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Re: [Qemu-devel] [PATCH v3 0/2] PCI-e device multi-function hot-add supp
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v3 0/2] PCI-e device multi-function hot-add support |
Date: |
Wed, 21 Oct 2015 12:11:22 +0300 |
On Wed, Oct 21, 2015 at 04:32:17PM +0800, Cao jin wrote:
> Hello Michael
>
> On 10/13/2015 09:10 PM, Michael S. Tsirkin wrote:
> >On Tue, Oct 13, 2015 at 07:54:07PM +0800, Cao jin wrote:
> >>
> >>
> >>On 10/13/2015 04:49 PM, Michael S. Tsirkin wrote:
> >>>On Tue, Oct 13, 2015 at 04:41:33PM +0800, Cao jin wrote:
> >>>>Support PCI-e device hot-add multi-function via device_add, just ensure
> >>>>add the function 0 is added last. While allow user to roll back in the
> >>>>middle via device_del, in case user regret.
> >>>
> >>>This patch doesn't seem to account of AIR though.
> >>>
> >>
> >>Yes, but the AIR function seems never be used(nobody calls the function
> >>pcie_ari_init()), so I am a little confused about should it be consindered?
> >
> >Yes please - we'll likely use that in the future. Pls add an API
> >that takes ari into account.
> >
> after analysed the code and read the spec, but still a little confused about
> "add an API that takes ari into account". what is new API for? Could you
> give a detailed description?
You are assuming PCI_FUNC == 0 means function 9. But the real
rule is: for an express device associated with an upstream port, it's
devfn == 0. For any other device (non express or not connected
to an upstream port) - PCI_FUNC == 0.
I think a reasonable API could be e.g.
bool pci_is_function_0()
with a comment explaining the issues.
> AFAICT now, taking ari into account will affect the "addr" property of PCI
> device(maybe also need a new prop of "ari=on" to enable ari).
>
> >>>>changelog:
> >>>>1. Flag device as unexposed when func 0 doesn`t exist, via return 0xFF
> >>>> in case of gratuitous pci bus scan.
> >>>>2. Since device is unexposed to guest, can remove function individually,
> >>>> without interaction with the guest.
> >>>>
> >>>>Cao jin (2):
> >>>> enable multi-function hot-add
> >>>> remove function during multi-function hot-add
> >>>>
> >>>> hw/pci/pci.c | 10 ++++++++++
> >>>> hw/pci/pci_host.c | 6 +++++-
> >>>> hw/pci/pcie.c | 38 +++++++++++++++++++++++++-------------
> >>>> 3 files changed, 40 insertions(+), 14 deletions(-)
> >>>>
> >>>>--
> >>>>2.1.0
> >>>.
> >>>
> >>
> >>--
> >>Yours Sincerely,
> >>
> >>Cao Jin
> >.
> >
>
> --
> Yours Sincerely,
>
> Cao Jin
Re: [Qemu-devel] [PATCH v3 0/2] PCI-e device multi-function hot-add support, Michael S. Tsirkin, 2015/10/13
Re: [Qemu-devel] [PATCH v3 0/2] PCI-e device multi-function hot-add support, Michael S. Tsirkin, 2015/10/15