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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 3 of 4 v3] libxl: Introduce pci_assignable_add and pci_assignable_remove
Introduce libxl helper functions to prepare devices to be passed
through to guests. This is meant to replace of all the manual sysfs
commands which are currently required.
pci_assignable_add accepts a BDF for a device and will:
* Unbind a device from its current driver, if any
* If "rebind" is set, it will store the path of the driver from which we
unplugged it in /libxl/pciback/$BDF/driver_path
* If create a slot for it in pciback if one doesn't yet exist
* Bind the device to pciback
At this point it will show up in pci_assignable_list, and is ready to
be passed through to a guest.
pci_assignable_remove accepts a BDF for a device and will:
* Unbind the device from pciback
* Remove the slot from pciback
* If "rebind" is set, and /libx/pciback/$BDF/driver_path exists, it
will attempt to rebind the device to its original driver.
Both functions are idempotent: if the desired end state has already
been reached, they return SUCCESS.
NB that "$BDF" in this case uses '-' instead of ':' and '.', because
':' and '.' are illegal characters in xenstore paths.
v2:
- sysfs_dev_unbind uses a local var for the path pointer, and sets
only at the end
- Actually read pci domain when looking at slots, instead of assuming
0000
- Call LOG_ERRNO after failed sysfs_write_bdf calls, rather than just
LOG
- Removed stray FIXME
- Made xenstore reads and writes single operations, and removed
transaction infrastructure
- Wrapped a couple of lines that were above 80 characters
- Added a comment explaining the patch's treatment of slots
- Clarified patch description of when it creates slots
v3:
- Fix bug in pciback_dev_has_slot() introduced in v2.
- Raise loglevel to WARNING when pci device is already assigned
- Update comment in libxl.h to make add and remove explicitly
idempotent
Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
diff -r 62e682bdb103 -r d6739b5dfd9a tools/libxl/libxl.h
--- a/tools/libxl/libxl.h Tue May 15 15:26:24 2012 +0100
+++ b/tools/libxl/libxl.h Tue May 15 15:26:25 2012 +0100
@@ -718,10 +718,29 @@ int libxl_device_pci_destroy(libxl_ctx *
libxl_device_pci *libxl_device_pci_list(libxl_ctx *ctx, uint32_t domid, int
*num);
/*
- * Similar to libxl_device_pci_list but returns all devices which
- * could be assigned to a domain (i.e. are bound to the backend
- * driver) but are not currently.
+ * Functions related to making devices assignable -- that is, bound to
+ * the pciback driver, ready to be given to a guest via
+ * libxl_pci_device_add.
+ *
+ * - ..._add() will unbind the device from its current driver (if
+ * already bound) and re-bind it to pciback; at that point it will be
+ * ready to be assigned to a VM. If rebind is set, it will store the
+ * path to the old driver in xenstore so that it can be handed back to
+ * dom0 on restore.
+ *
+ * - ..._remove() will unbind the device from pciback, and if
+ * rebind is non-zero, attempt to assign it back to the driver
+ * from whence it came.
+ *
+ * - ..._list() will return a list of the PCI devices available to be
+ * assigned.
+ *
+ * add and remove are idempotent: if the device in question is already
+ * added or is not bound, the functions will emit a warning but return
+ * SUCCESS.
*/
+int libxl_device_pci_assignable_add(libxl_ctx *ctx, libxl_device_pci *pcidev,
int rebind);
+int libxl_device_pci_assignable_remove(libxl_ctx *ctx, libxl_device_pci
*pcidev, int rebind);
libxl_device_pci *libxl_device_pci_assignable_list(libxl_ctx *ctx, int *num);
/* CPUID handling */
diff -r 62e682bdb103 -r d6739b5dfd9a tools/libxl/libxl_pci.c
--- a/tools/libxl/libxl_pci.c Tue May 15 15:26:24 2012 +0100
+++ b/tools/libxl/libxl_pci.c Tue May 15 15:26:25 2012 +0100
@@ -21,6 +21,7 @@
#define PCI_BDF "%04x:%02x:%02x.%01x"
#define PCI_BDF_SHORT "%02x:%02x.%01x"
#define PCI_BDF_VDEVFN "%04x:%02x:%02x.%01x@%02x"
+#define PCI_BDF_XSPATH "%04x-%02x-%02x-%01x"
static unsigned int pcidev_encode_bdf(libxl_device_pci *pcidev)
{
@@ -408,6 +409,334 @@ out:
return pcidevs;
}
+/* Unbind device from its current driver, if any. If driver_path is non-NULL,
+ * store the path to the original driver in it. */
+static int sysfs_dev_unbind(libxl__gc *gc, libxl_device_pci *pcidev,
+ char **driver_path)
+{
+ libxl_ctx *ctx = libxl__gc_owner(gc);
+ char * spath, *dp = NULL;
+ struct stat st;
+
+ spath = libxl__sprintf(gc, SYSFS_PCI_DEV"/"PCI_BDF"/driver",
+ pcidev->domain,
+ pcidev->bus,
+ pcidev->dev,
+ pcidev->func);
+ if ( !lstat(spath, &st) ) {
+ /* Find the canonical path to the driver. */
+ dp = libxl__zalloc(gc, PATH_MAX);
+ dp = realpath(spath, dp);
+ if ( !dp ) {
+ LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "realpath() failed");
+ return -1;
+ }
+
+ LIBXL__LOG(ctx, LIBXL__LOG_DEBUG, "Driver re-plug path: %s",
+ dp);
+
+ /* Unbind from the old driver */
+ spath = libxl__sprintf(gc, "%s/unbind", dp);
+ if ( sysfs_write_bdf(gc, spath, pcidev) < 0 ) {
+ LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "Couldn't unbind device");
+ return -1;
+ }
+ }
+
+ if ( driver_path )
+ *driver_path = dp;
+
+ return 0;
+}
+
+/*
+ * A brief comment about slots. I don't know what slots are for; however,
+ * I have by experimentation determined:
+ * - Before a device can be bound to pciback, its BDF must first be listed
+ * in pciback/slots
+ * - The way to get the BDF listed there is to write BDF to
+ * pciback/new_slot
+ * - Writing the same BDF to pciback/new_slot is not idempotent; it results
+ * in two entries of the BDF in pciback/slots
+ * It's not clear whether having two entries in pciback/slots is a problem
+ * or not. Just to be safe, this code does the conservative thing, and
+ * first checks to see if there is a slot, adding one only if one does not
+ * already exist.
+ */
+
+/* Scan through /sys/.../pciback/slots looking for pcidev's BDF */
+static int pciback_dev_has_slot(libxl__gc *gc, libxl_device_pci *pcidev)
+{
+ libxl_ctx *ctx = libxl__gc_owner(gc);
+ FILE *f;
+ int rc = 0;
+ unsigned dom, bus, dev, func;
+
+ f = fopen(SYSFS_PCIBACK_DRIVER"/slots", "r");
+
+ if (f == NULL) {
+ LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "Couldn't open %s",
+ SYSFS_PCIBACK_DRIVER"/slots");
+ return ERROR_FAIL;
+ }
+
+ while(fscanf(f, "%x:%x:%x.%x\n", &dom, &bus, &dev, &func)==4) {
+ if(dom == pcidev->domain
+ && bus == pcidev->bus
+ && dev == pcidev->dev
+ && func == pcidev->func) {
+ rc = 1;
+ goto out;
+ }
+ }
+out:
+ fclose(f);
+ return rc;
+}
+
+static int pciback_dev_is_assigned(libxl__gc *gc, libxl_device_pci *pcidev)
+{
+ libxl_ctx *ctx = libxl__gc_owner(gc);
+ char * spath;
+ int rc;
+ struct stat st;
+
+ spath = libxl__sprintf(gc, SYSFS_PCIBACK_DRIVER"/"PCI_BDF,
+ pcidev->domain, pcidev->bus,
+ pcidev->dev, pcidev->func);
+ rc = lstat(spath, &st);
+
+ if( rc == 0 )
+ return 1;
+ if ( rc < 0 && errno == ENOENT )
+ return 0;
+ LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "Accessing %s", spath);
+ return -1;
+}
+
+static int pciback_dev_assign(libxl__gc *gc, libxl_device_pci *pcidev)
+{
+ libxl_ctx *ctx = libxl__gc_owner(gc);
+ int rc;
+
+ if ( (rc=pciback_dev_has_slot(gc, pcidev)) < 0 ) {
+ LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR,
+ "Error checking for pciback slot");
+ return ERROR_FAIL;
+ } else if (rc == 0) {
+ if ( sysfs_write_bdf(gc, SYSFS_PCIBACK_DRIVER"/new_slot",
+ pcidev) < 0 ) {
+ LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR,
+ "Couldn't bind device to pciback!");
+ return ERROR_FAIL;
+ }
+ }
+
+ if ( sysfs_write_bdf(gc, SYSFS_PCIBACK_DRIVER"/bind", pcidev) < 0 ) {
+ LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR,
+ "Couldn't bind device to pciback!");
+ return ERROR_FAIL;
+ }
+ return 0;
+}
+
+static int pciback_dev_unassign(libxl__gc *gc, libxl_device_pci *pcidev)
+{
+ libxl_ctx *ctx = libxl__gc_owner(gc);
+
+ /* Remove from pciback */
+ if ( sysfs_dev_unbind(gc, pcidev, NULL) < 0 ) {
+ LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "Couldn't unbind device!");
+ return ERROR_FAIL;
+ }
+
+ /* Remove slot if necessary */
+ if ( pciback_dev_has_slot(gc, pcidev) > 0 ) {
+ if ( sysfs_write_bdf(gc, SYSFS_PCIBACK_DRIVER"/remove_slot",
+ pcidev) < 0 ) {
+ LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR,
+ "Couldn't remove pciback slot");
+ return ERROR_FAIL;
+ }
+ }
+ return 0;
+}
+
+#define PCIBACK_INFO_PATH "/libxl/pciback"
+
+static void pci_assignable_driver_path_write(libxl__gc *gc,
+ libxl_device_pci *pcidev,
+ char *driver_path)
+{
+ libxl_ctx *ctx = libxl__gc_owner(gc);
+ char *path;
+
+ path = libxl__sprintf(gc, PCIBACK_INFO_PATH"/"PCI_BDF_XSPATH"/driver_path",
+ pcidev->domain,
+ pcidev->bus,
+ pcidev->dev,
+ pcidev->func);
+ if ( libxl__xs_write(gc, XBT_NULL, path, "%s", driver_path) < 0 ) {
+ LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_WARNING,
+ "Write of %s to node %s failed.",
+ driver_path, path);
+ }
+}
+
+static char * pci_assignable_driver_path_read(libxl__gc *gc,
+ libxl_device_pci *pcidev)
+{
+ return libxl__xs_read(gc, XBT_NULL,
+ libxl__sprintf(gc,
+ PCIBACK_INFO_PATH "/" PCI_BDF_XSPATH "/driver_path",
+ pcidev->domain,
+ pcidev->bus,
+ pcidev->dev,
+ pcidev->func));
+}
+
+static void pci_assignable_driver_path_remove(libxl__gc *gc,
+ libxl_device_pci *pcidev)
+{
+ libxl_ctx *ctx = libxl__gc_owner(gc);
+
+ /* Remove the xenstore entry */
+ xs_rm(ctx->xsh, XBT_NULL,
+ libxl__sprintf(gc, PCIBACK_INFO_PATH "/" PCI_BDF_XSPATH,
+ pcidev->domain,
+ pcidev->bus,
+ pcidev->dev,
+ pcidev->func) );
+}
+
+static int libxl__device_pci_assignable_add(libxl__gc *gc,
+ libxl_device_pci *pcidev,
+ int rebind)
+{
+ libxl_ctx *ctx = libxl__gc_owner(gc);
+ unsigned dom, bus, dev, func;
+ char *spath, *driver_path = NULL;
+ struct stat st;
+
+ /* Local copy for convenience */
+ dom = pcidev->domain;
+ bus = pcidev->bus;
+ dev = pcidev->dev;
+ func = pcidev->func;
+
+ /* See if the device exists */
+ spath = libxl__sprintf(gc, SYSFS_PCI_DEV"/"PCI_BDF, dom, bus, dev, func);
+ if ( lstat(spath, &st) ) {
+ LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "Couldn't lstat %s", spath);
+ return ERROR_FAIL;
+ }
+
+ /* Check to see if it's already assigned to pciback */
+ if ( pciback_dev_is_assigned(gc, pcidev) ) {
+ LIBXL__LOG(ctx, LIBXL__LOG_WARNING, PCI_BDF" already assigned to
pciback",
+ dom, bus, dev, func);
+ return 0;
+ }
+
+ /* Check to see if there's already a driver that we need to unbind from */
+ if ( sysfs_dev_unbind(gc, pcidev, &driver_path ) ) {
+ LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
+ "Couldn't unbind "PCI_BDF" from driver",
+ dom, bus, dev, func);
+ return ERROR_FAIL;
+ }
+
+ /* Store driver_path for rebinding to dom0 */
+ if ( rebind ) {
+ if ( driver_path ) {
+ pci_assignable_driver_path_write(gc, pcidev, driver_path);
+ } else {
+ LIBXL__LOG(ctx, LIBXL__LOG_WARNING,
+ PCI_BDF" not bound to a driver, will not be rebound.",
+ dom, bus, dev, func);
+ }
+ }
+
+ if ( pciback_dev_assign(gc, pcidev) ) {
+ LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "Couldn't bind device to pciback!");
+ return ERROR_FAIL;
+ }
+
+ return 0;
+}
+
+static int libxl__device_pci_assignable_remove(libxl__gc *gc,
+ libxl_device_pci *pcidev,
+ int rebind)
+{
+ libxl_ctx *ctx = libxl__gc_owner(gc);
+ int rc;
+ char *driver_path;
+
+ /* Unbind from pciback */
+ if ( (rc=pciback_dev_is_assigned(gc, pcidev)) < 0 ) {
+ LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "Checking if pciback was assigned");
+ return ERROR_FAIL;
+ } else if ( rc ) {
+ pciback_dev_unassign(gc, pcidev);
+ } else {
+ LIBXL__LOG(ctx, LIBXL__LOG_WARNING,
+ "Not bound to pciback");
+ }
+
+ /* Rebind if necessary */
+ driver_path = pci_assignable_driver_path_read(gc, pcidev);
+
+ if ( driver_path ) {
+ if ( rebind ) {
+ LIBXL__LOG(ctx, LIBXL__LOG_INFO, "Rebinding to driver at %s",
+ driver_path);
+
+ if ( sysfs_write_bdf(gc,
+ libxl__sprintf(gc, "%s/bind", driver_path),
+ pcidev) < 0 ) {
+ LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR,
+ "Couldn't bind device to %s", driver_path);
+ return -1;
+ }
+ }
+
+ pci_assignable_driver_path_remove(gc, pcidev);
+ } else {
+ if ( rebind ) {
+ LIBXL__LOG(ctx, LIBXL__LOG_WARNING,
+ "Couldn't find path for original driver; not
rebinding");
+ }
+ }
+
+ return 0;
+}
+
+int libxl_device_pci_assignable_add(libxl_ctx *ctx, libxl_device_pci *pcidev,
+ int rebind)
+{
+ GC_INIT(ctx);
+ int rc;
+
+ rc = libxl__device_pci_assignable_add(gc, pcidev, rebind);
+
+ GC_FREE;
+ return rc;
+}
+
+
+int libxl_device_pci_assignable_remove(libxl_ctx *ctx, libxl_device_pci
*pcidev,
+ int rebind)
+{
+ GC_INIT(ctx);
+ int rc;
+
+ rc = libxl__device_pci_assignable_remove(gc, pcidev, rebind);
+
+ GC_FREE;
+ return rc;
+}
+
/*
* This function checks that all functions of a device are bound to pciback
* driver. It also initialises a bit-mask of which function numbers are present
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