From: Wei Hu <weh@microsoft.com>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
"robh@kernel.org" <robh@kernel.org>,
"bhelgaas@google.com" <bhelgaas@google.com>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Dexuan Cui <decui@microsoft.com>,
Michael Kelley <mikelley@microsoft.com>
Subject: RE: [PATCH v4] PCI: hv: Fix a timing issue which causes kdump to fail occasionally
Date: Mon, 27 Jul 2020 12:10:40 +0000 [thread overview]
Message-ID: <SG2P153MB0377B86BE7882BC25857A64DBB720@SG2P153MB0377.APCP153.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <20200727111852.GA14239@e121166-lin.cambridge.arm.com>
> -----Original Message-----
> From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Sent: Monday, July 27, 2020 7:19 PM
> To: Wei Hu <weh@microsoft.com>
> Cc: KY Srinivasan <kys@microsoft.com>; Haiyang Zhang
> <haiyangz@microsoft.com>; Stephen Hemminger <sthemmin@microsoft.com>;
> wei.liu@kernel.org; robh@kernel.org; bhelgaas@google.com; linux-
> hyperv@vger.kernel.org; linux-pci@vger.kernel.org; linux-
> kernel@vger.kernel.org; Dexuan Cui <decui@microsoft.com>; Michael Kelley
> <mikelley@microsoft.com>
> Subject: Re: [PATCH v4] PCI: hv: Fix a timing issue which causes kdump to fail
> occasionally
>
> On Mon, Jul 27, 2020 at 03:17:31PM +0800, Wei Hu wrote:
> > Kdump could fail sometime on Hyper-V guest over Accelerated Network
> > interface. This is because the retry in hv_pci_enter_d0() releases
> > child device strurctures in hv_pci_bus_exit(). Although there is a
> > second asynchronous device relations message sending from the host, if
> > this message arrives guest after hv_send_resource_allocated() is
> > called, the retry would fail.
> >
> > Fix the problem by moving retry to hv_pci_probe() and starting retry
> > from hv_pci_query_relations() call. This will cause a device
> > relations message to arrive guest synchronously. The guest would be
> > able to rebuild the child device structures before calling
> > hv_send_resource_allocated().
> >
> > This problem only happens on Accelerated Network or SRIOV devices as
> > only such devices currently are attached under vmbus PCI bridge.
> >
> > Fixes: c81992e7f4aa ("PCI: hv: Retry PCI bus D0 entry on invalid
> > device state")
> > Signed-off-by: Wei Hu <weh@microsoft.com>
> > Reviewed-by: Michael Kelley <mikelley@microsoft.com>
> > ---
> > v2: Adding Fixes tag according to Michael Kelley's review comment.
> > v3: Fix couple typos and reword commit message to make it clearer.
> > Thanks the comments from Bjorn Helgaas.
> > v4: Adding more problem descritpions in the commit message
> > and code upon request from Lorenze Pieralisi.
> >
> > drivers/pci/controller/pci-hyperv.c | 71
> > +++++++++++++++--------------
> > 1 file changed, 37 insertions(+), 34 deletions(-)
> >
> > diff --git a/drivers/pci/controller/pci-hyperv.c
> > b/drivers/pci/controller/pci-hyperv.c
>
> I edited commit log and a comment in the code to fix a typo and pushed out to
> pci/hv.
>
> Thanks,
> Lorenzo
>
Thanks Lorenzo. Appreciate your helps!
Wei
prev parent reply other threads:[~2020-07-27 12:10 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-27 7:17 [PATCH v4] PCI: hv: Fix a timing issue which causes kdump to fail occasionally Wei Hu
2020-07-27 11:18 ` Lorenzo Pieralisi
2020-07-27 12:10 ` Wei Hu [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=SG2P153MB0377B86BE7882BC25857A64DBB720@SG2P153MB0377.APCP153.PROD.OUTLOOK.COM \
--to=weh@microsoft.com \
--cc=bhelgaas@google.com \
--cc=decui@microsoft.com \
--cc=haiyangz@microsoft.com \
--cc=kys@microsoft.com \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=lorenzo.pieralisi@arm.com \
--cc=mikelley@microsoft.com \
--cc=robh@kernel.org \
--cc=sthemmin@microsoft.com \
--cc=wei.liu@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).