2014-08-01 23:25 GMT+08:00 Alex Williamson <alex.william...@redhat.com>: > On Fri, 2014-08-01 at 09:35 +0800, Le Tan wrote: >> Hi Alex, >> >> 2014-07-30 22:46 GMT+08:00 Alex Williamson <alex.william...@redhat.com>: >> > On Wed, 2014-07-30 at 22:16 +0800, Le Tan wrote: >> >> Hi Michael, >> >> >> >> 2014-07-30 21:16 GMT+08:00 Michael S. Tsirkin <m...@redhat.com>: >> >> > On Wed, Jul 30, 2014 at 08:24:04PM +0800, Le Tan wrote: >> >> >> Hi, >> >> >> I am testing vfio in L1 with my VT-d emulation project. I assigned one >> >> >> of the two AHCI controllers in L1 to L2 via vfio. After I ran the QEMU >> >> >> in L1, it complains that: >> >> >> qemu-system-x86_64: vfio: Cannot reset device 0000:00:03.0, no >> >> >> available reset mechanism. >> >> >> qemu-system-x86_64: vfio: Cannot reset device 0000:00:03.0, no >> >> >> available reset mechanism. >> >> >> >> >> >> Then L2 paused when the SeaBIOS executed in ahci_controller_setup(). I >> >> >> look into this and found that: >> >> >> val = ahci_ctrl_readl(ctrl, HOST_CTL); >> >> >> ahci_ctrl_writel(ctrl, HOST_CTL, val | HOST_CTL_AHCI_EN); >> >> >> When the BIOS tried to read the HOST_CTL, it returns 0x80000002, which >> >> >> bit 2 (Interrupt Enable) is 1. The AHCI manual says that this bit >> >> >> should be cleared by default. So maybe L1 didn't reset the device >> >> >> before assigning it to L2? >> >> >> Then the BIOS tried to write back to HOST_CTL and it was stuck here. :( >> >> >> >> >> >> So can anyone give me some advice? About the state of PCI device or >> >> >> bus-level reset? >> >> >> >> >> >> Here is the detail of the environment and the way I did the vfio. >> >> >> 1. lspci in L1 said: >> >> >> 00:03.0 SATA controller [0106]: Intel Corporation 82801IR/IO/IH >> >> >> (ICH9R/DO/DH) 6 port SATA Controller [AHCI mode] [8086:2922] (rev 02) >> >> >> 00:1f.0 ISA bridge [0601]: Intel Corporation 82801IB (ICH9) LPC >> >> >> Interface Controller [8086:2918] (rev 02) >> >> >> 00:1f.2 SATA controller [0106]: Intel Corporation 82801IR/IO/IH >> >> >> (ICH9R/DO/DH) 6 port SATA Controller [AHCI mode] [8086:2922] (rev 02) >> >> >> 00:1f.3 SMBus [0c05]: Intel Corporation 82801I (ICH9 Family) SMBus >> >> >> Controller [8086:2930] (rev 02) >> >> >> 2. Unbind 00:03.0 and do vfio: >> >> >> modprobe -r vfio_iommu_type1 >> >> >> modprobe vfio_iommu_type1 allow_unsafe_interrupts=1 >> >> >> modprobe vfio-pci >> >> >> echo 0000:00:03.0 > /sys/bus/pci/devices/0000\:00\:03.0/driver/unbind >> >> >> echo "8086 2922" > /sys/bus/pci/drivers/vfio-pci/new_id >> >> >> 3. run L2 with "-device vfio-pci,host=00:03.0" >> >> >> >> >> >> Any help is appreciated! Thanks very much! >> >> >> >> >> >> Regards, >> >> >> Le >> >> > >> >> > Clearly, bus level reset can't work for the root bus :) >> >> >> >> Thanks very much! >> >> I test the vfio with a second-bus ahci controller and it didn't >> >> complain about the lack of reset mechanism. :) And the return val of >> >> HOST_CTL is normal now (the same as emulated ahci controller). >> >> However, it still paused when the BIOS tried to write to the HOST_CTL. >> >> Do you have any idea? >> >> And we should just test vfio and legacy pci-assignment with second bus >> >> devices, not considering the root-bus devices? >> > >> > AHCI seems like a poor choice of device for this work, they typically >> > don't support any kind of reset and they can be troublesome even for the >> > L1 assignment. You really want something with FLR support so that both >> > the host and L1 guest can potentially reset the device. That said, you >> > may still run into bugs with a L1 guest directed FLR. Thanks, >> > >> > Alex >> > >> >> So what device do you think is suitable for the pci-assign test? e1000? >> I just tested it with sound card ac97 and USB controller. But I don't >> know how to attach them to a pcie-to-pci bridge, so maybe they weren't >> reset before being assigned to L2. But it seems that they can work. >> 1. With the sound card, I assigned it to L2 via both vfio and legacy >> pci-assign and I could hear the music played in L2 from host's >> speakers. Of course, the vfio also complained about the lack of reset >> mechanism. > > First off, maybe I'm a little confused, are you trying to assigned > emulated devices for the L1 guest to the L2 guest or are these assigned > devices to the L1 guest that you want to re-assign to L2? AFAIK, we > don't have any emulated devices that support reset, but it wouldn't be > that hard to add a PM capability to one that advertises a soft reset on > D3hot->D0 transition and calls the QEMU driver reset function when that > occurs. This would provide the most flexibility.
I am trying to assign emulated devices for the L1 guest to the L2 guest. According to Jan's suggestions, I will first go on to add more features to the VT-d emulation. Thanks very much! Learn a lot from you! :) Le > The other choice is to create a topology where an individual device can > be reset via a bus reset, so putting a single device behind a bridge, > root port, or downstream switch port. > > Otherwise, the emulated e1000 is probably a reasonable choice, network > drivers generally seem to be pretty good about accepting a device in a > running state since it might have been used as a boot device. > > If you're looking at re-assigning an L1 assigned device to an L2 guest, > I'm not sure how that's supposed to work. The VT-d emulation would need > to somehow push L2 physical mappings to the host, but the L1 guest > doesn't know the true isolation constraints of the host devices and > whether they can actually be mapped separately from other devices. > Since we try to use as few IOMMU domains as possible, you'd end up > modifying translations for all devices assigned to the L1 guest. > >> 2. With the USB controller, I used "-usb -usbdevice disk:file" to >> attach a USB disk to L1. But there were 4 related devices in L1, so I >> didn't know what should be assigned to L2. the info qtree was like >> this: >> dev: ich9-usb-uhci3, id "" >> masterbus = "usb-bus.0" >> firstport = 4 (0x4) >> bandwidth = 1280 (0x500) >> maxframes = 128 (0x80) >> addr = 1d.2 >> dev: ich9-usb-uhci2, id "" >> masterbus = "usb-bus.0" >> firstport = 2 (0x2) >> bandwidth = 1280 (0x500) >> maxframes = 128 (0x80) >> addr = 1d.1 >> dev: ich9-usb-uhci1, id "" >> masterbus = "usb-bus.0" >> firstport = 0 (0x0) >> bandwidth = 1280 (0x500) >> maxframes = 128 (0x80) >> addr = 1d.0 >> dev: ich9-usb-ehci1, id "" >> maxframes = 128 (0x80) >> addr = 1d.7 >> bus: usb-bus.0 >> type usb-bus >> dev: usb-storage, id "" >> drive = "" >> logical_block_size = 512 (0x200) >> physical_block_size = 512 (0x200) >> min_io_size = 0 (0x0) >> opt_io_size = 0 (0x0) >> bootindex = -1 (0xffffffffffffffff) >> discard_granularity = 4294967295 (0xffffffff) >> removable = false >> port = "" >> serial = "" >> full-path = true >> msos-desc = true >> addr 0.1, port 1, speed 480, name QEMU USB MSD, attached >> bus: scsi.0 >> type SCSI >> dev: scsi-disk, id "" >> drive = "usb0" >> logical_block_size = 512 (0x200) >> physical_block_size = 512 (0x200) >> min_io_size = 0 (0x0) >> opt_io_size = 0 (0x0) >> Then I tried to unbind and bind both 1d.7 and 1d.0. Then I assigned >> 1d.0 to L2. L2 could boot smoothly and I could mount and access the >> USB disk. >> So what do you think? > > Sounds like a reasonable test of L1 emulated assigned to L2. Thanks, > > Alex > >
