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From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Jan Beulich <jbeulich@suse.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: Juergen Gross <jgross@suse.com>, Konrad Wilk <konrad.wilk@oracle.com>
Subject: Re: [PATCH 1/3] xen-pciback: redo VF placement in the virtual topology
Date: Thu, 8 Apr 2021 18:28:31 -0400	[thread overview]
Message-ID: <b41663ff-6a90-877d-9cd3-7e052c28eb6a@oracle.com> (raw)
In-Reply-To: <32d6a8d4-c06f-7fe0-1376-4b80fac8c6de@suse.com>


On 4/7/21 10:37 AM, Jan Beulich wrote:
> The commit referenced below was incomplete: It merely affected what
> would get written to the vdev-<N> xenstore node. The guest would still
> find the function at the original function number as long as 
> __xen_pcibk_get_pci_dev() wouldn't be in sync. The same goes for AER wrt
> __xen_pcibk_get_pcifront_dev().
>
> Undo overriding the function to zero and instead make sure that VFs at
> function zero remain alone in their slot. This has the added benefit of
> improving overall capacity, considering that there's only a total of 32
> slots available right now (PCI segment and bus can both only ever be
> zero at present).
>
> Fixes: 8a5248fe10b1 ("xen PV passthru: assign SR-IOV virtual functions to separate virtual slots")
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> Cc: stable@vger.kernel.org
> ---
> Like the original change this has the effect of changing where devices
> would appear in the guest, when there are multiple of them. I don't see
> an immediate problem with this, but if there is we may need to reduce
> the effect of the change.
> Taking into account, besides the described breakage, how xen-pcifront's
> pcifront_scan_bus() works, I also wonder what problem it was in the
> first place that needed fixing. It may therefore also be worth to
> consider simply reverting the original change.


Perhaps this is no longer a problem, it's been 9 years since that patch. Have you tried reverting to 8a5248fe10b101104d92d01438f918e899414fd1~1 and testing that?


-boris



  reply	other threads:[~2021-04-08 22:28 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-07 14:35 [PATCH 0/3] xen-pciback: a fix, a workaround, and some simplification Jan Beulich
2021-04-07 14:37 ` [PATCH 1/3] xen-pciback: redo VF placement in the virtual topology Jan Beulich
2021-04-08 22:28   ` Boris Ostrovsky [this message]
2021-04-09  8:16     ` Jan Beulich
2021-04-07 14:37 ` [PATCH 2/3] xen-pciback: reconfigure also from backend watch handler Jan Beulich
2021-04-09 21:43   ` Boris Ostrovsky
2021-04-12  9:44     ` Jan Beulich
2021-04-12 15:55       ` Boris Ostrovsky
2021-04-07 14:37 ` [PATCH 3/3] xen-pciback: simplify vpci's find hook Jan Beulich
2021-04-09 21:45   ` Boris Ostrovsky
2021-04-12  9:50     ` Jan Beulich
2021-04-12 16:05       ` Boris Ostrovsky
2021-04-13  8:09         ` Jan Beulich
2021-04-13 12:54           ` Boris Ostrovsky
2021-04-23  8:05   ` Juergen Gross

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