On Wed, Jul 30, 2014 at 10:16:32PM +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? > Thanks again! > > Regards, > Le
If you want it to work for root bus, you need to implement a device/function level reset mechanism, e.g. using PM or FLR. > > -- > > MST
