[RESEND PATCH v2 14/18] xen: pvblock: Read XenStore configuration and initialize

Anastasiia Lukianenko
2020-08-06T09:42:57Z

From: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com>

Read essential virtual block device configuration data from XenStore,
initialize front ring and event channel.
Update block device description with actual block size.

Use code for XenStore from mini-os.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com>
---

Changes since v1:
- add comments
- correct code style

drivers/xen/pvblock.c | 285 +++++++++++++++++++++++++++++++++++++++++-
1 file changed, 284 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/pvblock.c b/drivers/xen/pvblock.c
index 3ed62cac5d..e247ce33a3 100644
--- a/drivers/xen/pvblock.c
+++ b/drivers/xen/pvblock.c
@@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0+
/*
+ * (C) 2007-2008 Samuel Thibault.
* (C) Copyright 2020 EPAM Systems Inc.
*/
#include <blk.h>
@@ -9,26 +10,302 @@
#include <malloc.h>
#include <part.h>

+#include <asm/armv8/mmu.h>
+#include <asm/io.h>
+#include <asm/xen/system.h>
+
+#include <linux/compat.h>
+
+#include <xen/events.h>
+#include <xen/gnttab.h>
+#include <xen/hvm.h>
#include <xen/xenbus.h>

+#include <xen/interface/io/ring.h>
+#include <xen/interface/io/blkif.h>
+#include <xen/interface/io/protocols.h>
+
#define DRV_NAME "pvblock"
#define DRV_NAME_BLK "pvblock_blk"

+#define O_RDONLY 00
+#define O_RDWR 02
+
+struct blkfront_info {
+ u64 sectors;
+ unsigned int sector_size;
+ int mode;
+ int info;
+ int barrier;
+ int flush;
+};
+
+/**
+ * struct blkfront_dev - Struct representing blkfront device
+ * @dom: Domain id
+ * @ring: Front_ring structure
+ * @ring_ref: The grant reference, allowing us to grant access
+ * to the ring to the other end/domain
+ * @evtchn: Event channel used to signal ring events
+ * @handle: Events handle
+ * @nodename: Device XenStore path in format "device/vbd/" + @devid
+ * @backend: Backend XenStore path
+ * @info: Private data
+ * @devid: Device id
+ */
struct blkfront_dev {
- char dummy;
+ domid_t dom;
+
+ struct blkif_front_ring ring;
+ grant_ref_t ring_ref;
+ evtchn_port_t evtchn;
+ blkif_vdev_t handle;
+
+ char *nodename;
+ char *backend;
+ struct blkfront_info info;
+ unsigned int devid;
};

struct blkfront_platdata {
unsigned int devid;
};

+static void free_blkfront(struct blkfront_dev *dev)
+{
+ mask_evtchn(dev->evtchn);
+ free(dev->backend);
+
+ gnttab_end_access(dev->ring_ref);
+ free(dev->ring.sring);
+
+ unbind_evtchn(dev->evtchn);
+
+ free(dev->nodename);
+ free(dev);
+}
+
+static void blkfront_handler(evtchn_port_t port, struct pt_regs *regs,
+ void *data)
+{
+ printf("%s [Port %d] - event received\n", __func__, port);
+}
+
static int init_blkfront(unsigned int devid, struct blkfront_dev *dev)
{
+ xenbus_transaction_t xbt;
+ char *err = NULL;
+ char *message = NULL;
+ struct blkif_sring *s;
+ int retry = 0;
+ char *msg = NULL;
+ char *c;
+ char nodename[32];
+ char path[ARRAY_SIZE(nodename) + strlen("/backend-id") + 1];
+
+ sprintf(nodename, "device/vbd/%d", devid);
+
+ memset(dev, 0, sizeof(*dev));
+ dev->nodename = strdup(nodename);
+ dev->devid = devid;
+
+ snprintf(path, sizeof(path), "%s/backend-id", nodename);
+ dev->dom = xenbus_read_integer(path);
+ evtchn_alloc_unbound(dev->dom, blkfront_handler, dev, &dev->evtchn);
+
+ s = (struct blkif_sring *)memalign(PAGE_SIZE, PAGE_SIZE);
+ if (!s) {
+ printf("Failed to allocate shared ring\n");
+ goto error;
+ }
+
+ SHARED_RING_INIT(s);
+ FRONT_RING_INIT(&dev->ring, s, PAGE_SIZE);
+
+ dev->ring_ref = gnttab_grant_access(dev->dom, virt_to_pfn(s), 0);
+
+again:
+ err = xenbus_transaction_start(&xbt);
+ if (err) {
+ printf("starting transaction\n");
+ free(err);
+ }
+
+ err = xenbus_printf(xbt, nodename, "ring-ref", "%u", dev->ring_ref);
+ if (err) {
+ message = "writing ring-ref";
+ goto abort_transaction;
+ }
+ err = xenbus_printf(xbt, nodename, "event-channel", "%u", dev->evtchn);
+ if (err) {
+ message = "writing event-channel";
+ goto abort_transaction;
+ }
+ err = xenbus_printf(xbt, nodename, "protocol", "%s",
+ XEN_IO_PROTO_ABI_NATIVE);
+ if (err) {
+ message = "writing protocol";
+ goto abort_transaction;
+ }
+
+ snprintf(path, sizeof(path), "%s/state", nodename);
+ err = xenbus_switch_state(xbt, path, XenbusStateConnected);
+ if (err) {
+ message = "switching state";
+ goto abort_transaction;
+ }
+
+ err = xenbus_transaction_end(xbt, 0, &retry);
+ free(err);
+ if (retry) {
+ goto again;
+ printf("completing transaction\n");
+ }
+
+ goto done;
+
+abort_transaction:
+ free(err);
+ err = xenbus_transaction_end(xbt, 1, &retry);
+ printf("Abort transaction %s\n", message);
+ goto error;
+
+done:
+ snprintf(path, sizeof(path), "%s/backend", nodename);
+ msg = xenbus_read(XBT_NIL, path, &dev->backend);
+ if (msg) {
+ printf("Error %s when reading the backend path %s\n",
+ msg, path);
+ goto error;
+ }
+
+ dev->handle = strtoul(strrchr(nodename, '/') + 1, NULL, 0);
+
+ {
+ XenbusState state;
+ char path[strlen(dev->backend) +
+ strlen("/feature-flush-cache") + 1];
+
+ snprintf(path, sizeof(path), "%s/mode", dev->backend);
+ msg = xenbus_read(XBT_NIL, path, &c);
+ if (msg) {
+ printf("Error %s when reading the mode\n", msg);
+ goto error;
+ }
+ if (*c == 'w')
+ dev->info.mode = O_RDWR;
+ else
+ dev->info.mode = O_RDONLY;
+ free(c);
+
+ snprintf(path, sizeof(path), "%s/state", dev->backend);
+
+ msg = NULL;
+ state = xenbus_read_integer(path);
+ while (!msg && state < XenbusStateConnected)
+ msg = xenbus_wait_for_state_change(path, &state);
+ if (msg || state != XenbusStateConnected) {
+ printf("backend not available, state=%d\n", state);
+ goto error;
+ }
+
+ snprintf(path, sizeof(path), "%s/info", dev->backend);
+ dev->info.info = xenbus_read_integer(path);
+
+ snprintf(path, sizeof(path), "%s/sectors", dev->backend);
+ /*
+ * FIXME: read_integer returns an int, so disk size
+ * limited to 1TB for now
+ */
+ dev->info.sectors = xenbus_read_integer(path);
+
+ snprintf(path, sizeof(path), "%s/sector-size", dev->backend);
+ dev->info.sector_size = xenbus_read_integer(path);
+
+ snprintf(path, sizeof(path), "%s/feature-barrier",
+ dev->backend);
+ dev->info.barrier = xenbus_read_integer(path);
+
+ snprintf(path, sizeof(path), "%s/feature-flush-cache",
+ dev->backend);
+ dev->info.flush = xenbus_read_integer(path);
+ }
+ unmask_evtchn(dev->evtchn);
+
+ debug("%llu sectors of %u bytes\n",
+ dev->info.sectors, dev->info.sector_size);
+
return 0;
+
+error:
+ free(msg);
+ free(err);
+ free_blkfront(dev);
+ return -ENODEV;
}

static void shutdown_blkfront(struct blkfront_dev *dev)
{
+ char *err = NULL, *err2;
+ XenbusState state;
+
+ char path[strlen(dev->backend) + strlen("/state") + 1];
+ char nodename[strlen(dev->nodename) + strlen("/event-channel") + 1];
+
+ debug("Close " DRV_NAME ", device ID %d\n", dev->devid);
+
+ snprintf(path, sizeof(path), "%s/state", dev->backend);
+ snprintf(nodename, sizeof(nodename), "%s/state", dev->nodename);
+
+ if ((err = xenbus_switch_state(XBT_NIL, nodename,
+ XenbusStateClosing)) != NULL) {
+ printf("%s: error changing state to %d: %s\n", __func__,
+ XenbusStateClosing, err);
+ goto close;
+ }
+
+ state = xenbus_read_integer(path);
+ while (!err && state < XenbusStateClosing)
+ err = xenbus_wait_for_state_change(path, &state);
+ free(err);
+
+ if ((err = xenbus_switch_state(XBT_NIL, nodename,
+ XenbusStateClosed)) != NULL) {
+ printf("%s: error changing state to %d: %s\n", __func__,
+ XenbusStateClosed, err);
+ goto close;
+ }
+
+ state = xenbus_read_integer(path);
+ while (state < XenbusStateClosed) {
+ err = xenbus_wait_for_state_change(path, &state);
+ free(err);
+ }
+
+ if ((err = xenbus_switch_state(XBT_NIL, nodename,
+ XenbusStateInitialising)) != NULL) {
+ printf("%s: error changing state to %d: %s\n", __func__,
+ XenbusStateInitialising, err);
+ goto close;
+ }
+
+ state = xenbus_read_integer(path);
+ while (!err &&
+ (state < XenbusStateInitWait || state >= XenbusStateClosed))
+ err = xenbus_wait_for_state_change(path, &state);
+
+close:
+ free(err);
+
+ snprintf(nodename, sizeof(nodename), "%s/ring-ref", dev->nodename);
+ err2 = xenbus_rm(XBT_NIL, nodename);
+ free(err2);
+ snprintf(nodename, sizeof(nodename), "%s/event-channel", dev->nodename);
+ err2 = xenbus_rm(XBT_NIL, nodename);
+ free(err2);
+
+ if (!err)
+ free_blkfront(dev);
}

ulong pvblock_blk_read(struct udevice *udev, lbaint_t blknr, lbaint_t blkcnt,
@@ -73,6 +350,7 @@ static int pvblock_blk_probe(struct udevice *udev)
{
struct blkfront_dev *blk_dev = dev_get_priv(udev);
struct blkfront_platdata *platdata = dev_get_platdata(udev);
+ struct blk_desc *desc = dev_get_uclass_platdata(udev);
int ret, devid;

devid = platdata->devid;
@@ -81,6 +359,11 @@ static int pvblock_blk_probe(struct udevice *udev)
ret = init_blkfront(devid, blk_dev);
if (ret < 0)
return ret;
+
+ desc->blksz = blk_dev->info.sector_size;
+ desc->lba = blk_dev->info.sectors;
+ desc->log2blksz = LOG2(blk_dev->info.sector_size);
+
return 0;
}

--
2.17.1