From: Bjorn Helgaas <helgaas@kernel.org>
To: Robert Straw <drbawb@fatalsyntax.com>
Cc: bhelgaas@google.com, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org,
Alex Williamson <alex.williamson@redhat.com>
Subject: Re: [PATCH] pci: add NVMe FLR quirk to the SM951 SSD
Date: Fri, 30 Apr 2021 15:51:05 -0500 [thread overview]
Message-ID: <20210430205105.GA683965@bjorn-Precision-5520> (raw)
In-Reply-To: <20210429230730.201266-1-drbawb@fatalsyntax.com>
[+cc Alex, author of ffb0863426eb]
Please make your subject line match ffb0863426eb ("PCI: Disable
Samsung SM961/PM961 NVMe before FLR")
On Thu, Apr 29, 2021 at 06:07:30PM -0500, Robert Straw wrote:
> The SM951/PM951, when used in conjunction with the vfio-pci driver and
> passed to a KVM guest, can exhibit the fatal state addressed by the
> existing `nvme_disable_and_flr` quirk. If the guest cleanly shuts down
> the SSD, and vfio-pci attempts an FLR to the device while it is in this
> state, the nvme driver will fail when it attempts to bind to the device
> after the FLR due to the frozen config area, e.g:
>
> nvme nvme2: frozen state error detected, reset controller
> nvme nvme2: Removing after probe failure status: -12
>
> By including this older model (Samsung 950 PRO) of the controller in the
> existing quirk: the device is able to be cleanly reset after being used
> by a KVM guest.
I don't see anything in the PCIe spec about software being required to
do something special before initiating an FLR, so I assume this is a
hardware defect in the Samsung 950 PRO? Has Samsung published an
erratum or at least acknowledged it?
There's always the possibility that we are doing something wrong in
Linux *after* the FLR, e.g., not waiting long enough, not
reinitializing something correctly, etc.
> Signed-off-by: Robert Straw <drbawb@fatalsyntax.com>
> ---
> drivers/pci/quirks.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 653660e3b..e339ca238 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -3920,6 +3920,7 @@ static const struct pci_dev_reset_methods pci_dev_reset_methods[] = {
> reset_ivb_igd },
> { PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_IVB_M2_VGA,
> reset_ivb_igd },
> + { PCI_VENDOR_ID_SAMSUNG, 0xa802, nvme_disable_and_flr },
> { PCI_VENDOR_ID_SAMSUNG, 0xa804, nvme_disable_and_flr },
> { PCI_VENDOR_ID_INTEL, 0x0953, delay_250ms_after_flr },
> { PCI_VENDOR_ID_CHELSIO, PCI_ANY_ID,
> --
> 2.31.1
>
next prev parent reply other threads:[~2021-04-30 20:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 23:07 [PATCH] pci: add NVMe FLR quirk to the SM951 SSD Robert Straw
2021-04-30 20:51 ` Bjorn Helgaas [this message]
2021-04-30 22:34 ` Robert Straw
2021-05-15 17:20 ` Robert Straw
2021-05-19 8:44 ` Christoph Hellwig
2021-05-19 12:54 ` Robert Straw
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=20210430205105.GA683965@bjorn-Precision-5520 \
--to=helgaas@kernel.org \
--cc=alex.williamson@redhat.com \
--cc=bhelgaas@google.com \
--cc=drbawb@fatalsyntax.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.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).