[libvirt-users] multiple devices in the same iommu group in L1 guest
Hi, I have a guest enabled vIOMMU, but on the guest there are several devices in the same iommu group. Could someone help to check if I missed something? Thank you very much! 1. guest xml: # virsh edit q ... <os> <type arch='x86_64' machine='pc-q35-rhel7.5.0'>hvm</type> <loader readonly='yes' secure='yes' type='pflash'>/usr/share/OVMF/OVMF_CODE.secboot.fd</loader> <nvram>/var/lib/libvirt/qemu/nvram/q_VARS.fd</nvram> </os> ... <features> ... <ioapic driver='qemu'/> </features> <cpu mode='host-passthrough' check='none'> <feature policy='require' name='vmx'/> </cpu> ... <devices> ... <controller type='pci' index='7' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='7' port='0x15'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x5'/> </controller> <interface type='network'> <mac address='52:54:00:b9:ff:90'/> <source network='default'/> <model type='e1000'/> <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/> </interface> <iommu model='intel'> <driver intremap='on' caching_mode='on' iotlb='on'/> </iommu> </devices> ... 2. guest has 'intel_iommu=on' enabled in kernel cmdline, then reboot guest 3. log in guest to check: # dmesg | grep -i DMAR [ 0.000000] ACPI: DMAR 000000007d83f000 00050 (v01 BOCHS BXPCDMAR 00000001 BXPC 00000001) [ 0.000000] DMAR: IOMMU enabled [ 0.155178] DMAR: Host address width 39 [ 0.155180] DMAR: DRHD base: 0x000000fed90000 flags: 0x1 [ 0.155221] DMAR: dmar0: reg_base_addr fed90000 ver 1:0 cap 12008c22260286 ecap f00f5e [ 0.155228] DMAR: ATSR flags: 0x1 [ 0.155231] DMAR-IR: IOAPIC id 0 under DRHD base 0xfed90000 IOMMU 0 [ 0.155232] DMAR-IR: Queued invalidation will be enabled to support x2apic and Intr-remapping. [ 0.156843] DMAR-IR: Enabled IRQ remapping in x2apic mode [ 2.112369] DMAR: No RMRR found [ 2.112505] DMAR: dmar0: Using Queued invalidation [ 2.112669] DMAR: Setting RMRR: [ 2.112671] DMAR: Prepare 0-16MiB unity mapping for LPC [ 2.112820] DMAR: Setting identity map for device 0000:00:1f.0 [0x0 - 0xffffff] [ 2.211577] DMAR: Intel(R) Virtualization Technology for Directed I/O ===> This is expected # dmesg | grep -i iommu |grep device [ 2.212267] iommu: Adding device 0000:00:00.0 to group 0 [ 2.212287] iommu: Adding device 0000:00:01.0 to group 1 [ 2.212372] iommu: Adding device 0000:00:02.0 to group 2 [ 2.212392] iommu: Adding device 0000:00:02.1 to group 2 [ 2.212411] iommu: Adding device 0000:00:02.2 to group 2 [ 2.212444] iommu: Adding device 0000:00:02.3 to group 2 [ 2.212464] iommu: Adding device 0000:00:02.4 to group 2 [ 2.212482] iommu: Adding device 0000:00:02.5 to group 2 [ 2.212520] iommu: Adding device 0000:00:1d.0 to group 3 [ 2.212533] iommu: Adding device 0000:00:1d.1 to group 3 [ 2.212541] iommu: Adding device 0000:00:1d.2 to group 3 [ 2.212550] iommu: Adding device 0000:00:1d.7 to group 3 [ 2.212567] iommu: Adding device 0000:00:1f.0 to group 4 [ 2.212576] iommu: Adding device 0000:00:1f.2 to group 4 [ 2.212585] iommu: Adding device 0000:00:1f.3 to group 4 [ 2.212599] iommu: Adding device 0000:01:00.0 to group 2 [ 2.212605] iommu: Adding device 0000:02:01.0 to group 2 [ 2.212621] iommu: Adding device 0000:04:00.0 to group 2 [ 2.212634] iommu: Adding device 0000:05:00.0 to group 2 [ 2.212646] iommu: Adding device 0000:06:00.0 to group 2 [ 2.212657] iommu: Adding device 0000:07:00.0 to group 2 ====> several devices in the same iommu group # virsh nodedev-dumpxml pci_0000_07_00_0 <device> <name>pci_0000_07_00_0</name> <path>/sys/devices/pci0000:00/0000:00:02.5/0000:07:00.0</path> <parent>pci_0000_00_02_5</parent> <driver> <name>e1000</name> </driver> <capability type='pci'> <domain>0</domain> <bus>7</bus> <slot>0</slot> <function>0</function> <product id='0x100e'>82540EM Gigabit Ethernet Controller</product> <vendor id='0x8086'>Intel Corporation</vendor> <iommuGroup number='2'> <address domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> <address domain='0x0000' bus='0x00' slot='0x02' function='0x1'/> <address domain='0x0000' bus='0x00' slot='0x02' function='0x2'/> <address domain='0x0000' bus='0x00' slot='0x02' function='0x3'/> <address domain='0x0000' bus='0x00' slot='0x02' function='0x4'/> <address domain='0x0000' bus='0x00' slot='0x02' function='0x5'/> <address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/> <address domain='0x0000' bus='0x02' slot='0x01' function='0x0'/> <address domain='0x0000' bus='0x04' slot='0x00' function='0x0'/> <address domain='0x0000' bus='0x05' slot='0x00' function='0x0'/> <address domain='0x0000' bus='0x06' slot='0x00' function='0x0'/> <address domain='0x0000' bus='0x07' slot='0x00' function='0x0'/> </iommuGroup> </capability> </device> Thus, can not attach the device to L2 guest: # cat hostdev.xml <hostdev mode='subsystem' type='pci' managed='yes'> <source> <address domain='0x0000' bus='0x07' slot='0x00' function='0x0'/> </source> </hostdev> # virsh attach-device rhel hostdev.xml error: Failed to attach device from hostdev.xml error: internal error: unable to execute QEMU command 'device_add': vfio error: 0000:07:00.0: group 2 is not viable ------- Best Regards, Yalan Zhang IRC: yalzhang Internal phone: 8389413
On 07/03/2018 09:37 AM, Yalan Zhang wrote:
Hi,
I have a guest enabled vIOMMU, but on the guest there are several devices in the same iommu group. Could someone help to check if I missed something? Thank you very much!
1. guest xml: # virsh edit q ... <os> <type arch='x86_64' machine='pc-q35-rhel7.5.0'>hvm</type> <loader readonly='yes' secure='yes' type='pflash'>/usr/share/OVMF/OVMF_CODE.secboot.fd</loader> <nvram>/var/lib/libvirt/qemu/nvram/q_VARS.fd</nvram> </os> ... <features> ... <ioapic driver='qemu'/> </features> <cpu mode='host-passthrough' check='none'> <feature policy='require' name='vmx'/> </cpu> ... <devices> ... <controller type='pci' index='7' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='7' port='0x15'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x5'/> </controller> <interface type='network'> <mac address='52:54:00:b9:ff:90'/> <source network='default'/> <model type='e1000'/> <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/> </interface> <iommu model='intel'> <driver intremap='on' caching_mode='on' iotlb='on'/> </iommu> </devices> ... 2. guest has 'intel_iommu=on' enabled in kernel cmdline, then reboot guest
3. log in guest to check: # dmesg | grep -i DMAR [ 0.000000] ACPI: DMAR 000000007d83f000 00050 (v01 BOCHS BXPCDMAR 00000001 BXPC 00000001) [ 0.000000] DMAR: IOMMU enabled [ 0.155178] DMAR: Host address width 39 [ 0.155180] DMAR: DRHD base: 0x000000fed90000 flags: 0x1 [ 0.155221] DMAR: dmar0: reg_base_addr fed90000 ver 1:0 cap 12008c22260286 ecap f00f5e [ 0.155228] DMAR: ATSR flags: 0x1 [ 0.155231] DMAR-IR: IOAPIC id 0 under DRHD base 0xfed90000 IOMMU 0 [ 0.155232] DMAR-IR: Queued invalidation will be enabled to support x2apic and Intr-remapping. [ 0.156843] DMAR-IR: Enabled IRQ remapping in x2apic mode [ 2.112369] DMAR: No RMRR found [ 2.112505] DMAR: dmar0: Using Queued invalidation [ 2.112669] DMAR: Setting RMRR: [ 2.112671] DMAR: Prepare 0-16MiB unity mapping for LPC [ 2.112820] DMAR: Setting identity map for device 0000:00:1f.0 [0x0 - 0xffffff] [ 2.211577] DMAR: Intel(R) Virtualization Technology for Directed I/O ===> This is expected
# dmesg | grep -i iommu |grep device [ 2.212267] iommu: Adding device 0000:00:00.0 to group 0 [ 2.212287] iommu: Adding device 0000:00:01.0 to group 1 [ 2.212372] iommu: Adding device 0000:00:02.0 to group 2 [ 2.212392] iommu: Adding device 0000:00:02.1 to group 2 [ 2.212411] iommu: Adding device 0000:00:02.2 to group 2 [ 2.212444] iommu: Adding device 0000:00:02.3 to group 2 [ 2.212464] iommu: Adding device 0000:00:02.4 to group 2 [ 2.212482] iommu: Adding device 0000:00:02.5 to group 2 [ 2.212520] iommu: Adding device 0000:00:1d.0 to group 3 [ 2.212533] iommu: Adding device 0000:00:1d.1 to group 3 [ 2.212541] iommu: Adding device 0000:00:1d.2 to group 3 [ 2.212550] iommu: Adding device 0000:00:1d.7 to group 3 [ 2.212567] iommu: Adding device 0000:00:1f.0 to group 4 [ 2.212576] iommu: Adding device 0000:00:1f.2 to group 4 [ 2.212585] iommu: Adding device 0000:00:1f.3 to group 4 [ 2.212599] iommu: Adding device 0000:01:00.0 to group 2 [ 2.212605] iommu: Adding device 0000:02:01.0 to group 2 [ 2.212621] iommu: Adding device 0000:04:00.0 to group 2 [ 2.212634] iommu: Adding device 0000:05:00.0 to group 2 [ 2.212646] iommu: Adding device 0000:06:00.0 to group 2 [ 2.212657] iommu: Adding device 0000:07:00.0 to group 2 ====> several devices in the same iommu group
# virsh nodedev-dumpxml pci_0000_07_00_0 <device> <name>pci_0000_07_00_0</name> <path>/sys/devices/pci0000:00/0000:00:02.5/0000:07:00.0</path> <parent>pci_0000_00_02_5</parent> <driver> <name>e1000</name> </driver> <capability type='pci'> <domain>0</domain> <bus>7</bus> <slot>0</slot> <function>0</function> <product id='0x100e'>82540EM Gigabit Ethernet Controller</product> <vendor id='0x8086'>Intel Corporation</vendor> <iommuGroup number='2'> <address domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> <address domain='0x0000' bus='0x00' slot='0x02' function='0x1'/> <address domain='0x0000' bus='0x00' slot='0x02' function='0x2'/> <address domain='0x0000' bus='0x00' slot='0x02' function='0x3'/> <address domain='0x0000' bus='0x00' slot='0x02' function='0x4'/> <address domain='0x0000' bus='0x00' slot='0x02' function='0x5'/> <address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/> <address domain='0x0000' bus='0x02' slot='0x01' function='0x0'/> <address domain='0x0000' bus='0x04' slot='0x00' function='0x0'/> <address domain='0x0000' bus='0x05' slot='0x00' function='0x0'/> <address domain='0x0000' bus='0x06' slot='0x00' function='0x0'/> <address domain='0x0000' bus='0x07' slot='0x00' function='0x0'/> </iommuGroup>
All devices plugged into the same slot on pcie-root are in the same iommu group, and all devices are in the same iommu group as the pcie-root-port they are plugged into. Since libvirt groups 8 pcie-root-ports onto a single pcie-root slot (to conserve the relatively limited number of slots), all the devices plugged into those 8 pcie-root-ports are in the same iommu group. This can be solved by putting the pcie-root-ports *of the devices you want to assign to L2 guests* onto pcie-root slots by themselves, i.e. instead of addressing it at 00:02.5, address it at 00:10.0 (and don't put any other pcie-root-ports at 00:10.x). I had thought there was an open BZ about this, but can't find one anywhere. At first glance it would seem that, since the pcie-root-ports and iommu controller are all emulated devices, it would be simple to just report all the pcie-root-ports as being on different iommu groups regardless of their placement on pcie-root, but I believe when this was brought up doubt was expressed over whether or not qemu truly can guarantee that the devices are fully isolated from each other.
</capability> </device>
Thus, can not attach the device to L2 guest: # cat hostdev.xml <hostdev mode='subsystem' type='pci' managed='yes'> <source> <address domain='0x0000' bus='0x07' slot='0x00' function='0x0'/> </source> </hostdev> # virsh attach-device rhel hostdev.xml error: Failed to attach device from hostdev.xml error: internal error: unable to execute QEMU command 'device_add': vfio error: 0000:07:00.0: group 2 is not viable
------- Best Regards, Yalan Zhang IRC: yalzhang Internal phone: 8389413
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