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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] libxl: Create empty file for Phy cdrom
commit 4e41947bad8189d5b40cd29894f554b740ce272f
Author: Jason Andryuk <jandryuk@xxxxxxxxx>
AuthorDate: Wed Feb 14 10:40:56 2024 +0100
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Feb 14 10:40:56 2024 +0100
libxl: Create empty file for Phy cdrom
With a device model stubdom, dom0 exports a PV disk to the stubdom.
Inside the stubdom, QEMU emulates a cdrom to the guest with a
host_device pointing at the PV frontend (/dev/xvdc)
An empty cdrom drive causes problems booting the stubdom. The PV disk
protocol isn't designed to support no media. That can be partially
hacked around, but the stubdom kernel waits for all block devices to
transition to Connected. Since the backend never connects empty media,
stubdom launch times out and it is destroyed.
Empty media and the PV disks not connecting is fine at runtime since the
stubdom keeps running irrespective of the disk state.
Empty media can be worked around my providing an empty file to the
stubdom for the PV disk source. This works as the disk is exposed as a
zero-size disk. Dynamically create the empty file as needed and remove
in the stubdom cleanup.
libxl__device_disk_set_backend() needs to allow through these "empty"
disks with a pdev_path.
Fixup the params writing since scripts have trouble with an empty params
field.
This works for non-stubdom HVMs as well.
Signed-off-by: Jason Andryuk <jandryuk@xxxxxxxxx>
Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
tools/libs/light/libxl_device.c | 5 ++++-
tools/libs/light/libxl_disk.c | 36 ++++++++++++++++++++++++++++++++----
tools/libs/light/libxl_domain.c | 4 ++++
tools/libs/light/libxl_internal.h | 1 +
4 files changed, 41 insertions(+), 5 deletions(-)
diff --git a/tools/libs/light/libxl_device.c b/tools/libs/light/libxl_device.c
index ae2b71b0bf..8bd780493f 100644
--- a/tools/libs/light/libxl_device.c
+++ b/tools/libs/light/libxl_device.c
@@ -427,7 +427,10 @@ int libxl__device_disk_set_backend(libxl__gc *gc,
libxl_device_disk *disk) {
LOG(ERROR, "Disk vdev=%s is empty but not cdrom", disk->vdev);
return ERROR_INVAL;
}
- if (disk->pdev_path != NULL && strcmp(disk->pdev_path, "")) {
+ if (disk->pdev_path != NULL &&
+ (strcmp(disk->pdev_path, "") &&
+ strncmp(disk->pdev_path, LIBXL_STUBDOM_EMPTY_CDROM,
+ strlen(LIBXL_STUBDOM_EMPTY_CDROM)))) {
LOG(ERROR,
"Disk vdev=%s is empty but an image has been provided: %s",
disk->vdev, disk->pdev_path);
diff --git a/tools/libs/light/libxl_disk.c b/tools/libs/light/libxl_disk.c
index 59ff996837..95b32f9d29 100644
--- a/tools/libs/light/libxl_disk.c
+++ b/tools/libs/light/libxl_disk.c
@@ -201,6 +201,32 @@ static int libxl__device_disk_setdefault(libxl__gc *gc,
uint32_t domid,
disk->backend = LIBXL_DISK_BACKEND_QDISK;
}
+ if (disk->is_cdrom &&
+ disk->format == LIBXL_DISK_FORMAT_EMPTY &&
+ disk->backend == LIBXL_DISK_BACKEND_PHY &&
+ disk->backend_domid == LIBXL_TOOLSTACK_DOMID) {
+ uint32_t target_domid;
+ int fd;
+
+ if (libxl_is_stubdom(CTX, domid, &target_domid)) {
+ LOGED(DEBUG, domid, "Using target_domid %u", target_domid);
+ } else {
+ target_domid = domid;
+ }
+ free(disk->pdev_path);
+ disk->pdev_path =
+ libxl__sprintf(NOGC, LIBXL_STUBDOM_EMPTY_CDROM ".%u",
+ target_domid);
+ fd = creat(disk->pdev_path, 0400);
+ if (fd < 0) {
+ LOGED(ERROR, domid, "Failed to create empty cdrom \"%s\"",
+ disk->pdev_path);
+ return ERROR_FAIL;
+ }
+
+ close(fd);
+ }
+
rc = libxl__device_disk_set_backend(gc, disk);
return rc;
}
@@ -998,7 +1024,7 @@ static void cdrom_insert_ejected(libxl__egc *egc,
empty = flexarray_make(gc, 4, 1);
flexarray_append_pair(empty, "type",
libxl__device_disk_string_of_backend(disk->backend));
- flexarray_append_pair(empty, "params", "");
+ flexarray_append_pair(empty, "params", disk->pdev_path ?: "");
for (;;) {
rc = libxl__xs_transaction_start(gc, &t);
@@ -1174,13 +1200,15 @@ static void cdrom_insert_inserted(libxl__egc *egc,
insert = flexarray_make(gc, 4, 1);
flexarray_append_pair(insert, "type",
libxl__device_disk_string_of_backend(disk->backend));
- if (disk->format != LIBXL_DISK_FORMAT_EMPTY)
+ if (disk->backend == LIBXL_DISK_BACKEND_QDISK &&
+ disk->format != LIBXL_DISK_FORMAT_EMPTY) {
flexarray_append_pair(insert, "params",
GCSPRINTF("%s:%s",
libxl__device_disk_string_of_format(disk->format),
disk->pdev_path));
- else
- flexarray_append_pair(insert, "params", "");
+ } else {
+ flexarray_append_pair(insert, "params", disk->pdev_path ?: "");
+ }
for (;;) {
rc = libxl__xs_transaction_start(gc, &t);
diff --git a/tools/libs/light/libxl_domain.c b/tools/libs/light/libxl_domain.c
index 5ee1544d9c..6751fc785f 100644
--- a/tools/libs/light/libxl_domain.c
+++ b/tools/libs/light/libxl_domain.c
@@ -1525,6 +1525,10 @@ static void devices_destroy_cb(libxl__egc *egc,
if (rc < 0)
LOGD(ERROR, domid, "libxl__devices_destroy failed");
+ /* Remove the file after the hotplug scripts have run. The scripts won't
+ * run if the file doesn't exist when they are run. */
+ libxl__remove_file(gc, GCSPRINTF(LIBXL_STUBDOM_EMPTY_CDROM ".%u", domid));
+
vm_path = libxl__xs_read(gc, XBT_NULL, GCSPRINTF("%s/vm", dom_path));
if (vm_path)
if (!xs_rm(ctx->xsh, XBT_NULL, vm_path))
diff --git a/tools/libs/light/libxl_internal.h
b/tools/libs/light/libxl_internal.h
index d5732d1c37..094d0df9b1 100644
--- a/tools/libs/light/libxl_internal.h
+++ b/tools/libs/light/libxl_internal.h
@@ -120,6 +120,7 @@
#define STUBDOM_CONSOLE_SERIAL 3
#define STUBDOM_SPECIAL_CONSOLES 3
#define LIBXL_LINUX_STUBDOM_MEM 128
+#define LIBXL_STUBDOM_EMPTY_CDROM XEN_RUN_DIR "/empty-cdrom" /* .$domid */
#define TAP_DEVICE_SUFFIX "-emu"
#define DOMID_XS_PATH "domid"
#define PVSHIM_BASENAME "xen-shim"
--
generated by git-patchbot for /home/xen/git/xen.git#master
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