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Subject: Re: [PATCH 1/3] virtio: Basic implementation of virtio pstore driver
On Sat, Aug 20, 2016 at 05:07:42PM +0900, Namhyung Kim wrote:
> The virtio pstore driver provides interface to the pstore subsystem so
> that the guest kernel's log/dump message can be saved on the host
> machine. Users can access the log file directly on the host, or on the
> guest at the next boot using pstore filesystem. It currently deals with
> kernel log (printk) buffer only, but we can extend it to have other
> information (like ftrace dump) later.
>
> It supports legacy PCI device using single order-2 page buffer.
Do you mean a legacy virtio device? I don't see why
you would want to support pre-1.0 mode.
If you drop that, you can drop all cpu_to_virtio things
and just use __le accessors.
> It uses
> two virtqueues - one for (sync) read and another for (async) write.
> Since it cannot wait for write finished, it supports up to 128
> concurrent IO. The buffer size is configurable now.
>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Anthony Liguori <aliguori@amazon.com>
> Cc: Anton Vorontsov <anton@enomsg.org>
> Cc: Colin Cross <ccross@android.com>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: kvm@vger.kernel.org
> Cc: qemu-devel@nongnu.org
> Cc: virtualization@lists.linux-foundation.org
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
> drivers/virtio/Kconfig | 10 +
> drivers/virtio/Makefile | 1 +
> drivers/virtio/virtio_pstore.c | 417 +++++++++++++++++++++++++++++++++++++
> include/uapi/linux/Kbuild | 1 +
> include/uapi/linux/virtio_ids.h | 1 +
> include/uapi/linux/virtio_pstore.h | 74 +++++++
> 6 files changed, 504 insertions(+)
> create mode 100644 drivers/virtio/virtio_pstore.c
> create mode 100644 include/uapi/linux/virtio_pstore.h
>
> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
> index 77590320d44c..8f0e6c796c12 100644
> --- a/drivers/virtio/Kconfig
> +++ b/drivers/virtio/Kconfig
> @@ -58,6 +58,16 @@ config VIRTIO_INPUT
>
> If unsure, say M.
>
> +config VIRTIO_PSTORE
> + tristate "Virtio pstore driver"
> + depends on VIRTIO
> + depends on PSTORE
> + ---help---
> + This driver supports virtio pstore devices to save/restore
> + panic and oops messages on the host.
> +
> + If unsure, say M.
> +
> config VIRTIO_MMIO
> tristate "Platform bus driver for memory mapped virtio devices"
> depends on HAS_IOMEM && HAS_DMA
> diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
> index 41e30e3dc842..bee68cb26d48 100644
> --- a/drivers/virtio/Makefile
> +++ b/drivers/virtio/Makefile
> @@ -5,3 +5,4 @@ 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_PSTORE) += virtio_pstore.o
> diff --git a/drivers/virtio/virtio_pstore.c b/drivers/virtio/virtio_pstore.c
> new file mode 100644
> index 000000000000..0a63c7db4278
> --- /dev/null
> +++ b/drivers/virtio/virtio_pstore.c
> @@ -0,0 +1,417 @@
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/pstore.h>
> +#include <linux/virtio.h>
> +#include <linux/virtio_config.h>
> +#include <uapi/linux/virtio_ids.h>
> +#include <uapi/linux/virtio_pstore.h>
> +
> +#define VIRT_PSTORE_ORDER 2
> +#define VIRT_PSTORE_BUFSIZE (4096 << VIRT_PSTORE_ORDER)
> +#define VIRT_PSTORE_NR_REQ 128
> +
> +struct virtio_pstore {
> + struct virtio_device *vdev;
> + struct virtqueue *vq[2];
I'd add named fields instead of an array here, vq[0]
vq[1] all over the place is hard to read.
> + struct pstore_info pstore;
> + struct virtio_pstore_req req[VIRT_PSTORE_NR_REQ];
> + struct virtio_pstore_res res[VIRT_PSTORE_NR_REQ];
> + unsigned int req_id;
> +
> + /* Waiting for host to ack */
> + wait_queue_head_t acked;
> + int failed;
> +};
> +
> +#define TYPE_TABLE_ENTRY(_entry) \
> + { PSTORE_TYPE_##_entry, VIRTIO_PSTORE_TYPE_##_entry }
> +
> +struct type_table {
> + int pstore;
> + u16 virtio;
> +} type_table[] = {
> + TYPE_TABLE_ENTRY(DMESG),
> +};
> +
> +#undef TYPE_TABLE_ENTRY
let's avoid macros for now pls. In fact, I would just open-code this
in to_virtio_type below. We can always change our minds later if
lots of types are added.
> +
> +
single emoty line pls
> +static u16 to_virtio_type(struct virtio_pstore *vps, enum pstore_type_id type)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < ARRAY_SIZE(type_table); i++) {
> + if (type == type_table[i].pstore)
> + return cpu_to_virtio16(vps->vdev, type_table[i].virtio);
> + }
> +
> + return cpu_to_virtio16(vps->vdev, VIRTIO_PSTORE_TYPE_UNKNOWN);
This assigns u16 to __virtio type, sparse will warn
if you enable endian-ness checks.
Pls fix that and generally, please make sure this is
clean from sparse warnings.
> +}
> +
> +static enum pstore_type_id from_virtio_type(struct virtio_pstore *vps, u16 type)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < ARRAY_SIZE(type_table); i++) {
> + if (virtio16_to_cpu(vps->vdev, type) == type_table[i].virtio)
> + return type_table[i].pstore;
> + }
> +
> + return PSTORE_TYPE_UNKNOWN;
> +}
> +
> +static void virtpstore_ack(struct virtqueue *vq)
> +{
> + struct virtio_pstore *vps = vq->vdev->priv;
> +
> + wake_up(&vps->acked);
> +}
> +
> +static void virtpstore_check(struct virtqueue *vq)
> +{
> + struct virtio_pstore *vps = vq->vdev->priv;
> + struct virtio_pstore_res *res;
> + unsigned int len;
> +
> + res = virtqueue_get_buf(vq, &len);
> + if (res == NULL)
> + return;
> +
> + if (virtio32_to_cpu(vq->vdev, res->ret) < 0)
> + vps->failed = 1;
> +}
> +
> +static void virt_pstore_get_reqs(struct virtio_pstore *vps,
> + struct virtio_pstore_req **preq,
> + struct virtio_pstore_res **pres)
> +{
> + unsigned int idx = vps->req_id++ % VIRT_PSTORE_NR_REQ;
> +
> + *preq = &vps->req[idx];
> + *pres = &vps->res[idx];
> +
> + memset(*preq, 0, sizeof(**preq));
> + memset(*pres, 0, sizeof(**pres));
> +}
> +
> +static int virt_pstore_open(struct pstore_info *psi)
> +{
> + struct virtio_pstore *vps = psi->data;
> + struct virtio_pstore_req *req;
> + struct virtio_pstore_res *res;
> + struct scatterlist sgo[1], sgi[1];
> + struct scatterlist *sgs[2] = { sgo, sgi };
> + unsigned int len;
> +
> + virt_pstore_get_reqs(vps, &req, &res);
> +
> + req->cmd = cpu_to_virtio16(vps->vdev, VIRTIO_PSTORE_CMD_OPEN);
> +
> + sg_init_one(sgo, req, sizeof(*req));
> + sg_init_one(sgi, res, sizeof(*res));
> + virtqueue_add_sgs(vps->vq[0], sgs, 1, 1, vps, GFP_KERNEL);
> + virtqueue_kick(vps->vq[0]);
> +
> + wait_event(vps->acked, virtqueue_get_buf(vps->vq[0], &len));
Does this block userspace in an uninterruptible wait if
hardware is slow? That's not nice.
> + return virtio32_to_cpu(vps->vdev, res->ret);
> +}
> +
> +static int virt_pstore_close(struct pstore_info *psi)
> +{
> + struct virtio_pstore *vps = psi->data;
> + struct virtio_pstore_req *req = &vps->req[vps->req_id];
> + struct virtio_pstore_res *res = &vps->res[vps->req_id];
> + struct scatterlist sgo[1], sgi[1];
> + struct scatterlist *sgs[2] = { sgo, sgi };
> + unsigned int len;
> +
> + virt_pstore_get_reqs(vps, &req, &res);
> +
> + req->cmd = cpu_to_virtio16(vps->vdev, VIRTIO_PSTORE_CMD_CLOSE);
> +
> + sg_init_one(sgo, req, sizeof(*req));
> + sg_init_one(sgi, res, sizeof(*res));
> + virtqueue_add_sgs(vps->vq[0], sgs, 1, 1, vps, GFP_KERNEL);
> + virtqueue_kick(vps->vq[0]);
> +
> + wait_event(vps->acked, virtqueue_get_buf(vps->vq[0], &len));
> + return virtio32_to_cpu(vps->vdev, res->ret);
> +}
> +
> +static ssize_t virt_pstore_read(u64 *id, enum pstore_type_id *type,
> + int *count, struct timespec *time,
> + char **buf, bool *compressed,
> + ssize_t *ecc_notice_size,
> + struct pstore_info *psi)
> +{
> + struct virtio_pstore *vps = psi->data;
> + struct virtio_pstore_req *req;
> + struct virtio_pstore_res *res;
> + struct virtio_pstore_fileinfo info;
> + struct scatterlist sgo[1], sgi[3];
> + struct scatterlist *sgs[2] = { sgo, sgi };
> + unsigned int len;
> + unsigned int flags;
> + int ret;
> + void *bf;
> +
> + virt_pstore_get_reqs(vps, &req, &res);
> +
> + req->cmd = cpu_to_virtio16(vps->vdev, VIRTIO_PSTORE_CMD_READ);
> +
> + sg_init_one(sgo, req, sizeof(*req));
> + sg_init_table(sgi, 3);
> + sg_set_buf(&sgi[0], res, sizeof(*res));
> + sg_set_buf(&sgi[1], &info, sizeof(info));
> + sg_set_buf(&sgi[2], psi->buf, psi->bufsize);
> + virtqueue_add_sgs(vps->vq[0], sgs, 1, 1, vps, GFP_KERNEL);
> + virtqueue_kick(vps->vq[0]);
> +
> + wait_event(vps->acked, virtqueue_get_buf(vps->vq[0], &len));
> + if (len < sizeof(*res) + sizeof(info))
> + return -1;
> +
> + ret = virtio32_to_cpu(vps->vdev, res->ret);
> + if (ret < 0)
> + return ret;
> +
> + len = virtio32_to_cpu(vps->vdev, info.len);
> +
> + bf = kmalloc(len, GFP_KERNEL);
> + if (bf == NULL)
> + return -ENOMEM;
> +
> + *id = virtio64_to_cpu(vps->vdev, info.id);
> + *type = from_virtio_type(vps, info.type);
> + *count = virtio32_to_cpu(vps->vdev, info.count);
> +
> + flags = virtio32_to_cpu(vps->vdev, info.flags);
> + *compressed = flags & VIRTIO_PSTORE_FL_COMPRESSED;
> +
> + time->tv_sec = virtio64_to_cpu(vps->vdev, info.time_sec);
> + time->tv_nsec = virtio32_to_cpu(vps->vdev, info.time_nsec);
> +
> + memcpy(bf, psi->buf, len);
> + *buf = bf;
> +
> + return len;
> +}
> +
> +static int notrace virt_pstore_write(enum pstore_type_id type,
> + enum kmsg_dump_reason reason,
> + u64 *id, unsigned int part, int count,
> + bool compressed, size_t size,
> + struct pstore_info *psi)
> +{
> + struct virtio_pstore *vps = psi->data;
> + struct virtio_pstore_req *req;
> + struct virtio_pstore_res *res;
> + struct scatterlist sgo[2], sgi[1];
> + struct scatterlist *sgs[2] = { sgo, sgi };
> + unsigned int flags = compressed ? VIRTIO_PSTORE_FL_COMPRESSED : 0;
> +
> + if (vps->failed)
> + return -1;
> +
> + *id = vps->req_id;
> + virt_pstore_get_reqs(vps, &req, &res);
> +
> + req->cmd = cpu_to_virtio16(vps->vdev, VIRTIO_PSTORE_CMD_WRITE);
> + req->type = to_virtio_type(vps, type);
> + req->flags = cpu_to_virtio32(vps->vdev, flags);
> +
> + sg_init_table(sgo, 2);
> + sg_set_buf(&sgo[0], req, sizeof(*req));
> + sg_set_buf(&sgo[1], pstore_get_buf(psi), size);
> + sg_init_one(sgi, res, sizeof(*res));
> + virtqueue_add_sgs(vps->vq[1], sgs, 1, 1, vps, GFP_ATOMIC);
> + virtqueue_kick(vps->vq[1]);
> +
> + return 0;
> +}
> +
> +static int virt_pstore_erase(enum pstore_type_id type, u64 id, int count,
> + struct timespec time, struct pstore_info *psi)
> +{
> + struct virtio_pstore *vps = psi->data;
> + struct virtio_pstore_req *req;
> + struct virtio_pstore_res *res;
> + struct scatterlist sgo[1], sgi[1];
> + struct scatterlist *sgs[2] = { sgo, sgi };
> + unsigned int len;
> +
> + virt_pstore_get_reqs(vps, &req, &res);
> +
> + req->cmd = cpu_to_virtio16(vps->vdev, VIRTIO_PSTORE_CMD_ERASE);
> + req->type = to_virtio_type(vps, type);
> + req->id = cpu_to_virtio64(vps->vdev, id);
> + req->count = cpu_to_virtio32(vps->vdev, count);
> +
> + sg_init_one(sgo, req, sizeof(*req));
> + sg_init_one(sgi, res, sizeof(*res));
> + virtqueue_add_sgs(vps->vq[0], sgs, 1, 1, vps, GFP_KERNEL);
> + virtqueue_kick(vps->vq[0]);
> +
> + wait_event(vps->acked, virtqueue_get_buf(vps->vq[0], &len));
> + return virtio32_to_cpu(vps->vdev, res->ret);
> +}
> +
> +static int virt_pstore_init(struct virtio_pstore *vps)
> +{
> + struct pstore_info *psinfo = &vps->pstore;
> + int err;
> +
> + if (!psinfo->bufsize)
> + psinfo->bufsize = VIRT_PSTORE_BUFSIZE;
> +
> + psinfo->buf = alloc_pages_exact(psinfo->bufsize, GFP_KERNEL);
> + if (!psinfo->buf) {
> + pr_err("cannot allocate pstore buffer\n");
> + return -ENOMEM;
> + }
> +
> + psinfo->owner = THIS_MODULE;
> + psinfo->name = "virtio";
> + psinfo->open = virt_pstore_open;
> + psinfo->close = virt_pstore_close;
> + psinfo->read = virt_pstore_read;
> + psinfo->erase = virt_pstore_erase;
> + psinfo->write = virt_pstore_write;
> + psinfo->flags = PSTORE_FLAGS_DMESG;
> +
> + psinfo->data = vps;
> + spin_lock_init(&psinfo->buf_lock);
> +
> + err = pstore_register(psinfo);
> + if (err)
> + kfree(psinfo->buf);
> +
> + return err;
> +}
> +
> +static int virt_pstore_exit(struct virtio_pstore *vps)
> +{
> + struct pstore_info *psinfo = &vps->pstore;
> +
> + pstore_unregister(psinfo);
> +
> + free_pages_exact(psinfo->buf, psinfo->bufsize);
> + psinfo->buf = NULL;
> + psinfo->bufsize = 0;
> +
> + return 0;
> +}
> +
> +static int virtpstore_init_vqs(struct virtio_pstore *vps)
> +{
> + vq_callback_t *callbacks[] = { virtpstore_ack, virtpstore_check };
> + const char *names[] = { "pstore_read", "pstore_write" };
> +
> + return vps->vdev->config->find_vqs(vps->vdev, 2, vps->vq,
> + callbacks, names);
> +}
> +
> +static void virtpstore_init_config(struct virtio_pstore *vps)
> +{
> + u32 bufsize;
> +
> + virtio_cread(vps->vdev, struct virtio_pstore_config, bufsize, &bufsize);
> +
> + vps->pstore.bufsize = PAGE_ALIGN(bufsize);
> +}
> +
> +static void virtpstore_confirm_config(struct virtio_pstore *vps)
> +{
> + u32 bufsize = vps->pstore.bufsize;
> +
> + virtio_cwrite(vps->vdev, struct virtio_pstore_config, bufsize,
> + &bufsize);
> +}
> +
> +static int virtpstore_probe(struct virtio_device *vdev)
> +{
> + struct virtio_pstore *vps;
> + int err;
> +
> + if (!vdev->config->get) {
> + dev_err(&vdev->dev, "driver init: config access disabled\n");
> + return -EINVAL;
> + }
> +
> + vdev->priv = vps = kzalloc(sizeof(*vps), GFP_KERNEL);
> + if (!vps) {
> + err = -ENOMEM;
> + goto out;
> + }
> + vps->vdev = vdev;
> +
> + err = virtpstore_init_vqs(vps);
> + if (err < 0)
> + goto out_free;
> +
> + virtpstore_init_config(vps);
> +
> + err = virt_pstore_init(vps);
> + if (err)
> + goto out_del_vq;
> +
> + virtpstore_confirm_config(vps);
> +
> + init_waitqueue_head(&vps->acked);
> +
> + virtio_device_ready(vdev);
> +
> + dev_info(&vdev->dev, "driver init: ok (bufsize = %luK, flags = %x)\n",
> + vps->pstore.bufsize >> 10, vps->pstore.flags);
> +
> + return 0;
> +
> +out_del_vq:
> + vdev->config->del_vqs(vdev);
> +out_free:
> + kfree(vps);
> +out:
> + dev_err(&vdev->dev, "driver init: failed with %d\n", err);
> + return err;
> +}
> +
> +static void virtpstore_remove(struct virtio_device *vdev)
> +{
> + struct virtio_pstore *vps = vdev->priv;
> +
> + virt_pstore_exit(vps);
> +
> + /* Now we reset the device so we can clean up the queues. */
> + vdev->config->reset(vdev);
> +
> + vdev->config->del_vqs(vdev);
> +
> + kfree(vps);
> +}
> +
> +static unsigned int features[] = {
> +};
> +
> +static struct virtio_device_id id_table[] = {
> + { VIRTIO_ID_PSTORE, VIRTIO_DEV_ANY_ID },
> + { 0 },
> +};
> +
> +static struct virtio_driver virtio_pstore_driver = {
> + .driver.name = KBUILD_MODNAME,
> + .driver.owner = THIS_MODULE,
> + .feature_table = features,
> + .feature_table_size = ARRAY_SIZE(features),
> + .id_table = id_table,
> + .probe = virtpstore_probe,
> + .remove = virtpstore_remove,
> +};
> +
> +module_virtio_driver(virtio_pstore_driver);
> +MODULE_DEVICE_TABLE(virtio, id_table);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Namhyung Kim <namhyung@kernel.org>");
> +MODULE_DESCRIPTION("Virtio pstore driver");
> diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
> index 6d4e92ccdc91..9bbb1554d8b2 100644
> --- a/include/uapi/linux/Kbuild
> +++ b/include/uapi/linux/Kbuild
> @@ -449,6 +449,7 @@ header-y += virtio_ids.h
> header-y += virtio_input.h
> header-y += virtio_net.h
> header-y += virtio_pci.h
> +header-y += virtio_pstore.h
> header-y += virtio_ring.h
> header-y += virtio_rng.h
> header-y += virtio_scsi.h
> diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h
> index 77925f587b15..c72a9ab588c0 100644
> --- a/include/uapi/linux/virtio_ids.h
> +++ b/include/uapi/linux/virtio_ids.h
> @@ -41,5 +41,6 @@
> #define VIRTIO_ID_CAIF 12 /* Virtio caif */
> #define VIRTIO_ID_GPU 16 /* virtio GPU */
> #define VIRTIO_ID_INPUT 18 /* virtio input */
> +#define VIRTIO_ID_PSTORE 22 /* virtio pstore */
>
> #endif /* _LINUX_VIRTIO_IDS_H */
> diff --git a/include/uapi/linux/virtio_pstore.h b/include/uapi/linux/virtio_pstore.h
> new file mode 100644
> index 000000000000..f4b0d204d8ae
> --- /dev/null
> +++ b/include/uapi/linux/virtio_pstore.h
> @@ -0,0 +1,74 @@
> +#ifndef _LINUX_VIRTIO_PSTORE_H
> +#define _LINUX_VIRTIO_PSTORE_H
> +/* This header is BSD licensed so anyone can use the definitions to implement
> + * compatible drivers/servers.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + * notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + * notice, this list of conditions and the following disclaimer in the
> + * documentation and/or other materials provided with the distribution.
> + * 3. Neither the name of IBM nor the names of its contributors
> + * may be used to endorse or promote products derived from this software
> + * without specific prior written permission.
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> + * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
> + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
> + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
> + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
> + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
> + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
> + * SUCH DAMAGE. */
> +#include <linux/types.h>
> +#include <linux/virtio_types.h>
> +
> +#define VIRTIO_PSTORE_CMD_NULL 0
> +#define VIRTIO_PSTORE_CMD_OPEN 1
> +#define VIRTIO_PSTORE_CMD_READ 2
> +#define VIRTIO_PSTORE_CMD_WRITE 3
> +#define VIRTIO_PSTORE_CMD_ERASE 4
> +#define VIRTIO_PSTORE_CMD_CLOSE 5
> +
> +#define VIRTIO_PSTORE_TYPE_UNKNOWN 0
> +#define VIRTIO_PSTORE_TYPE_DMESG 1
> +
> +#define VIRTIO_PSTORE_FL_COMPRESSED 1
> +
> +struct virtio_pstore_req {
> + __virtio16 cmd;
> + __virtio16 type;
> + __virtio32 flags;
> + __virtio64 id;
> + __virtio32 count;
> + __virtio32 reserved;
> +};
> +
> +struct virtio_pstore_res {
> + __virtio16 cmd;
> + __virtio16 type;
> + __virtio32 ret;
> +};
> +
> +struct virtio_pstore_fileinfo {
> + __virtio64 id;
> + __virtio32 count;
> + __virtio16 type;
> + __virtio16 unused;
> + __virtio32 flags;
> + __virtio32 len;
> + __virtio64 time_sec;
> + __virtio32 time_nsec;
> + __virtio32 reserved;
> +};
> +
> +struct virtio_pstore_config {
> + __virtio32 bufsize;
> +};
> +
What exactly does each field mean? I'm especially
interested in time fields - maintaining a consistent
time between host and guest is not a simple problem.
> +#endif /* _LINUX_VIRTIO_PSTORE_H */
> --
> 2.9.3
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