@@ -104,7 +104,7 @@ static void emulated_ccw_3270_realize(DeviceState *ds, Error **errp)
SubchDev *sch;
Error *err = NULL;
- sch = css_create_sch(cdev->devno, true, cbus->squash_mcss, errp);
+ sch = css_create_sch(cdev->devno, cbus->squash_mcss, errp);
if (!sch) {
return;
}
@@ -123,6 +123,11 @@ static Property virtual_css_bridge_properties[] = {
DEFINE_PROP_END_OF_LIST(),
};
+static bool prop_get_true(Object *obj, Error **errp)
+{
+ return true;
+}
+
static void virtual_css_bridge_class_init(ObjectClass *klass, void *data)
{
HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(klass);
@@ -131,6 +136,12 @@ static void virtual_css_bridge_class_init(ObjectClass *klass, void *data)
hc->unplug = ccw_device_unplug;
set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
dc->props = virtual_css_bridge_properties;
+ object_class_property_add_bool(klass, "cssid-unrestricted",
+ prop_get_true, NULL, NULL);
+ object_class_property_set_description(klass, "cssid-unrestricted",
+ "A css device can use any cssid, regardless whether virtual"
+ " or not (read only, always true)",
+ NULL);
}
static const TypeInfo virtual_css_bridge_info = {
@@ -2370,22 +2370,12 @@ const PropertyInfo css_devid_ro_propinfo = {
.get = get_css_devid,
};
-SubchDev *css_create_sch(CssDevId bus_id, bool is_virtual, bool squash_mcss,
- Error **errp)
+SubchDev *css_create_sch(CssDevId bus_id, bool squash_mcss, Error **errp)
{
uint16_t schid = 0;
SubchDev *sch;
if (bus_id.valid) {
- if (is_virtual != (bus_id.cssid == VIRTUAL_CSSID)) {
- error_setg(errp, "cssid %hhx not valid for %s devices",
- bus_id.cssid,
- (is_virtual ? "virtual" : "non-virtual"));
- return NULL;
- }
- }
-
- if (bus_id.valid) {
if (squash_mcss) {
bus_id.cssid = channel_subsys.default_cssid;
} else if (!channel_subsys.css[bus_id.cssid]) {
@@ -2396,19 +2386,8 @@ SubchDev *css_create_sch(CssDevId bus_id, bool is_virtual, bool squash_mcss,
bus_id.devid, &schid, errp)) {
return NULL;
}
- } else if (squash_mcss || is_virtual) {
- bus_id.cssid = channel_subsys.default_cssid;
-
- if (!css_find_free_subch_and_devno(bus_id.cssid, &bus_id.ssid,
- &bus_id.devid, &schid, errp)) {
- return NULL;
- }
} else {
- for (bus_id.cssid = 0; bus_id.cssid < MAX_CSSID; ++bus_id.cssid) {
- if (bus_id.cssid == VIRTUAL_CSSID) {
- continue;
- }
-
+ for (bus_id.cssid = channel_subsys.default_cssid;;) {
if (!channel_subsys.css[bus_id.cssid]) {
css_create_css_image(bus_id.cssid, false);
}
@@ -2418,7 +2397,8 @@ SubchDev *css_create_sch(CssDevId bus_id, bool is_virtual, bool squash_mcss,
NULL)) {
break;
}
- if (bus_id.cssid == MAX_CSSID) {
+ bus_id.cssid = (bus_id.cssid + 1) % MAX_CSSID;
+ if (bus_id.cssid == channel_subsys.default_cssid) {
error_setg(errp, "Virtual channel subsystem is full!");
return NULL;
}
@@ -77,7 +77,7 @@ static void s390_ccw_realize(S390CCWDevice *cdev, char *sysfsdev, Error **errp)
goto out_err_propagate;
}
- sch = css_create_sch(ccw_dev->devno, false, cbus->squash_mcss, &err);
+ sch = css_create_sch(ccw_dev->devno, cbus->squash_mcss, &err);
if (!sch) {
goto out_mdevid_free;
}
@@ -302,7 +302,6 @@ static void ccw_init(MachineState *machine)
/*
* Non mcss-e enabled guests only see the devices from the default
* css, which is determined by the value of the squash_mcss property.
- * Note: we must not squash non virtual devices to css 0xFE.
*/
if (css_bus->squash_mcss) {
ret = css_create_css_image(0, true);
@@ -701,7 +701,7 @@ static void virtio_ccw_device_realize(VirtioCcwDevice *dev, Error **errp)
SubchDev *sch;
Error *err = NULL;
- sch = css_create_sch(ccw_dev->devno, true, cbus->squash_mcss, errp);
+ sch = css_create_sch(ccw_dev->devno, cbus->squash_mcss, errp);
if (!sch) {
return;
}
@@ -272,12 +272,9 @@ extern const PropertyInfo css_devid_ro_propinfo;
* default css image for it.
* If @p bus_id is valid, and @p squash_mcss is false, verify that it is
* not already in use, and find a free devno for it.
- * If @p bus_id is not valid, and if either @p squash_mcss or @p is_virtual
- * is true, find a free subchannel id and device number across all
- * subchannel sets from the default css image.
- * If @p bus_id is not valid, and if both @p squash_mcss and @p is_virtual
- * are false, find a non-full css image and find a free subchannel id and
- * device number across all subchannel sets from it.
+ * If @p bus_id is not valid find a free subchannel id and device number
+ * across all subchannel sets and all css images starting from the default
+ * css image.
*
* If either of the former actions succeed, allocate a subchannel structure,
* initialise it with the bus id, subchannel id and device number, register
@@ -286,8 +283,7 @@ extern const PropertyInfo css_devid_ro_propinfo;
* The caller becomes owner of the returned subchannel structure and
* is responsible for unregistering and freeing it.
*/
-SubchDev *css_create_sch(CssDevId bus_id, bool is_virtual, bool squash_mcss,
- Error **errp);
+SubchDev *css_create_sch(CssDevId bus_id, bool squash_mcss, Error **errp);
/** Turn on css migration */
void css_register_vmstate(void);
The default css 0xfe is currently restricted to virtual subchannel devices. The hope when the decision was made was, that non-virtual subchannel devices will come around when guest can exploit multiple channel subsystems. Since the guests generally don't do, the pain of the partitioned (cssid) namespace outweighs the gain. Let us remove the corresponding restrictions (virtual devices can be put only in 0xfe and non-virtual devices in any css except the 0xfe -- while s390-squash-mcss then remaps everything to cssid 0). At the same time, change our schema for generating css bus ids to put both virtual and non-virtual devices into the default css (spilling over into other css images, if needed). The intention is to deprecate s390-squash-mcss. With this change devices without a specified devno won't end up hidden to guests not supporting multiple channel subsystems, unless this can not be avoided (default css full). Let us also advertise the changes to the management software (so it can tell are cssids unrestricted or restricted). The adverse effect of getting rid of the restriction on migration should not be too severe. Vfio-ccw devices are not live-migratable yet, and for virtual devices using the extra freedom would only make sense with the aforementioned guest support in place. The auto-generated bus ids are affected by both changes. We hope to not encounter any auto-generated bus ids in production as Libvirt is always explicit about the bus id. Since 8ed179c937 ("s390x/css: catch section mismatch on load", 2017-05-18) the worst that can happen because the same device ended up having a different bus id is a cleanly failed migration. I find it hard to reason about the impact of changed auto-generated bus ids on migration for command line users as I don't know which rules is such an user supposed to follow. Another pain-point is down- or upgrade of QEMU for command line users. The old way and the new way of doing vfio-ccw are mutually incompatible. Libvirt is only going to support the new way, so for libvirt users, the possible problems at QEMU downgrade are the following. If a domain contains virtual devices placed into a css different than 0xfe the domain will refuse to start with a QEMU not having this patch. Putting devices into a css different that 0xfe however won't make much sense in the near future (guest support). Libvirt will refuse to do vfio-ccw with a QEMU not having this patch. This is business as usual. Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com> --- hw/s390x/3270-ccw.c | 2 +- hw/s390x/css-bridge.c | 11 +++++++++++ hw/s390x/css.c | 28 ++++------------------------ hw/s390x/s390-ccw.c | 2 +- hw/s390x/s390-virtio-ccw.c | 1 - hw/s390x/virtio-ccw.c | 2 +- include/hw/s390x/css.h | 12 ++++-------- 7 files changed, 22 insertions(+), 36 deletions(-)