Yuval Shaia
2019-Apr-04 06:41 UTC
[Qemu-devel] [PATCH v4 2/5] virtio-pmem: Add virtio pmem driver
On Wed, Apr 03, 2019 at 08:40:13AM -0400, Pankaj Gupta wrote:> > > Subject: Re: [Qemu-devel] [PATCH v4 2/5] virtio-pmem: Add virtio pmem driver > > > > On Wed, Apr 03, 2019 at 04:10:15PM +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 at redhat.com> > > > --- > > > drivers/nvdimm/virtio_pmem.c | 84 +++++++++++++++++++++ > > > drivers/virtio/Kconfig | 10 +++ > > > drivers/virtio/Makefile | 1 + > > > drivers/virtio/pmem.c | 125 +++++++++++++++++++++++++++++++ > > > include/linux/virtio_pmem.h | 60 +++++++++++++++ > > > include/uapi/linux/virtio_ids.h | 1 + > > > include/uapi/linux/virtio_pmem.h | 10 +++ > > > 7 files changed, 291 insertions(+) > > > create mode 100644 drivers/nvdimm/virtio_pmem.c > > > create mode 100644 drivers/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/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c > > > new file mode 100644 > > > index 000000000000..2a1b1ba2c1ff > > > --- /dev/null > > > +++ b/drivers/nvdimm/virtio_pmem.c > > > @@ -0,0 +1,84 @@ > > > +// SPDX-License-Identifier: GPL-2.0 > > > > Is this comment stile (//) acceptable? > > In existing code, i can see same comment > pattern for license at some places.Is it preferred for new code?> > > > > > +/* > > > + * 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); > > > + list_del(&vpmem->req_list); > > > + req_buf->wq_buf_avail = true; > > > + wake_up(&req_buf->wq_buf); > > > + } > > > + } > > > + 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; > > > + 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(); > > > > [1] > > > > > + req = kmalloc(sizeof(*req), GFP_KERNEL); > > > + if (!req) > > > + return -ENOMEM; > > > + > > > + req->done = req->wq_buf_avail = false; > > > + strcpy(req->name, "FLUSH"); > > > + init_waitqueue_head(&req->host_acked); > > > + init_waitqueue_head(&req->wq_buf); > > > + 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); > > > + err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req, GFP_ATOMIC); > > > > Is it okay to use GFP_ATOMIC in a might-sleep ([1]) function? > > might sleep will give us a warning if we try to sleep from non-sleepable > context. > > We are doing it other way, i.e might_sleep is not inside GFP_ATOMIC. > > > > > > + if (err) { > > > + dev_err(&vdev->dev, "failed to send command to virtio pmem device\n"); > > > + > > > + list_add_tail(&vpmem->req_list, &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); > > > + } > > > + virtqueue_kick(vpmem->req_vq); > > > > You probably want to check return value here. > > Don't think it will matter in this case?Have no idea, if it fails maybe you will never get to host_acked.> > > > > > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > > > + > > > + /* When host has read buffer, this completes via host_ack */ > > > + wait_event(req->host_acked, req->done); > > > + err = req->ret; > > > + kfree(req); > > > + > > > + return err; > > > +}; > > > +EXPORT_SYMBOL_GPL(virtio_pmem_flush); > > > +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/drivers/virtio/Makefile b/drivers/virtio/Makefile > > > index 3a2b5c5dcf46..143ce91eabe9 100644 > > > --- a/drivers/virtio/Makefile > > > +++ b/drivers/virtio/Makefile > > > @@ -6,3 +6,4 @@ virtio_pci-y := virtio_pci_modern.o virtio_pci_common.o > > > virtio_pci-$(CONFIG_VIRTIO_PCI_LEGACY) += virtio_pci_legacy.o > > > obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o > > > obj-$(CONFIG_VIRTIO_INPUT) += virtio_input.o > > > +obj-$(CONFIG_VIRTIO_PMEM) += pmem.o ../nvdimm/virtio_pmem.o > > > diff --git a/drivers/virtio/pmem.c b/drivers/virtio/pmem.c > > > new file mode 100644 > > > index 000000000000..52f74064f67e > > > --- /dev/null > > > +++ b/drivers/virtio/pmem.c > > > @@ -0,0 +1,125 @@ > > > +// SPDX-License-Identifier: GPL-2.0 > > > > Ditto > > > > > +/* > > > + * 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 <../../drivers/nvdimm/nd.h> > > > > Should this file be moved to include/ directory? > > We are not touching the directory structure of nd & nd_pmem > kernel driver.But since this file becomes public it should be considered, right?> > > > > > + > > > +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) > > > +{ > > > + struct virtqueue *vq; > > > + > > > + /* single vq */ > > > + vpmem->req_vq = vq = virtio_find_single_vq(vpmem->vdev, > > > + host_ack, "flush_queue"); > > > + if (IS_ERR(vq)) > > > + return PTR_ERR(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 nvdimm_bus *nvdimm_bus; > > > + 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 disabled\n", > > > + __func__); > > > + return -EINVAL; > > > + } > > > + > > > + vdev->priv = vpmem = devm_kzalloc(&vdev->dev, sizeof(*vpmem), > > > + GFP_KERNEL); > > > > Suggesting to indent it right so it will be under &vdev > > o.k > > > > > > + if (!vpmem) { > > > + err = -ENOMEM; > > > + goto out_err; > > > + } > > > + > > > + vpmem->vdev = vdev; > > > + err = init_vq(vpmem); > > > + if (err) > > > + goto out_err; > > > > No need to free vpmem here? > > No. devm_kzalloc will take care of it.Nice.> > > > > > + > > > + 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 = nvdimm_bus_register(&vdev->dev, > > > + &vpmem->nd_desc); > > > + if (!nvdimm_bus) > > > + goto out_vq; > > > > Ditto (i'm probably missing something here) > > > > > + > > > + dev_set_drvdata(&vdev->dev, nvdimm_bus); > > > + memset(&ndr_desc, 0, sizeof(ndr_desc)); > > > > Any reason not to use compiler initialization? > > i.e. > > struct nd_region_desc ndr_desc = {}; > > will change. > > > > > > + > > > + ndr_desc.res = &res; > > > + ndr_desc.numa_node = nid; > > > + ndr_desc.flush = virtio_pmem_flush; > > > + set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags); > > > + set_bit(ND_REGION_ASYNC, &ndr_desc.flags); > > > + nd_region = nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc); > > > + nd_region->provider_data = dev_to_virtio > > > + (nd_region->dev.parent->parent); > > > + > > > + if (!nd_region) > > > + goto out_nd; > > > + > > > + //virtio_device_ready(vdev); > > > > Left over > > o.k > > > > > > + return 0; > > > +out_nd: > > > + err = -ENXIO; > > > + nvdimm_bus_unregister(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 virtio_pmem *vpmem = vdev->priv; > > > + struct nvdimm_bus *nvdimm_bus = dev_get_drvdata(&vdev->dev); > > > + > > > + nvdimm_bus_unregister(nvdimm_bus); > > > + vdev->config->del_vqs(vdev); > > > > I think you should also call vdev->config->reset > > o.k. Here device will be removed completely, still its required?I had a bad experience with unloading virtio PCI driver and it gone after i added call to 'reset'. See the warning in function virtio_dev_remove.> > > > > > + kfree(vpmem); > > > +} > > > + > > > +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/include/linux/virtio_pmem.h b/include/linux/virtio_pmem.h > > > new file mode 100644 > > > index 000000000000..224f9d934be6 > > > --- /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 virtio_pmem_flush(struct nd_region *nd_region); > > > +#endif > > > diff --git a/include/uapi/linux/virtio_ids.h > > > b/include/uapi/linux/virtio_ids.h > > > index 6d5c3b2d4f4d..346389565ac1 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 25 /* virtio pmem */ > > > > Any reason for the jump here? are 21 to 24 already taken or you just > > want to be on the safe side? > > They are already reserved.Can you direct me to how to find a free ID?> > Thanks, > Pankaj > > > > > > > > > #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 > > > > > > > > > >
Pankaj Gupta
2019-Apr-04 07:14 UTC
[Qemu-devel] [PATCH v4 2/5] virtio-pmem: Add virtio pmem driver
> > > > > Subject: Re: [Qemu-devel] [PATCH v4 2/5] virtio-pmem: Add virtio pmem > > > driver > > > > > > On Wed, Apr 03, 2019 at 04:10:15PM +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 at redhat.com> > > > > --- > > > > drivers/nvdimm/virtio_pmem.c | 84 +++++++++++++++++++++ > > > > drivers/virtio/Kconfig | 10 +++ > > > > drivers/virtio/Makefile | 1 + > > > > drivers/virtio/pmem.c | 125 +++++++++++++++++++++++++++++++ > > > > include/linux/virtio_pmem.h | 60 +++++++++++++++ > > > > include/uapi/linux/virtio_ids.h | 1 + > > > > include/uapi/linux/virtio_pmem.h | 10 +++ > > > > 7 files changed, 291 insertions(+) > > > > create mode 100644 drivers/nvdimm/virtio_pmem.c > > > > create mode 100644 drivers/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/virtio_pmem.c > > > > b/drivers/nvdimm/virtio_pmem.c > > > > new file mode 100644 > > > > index 000000000000..2a1b1ba2c1ff > > > > --- /dev/null > > > > +++ b/drivers/nvdimm/virtio_pmem.c > > > > @@ -0,0 +1,84 @@ > > > > +// SPDX-License-Identifier: GPL-2.0 > > > > > > Is this comment stile (//) acceptable? > > > > In existing code, i can see same comment > > pattern for license at some places. > > Is it preferred for new code?will change.> > > > > > > > > > +/* > > > > + * 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); > > > > + list_del(&vpmem->req_list); > > > > + req_buf->wq_buf_avail = true; > > > > + wake_up(&req_buf->wq_buf); > > > > + } > > > > + } > > > > + 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; > > > > + 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(); > > > > > > [1] > > > > > > > + req = kmalloc(sizeof(*req), GFP_KERNEL); > > > > + if (!req) > > > > + return -ENOMEM; > > > > + > > > > + req->done = req->wq_buf_avail = false; > > > > + strcpy(req->name, "FLUSH"); > > > > + init_waitqueue_head(&req->host_acked); > > > > + init_waitqueue_head(&req->wq_buf); > > > > + 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); > > > > + err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req, GFP_ATOMIC); > > > > > > Is it okay to use GFP_ATOMIC in a might-sleep ([1]) function? > > > > might sleep will give us a warning if we try to sleep from non-sleepable > > context. > > > > We are doing it other way, i.e might_sleep is not inside GFP_ATOMIC. > > > > > > > > > + if (err) { > > > > + dev_err(&vdev->dev, "failed to send command to virtio pmem > > > > device\n"); > > > > + > > > > + list_add_tail(&vpmem->req_list, &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); > > > > + } > > > > + virtqueue_kick(vpmem->req_vq); > > > > > > You probably want to check return value here. > > > > Don't think it will matter in this case? > > Have no idea, if it fails maybe you will never get to host_acked.I am not sure about this. Surely will check.> > > > > > > > > > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > > > > + > > > > + /* When host has read buffer, this completes via host_ack */ > > > > + wait_event(req->host_acked, req->done); > > > > + err = req->ret; > > > > + kfree(req); > > > > + > > > > + return err; > > > > +}; > > > > +EXPORT_SYMBOL_GPL(virtio_pmem_flush); > > > > +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/drivers/virtio/Makefile b/drivers/virtio/Makefile > > > > index 3a2b5c5dcf46..143ce91eabe9 100644 > > > > --- a/drivers/virtio/Makefile > > > > +++ b/drivers/virtio/Makefile > > > > @@ -6,3 +6,4 @@ virtio_pci-y := virtio_pci_modern.o virtio_pci_common.o > > > > virtio_pci-$(CONFIG_VIRTIO_PCI_LEGACY) += virtio_pci_legacy.o > > > > obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o > > > > obj-$(CONFIG_VIRTIO_INPUT) += virtio_input.o > > > > +obj-$(CONFIG_VIRTIO_PMEM) += pmem.o ../nvdimm/virtio_pmem.o > > > > diff --git a/drivers/virtio/pmem.c b/drivers/virtio/pmem.c > > > > new file mode 100644 > > > > index 000000000000..52f74064f67e > > > > --- /dev/null > > > > +++ b/drivers/virtio/pmem.c > > > > @@ -0,0 +1,125 @@ > > > > +// SPDX-License-Identifier: GPL-2.0 > > > > > > Ditto > > > > > > > +/* > > > > + * 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 <../../drivers/nvdimm/nd.h> > > > > > > Should this file be moved to include/ directory? > > > > We are not touching the directory structure of nd & nd_pmem > > kernel driver. > > But since this file becomes public it should be considered, right?IIRC I tried to do it but that required changes in existing pmem code directory structure for conflict resolution. I would suggest to keep the directory structure as it is currently and submit a followup patch to do this after current code is merged upstream.> > > > > > > > > > + > > > > +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) > > > > +{ > > > > + struct virtqueue *vq; > > > > + > > > > + /* single vq */ > > > > + vpmem->req_vq = vq = virtio_find_single_vq(vpmem->vdev, > > > > + host_ack, "flush_queue"); > > > > + if (IS_ERR(vq)) > > > > + return PTR_ERR(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 nvdimm_bus *nvdimm_bus; > > > > + 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 disabled\n", > > > > + __func__); > > > > + return -EINVAL; > > > > + } > > > > + > > > > + vdev->priv = vpmem = devm_kzalloc(&vdev->dev, sizeof(*vpmem), > > > > + GFP_KERNEL); > > > > > > Suggesting to indent it right so it will be under &vdev > > > > o.k > > > > > > > > > + if (!vpmem) { > > > > + err = -ENOMEM; > > > > + goto out_err; > > > > + } > > > > + > > > > + vpmem->vdev = vdev; > > > > + err = init_vq(vpmem); > > > > + if (err) > > > > + goto out_err; > > > > > > No need to free vpmem here? > > > > No. devm_kzalloc will take care of it. > > Nice. > > > > > > > > > > + > > > > + 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 = nvdimm_bus_register(&vdev->dev, > > > > + &vpmem->nd_desc); > > > > + if (!nvdimm_bus) > > > > + goto out_vq; > > > > > > Ditto (i'm probably missing something here) > > > > > > > + > > > > + dev_set_drvdata(&vdev->dev, nvdimm_bus); > > > > + memset(&ndr_desc, 0, sizeof(ndr_desc)); > > > > > > Any reason not to use compiler initialization? > > > i.e. > > > struct nd_region_desc ndr_desc = {}; > > > > will change. > > > > > > > > > + > > > > + ndr_desc.res = &res; > > > > + ndr_desc.numa_node = nid; > > > > + ndr_desc.flush = virtio_pmem_flush; > > > > + set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags); > > > > + set_bit(ND_REGION_ASYNC, &ndr_desc.flags); > > > > + nd_region = nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc); > > > > + nd_region->provider_data = dev_to_virtio > > > > + (nd_region->dev.parent->parent); > > > > + > > > > + if (!nd_region) > > > > + goto out_nd; > > > > + > > > > + //virtio_device_ready(vdev); > > > > > > Left over > > > > o.k > > > > > > > > > + return 0; > > > > +out_nd: > > > > + err = -ENXIO; > > > > + nvdimm_bus_unregister(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 virtio_pmem *vpmem = vdev->priv; > > > > + struct nvdimm_bus *nvdimm_bus = dev_get_drvdata(&vdev->dev); > > > > + > > > > + nvdimm_bus_unregister(nvdimm_bus); > > > > + vdev->config->del_vqs(vdev); > > > > > > I think you should also call vdev->config->reset > > > > o.k. Here device will be removed completely, still its required? > > I had a bad experience with unloading virtio PCI driver and it gone after i > added call to 'reset'. > See the warning in function virtio_dev_remove.Fair point. I will add call to vdev->config->reset.> > > > > > > > > > + kfree(vpmem); > > > > +} > > > > + > > > > +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/include/linux/virtio_pmem.h b/include/linux/virtio_pmem.h > > > > new file mode 100644 > > > > index 000000000000..224f9d934be6 > > > > --- /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 virtio_pmem_flush(struct nd_region *nd_region); > > > > +#endif > > > > diff --git a/include/uapi/linux/virtio_ids.h > > > > b/include/uapi/linux/virtio_ids.h > > > > index 6d5c3b2d4f4d..346389565ac1 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 25 /* virtio pmem */ > > > > > > Any reason for the jump here? are 21 to 24 already taken or you just > > > want to be on the safe side? > > > > They are already reserved. > > Can you direct me to how to find a free ID?I referred 'content.tex' in virtio-spec. I have also posted a draft spec document[1] for virtio-pmem. [1] https://lists.oasis-open.org/archives/virtio-dev/201903/msg00083.html Thanks for the suggestions. Best regards, Pankaj> > > > > Thanks, > > Pankaj > > > > > > > > > > > > > #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 > > > > > > > > > > > > > > >