From: Ram Pai <linuxram@us.ibm.com>
To: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: svaidy@linux.vnet.ibm.com, Ram Pai <linuxram@us.ibm.com>,
Yinghai Lu <yinghai.lu@oracle.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [BUGFIX][PATCH] pci: check for 4k resource_size alignment in sriov_init
Date: Mon, 13 Feb 2012 11:08:08 +0800 [thread overview]
Message-ID: <20120213030808.GA18296@ram-ThinkPad-T61> (raw)
In-Reply-To: <20120210115452.4bfefa05@jbarnes-desktop>
On Fri, Feb 10, 2012 at 11:54:52AM -0800, Jesse Barnes wrote:
> On Wed, 1 Feb 2012 18:32:06 +0530
> Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> wrote:
>
> > * Ram Pai <linuxram@us.ibm.com> [2012-02-01 14:21:45]:
> >
> > > On Tue, Jan 31, 2012 at 11:14:02PM +0530, Vaidyanathan Srinivasan wrote:
> > > > * Ram Pai <linuxram@us.ibm.com> [2012-01-30 11:18:45]:
> > > >
> > > > > On Sat, Jan 28, 2012 at 12:40:32AM +0530, Vaidyanathan Srinivasan wrote:
> > > > > > Hi Ram and Jesse,
> > > > > >
> > > > > > I found a trivial issue with page size alignment check on IBM POWER
> > > > > > box with 64k base page size. In sriov_init(), changing the check from
> > > > > > PAGE_SIZE (arch and config dependent) to HW_PAGE_SIZE (always 4k) was
> > > > > > required to use one of the sriov adapter as PF since the
> > > > > > resource_size() comes up as 0x8000 and PAGE_SIZE would be 0x10000 for
> > > > > > pseries boxes.
> > > > > >
> > > > > > I think resource_size() could be less than SystemPageSize, but I would
> > > > > > like your comments/ack/nack on any consequences of checking for only
> > > > > > 4k alignment here in a system with larger base page size.
> > > > >
> > > > > As per the SRIOV specs, the resource has to be System page size aligned.
> > > > >
> > > > > PFs are required to support 4-KB, 8-KB, 64-KB, 256-KB, 1-MB, and 4-MB
> > > > > page sizes. In your case if your adapter's PF is not supporting 64K page size
> > > > > then I think it is not conforming to the PCI SRIOV spec.
> > > >
> > > > Hi Ram,
> > > >
> > > > Thanks for the pointer. I did some more experiments and found that
> > > > the card does support 64k page size, but the PCI_SRIOV_SYS_PGSIZE was
> > > > set to default 4k when we do the query and check resource_size().
> > > >
> > > > You were correct, the resource_size() has to come up with 64k on 64k
> > > > PAGE_SIZE system. We should not change that check. I was able to
> > > > get a working solution by setting PCI_SRIOV_SYS_PGSIZE to 64k before
> > > > we do the query.
> > > >
> > > > This was the case in the original code before you moved these to
> > > > sriov_enable(). If it is ok to leave the SYS_PGSIZE setting in
> > > > sriov_init(), then I have the following fix that works for me.
> > > >
> > > > Please review and let me know your comments.
> > > >
> > > > Thanks,
> > > > Vaidy
> > > > ---
> > > >
> > > > pci: set pci sriov page size before reading sriov bar
> > > >
> > > > For an SRIOV device, PCI_SRIOV_SYS_PGSIZE should be set before
> > > > the PCI_SRIOV_BAR is queried. The sys pagesize defaults to 4k,
> > > > so this change is required on powerpc box with 64k base page size.
> > > >
> > > > This is a regression caused due to moving SRIOV init to sriov_enable().
> > > >
> > > > | commit afd24ece5c76af87f6fc477f2747b83a764f161c
> > > > | Author: Ram Pai <linuxram@us.ibm.com>
> > > >
> > > > | PCI: delay configuration of SRIOV capability
> > > > | The SRIOV capability, namely page size and total_vfs of a device are
> > > > | configured during enumeration phase of the device. This can potentially
> > > > | interfere with the PCI operations of the platform, if the IOV capability
> > > > | of the device is not enabled.
> > > >
> > > > Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
> > > >
> > > > diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> > > > index 0321fa3..0dab5ec 100644
> > > > --- a/drivers/pci/iov.c
> > > > +++ b/drivers/pci/iov.c
> > > > @@ -347,8 +347,6 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
> > > > return rc;
> > > > }
> > > >
> > > > - pci_write_config_dword(dev, iov->pos + PCI_SRIOV_SYS_PGSIZE, iov->pgsz);
> > > > -
> > > > iov->ctrl |= PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE;
> > > > pci_cfg_access_lock(dev);
> > > > pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
> > > > @@ -466,6 +464,7 @@ found:
> > > > return -EIO;
> > > >
> > > > pgsz &= ~(pgsz - 1);
> > > > + pci_write_config_dword(dev, pos + PCI_SRIOV_SYS_PGSIZE, pgsz);
> > > >
> > > > nres = 0;
> > > > for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
> > >
> > >
> > > ACK. I think it is better to revert afd24ece5c76af87f6fc477f2747b83a764f161c.
> >
> > Hi Ram,
> >
> > Thanks for the ack. But afd24ece5c76af87f6fc477f2747b83a764f161c has
> > one more change of moving
> > pci_write_config_word(dev, pos + PCI_SRIOV_NUM_VF, total) to sriov_enable().
> >
> > This change is required so that we set the PCI_SRIOV_NUM_VF only
> > during sriov_enable.
> >
> > So we should not revert the entire commit, we can just add this change.
>
> So which is it Ram, the ack or the revert? :)
Jesse,
As Vaidy mentioned, revert is not the right solution. So dont revert.
But apply Vaidy's patch.
>
> Having the right page size early seems like the right solution...
Yes.
RP
prev parent reply other threads:[~2012-02-13 3:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-27 19:10 [BUGFIX][PATCH] pci: check for 4k resource_size alignment in sriov_init Vaidyanathan Srinivasan
2012-01-27 21:05 ` Yinghai Lu
2012-01-29 13:11 ` Vaidyanathan Srinivasan
2012-01-30 3:18 ` Ram Pai
2012-01-31 17:44 ` Vaidyanathan Srinivasan
2012-02-01 6:21 ` Ram Pai
2012-02-01 13:02 ` Vaidyanathan Srinivasan
2012-02-10 19:54 ` Jesse Barnes
2012-02-13 3:08 ` Ram Pai [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=20120213030808.GA18296@ram-ThinkPad-T61 \
--to=linuxram@us.ibm.com \
--cc=jbarnes@virtuousgeek.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=svaidy@linux.vnet.ibm.com \
--cc=yinghai.lu@oracle.com \
/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).