Re: [RFC PATCH] vfio/pci: Use kernel VPD access functions
> On Sep 11, 2015, at 6:11 PM, Rustad, Mark D wrote: > > Superficially this looks pretty good. I need to think harder to be sure of > the details. This is the first time I've looked at all at any of the vfio code, but this is still looking good to me. Thanks for taking this on and exposing the vfio code to me. I hope more devices will be able to take advantage of the quirk and get their VPD issues resolved. I did run this on a host with a device with VPD assigned to a guest and did not see any trouble when accessing it concurrently from both the guest and the host on the same and different functions. I don't think my particular environment is ideal to fully reproduce the problem (no writable VPD area), but my initial testing looks good. Acked-by: Mark Rustad -- Mark Rustad, Networking Division, Intel Corporation signature.asc Description: Message signed with OpenPGP using GPGMail
Re: [RFC PATCH] vfio/pci: Use kernel VPD access functions
On Sat, 2015-09-12 at 01:11 +, Rustad, Mark D wrote:
> Alex,
>
> > On Sep 11, 2015, at 11:16 AM, Alex Williamson
> > wrote:
> >
> > RFC - Is this something we should do?
>
> Superficially this looks pretty good. I need to think harder to be sure of
> the details.
>
> > Should we consider providing
> > similar emulation through PCI sysfs to allow lspci to also make use
> > of the vpd interfaces?
>
> It looks to me like lspci already uses the vpd attribute in sysfs to access
> VPD, so maybe nothing more than this is needed. No doubt lspci can be coerced
> into accessing VPD directly, but is that really worth going after? I'm not so
> sure.
>
> An strace of lspci accessing a device with VPD shows me:
>
> write(1, "\tCapabilities: [e0] Vital Produc"..., 39 Capabilities: [e0]
> Vital Product Data
> ) = 39
> open("/sys/bus/pci/devices/:02:00.0/vpd", O_RDONLY) = 4
> ^^^ accesses to this should be safe,
> I think
>
> pread(4, "\202", 1, 0) = 1
> pread(4, "\10\0", 2, 1) = 2
> pread(4, "PVL Dell", 8, 3) = 8
> write(1, "\t\tProduct Name: PVL Dell\n", 25 Product Name: PVL Dell
> ) = 25
>
> and so forth.
Oh good, so aside from some rouge admin poking around with setpci access
through pci-sysfs is hopefully not an issue. Thanks for looking into
it.
Alex
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Re: [RFC PATCH] vfio/pci: Use kernel VPD access functions
Alex,
> On Sep 11, 2015, at 11:16 AM, Alex Williamson
> wrote:
>
> RFC - Is this something we should do?
Superficially this looks pretty good. I need to think harder to be sure of the
details.
> Should we consider providing
> similar emulation through PCI sysfs to allow lspci to also make use
> of the vpd interfaces?
It looks to me like lspci already uses the vpd attribute in sysfs to access
VPD, so maybe nothing more than this is needed. No doubt lspci can be coerced
into accessing VPD directly, but is that really worth going after? I'm not so
sure.
An strace of lspci accessing a device with VPD shows me:
write(1, "\tCapabilities: [e0] Vital Produc"..., 39 Capabilities: [e0]
Vital Product Data
) = 39
open("/sys/bus/pci/devices/:02:00.0/vpd", O_RDONLY) = 4
^^^ accesses to this should be safe, I
think
pread(4, "\202", 1, 0) = 1
pread(4, "\10\0", 2, 1) = 2
pread(4, "PVL Dell", 8, 3) = 8
write(1, "\t\tProduct Name: PVL Dell\n", 25 Product Name: PVL Dell
) = 25
and so forth.
--
Mark Rustad, Networking Division, Intel Corporation
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