From: Eric Auger <eric.auger@redhat.com>
To: eric.auger.pro@gmail.com, eric.auger@redhat.com,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
alex.williamson@redhat.com
Subject: [PATCH] vfio_pci: Enable memory accesses before calling pci_map_rom
Date: Wed, 13 Feb 2019 11:14:06 +0100 [thread overview]
Message-ID: <20190213101406.3934-1-eric.auger@redhat.com> (raw)
pci_map_rom/pci_get_rom_size() performs memory access in the ROM.
In case the Memory Space accesses were disabled, readw() is likely to
crash the host with a synchronous external abort (aarch64).
In case memory accesses were disabled, re-enable them before the call
and disable them back again just after.
Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
drivers/vfio/pci/vfio_pci.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index ff60bd1ea587..96b8bbd909d7 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -706,8 +706,10 @@ static long vfio_pci_ioctl(void *device_data,
break;
case VFIO_PCI_ROM_REGION_INDEX:
{
+ bool mem_access_disabled;
void __iomem *io;
size_t size;
+ u16 cmd;
info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
info.flags = 0;
@@ -723,6 +725,13 @@ static long vfio_pci_ioctl(void *device_data,
break;
}
+ pci_read_config_word(pdev, PCI_COMMAND, &cmd);
+ mem_access_disabled = !(cmd & PCI_COMMAND_MEMORY);
+ if (mem_access_disabled) {
+ cmd |= PCI_COMMAND_MEMORY;
+ pci_write_config_word(pdev, PCI_COMMAND, cmd);
+ }
+
/* Is it really there? */
io = pci_map_rom(pdev, &size);
if (!io || !size) {
@@ -731,6 +740,11 @@ static long vfio_pci_ioctl(void *device_data,
}
pci_unmap_rom(pdev, io);
+ if (mem_access_disabled) {
+ cmd &= ~PCI_COMMAND_MEMORY;
+ pci_write_config_word(pdev, PCI_COMMAND, cmd);
+ }
+
info.flags = VFIO_REGION_INFO_FLAG_READ;
break;
}
--
2.20.1
next reply other threads:[~2019-02-13 10:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-13 10:14 Eric Auger [this message]
2019-02-13 10:39 ` [PATCH] vfio_pci: Enable memory accesses before calling pci_map_rom Auger Eric
2019-02-13 16:28 ` Konrad Rzeszutek Wilk
2019-02-13 17:11 ` Alex Williamson
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=20190213101406.3934-1-eric.auger@redhat.com \
--to=eric.auger@redhat.com \
--cc=alex.williamson@redhat.com \
--cc=eric.auger.pro@gmail.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).