From: Alex Williamson <alex.williamson@redhat.com>
To: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, cohuck@redhat.com, cjia@nvidia.com
Subject: [PATCH v2] vfio-pci: Mask cap zero
Date: Tue, 05 May 2020 16:27:01 -0600 [thread overview]
Message-ID: <158871758778.17183.9778359960687348692.stgit@gimli.home> (raw)
The PCI Code and ID Assignment Specification changed capability ID 0
from reserved to a NULL capability in the v1.1 revision. The NULL
capability is defined to include only the 16-bit capability header,
ie. only the ID and next pointer. Unfortunately vfio-pci creates a
map of config space, where ID 0 is used to reserve the standard type
0 header. Finding an actual capability with this ID therefore results
in a bogus range marked in that map and conflicts with subsequent
capabilities. As this seems to be a dummy capability anyway and we
already support dropping capabilities, let's hide this one rather than
delving into the potentially subtle dependencies within our map.
Seen on an NVIDIA Tesla T4.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
drivers/vfio/pci/vfio_pci_config.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
index 3dcddbd572e6..0d110e268094 100644
--- a/drivers/vfio/pci/vfio_pci_config.c
+++ b/drivers/vfio/pci/vfio_pci_config.c
@@ -1486,7 +1486,12 @@ static int vfio_cap_init(struct vfio_pci_device *vdev)
if (ret)
return ret;
- if (cap <= PCI_CAP_ID_MAX) {
+ /*
+ * ID 0 is a NULL capability, conflicting with our fake
+ * PCI_CAP_ID_BASIC. As it has no content, consider it
+ * hidden for now.
+ */
+ if (cap && cap <= PCI_CAP_ID_MAX) {
len = pci_cap_length[cap];
if (len == 0xFF) { /* Variable length */
len = vfio_cap_len(vdev, cap, pos);
next reply other threads:[~2020-05-05 22:27 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 22:27 Alex Williamson [this message]
2020-05-06 11:26 ` [PATCH v2] vfio-pci: Mask cap zero Cornelia Huck
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=158871758778.17183.9778359960687348692.stgit@gimli.home \
--to=alex.williamson@redhat.com \
--cc=cjia@nvidia.com \
--cc=cohuck@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@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).