From d3256f88d988809ae006aa28d6df88b37b253bc1 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Mon, 16 Oct 2023 13:01:39 +0100 Subject: [PATCH] hw/xen: automatically assign device index to block devices There's no need to force the user to assign a vdev. We can automatically assign one, starting at xvda and searching until we find the first disk name that's unused. This means we can now allow '-drive if=xen,file=xxx' to work without an explicit separate -driver argument, just like if=virtio. Rip out the legacy handling from the xenpv machine, which was scribbling over any disks configured by the toolstack, and didn't work with anything but raw images. Signed-off-by: David Woodhouse Acked-by: Kevin Wolf Reviewed-by: Paul Durrant --- blockdev.c | 15 +++- hw/block/xen-block.c | 118 ++++++++++++++++++++++++++-- hw/xen/xen_devconfig.c | 28 ------- hw/xenpv/xen_machine_pv.c | 9 --- include/hw/xen/xen-legacy-backend.h | 1 - 5 files changed, 125 insertions(+), 46 deletions(-) diff --git a/blockdev.c b/blockdev.c index 1517dc6210..e9b7e38dc4 100644 --- a/blockdev.c +++ b/blockdev.c @@ -255,13 +255,13 @@ void drive_check_orphaned(void) * Ignore default drives, because we create certain default * drives unconditionally, then leave them unclaimed. Not the * users fault. - * Ignore IF_VIRTIO, because it gets desugared into -device, - * so we can leave failing to -device. + * Ignore IF_VIRTIO or IF_XEN, because it gets desugared into + * -device, so we can leave failing to -device. * Ignore IF_NONE, because leaving unclaimed IF_NONE remains * available for device_add is a feature. */ if (dinfo->is_default || dinfo->type == IF_VIRTIO - || dinfo->type == IF_NONE) { + || dinfo->type == IF_XEN || dinfo->type == IF_NONE) { continue; } if (!blk_get_attached_dev(blk)) { @@ -977,6 +977,15 @@ DriveInfo *drive_new(QemuOpts *all_opts, BlockInterfaceType block_default_type, qemu_opt_set(devopts, "driver", "virtio-blk", &error_abort); qemu_opt_set(devopts, "drive", qdict_get_str(bs_opts, "id"), &error_abort); + } else if (type == IF_XEN) { + QemuOpts *devopts; + devopts = qemu_opts_create(qemu_find_opts("device"), NULL, 0, + &error_abort); + qemu_opt_set(devopts, "driver", + (media == MEDIA_CDROM) ? "xen-cdrom" : "xen-disk", + &error_abort); + qemu_opt_set(devopts, "drive", qdict_get_str(bs_opts, "id"), + &error_abort); } filename = qemu_opt_get(legacy_opts, "file"); diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c index bfa53960c3..6d64ede94f 100644 --- a/hw/block/xen-block.c +++ b/hw/block/xen-block.c @@ -27,13 +27,119 @@ #include "sysemu/block-backend.h" #include "sysemu/iothread.h" #include "dataplane/xen-block.h" +#include "hw/xen/interface/io/xs_wire.h" #include "trace.h" +#define XVDA_MAJOR 202 +#define XVDQ_MAJOR (1 << 20) +#define XVDBGQCV_MAJOR ((1 << 21) - 1) +#define HDA_MAJOR 3 +#define HDC_MAJOR 22 +#define SDA_MAJOR 8 + + +static int vdev_to_diskno(unsigned int vdev_nr) +{ + switch (vdev_nr >> 8) { + case XVDA_MAJOR: + case SDA_MAJOR: + return (vdev_nr >> 4) & 0x15; + + case HDA_MAJOR: + return (vdev_nr >> 6) & 1; + + case HDC_MAJOR: + return ((vdev_nr >> 6) & 1) + 2; + + case XVDQ_MAJOR ... XVDBGQCV_MAJOR: + return (vdev_nr >> 8) & 0xfffff; + + default: + return -1; + } +} + +#define MAX_AUTO_VDEV 4096 + +/* + * Find a free device name in the xvda → xvdfan range and set it in + * blockdev->props.vdev. Our definition of "free" is that there must + * be no other disk or partition with the same disk number. + * + * You are technically permitted to have all of hda, hda1, sda, sda1, + * xvda and xvda1 as *separate* PV block devices with separate backing + * stores. That doesn't make it a good idea. This code will skip xvda + * if *any* of those "conflicting" devices already exists. + * + * The limit of xvdfan (disk 4095) is fairly arbitrary just to avoid a + * stupidly sized bitmap, but Linux as of v6.6 doesn't support anything + * higher than that anyway. + */ +static bool xen_block_find_free_vdev(XenBlockDevice *blockdev, Error **errp) +{ + XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(blockdev))); + unsigned long used_devs[BITS_TO_LONGS(MAX_AUTO_VDEV)]; + XenBlockVdev *vdev = &blockdev->props.vdev; + char fe_path[XENSTORE_ABS_PATH_MAX + 1]; + char **existing_frontends; + unsigned int nr_existing = 0; + unsigned int vdev_nr; + int i, disk = 0; + + snprintf(fe_path, sizeof(fe_path), "/local/domain/%u/device/vbd", + blockdev->xendev.frontend_id); + + existing_frontends = qemu_xen_xs_directory(xenbus->xsh, XBT_NULL, fe_path, + &nr_existing); + if (!existing_frontends && errno != ENOENT) { + error_setg_errno(errp, errno, "cannot read %s", fe_path); + return false; + } + + memset(used_devs, 0, sizeof(used_devs)); + for (i = 0; i < nr_existing; i++) { + if (qemu_strtoui(existing_frontends[i], NULL, 10, &vdev_nr)) { + free(existing_frontends[i]); + continue; + } + + free(existing_frontends[i]); + + disk = vdev_to_diskno(vdev_nr); + if (disk < 0 || disk >= MAX_AUTO_VDEV) { + continue; + } + + set_bit(disk, used_devs); + } + free(existing_frontends); + + disk = find_first_zero_bit(used_devs, MAX_AUTO_VDEV); + if (disk == MAX_AUTO_VDEV) { + error_setg(errp, "cannot find device vdev for block device"); + return false; + } + + vdev->type = XEN_BLOCK_VDEV_TYPE_XVD; + vdev->partition = 0; + vdev->disk = disk; + if (disk < (1 << 4)) { + vdev->number = (XVDA_MAJOR << 8) | (disk << 4); + } else { + vdev->number = (XVDQ_MAJOR << 8) | (disk << 8); + } + return true; +} + static char *xen_block_get_name(XenDevice *xendev, Error **errp) { XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev); XenBlockVdev *vdev = &blockdev->props.vdev; + if (vdev->type == XEN_BLOCK_VDEV_TYPE_INVALID && + !xen_block_find_free_vdev(blockdev, errp)) { + return NULL; + } return g_strdup_printf("%lu", vdev->number); } @@ -482,10 +588,10 @@ static void xen_block_set_vdev(Object *obj, Visitor *v, const char *name, case XEN_BLOCK_VDEV_TYPE_DP: case XEN_BLOCK_VDEV_TYPE_XVD: if (vdev->disk < (1 << 4) && vdev->partition < (1 << 4)) { - vdev->number = (202 << 8) | (vdev->disk << 4) | + vdev->number = (XVDA_MAJOR << 8) | (vdev->disk << 4) | vdev->partition; } else if (vdev->disk < (1 << 20) && vdev->partition < (1 << 8)) { - vdev->number = (1 << 28) | (vdev->disk << 8) | + vdev->number = (XVDQ_MAJOR << 8) | (vdev->disk << 8) | vdev->partition; } else { goto invalid; @@ -495,10 +601,11 @@ static void xen_block_set_vdev(Object *obj, Visitor *v, const char *name, case XEN_BLOCK_VDEV_TYPE_HD: if ((vdev->disk == 0 || vdev->disk == 1) && vdev->partition < (1 << 6)) { - vdev->number = (3 << 8) | (vdev->disk << 6) | vdev->partition; + vdev->number = (HDA_MAJOR << 8) | (vdev->disk << 6) | + vdev->partition; } else if ((vdev->disk == 2 || vdev->disk == 3) && vdev->partition < (1 << 6)) { - vdev->number = (22 << 8) | ((vdev->disk - 2) << 6) | + vdev->number = (HDC_MAJOR << 8) | ((vdev->disk - 2) << 6) | vdev->partition; } else { goto invalid; @@ -507,7 +614,8 @@ static void xen_block_set_vdev(Object *obj, Visitor *v, const char *name, case XEN_BLOCK_VDEV_TYPE_SD: if (vdev->disk < (1 << 4) && vdev->partition < (1 << 4)) { - vdev->number = (8 << 8) | (vdev->disk << 4) | vdev->partition; + vdev->number = (SDA_MAJOR << 8) | (vdev->disk << 4) | + vdev->partition; } else { goto invalid; } diff --git a/hw/xen/xen_devconfig.c b/hw/xen/xen_devconfig.c index 9b7304e544..3f77c675c6 100644 --- a/hw/xen/xen_devconfig.c +++ b/hw/xen/xen_devconfig.c @@ -46,34 +46,6 @@ static int xen_config_dev_all(char *fe, char *be) /* ------------------------------------------------------------- */ -int xen_config_dev_blk(DriveInfo *disk) -{ - char fe[256], be[256], device_name[32]; - int vdev = 202 * 256 + 16 * disk->unit; - int cdrom = disk->media_cd; - const char *devtype = cdrom ? "cdrom" : "disk"; - const char *mode = cdrom ? "r" : "w"; - const char *filename = qemu_opt_get(disk->opts, "file"); - - snprintf(device_name, sizeof(device_name), "xvd%c", 'a' + disk->unit); - xen_pv_printf(NULL, 1, "config disk %d [%s]: %s\n", - disk->unit, device_name, filename); - xen_config_dev_dirs("vbd", "qdisk", vdev, fe, be, sizeof(fe)); - - /* frontend */ - xenstore_write_int(fe, "virtual-device", vdev); - xenstore_write_str(fe, "device-type", devtype); - - /* backend */ - xenstore_write_str(be, "dev", device_name); - xenstore_write_str(be, "type", "file"); - xenstore_write_str(be, "params", filename); - xenstore_write_str(be, "mode", mode); - - /* common stuff */ - return xen_config_dev_all(fe, be); -} - int xen_config_dev_nic(NICInfo *nic) { char fe[256], be[256]; diff --git a/hw/xenpv/xen_machine_pv.c b/hw/xenpv/xen_machine_pv.c index 17cda5ec13..1533f5dfb4 100644 --- a/hw/xenpv/xen_machine_pv.c +++ b/hw/xenpv/xen_machine_pv.c @@ -32,7 +32,6 @@ static void xen_init_pv(MachineState *machine) { - DriveInfo *dinfo; int i; setup_xen_backend_ops(); @@ -64,14 +63,6 @@ static void xen_init_pv(MachineState *machine) vga_interface_created = true; } - /* configure disks */ - for (i = 0; i < 16; i++) { - dinfo = drive_get(IF_XEN, 0, i); - if (!dinfo) - continue; - xen_config_dev_blk(dinfo); - } - /* configure nics */ for (i = 0; i < nb_nics; i++) { if (!nd_table[i].model || 0 != strcmp(nd_table[i].model, "xen")) diff --git a/include/hw/xen/xen-legacy-backend.h b/include/hw/xen/xen-legacy-backend.h index 6c307c5f2c..fc42146bc2 100644 --- a/include/hw/xen/xen-legacy-backend.h +++ b/include/hw/xen/xen-legacy-backend.h @@ -81,7 +81,6 @@ extern struct XenDevOps xen_usb_ops; /* xen-usb.c */ /* configuration (aka xenbus setup) */ void xen_config_cleanup(void); -int xen_config_dev_blk(DriveInfo *disk); int xen_config_dev_nic(NICInfo *nic); int xen_config_dev_vfb(int vdev, const char *type); int xen_config_dev_vkbd(int vdev); -- 2.39.2