Re: [Xen-devel] Some Xen pci-passthrough questions

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 10/27/2017 04:16 AM, Sander Eikelenboom wrote:
> On 27/10/17 00:30, Boris Ostrovsky wrote:
> > On 10/26/2017 04:48 PM, Sander Eikelenboom wrote:
> >
> > - Enabling the xen pt logging in qemu spit out some things, i wonder if they 
> > are normal:
> >
> >          qemu-system-i386: -serial pty: char device redirected to /dev/pts/16 
> > (label serial0)
> >          [00:05.0] xen_pt_realize: Assigning real physical device 08:00.0 to 
> > devfn 0x28
> >          [00:05.0] xen_pt_register_regions: IO region 0 registered 
> > (size=0x00002000 base_addr=0xfe1fe000 type: 0x4)
> >
> >      Are these somehow expected / benign (they also occur when pci passthrough 
> > is succesful) ?:
> >          [00:05.0] xen_pt_config_reg_init: Offset 0x000e mismatch! 
> > Emulated=0x0080, host=0x0000, syncing to 0x0080.
> >          [00:05.0] xen_pt_config_reg_init: Offset 0x0010 mismatch! 
> > Emulated=0x0000, host=0xfe1fe004, syncing to 0xfe1fe004.
> >          [00:05.0] xen_pt_config_reg_init: Offset 0x0052 mismatch! 
> > Emulated=0x0000, host=0x4803, syncing to 0x0003.
> >          [00:05.0] xen_pt_config_reg_init: Offset 0x0072 mismatch! 
> > Emulated=0x0000, host=0x0086, syncing to 0x0080.
> >          [00:05.0] xen_pt_config_reg_init: Offset 0x00a4 mismatch! 
> > Emulated=0x0000, host=0x8fc0, syncing to 0x8fc0.
> >          [00:05.0] xen_pt_config_reg_init: Offset 0x00b2 mismatch! 
> > Emulated=0x0000, host=0x1012, syncing to 0x1012.
> >
> >          [00:05.0] xen_pt_msix_init: get MSI-X table BAR base 0xfe1fe000
> >          [00:05.0] xen_pt_msix_init: table_off = 0x1000, total_entries = 8
> >          [00:05.0] xen_pt_msix_init: table_off = 0x1000, total_entries = 8, 
> > PCI_MSIX_ENTRY_SIZE = 0x10,  msix->table_offset_adjust = 0,  msix->table_base = 
> > 0xfe1fe000
> >          [00:05.0] xen_pt_msix_init: Error: Can't map physical MSI-X table: 
> > Invalid argument
> > That's mmap() of /dev/mem failing:
> >
> > mmap(NULL,
> >               total_entries * PCI_MSIX_ENTRY_SIZE +
> > msix->table_offset_adjust,
> >               PROT_READ,
> >               MAP_SHARED | MAP_LOCKED,
> >               fd,
> >               msix->table_base + table_off - msix->table_offset_adjust);
> >
> >
> > Are you running with Craig Bergstrom's patch?
> Yes sorry for not being clear (and using the log of running with the
> mmap patch), i specifically meant the "mismatch!" lines, although they
> also appear in the working case (without the patch) so they probably
> aren't an issue, but still thought it wouldn't hurt to ask :).
I believe these warnings are expected. At least in the case of BAR 
(offset 0x10) I can see that qemu initializes emulated register to 0 
(xen_pt_bar_reg_init()) which would not match what the actual HW has. 
But I'll let Antony or Stefan confirm that. (I do think the warnings 
look a bit too alarmist so perhaps they can be softened somewhat)
And as far as Craig's patch is concerned we know it's broken and will be 
reverted.
-boris

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