Thanks for info
See inline
On Wed, Nov 28, 2018 at 8:56 PM Alex Williamson <alex.william...@redhat.com>
wrote:
> On Wed, 28 Nov 2018 20:21:02 +0530
> gokul cg <gokulj...@gmail.com> wrote:
>
> > Hi Folks,
> >
> > Please excuse me , I just writing to you as i could see you had made
> > changes regarding iommu and I thought you could give help me here.
> >
> > We are testing visualization with QEMU-2.7.0 + Linux-4.8+, we are facing
> > issue while configuring pass through PCI devices in QEMU to pass it to
> > guest OS.
> > We are using following QEMU argument to configure PCI device as
> passthrough
> > device to guest, which was working with Linux 3.10 distro (hypervisor:
> QEMU
> > 1.7.2, Linux: 3.10+).
> >
> > /usr/bin/qemu-system-x86_64 -name guest_1 -S -machine
> > pc-i440fx-1.7,accel=kvm,usb=off -m 49152 \
> > -device kvm-pci-assign,host=0000:00:1f.3 -device
> > kvm-pci-assign,host=0000:09:0e.0 ..<etc..>
>
> Legacy KVM device assignment (aka kvm-pci-assign) has been deprecated
> for some time now, you'll find it doesn't even exist in newer kernels
> and QEMU.
>
> Understood .
> > Here is the error message that we will get when we try to configure PCI
> > devices as passthrough using kvm pci assignment method in Linux 4.8+
> > (hypervisor: QEMU 2.7.0, Linux: 4.8+).
> >
> > which is shown below.
> >
> > ---log---
> >
> > From QEMU:
> > qemu-system-x86_64: -device kvm-pci-assign,host=0000:00:1f.3: Failed to
> > assign device "(null)": Invalid argument
> >
> > From dmesg:
> > pci-stub 0000:00:1f.3: kvm assign device failed ret -22
> >
> > ---end----
> >
> > Info about devices (CPU: Intel(R) Xeon(R) CPU E5-2608L):
> >
> > root@shining-node:~# lspci -k -s 00:1f.3
> > 00:1f.3 SMBus: Intel Corporation C610/X99 series chipset SMBus Controller
> > (rev 05)
> > Subsystem: Intel Corporation C610/X99 series chipset SMBus
> > Controller
> > Kernel driver in use: pci-stub
> > Kernel modules: i2c_i801
>
> Why are you trying to assign an SMBus controller to a VM?
>
> We want guest of to read out eprom and sensor devices and manage our
chassis .
Our i2c devices are connected to Intel SMbus controller
> root@shining-node:~#
> > root@shining-node:~# lspci -k -s 09:0e.0
> > 09:0e.0 Network controller: Broadcom Limited Device b680 (rev 12)
> > root@shining-node:~#
> >
> > From the web search i could see that it is because there are multiple
> > devices in same iommu_group that the passthrough device belongs to.
> > When i check iommu_group , i have multiple devices in same group but all
> > those are intel devices under Wellsburg PCH.
>
> Nope, kvm-pci-assign doesn't make use of IOMMU groups, more likely just
> some state of disrepair as it's deprecated and replaced by vfio-pci,
> which does use iommu groups. So iommu groups will be a problem, but
> not in the configuration you're attempting to use above.
>
> The error i had pasted above "< pci-stub 0000:00:1f.3: kvm assign device
failed ret -22 >" is comming as iommu attach device
fails because of following check .
1094 int iommu_attach_device(struct iommu_domain *domain, struct device
*dev)
1095 {
1096 struct iommu_group *group;
1097 int ret;
1098
1099 group = iommu_group_get(dev);
1100 /* FIXME: Remove this when groups a mandatory for iommu
drivers */
1101 if (group == NULL)
1102 return __iommu_attach_device(domain, dev);
1103
> > root@shining-node:~# ls
> > /sys/bus/pci/devices/0000\:00\:1f.3/iommu_group/devices/
> > 0000:00:1f.0 0000:00:1f.2 0000:00:1f.3 0000:00:1f.6
> > root@shining-node:~#
> > root@shining-node:~# lspci -v -s 0000:00:1f
> > 00:1f.0 ISA bridge: Intel Corporation C610/X99 series chipset LPC
> > Controller (rev 05)
> > Subsystem: Intel Corporation C610/X99 series chipset LPC Controller
> > Flags: bus master, medium devsel, latency 0, NUMA node 0
> > Capabilities: [e0] Vendor Specific Information: Len=0c <?>
> > Kernel driver in use: lpc_ich
> > Kernel modules: lpc_ich
> >
> > 00:1f.2 SATA controller: Intel Corporation C610/X99 series chipset 6-Port
> > SATA Controller [AHCI mode] (rev 05) (prog-if 01 [AHCI 1.0])
> > Subsystem: Intel Corporation C610/X99 series chipset 6-Port SATA
> Controller
> > [AHCI mode]
> > Flags: bus master, 66MHz, medium devsel, latency 0, IRQ 35, NUMA node 0
> > I/O ports at 3068 [size=8]
> > I/O ports at 3074 [size=4]
> > I/O ports at 3060 [size=8]
> > I/O ports at 3070 [size=4]
> > I/O ports at 3020 [size=32]
> > Memory at 91d20000 (32-bit, non-prefetchable) [size=2K]
> > Capabilities: [80] MSI: Enable+ Count=1/1 Maskable- 64bit-
> > Capabilities: [70] Power Management version 3
> > Capabilities: [a8] SATA HBA v1.0
> > Kernel driver in use: ahci
> >
> > 00:1f.3 SMBus: Intel Corporation C610/X99 series chipset SMBus Controller
> > (rev 05)
> > Subsystem: Intel Corporation C610/X99 series chipset SMBus Controller
> > Flags: medium devsel, IRQ 18, NUMA node 0
> > Memory at 180000600000 (64-bit, non-prefetchable) [size=4K]
> > I/O ports at 3000 [size=32]
> > Kernel driver in use: pci-stub
> > Kernel modules: i2c_i801
> >
> > 00:1f.6 Signal processing controller: Intel Corporation C610/X99 series
> > chipset Thermal Subsystem (rev 05)
> > Subsystem: Intel Corporation C610/X99 series chipset Thermal Subsystem
> > Flags: bus master, fast devsel, latency 0, IRQ 255, NUMA node 0
> > Memory at 183fc0010000 (64-bit, non-prefetchable) [size=4K]
> > Capabilities: [50] Power Management version 3
> > Capabilities: [80] MSI: Enable- Count=1/1 Maskable- 64bit-
>
> Again I have to ask, why are these things you'd want to pass to a VM?
> The SATA controller is the only reasonable thing to assign here, but
> can easily be replaced by a plugin card with proper isolation or the
> performance can be nearly matched with virtio devices. These devices
> do not provide isolation between them therefore the assignment group is
> the full set of devices within the iommu group.
>
> This is our POC with one of our guest will have access to our sensor
devices . So need to do this .
> root@shining-node:~#
> >
> >
> > I have tried ACS override patch to rearrange these devices to different
> > iommu_group and its not working for these devices.I have tried to
> > passthrough vfio method, vfio complains that it needs all driver to be
> vfio
> > compatible.
> >
> > How can we achieve pci passthrough for Intel SMBus Controller [00:1f.3
> > here] with latest kernel(We use 4.8+ now)
>
> The only theoretically supported mechanism would be to assign all of
> the devices in the group to the VM, but you're putting the host system
> at risk by assigning system management controllers to a VM.
We don't wan't to do this . We just need only SMBUS controller to be
passed to guest .
Again, why
> would you want to assign the SMBus controller to a VM? The unsupported
> path is with the ACS override patch, using the multifunction option or
> specific vendor and device IDs. Thanks,
>
> I tried "ACS override patch" with multifunction option and specific vendor
and device IDs.
But it didn't works for us. I don't know whether this grouping is based on
DMAR/RMRR configuration in BIOS.
> Alex
>
-Gokul
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