio_pmem_driver); > > +MODULE_DEVICE_TABLE(virtio, id_table); > > +MODULE_DESCRIPTION("Virtio pmem driver"); > > +MODULE_LICENSE("GPL"); > > diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig > > index 35897649c24f..9f634a2ed638 100644 > > --- a/drivers/virtio/Kconfig > > +++ b/drivers/virtio/Kconfig > > @@ -42,6 +42,16 @@ config VIRTIO_PCI_LEGACY > > > > If unsure, say Y. > > > > +config VIRTIO_PMEM > > + tristate "Support for virtio pmem driver" > > + depends on VIRTIO > > + depends on LIBNVDIMM > > + help > > + This driver provides support for virtio based flushing interface > > + for persistent memory range. > > "This driver provides access to virtio-pmem devices, storage devices > that are mapped into the physical address space - similar to NVDIMMs - > with a virtio-based flushing interface." ... ? looks better. Incorporated. Thanks, Pankaj > > > + > > + If unsure, say M. > > + > > > -- > > Thanks, > > David / dhildenb >
>> >>> + } >>> + >>> + /* When host has read buffer, this completes via host_ack */ >> >> "A host repsonse results in "host_ack" getting called" ... ? >> >>> + wait_event(req->host_acked, req->done); >>> + err = req->ret; >>> +ret: >>> + kfree(req); >>> + return err; >>> +}; >>> + >>> +/* The asynchronous flush callback function */ >>> +int async_pmem_flush(struct nd_region *nd_region, struct bio *bio) >>> +{ >>> + int rc = 0; >>> + >>> + /* Create child bio for asynchronous flush and chain with >>> + * parent bio. Otherwise directly call nd_region flush. >>> + */ >>> + if (bio && bio->bi_iter.bi_sector != -1) { >>> + struct bio *child = bio_alloc(GFP_ATOMIC, 0); >>> + >>> + if (!child) >>> + return -ENOMEM; >>> + bio_copy_dev(child, bio); >>> + child->bi_opf = REQ_PREFLUSH; >>> + child->bi_iter.bi_sector = -1; >>> + bio_chain(child, bio); >>> + submit_bio(child); >> >> return 0; >> >> Then, drop the "else" case and "int rc" and do directly >> >> if (virtio_pmem_flush(nd_region)) >> return -EIO; > > and another 'return 0' here :) > > I don't like return from multiple places instead I prefer > single exit point from function. Makes this function more complicated than necessary. I agree when there are locks involved. > >> >>> + >>> + return 0; >>> +}; >>> + >>> +static int virtio_pmem_probe(struct virtio_device *vdev) >>> +{ >>> + int err = 0; >>> + struct resource res; >>> + struct virtio_pmem *vpmem; >>> + struct nd_region_desc ndr_desc = {}; >>> + int nid = dev_to_node(&vdev->dev); >>> + struct nd_region *nd_region; >> >> Nit: use reverse Christmas tree layout :) > > Done. > >> >>> + >>> + if (!vdev->config->get) { >>> + dev_err(&vdev->dev, "%s failure: config access disabled\n", >>> + __func__); >>> + return -EINVAL; >>> + } >>> + >>> + vpmem = devm_kzalloc(&vdev->dev, sizeof(*vpmem), GFP_KERNEL); >>> + if (!vpmem) { >>> + err = -ENOMEM; >>> + goto out_err; >>> + } >>> + >>> + vpmem->vdev = vdev; >>> + vdev->priv = vpmem; >>> + err = init_vq(vpmem); >>> + if (err) >>> + goto out_err; >>> + >>> + virtio_cread(vpmem->vdev, struct virtio_pmem_config, >>> + start, &vpmem->start); >>> + virtio_cread(vpmem->vdev, struct virtio_pmem_config, >>> + size, &vpmem->size); >>> + >>> + res.start = vpmem->start; >>> + res.end = vpmem->start + vpmem->size-1; >>> + vpmem->nd_desc.provider_name = "virtio-pmem"; >>> + vpmem->nd_desc.module = THIS_MODULE; >>> + >>> + vpmem->nvdimm_bus = nvdimm_bus_register(&vdev->dev, >>> + &vpmem->nd_desc); >>> + if (!vpmem->nvdimm_bus) >>> + goto out_vq; >>> + >>> + dev_set_drvdata(&vdev->dev, vpmem->nvdimm_bus); >>> + >>> + ndr_desc.res = &res; >>> + ndr_desc.numa_node = nid; >>> + ndr_desc.flush = async_pmem_flush; >>> + set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags); >>> + set_bit(ND_REGION_ASYNC, &ndr_desc.flags); >>> + nd_region = nvdimm_pmem_region_create(vpmem->nvdimm_bus, &ndr_desc); >>> + >> >> I'd drop this empty line. > > hmm. > The common pattern after allocating something, immediately check for it in the next line (like you do throughout this patch ;) ) ... >> You are not freeing "vdev->priv". > > vdev->priv is vpmem which is allocated using devm API. I'm confused. Looking at drivers/virtio/virtio_balloon.c: static void virtballoon_remove(struct virtio_device *vdev) { struct virtio_balloon *vb = vdev->priv; ... kfree(vb); } I think you should do the same here, vdev->priv is allocated in virtio_pmem_probe. But maybe I am missing something important here :) >> >>> + nvdimm_bus_unregister(nvdimm_bus); >>> + vdev->config->del_vqs(vdev); >>> + vdev->config->reset(vdev); >>> +} >>> +
> > >> > >>> + } > >>> + > >>> + /* When host has read buffer, this completes via host_ack */ > >> > >> "A host repsonse results in "host_ack" getting called" ... ? > >> > >>> + wait_event(req->host_acked, req->done); > >>> + err = req->ret; > >>> +ret: > >>> + kfree(req); > >>> + return err; > >>> +}; > >>> + > >>> +/* The asynchronous flush callback function */ > >>> +int async_pmem_flush(struct nd_region *nd_region, struct bio *bio) > >>> +{ > >>> + int rc = 0; > >>> + > >>> + /* Create child bio for asynchronous flush and chain with > >>> + * parent bio. Otherwise directly call nd_region flush. > >>> + */ > >>> + if (bio && bio->bi_iter.bi_sector != -1) { > >>> + struct bio *child = bio_alloc(GFP_ATOMIC, 0); > >>> + > >>> + if (!child) > >>> + return -ENOMEM; > >>> + bio_copy_dev(child, bio); > >>> + child->bi_opf = REQ_PREFLUSH; > >>> + child->bi_iter.bi_sector = -1; > >>> + bio_chain(child, bio); > >>> + submit_bio(child); > >> > >> return 0; > >> > >> Then, drop the "else" case and "int rc" and do directly > >> > >> if (virtio_pmem_flush(nd_region)) > >> return -EIO; > > > > and another 'return 0' here :) > > > > I don't like return from multiple places instead I prefer > > single exit point from function. > > Makes this function more complicated than necessary. I agree when there > are locks involved. o.k. I will change as you suggest :) > > > > >> > >>> + > >>> + return 0; > >>> +}; > >>> + > >>> +static int virtio_pmem_probe(struct virtio_device *vdev) > >>> +{ > >>> + int err = 0; > >>> + struct resource res; > >>> + struct virtio_pmem *vpmem; > >>> + struct nd_region_desc ndr_desc = {}; > >>> + int nid = dev_to_node(&vdev->dev); > >>> + struct nd_region *nd_region; > >> > >> Nit: use reverse Christmas tree layout :) > > > > Done. > > > >> > >>> + > >>> + if (!vdev->config->get) { > >>> + dev_err(&vdev->dev, "%s failure: config access disabled\n", > >>> + __func__); > >>> + return -EINVAL; > >>> + } > >>> + > >>> + vpmem = devm_kzalloc(&vdev->dev, sizeof(*vpmem), GFP_KERNEL); > >>> + if (!vpmem) { > >>> + err = -ENOMEM; > >>> + goto out_err; > >>> + } > >>> + > >>> + vpmem->vdev = vdev; > >>> + vdev->priv = vpmem; > >>> + err = init_vq(vpmem); > >>> + if (err) > >>> + goto out_err; > >>> + > >>> + virtio_cread(vpmem->vdev, struct virtio_pmem_config, > >>> + start, &vpmem->start); > >>> + virtio_cread(vpmem->vdev, struct virtio_pmem_config, > >>> + size, &vpmem->size); > >>> + > >>> + res.start = vpmem->start; > >>> + res.end = vpmem->start + vpmem->size-1; > >>> + vpmem->nd_desc.provider_name = "virtio-pmem"; > >>> + vpmem->nd_desc.module = THIS_MODULE; > >>> + > >>> + vpmem->nvdimm_bus = nvdimm_bus_register(&vdev->dev, > >>> + &vpmem->nd_desc); > >>> + if (!vpmem->nvdimm_bus) > >>> + goto out_vq; > >>> + > >>> + dev_set_drvdata(&vdev->dev, vpmem->nvdimm_bus); > >>> + > >>> + ndr_desc.res = &res; > >>> + ndr_desc.numa_node = nid; > >>> + ndr_desc.flush = async_pmem_flush; > >>> + set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags); > >>> + set_bit(ND_REGION_ASYNC, &ndr_desc.flags); > >>> + nd_region = nvdimm_pmem_region_create(vpmem->nvdimm_bus, &ndr_desc); > >>> + > >> > >> I'd drop this empty line. > > > > hmm. > > > > The common pattern after allocating something, immediately check for it > in the next line (like you do throughout this patch ;) ) Right. But rare times when I see space will beauty the code I tend to add it. Maybe I should not :) > > ... > >> You are not freeing "vdev->priv". > > > > vdev->priv is vpmem which is allocated using devm API. > > I'm confused. Looking at drivers/virtio/virtio_balloon.c: > > static void virtballoon_remove(struct virtio_device *vdev) > { > struct virtio_balloon *vb = vdev->priv; > > ... > > kfree(vb); > } > > I think you should do the same here, vdev->priv is allocated in > virtio_pmem_probe. > > But maybe I am missing something important here :) Because virtio_balloon use "kzalloc" for allocation and needs to be freed. But virtio pmem uses "devm_kzalloc" which takes care of automatically deleting the device memory when associated device is detached. Thanks, Pankaj > > >> > >>> + nvdimm_bus_unregister(nvdimm_bus); > >>> + vdev->config->del_vqs(vdev); > >>> + vdev->config->reset(vdev); > >>> +} > >>> + > > -- > > Thanks, > > David / dhildenb >
>> >> I think you should do the same here, vdev->priv is allocated in >> virtio_pmem_probe. >> >> But maybe I am missing something important here :) > > Because virtio_balloon use "kzalloc" for allocation and needs to be freed. > But virtio pmem uses "devm_kzalloc" which takes care of automatically deleting > the device memory when associated device is detached. Hehe, thanks, that was the part that I was missing!
> >> > >> I think you should do the same here, vdev->priv is allocated in > >> virtio_pmem_probe. > >> > >> But maybe I am missing something important here :) > > > > Because virtio_balloon use "kzalloc" for allocation and needs to be freed. > > But virtio pmem uses "devm_kzalloc" which takes care of automatically > > deleting > > the device memory when associated device is detached. > > Hehe, thanks, that was the part that I was missing! Thank you for the review. Best regards, Pankaj > > -- > > Thanks, > > David / dhildenb >
diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile index 6f2a088afad6..cefe233e0b52 100644 --- a/drivers/nvdimm/Makefile +++ b/drivers/nvdimm/Makefile @@ -5,6 +5,7 @@ obj-$(CONFIG_ND_BTT) += nd_btt.o obj-$(CONFIG_ND_BLK) += nd_blk.o obj-$(CONFIG_X86_PMEM_LEGACY) += nd_e820.o obj-$(CONFIG_OF_PMEM) += of_pmem.o +obj-$(CONFIG_VIRTIO_PMEM) += virtio_pmem.o nd_virtio.o nd_pmem-y := pmem.o diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c new file mode 100644 index 000000000000..ed7ddcc5a62c --- /dev/null +++ b/drivers/nvdimm/nd_virtio.c @@ -0,0 +1,129 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * virtio_pmem.c: Virtio pmem Driver + * + * Discovers persistent memory range information + * from host and provides a virtio based flushing + * interface. + */ +#include <linux/virtio_pmem.h> +#include "nd.h" + + /* The interrupt handler */ +void host_ack(struct virtqueue *vq) +{ + unsigned int len; + unsigned long flags; + struct virtio_pmem_request *req, *req_buf; + struct virtio_pmem *vpmem = vq->vdev->priv; + + spin_lock_irqsave(&vpmem->pmem_lock, flags); + while ((req = virtqueue_get_buf(vq, &len)) != NULL) { + req->done = true; + wake_up(&req->host_acked); + + if (!list_empty(&vpmem->req_list)) { + req_buf = list_first_entry(&vpmem->req_list, + struct virtio_pmem_request, list); + req_buf->wq_buf_avail = true; + wake_up(&req_buf->wq_buf); + list_del(&req_buf->list); + } + } + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); +} +EXPORT_SYMBOL_GPL(host_ack); + + /* The request submission function */ +int virtio_pmem_flush(struct nd_region *nd_region) +{ + int err, err1; + unsigned long flags; + struct scatterlist *sgs[2], sg, ret; + struct virtio_device *vdev = nd_region->provider_data; + struct virtio_pmem *vpmem = vdev->priv; + struct virtio_pmem_request *req; + + might_sleep(); + req = kmalloc(sizeof(*req), GFP_KERNEL); + if (!req) + return -ENOMEM; + + req->done = false; + strcpy(req->name, "FLUSH"); + init_waitqueue_head(&req->host_acked); + init_waitqueue_head(&req->wq_buf); + INIT_LIST_HEAD(&req->list); + sg_init_one(&sg, req->name, strlen(req->name)); + sgs[0] = &sg; + sg_init_one(&ret, &req->ret, sizeof(req->ret)); + sgs[1] = &ret; + + spin_lock_irqsave(&vpmem->pmem_lock, flags); + /* + * If virtqueue_add_sgs returns -ENOSPC then req_vq virtual + * queue does not have free descriptor. We add the request + * to req_list and wait for host_ack to wake us up when free + * slots are available. + */ + while ((err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req, + GFP_ATOMIC)) == -ENOSPC) { + + dev_err(&vdev->dev, "failed to send command to virtio pmem"\ + "device, no free slots in the virtqueue\n"); + req->wq_buf_avail = false; + list_add_tail(&req->list, &vpmem->req_list); + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); + + /* When host has read buffer, this completes via host_ack */ + wait_event(req->wq_buf, req->wq_buf_avail); + spin_lock_irqsave(&vpmem->pmem_lock, flags); + } + err1 = virtqueue_kick(vpmem->req_vq); + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); + + /* + * virtqueue_add_sgs failed with error different than -ENOSPC, we can't + * do anything about that. + */ + if (err || !err1) { + dev_info(&vdev->dev, "failed to send command to virtio pmem device\n"); + err = -EIO; + goto ret; + } + + /* When host has read buffer, this completes via host_ack */ + wait_event(req->host_acked, req->done); + err = req->ret; +ret: + kfree(req); + return err; +}; + +/* The asynchronous flush callback function */ +int async_pmem_flush(struct nd_region *nd_region, struct bio *bio) +{ + int rc = 0; + + /* Create child bio for asynchronous flush and chain with + * parent bio. Otherwise directly call nd_region flush. + */ + if (bio && bio->bi_iter.bi_sector != -1) { + struct bio *child = bio_alloc(GFP_ATOMIC, 0); + + if (!child) + return -ENOMEM; + bio_copy_dev(child, bio); + child->bi_opf = REQ_PREFLUSH; + child->bi_iter.bi_sector = -1; + bio_chain(child, bio); + submit_bio(child); + } else { + if (virtio_pmem_flush(nd_region)) + rc = -EIO; + } + + return rc; +}; +EXPORT_SYMBOL_GPL(async_pmem_flush); +MODULE_LICENSE("GPL"); diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c new file mode 100644 index 000000000000..cfc6381c4e5d --- /dev/null +++ b/drivers/nvdimm/virtio_pmem.c @@ -0,0 +1,117 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * virtio_pmem.c: Virtio pmem Driver + * + * Discovers persistent memory range information + * from host and registers the virtual pmem device + * with libnvdimm core. + */ +#include <linux/virtio_pmem.h> +#include "nd.h" + +static struct virtio_device_id id_table[] = { + { VIRTIO_ID_PMEM, VIRTIO_DEV_ANY_ID }, + { 0 }, +}; + + /* Initialize virt queue */ +static int init_vq(struct virtio_pmem *vpmem) +{ + /* single vq */ + vpmem->req_vq = virtio_find_single_vq(vpmem->vdev, + host_ack, "flush_queue"); + if (IS_ERR(vpmem->req_vq)) + return PTR_ERR(vpmem->req_vq); + + spin_lock_init(&vpmem->pmem_lock); + INIT_LIST_HEAD(&vpmem->req_list); + + return 0; +}; + +static int virtio_pmem_probe(struct virtio_device *vdev) +{ + int err = 0; + struct resource res; + struct virtio_pmem *vpmem; + struct nd_region_desc ndr_desc = {}; + int nid = dev_to_node(&vdev->dev); + struct nd_region *nd_region; + + if (!vdev->config->get) { + dev_err(&vdev->dev, "%s failure: config access disabled\n", + __func__); + return -EINVAL; + } + + vpmem = devm_kzalloc(&vdev->dev, sizeof(*vpmem), GFP_KERNEL); + if (!vpmem) { + err = -ENOMEM; + goto out_err; + } + + vpmem->vdev = vdev; + vdev->priv = vpmem; + err = init_vq(vpmem); + if (err) + goto out_err; + + virtio_cread(vpmem->vdev, struct virtio_pmem_config, + start, &vpmem->start); + virtio_cread(vpmem->vdev, struct virtio_pmem_config, + size, &vpmem->size); + + res.start = vpmem->start; + res.end = vpmem->start + vpmem->size-1; + vpmem->nd_desc.provider_name = "virtio-pmem"; + vpmem->nd_desc.module = THIS_MODULE; + + vpmem->nvdimm_bus = nvdimm_bus_register(&vdev->dev, + &vpmem->nd_desc); + if (!vpmem->nvdimm_bus) + goto out_vq; + + dev_set_drvdata(&vdev->dev, vpmem->nvdimm_bus); + + ndr_desc.res = &res; + ndr_desc.numa_node = nid; + ndr_desc.flush = async_pmem_flush; + set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags); + set_bit(ND_REGION_ASYNC, &ndr_desc.flags); + nd_region = nvdimm_pmem_region_create(vpmem->nvdimm_bus, &ndr_desc); + + if (!nd_region) + goto out_nd; + nd_region->provider_data = dev_to_virtio(nd_region->dev.parent->parent); + return 0; +out_nd: + err = -ENXIO; + nvdimm_bus_unregister(vpmem->nvdimm_bus); +out_vq: + vdev->config->del_vqs(vdev); +out_err: + dev_err(&vdev->dev, "failed to register virtio pmem memory\n"); + return err; +} + +static void virtio_pmem_remove(struct virtio_device *vdev) +{ + struct nvdimm_bus *nvdimm_bus = dev_get_drvdata(&vdev->dev); + + nvdimm_bus_unregister(nvdimm_bus); + vdev->config->del_vqs(vdev); + vdev->config->reset(vdev); +} + +static struct virtio_driver virtio_pmem_driver = { + .driver.name = KBUILD_MODNAME, + .driver.owner = THIS_MODULE, + .id_table = id_table, + .probe = virtio_pmem_probe, + .remove = virtio_pmem_remove, +}; + +module_virtio_driver(virtio_pmem_driver); +MODULE_DEVICE_TABLE(virtio, id_table); +MODULE_DESCRIPTION("Virtio pmem driver"); +MODULE_LICENSE("GPL"); diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig index 35897649c24f..9f634a2ed638 100644 --- a/drivers/virtio/Kconfig +++ b/drivers/virtio/Kconfig @@ -42,6 +42,16 @@ config VIRTIO_PCI_LEGACY If unsure, say Y. +config VIRTIO_PMEM + tristate "Support for virtio pmem driver" + depends on VIRTIO + depends on LIBNVDIMM + help + This driver provides support for virtio based flushing interface + for persistent memory range. + + If unsure, say M. + config VIRTIO_BALLOON tristate "Virtio balloon driver" depends on VIRTIO diff --git a/include/linux/virtio_pmem.h b/include/linux/virtio_pmem.h new file mode 100644 index 000000000000..ab1da877575d --- /dev/null +++ b/include/linux/virtio_pmem.h @@ -0,0 +1,60 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * virtio_pmem.h: virtio pmem Driver + * + * Discovers persistent memory range information + * from host and provides a virtio based flushing + * interface. + **/ + +#ifndef _LINUX_VIRTIO_PMEM_H +#define _LINUX_VIRTIO_PMEM_H + +#include <linux/virtio_ids.h> +#include <linux/module.h> +#include <linux/virtio_config.h> +#include <uapi/linux/virtio_pmem.h> +#include <linux/libnvdimm.h> +#include <linux/spinlock.h> + +struct virtio_pmem_request { + /* Host return status corresponding to flush request */ + int ret; + + /* command name*/ + char name[16]; + + /* Wait queue to process deferred work after ack from host */ + wait_queue_head_t host_acked; + bool done; + + /* Wait queue to process deferred work after virt queue buffer avail */ + wait_queue_head_t wq_buf; + bool wq_buf_avail; + struct list_head list; +}; + +struct virtio_pmem { + struct virtio_device *vdev; + + /* Virtio pmem request queue */ + struct virtqueue *req_vq; + + /* nvdimm bus registers virtio pmem device */ + struct nvdimm_bus *nvdimm_bus; + struct nvdimm_bus_descriptor nd_desc; + + /* List to store deferred work if virtqueue is full */ + struct list_head req_list; + + /* Synchronize virtqueue data */ + spinlock_t pmem_lock; + + /* Memory region information */ + uint64_t start; + uint64_t size; +}; + +void host_ack(struct virtqueue *vq); +int async_pmem_flush(struct nd_region *nd_region, struct bio *bio); +#endif diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h index 6d5c3b2d4f4d..32b2f94d1f58 100644 --- a/include/uapi/linux/virtio_ids.h +++ b/include/uapi/linux/virtio_ids.h @@ -43,5 +43,6 @@ #define VIRTIO_ID_INPUT 18 /* virtio input */ #define VIRTIO_ID_VSOCK 19 /* virtio vsock transport */ #define VIRTIO_ID_CRYPTO 20 /* virtio crypto */ +#define VIRTIO_ID_PMEM 27 /* virtio pmem */ #endif /* _LINUX_VIRTIO_IDS_H */ diff --git a/include/uapi/linux/virtio_pmem.h b/include/uapi/linux/virtio_pmem.h new file mode 100644 index 000000000000..fa3f7d52717a --- /dev/null +++ b/include/uapi/linux/virtio_pmem.h @@ -0,0 +1,10 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _UAPI_LINUX_VIRTIO_PMEM_H +#define _UAPI_LINUX_VIRTIO_PMEM_H + +struct virtio_pmem_config { + __le64 start; + __le64 size; +}; +#endif