Re: [openstack-dev] [nova][pci-passthrough] definitely specify VFIO driver as the host PCI driver for passthrough
On 2016年06月24日 16:55, Daniel P. Berrange wrote: On Fri, Jun 24, 2016 at 04:52:31PM +0800, Chen Fan wrote: On 2016年06月24日 16:20, Daniel P. Berrange wrote: On Fri, Jun 24, 2016 at 12:27:57PM +0800, Chen Fan wrote: hi all, in openstack, we can use the pci passthrough feature now, refer to https://wiki.openstack.org/wiki/Pci_passthrough but we can't definitely specify the host pci driver is LEGACY_KVM or newer VFIO, new VFIO driver is more safer, and higher-performance user-space driver than legacy kvm driver (pci-stub), the benefit relative to kvm assignment driver could refer to http://lwn.net/Articles/474088/. In additional, VFIO driver provides the GPU passthrough as primary card support. I think it is more useful for further GPU passthrough support in openstack. Openstack relies on the libvirt nodedev device configuration to do pci passthrough, with managed mode, the configured device is automatically detached and re-attached with KVM or VFIO driver that depended on the host driver modules configuration, so now we can't specify the driver in openstack to VFIO mode, I think we should need to add this feature support in openstack to get pci passhthrough more scalability. a simply idea is to add a option in nova.conf HOST_PCI_MODEL = VFIO /KVM to specify the pci passthrough device driver is using VFIO driver. any comments are welcome. :) I don't see any reason to add a configuration option. If the host is capable of doing VFIO, libvirt will always aim to use VFIO in preference to the legacy system. Hi Daniel, sorry, I directly reference the implementation of nodedev in libvirt, in function virHostdevPreparePCIDevices : 257 if (pcisrc->backend == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO) 258 virPCIDeviceSetStubDriver(pci, VIR_PCI_STUB_DRIVER_VFIO); 259 else if (pcisrc->backend == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_XEN) 260 virPCIDeviceSetStubDriver(pci, VIR_PCI_STUB_DRIVER_XEN); 261 else 262 virPCIDeviceSetStubDriver(pci, VIR_PCI_STUB_DRIVER_KVM); IIUC, the stub driver should be "legacy KVM", do we need to change the stub drvier to VIR_PCI_STUB_DRIVER_VFIO by default. If libvirt uses VFIO, then it'll use the VFIO stub driver, which is fine. Thanks for you kind explanation, I have reread //the code about the implementation of pci driver backend in libvirt, you are right, by default the backend driver is VFIO. Thanks, Chen Regards, Daniel -- Sincerely, Chen Fan __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
Re: [openstack-dev] [nova][pci-passthrough] definitely specify VFIO driver as the host PCI driver for passthrough
On Fri, Jun 24, 2016 at 04:52:31PM +0800, Chen Fan wrote: > > > On 2016年06月24日 16:20, Daniel P. Berrange wrote: > > On Fri, Jun 24, 2016 at 12:27:57PM +0800, Chen Fan wrote: > > > hi all, > > > in openstack, we can use the pci passthrough feature now, refer to > > > https://wiki.openstack.org/wiki/Pci_passthrough > > > but we can't definitely specify the host pci driver is LEGACY_KVM or > > > newer VFIO, > > > new VFIO driver is more safer, and higher-performance user-space > > > driver > > > than legacy kvm driver (pci-stub), the benefit relative to kvm > > > assignment driver > > > could refer to http://lwn.net/Articles/474088/. > > > In additional, VFIO driver provides the GPU passthrough as primary > > > card > > > support. > > > I think it is more useful for further GPU passthrough support in > > > openstack. > > > > > > Openstack relies on the libvirt nodedev device configuration to do > > > pci > > > passthrough, > > > with managed mode, the configured device is automatically detached > > > and > > > re-attached > > > with KVM or VFIO driver that depended on the host driver modules > > > configuration, > > > so now we can't specify the driver in openstack to VFIO mode, I > > > think > > > we should need > > > to add this feature support in openstack to get pci passhthrough > > > more > > > scalability. > > > > > > a simply idea is to add a option in nova.conf HOST_PCI_MODEL = VFIO > > > /KVM to specify > > > the pci passthrough device driver is using VFIO driver. > > > any comments are welcome. :) > > I don't see any reason to add a configuration option. If the host is > > capable of doing VFIO, libvirt will always aim to use VFIO in preference > > to the legacy system. > Hi Daniel, > > sorry, I directly reference the implementation of nodedev in libvirt, in > function > virHostdevPreparePCIDevices : > 257 if (pcisrc->backend == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO) > 258 virPCIDeviceSetStubDriver(pci, VIR_PCI_STUB_DRIVER_VFIO); > 259 else if (pcisrc->backend == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_XEN) > 260 virPCIDeviceSetStubDriver(pci, VIR_PCI_STUB_DRIVER_XEN); > 261 else > 262 virPCIDeviceSetStubDriver(pci, VIR_PCI_STUB_DRIVER_KVM); > > IIUC, the stub driver should be "legacy KVM", do we need to change the stub > drvier > to VIR_PCI_STUB_DRIVER_VFIO by default. If libvirt uses VFIO, then it'll use the VFIO stub driver, which is fine. Regards, Daniel -- |: http://berrange.com -o-http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
Re: [openstack-dev] [nova][pci-passthrough] definitely specify VFIO driver as the host PCI driver for passthrough
On 2016年06月24日 16:20, Daniel P. Berrange wrote: On Fri, Jun 24, 2016 at 12:27:57PM +0800, Chen Fan wrote: hi all, in openstack, we can use the pci passthrough feature now, refer to https://wiki.openstack.org/wiki/Pci_passthrough but we can't definitely specify the host pci driver is LEGACY_KVM or newer VFIO, new VFIO driver is more safer, and higher-performance user-space driver than legacy kvm driver (pci-stub), the benefit relative to kvm assignment driver could refer to http://lwn.net/Articles/474088/. In additional, VFIO driver provides the GPU passthrough as primary card support. I think it is more useful for further GPU passthrough support in openstack. Openstack relies on the libvirt nodedev device configuration to do pci passthrough, with managed mode, the configured device is automatically detached and re-attached with KVM or VFIO driver that depended on the host driver modules configuration, so now we can't specify the driver in openstack to VFIO mode, I think we should need to add this feature support in openstack to get pci passhthrough more scalability. a simply idea is to add a option in nova.conf HOST_PCI_MODEL = VFIO /KVM to specify the pci passthrough device driver is using VFIO driver. any comments are welcome. :) I don't see any reason to add a configuration option. If the host is capable of doing VFIO, libvirt will always aim to use VFIO in preference to the legacy system. Hi Daniel, sorry, I directly reference the implementation of nodedev in libvirt, in function virHostdevPreparePCIDevices : 257 if (pcisrc->backend == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO) 258 virPCIDeviceSetStubDriver(pci, VIR_PCI_STUB_DRIVER_VFIO); 259 else if (pcisrc->backend == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_XEN) 260 virPCIDeviceSetStubDriver(pci, VIR_PCI_STUB_DRIVER_XEN); 261 else 262 virPCIDeviceSetStubDriver(pci, VIR_PCI_STUB_DRIVER_KVM); IIUC, the stub driver should be "legacy KVM", do we need to change the stub drvier to VIR_PCI_STUB_DRIVER_VFIO by default. Thanks, Chen Regards, Daniel -- Sincerely, Chen Fan __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
Re: [openstack-dev] [nova][pci-passthrough] definitely specify VFIO driver as the host PCI driver for passthrough
On Fri, Jun 24, 2016 at 12:27:57PM +0800, Chen Fan wrote: > hi all, > in openstack, we can use the pci passthrough feature now, refer to > https://wiki.openstack.org/wiki/Pci_passthrough > but we can't definitely specify the host pci driver is LEGACY_KVM or > newer VFIO, > new VFIO driver is more safer, and higher-performance user-space driver > than legacy kvm driver (pci-stub), the benefit relative to kvm > assignment driver > could refer to http://lwn.net/Articles/474088/. > In additional, VFIO driver provides the GPU passthrough as primary card > support. > I think it is more useful for further GPU passthrough support in > openstack. > > Openstack relies on the libvirt nodedev device configuration to do pci > passthrough, > with managed mode, the configured device is automatically detached and > re-attached > with KVM or VFIO driver that depended on the host driver modules > configuration, > so now we can't specify the driver in openstack to VFIO mode, I think > we should need > to add this feature support in openstack to get pci passhthrough more > scalability. > > a simply idea is to add a option in nova.conf HOST_PCI_MODEL = VFIO > /KVM to specify > the pci passthrough device driver is using VFIO driver. > any comments are welcome. :) I don't see any reason to add a configuration option. If the host is capable of doing VFIO, libvirt will always aim to use VFIO in preference to the legacy system. Regards, Daniel -- |: http://berrange.com -o-http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
[openstack-dev] [nova][pci-passthrough] definitely specify VFIO driver as the host PCI driver for passthrough
hi all, in openstack, we can use the pci passthrough feature now, refer to https://wiki.openstack.org/wiki/Pci_passthrough but we can't definitely specify the host pci driver is LEGACY_KVM or newer VFIO, new VFIO driver is more safer, and higher-performance user-space driver than legacy kvm driver (pci-stub), the benefit relative to kvm assignment driver could refer to http://lwn.net/Articles/474088/. In additional, VFIO driver provides the GPU passthrough as primary card support. I think it is more useful for further GPU passthrough support in openstack. Openstack relies on the libvirt nodedev device configuration to do pci passthrough, with managed mode, the configured device is automatically detached and re-attached with KVM or VFIO driver that depended on the host driver modules configuration, so now we can't specify the driver in openstack to VFIO mode, I think we should need to add this feature support in openstack to get pci passhthrough more scalability. a simply idea is to add a option in nova.conf HOST_PCI_MODEL = VFIO /KVM to specify the pci passthrough device driver is using VFIO driver. any comments are welcome. :) Thanks, Chen -- Sincerely, Chen Fan __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
