[libvirt] [PATCH v2 0/2] default USB controller for PPC fix and API_UPDATE patch
Pavel Hrdina (2): qemu_migration: don't allow ABI changes for persistent migration qemu_domain: use correct default USB controller on ppc64 src/qemu/qemu_domain.c | 16 ++++++++++++---- src/qemu/qemu_migration.c | 1 - 2 files changed, 12 insertions(+), 5 deletions(-) -- 2.12.0
So far there is probably no change that is allowed to be done by the VIR_DOMAIN_DEF_PARSE_ABI_UPDATE flag that would break guest ABI but this may change in the future. The other cases where this flag is used is only when we are defining new domain or adding new device into a domain. Signed-off-by: Pavel Hrdina <phrdina@redhat.com> --- This patch is a product of a discussion about the last patch in v1 [1]. Currently we allow ABI changes for persistent migration however it might be something that user don't expect to be done. Technically it defines new domain on the destination which would fall into the same category as defining new domain from scratch without migration but it may be unexpected behavior because for live migration we don't allow ABI changes (for obvious reasons). At first I though that this is correct and we are doing the right thing, but now I'm not so sure about that and IMHO it would be probably better to not do ABI updates in this case like we don't do if libvirtd is restarted (for example because of an update) and also it would be consistent with the live migration. [1] <https://www.redhat.com/archives/libvir-list/2017-March/msg00057.html> src/qemu/qemu_migration.c | 1 - 1 file changed, 1 deletion(-) diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c index f5711bcf74..e45bb45670 100644 --- a/src/qemu/qemu_migration.c +++ b/src/qemu/qemu_migration.c @@ -1314,7 +1314,6 @@ qemuMigrationCookieXMLParse(qemuMigrationCookiePtr mig, mig->persistent = virDomainDefParseNode(doc, nodes[0], caps, driver->xmlopt, NULL, VIR_DOMAIN_DEF_PARSE_INACTIVE | - VIR_DOMAIN_DEF_PARSE_ABI_UPDATE | VIR_DOMAIN_DEF_PARSE_SKIP_VALIDATE); if (!mig->persistent) { /* virDomainDefParseNode already reported -- 2.12.0
On Tue, Mar 07, 2017 at 18:45:23 +0100, Pavel Hrdina wrote:
So far there is probably no change that is allowed to be done by the VIR_DOMAIN_DEF_PARSE_ABI_UPDATE flag that would break guest ABI but this may change in the future.
The other cases where this flag is used is only when we are defining new domain or adding new device into a domain.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com> ---
This patch is a product of a discussion about the last patch in v1 [1]. Currently we allow ABI changes for persistent migration however it might be something that user don't expect to be done.
Technically it defines new domain on the destination which would fall into the same category as defining new domain from scratch without migration but it may be unexpected behavior because for live migration we don't allow ABI changes (for obvious reasons).
At first I though that this is correct and we are doing the right thing, but now I'm not so sure about that and IMHO it would be probably better to not do ABI updates in this case like we don't do if libvirtd is restarted (for example because of an update) and also it would be consistent with the live migration.
This flag was invented so that libvirt could finally properly track the total memory size of the VM when NUMA is used. Prior to that the individual node sizes would not have to total up to the size declared in the <memory> element. While migrating a live VM we can't change this but other code expects that the size is correct. This patch would break this particular case. In general I'm not against a change, but the recalculation of the memory sizes should not be broken.
On Wed, 2017-03-08 at 09:22 +0100, Peter Krempa wrote:
So far there is probably no change that is allowed to be done by the VIR_DOMAIN_DEF_PARSE_ABI_UPDATE flag that would break guest ABI but this may change in the future. The other cases where this flag is used is only when we are defining new domain or adding new device into a domain. Signed-off-by: Pavel Hrdina <phrdina@redhat.com> --- This patch is a product of a discussion about the last patch in v1 [1]. Currently we allow ABI changes for persistent migration however it might be something that user don't expect to be done. Technically it defines new domain on the destination which would fall into the same category as defining new domain from scratch without migration but it may be unexpected behavior because for live migration we don't allow ABI changes (for obvious reasons). At first I though that this is correct and we are doing the right thing, but now I'm not so sure about that and IMHO it would be probably better to not do ABI updates in this case like we don't do if libvirtd is restarted (for example because of an update) and also it would be consistent with the live migration. This flag was invented so that libvirt could finally properly track the total memory size of the VM when NUMA is used. Prior to that the individual node sizes would not have to total up to the size declared in
On Tue, Mar 07, 2017 at 18:45:23 +0100, Pavel Hrdina wrote: the <memory> element. While migrating a live VM we can't change this but other code expects that the size is correct. This patch would break this particular case. In general I'm not against a change, but the recalculation of the memory sizes should not be broken.
I see. However, as it is now, we're granting blanket permission to update the guest ABI in whatever random way during a persistent migration, which at least to me feels like it's way too broad. Can we maybe introduce a less coarse-grained flag just for the memory update, and leave the broader ABI_UPDATE for cases such as defining an entirely new guest or attaching an entirely new device, eg. situations where any change we perform won't affect the existing guest? Or is it too late for that? -- Andrea Bolognani / Red Hat / Virtualization
The history of USB controller for ppc64 guest is complex and goes back to libvirt 1.3.1 where the fun started. Prior Libvirt 1.3.1 if no model for USB controller was specified we've simply passed "-usb" on QEMU command line. Since Libvirt 1.3.1 there is a patch (8156493d8db) that fixes this issue by using "-device pci-ohci,..." but it breaks migration with older Libvirts which was agreed that's acceptable. However this patch didn't reflect this change in the domain XML and the model was still missing. Since Libvirt 2.2.0 there is a patch (f55eaccb0c5) that fixes the issue with not setting the USB model into domain XML which we need to know about to not break the migration and since the default model was *pci-ohci* it was used as default in this patch as well. This patch tries to take all the previous changes into account and also change the default for newly defined domains that don't specify any model for USB controller. The VIR_DOMAIN_DEF_PARSE_ABI_UPDATE is set only if new domain is defined or new device is added into a domain which means that in all other cases we will use the old *pci-ohci* model instead of the better and not broken *nec-usb-xhci* model. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1373184 Signed-off-by: Pavel Hrdina <phrdina@redhat.com> --- No changes from v1, the current default pci-ohci is broken and if user don't care about the model we should default to nec-xhci. src/qemu/qemu_domain.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index 9be78bdbd4..12af0651a5 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -3012,7 +3012,8 @@ qemuDomainShmemDefPostParse(virDomainShmemDefPtr shm) static int qemuDomainControllerDefPostParse(virDomainControllerDefPtr cont, const virDomainDef *def, - virQEMUCapsPtr qemuCaps) + virQEMUCapsPtr qemuCaps, + unsigned int parseFlags) { switch ((virDomainControllerType)cont->type) { case VIR_DOMAIN_CONTROLLER_TYPE_SCSI: @@ -3040,9 +3041,16 @@ qemuDomainControllerDefPostParse(virDomainControllerDefPtr cont, * address is found */ cont->model = VIR_DOMAIN_CONTROLLER_MODEL_USB_NONE; } else if (ARCH_IS_PPC64(def->os.arch)) { - /* Default USB controller for ppc64 is pci-ohci */ - if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_PCI_OHCI)) + /* To not break migration we need to set default USB controller + * for ppc64 to pci-ohci if we cannot change ABI of the VM. + * The nec-usb-xhci controller is used as default only for + * newly defined domains or devices. */ + if ((parseFlags & VIR_DOMAIN_DEF_PARSE_ABI_UPDATE) && + virQEMUCapsGet(qemuCaps, QEMU_CAPS_NEC_USB_XHCI)) { + cont->model = VIR_DOMAIN_CONTROLLER_MODEL_USB_NEC_XHCI; + } else if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_PCI_OHCI)) { cont->model = VIR_DOMAIN_CONTROLLER_MODEL_USB_PCI_OHCI; + } } else { /* Default USB controller for anything else is piix3-uhci */ if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_PIIX3_USB_UHCI)) @@ -3241,7 +3249,7 @@ qemuDomainDeviceDefPostParse(virDomainDeviceDefPtr dev, if (dev->type == VIR_DOMAIN_DEVICE_CONTROLLER && qemuDomainControllerDefPostParse(dev->data.controller, def, - qemuCaps) < 0) + qemuCaps, parseFlags) < 0) goto cleanup; if (dev->type == VIR_DOMAIN_DEVICE_SHMEM && -- 2.12.0
participants (3)
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Andrea Bolognani -
Pavel Hrdina -
Peter Krempa