pc-bios/s390-ccw/dasd-ipl.c | 3 +++ pc-bios/s390-ccw/jump2ipl.c | 20 ++++++++++---------- 2 files changed, 13 insertions(+), 10 deletions(-)
Hi Conny, Thomas, I've come across a couple problems when installing a guest onto a vfio-ccw disk. They were noticed when booting off an ISO via virtio, and writing the new guest OS to a vfio-ccw connected disk. The installation works correctly, in that the disk can be booted and used perfectly fine. But the end of the install process reboots to the new disk, and we end up with an error that looks like this: Rebooting. LOADPARM=[ ] cio device error ssid : 0x0000000000000000 cssid : 0x0000000000000000 sch_no: 0x0000000000000002 ctrl-unit type: 0x0000000000003990 Interrupt Response Block Data: : 0x0000000000003990 Function Ctrl : [Start] Activity Ctrl : [Start-Pending] Status Ctrl : [Alert] [Primary] [Secondary] [Status-Pending] Device Status : Channel Status : [Program-Check] cpa=: 0x0000000000000008 prev_ccw=: 0x0008000080002018 this_ccw=: 0x0600001860000080 Eckd Dasd Sense Data (fmt 32-bytes): Channel Status : [Program-Check] Sense Condition Flags : Residual Count =: 0x0000000000000000 Phys Drive ID =: 0x0000000000000000 low cyl address =: 0x0000000000000000 head addr & hi cyl =: 0x0000000000000000 format/message =: 0x0000000000000000 fmt-dependent[0-7] =: 0x0000000000000000 fmt-dependent[8-15]=: 0x000000004a200f00 prog action code =: 0x0000000000000000 Configuration info =: 0x00000000000040e0 mcode / hi-cyl =: 0x0000000000000000 cyl & head addr [0]=: 0x0000000000000000 cyl & head addr [1]=: 0x0000000000000000 cyl & head addr [2]=: 0x0000000000000000 dasd-ipl: Failed to run Read IPL channel program The problem can be easily (and quickly) reproduced by defining XML with two different guest disks, such as: <disk type='block' device='disk'> <driver name='qemu' type='raw'/> <source dev='/dev/disk/by-path/ccw-0.0.1234'/> <target dev='vda' bus='virtio'/> <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0000'/> </disk> <hostdev mode='subsystem' type='mdev' managed='no' model='vfio-ccw'> <source> <address uuid='12345678-1234-1234-1234-123456789abc'/> </source> <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x1235'/> </hostdev> Boot the guest off disk 1234, issue `chreipl 0.0.1235`, and reboot. Interestingly, going the other direction (1235->1234) works fine. Two things occur here. First, the DASD IPL code builds a Read IPL Format-0 CCW at address zero, but assumes that the memory is already zero. If data is already present (which on reboot it does, and is probably a PSW), it might be included in that CCW. Patch 1 is a pretty straightforward fix for this. (Might this one be appropriate for 5.2?) Secondly, the jump code looks at a couple memory locations to determine what jump to perform. But in this virtio-to-vfio jump, we should give precedence to the data at address zero, rather than the not-yet-cleared memory. Patch 2 swaps the order of these checks to enable this, and doesn't appear to affect normal disk boots. But there are a hundred other boot combinations that I haven't tried here, so could use some feedback on this one. I do recognize that this leaves no difference between the "if (!memcmp())" case and not, but left it this way to help better visualize the change I'm making. Coda: I didn't include rebuilt bios patch(es) here, but certainly can. Also, I'm on holiday all next week; so apologies in advance for sending a couple patches and then hiding shortly thereafter. :) Eric Farman (2): pc-bios: s390x: Ensure Read IPL memory is clean pc-bios: s390x: Give precedence to reset PSW pc-bios/s390-ccw/dasd-ipl.c | 3 +++ pc-bios/s390-ccw/jump2ipl.c | 20 ++++++++++---------- 2 files changed, 13 insertions(+), 10 deletions(-) -- 2.17.1
On Thu, 19 Nov 2020 17:57:27 +0100 Eric Farman <farman@linux.ibm.com> wrote: > Hi Conny, Thomas, > > I've come across a couple problems when installing a guest onto a > vfio-ccw disk. They were noticed when booting off an ISO via virtio, > and writing the new guest OS to a vfio-ccw connected disk. The > installation works correctly, in that the disk can be booted and > used perfectly fine. But the end of the install process reboots to > the new disk, and we end up with an error that looks like this: > > Rebooting. > LOADPARM=[ ] > cio device error > ssid : 0x0000000000000000 > cssid : 0x0000000000000000 > sch_no: 0x0000000000000002 > ctrl-unit type: 0x0000000000003990 > > Interrupt Response Block Data: > : 0x0000000000003990 > Function Ctrl : [Start] > Activity Ctrl : [Start-Pending] > Status Ctrl : [Alert] [Primary] [Secondary] [Status-Pending] > Device Status : > Channel Status : [Program-Check] > cpa=: 0x0000000000000008 > prev_ccw=: 0x0008000080002018 > this_ccw=: 0x0600001860000080 > Eckd Dasd Sense Data (fmt 32-bytes): > Channel Status : [Program-Check] > Sense Condition Flags : > Residual Count =: 0x0000000000000000 > Phys Drive ID =: 0x0000000000000000 > low cyl address =: 0x0000000000000000 > head addr & hi cyl =: 0x0000000000000000 > format/message =: 0x0000000000000000 > fmt-dependent[0-7] =: 0x0000000000000000 > fmt-dependent[8-15]=: 0x000000004a200f00 > prog action code =: 0x0000000000000000 > Configuration info =: 0x00000000000040e0 > mcode / hi-cyl =: 0x0000000000000000 > cyl & head addr [0]=: 0x0000000000000000 > cyl & head addr [1]=: 0x0000000000000000 > cyl & head addr [2]=: 0x0000000000000000 > dasd-ipl: Failed to run Read IPL channel program > > The problem can be easily (and quickly) reproduced by defining > XML with two different guest disks, such as: > > <disk type='block' device='disk'> > <driver name='qemu' type='raw'/> > <source dev='/dev/disk/by-path/ccw-0.0.1234'/> > <target dev='vda' bus='virtio'/> > <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0000'/> > </disk> > <hostdev mode='subsystem' type='mdev' managed='no' model='vfio-ccw'> > <source> > <address uuid='12345678-1234-1234-1234-123456789abc'/> > </source> > <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x1235'/> > </hostdev> > > Boot the guest off disk 1234, issue `chreipl 0.0.1235`, and reboot. > Interestingly, going the other direction (1235->1234) works fine. > > Two things occur here. First, the DASD IPL code builds a Read IPL > Format-0 CCW at address zero, but assumes that the memory is already > zero. If data is already present (which on reboot it does, and is > probably a PSW), it might be included in that CCW. Patch 1 is a > pretty straightforward fix for this. (Might this one be appropriate > for 5.2?) That one is straightforward enough for 5.2, I guess. > > Secondly, the jump code looks at a couple memory locations to determine > what jump to perform. But in this virtio-to-vfio jump, we should give > precedence to the data at address zero, rather than the not-yet-cleared > memory. Patch 2 swaps the order of these checks to enable this, and > doesn't appear to affect normal disk boots. But there are a hundred > other boot combinations that I haven't tried here, so could use some > feedback on this one. I do recognize that this leaves no difference > between the "if (!memcmp())" case and not, but left it this way to > help better visualize the change I'm making. This is in code that usually gives me a headache :( > > Coda: > I didn't include rebuilt bios patch(es) here, but certainly can. I think it should not be too hard to have the person picking the patches generate them :) Especially if we end up going with patch 1 only for now. > Also, I'm on holiday all next week; so apologies in advance for > sending a couple patches and then hiding shortly thereafter. :) That's a time-proven strategy :) > > Eric Farman (2): > pc-bios: s390x: Ensure Read IPL memory is clean > pc-bios: s390x: Give precedence to reset PSW > > pc-bios/s390-ccw/dasd-ipl.c | 3 +++ > pc-bios/s390-ccw/jump2ipl.c | 20 ++++++++++---------- > 2 files changed, 13 insertions(+), 10 deletions(-) >
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