kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-10-09 18:15:49 +00:00
Code Issues Releases Packages Activity
No description
889,369 commits 116 branches 5,788 tags 5.6 GiB
  • C 96.9%
  • Assembly 0.9%
  • Rust 0.6%
  • Shell 0.6%
  • Python 0.5%
  • Other 0.3%
Find a file
Logan Gunthorpe db16360b59 PCI: Don't disable bridge BARs when assigning bus resources 
commit 9db8dc6d07 upstream.

Some PCI bridges implement BARs in addition to bridge windows.  For
example, here's a PLX switch:

  04:00.0 PCI bridge: PLX Technology, Inc. PEX 8724 24-Lane, 6-Port PCI
            Express Gen 3 (8 GT/s) Switch, 19 x 19mm FCBGA (rev ca)
	    (prog-if 00 [Normal decode])
      Flags: bus master, fast devsel, latency 0, IRQ 30, NUMA node 0
      Memory at 90a00000 (32-bit, non-prefetchable) [size=256K]
      Bus: primary=04, secondary=05, subordinate=0a, sec-latency=0
      I/O behind bridge: 00002000-00003fff
      Memory behind bridge: 90000000-909fffff
      Prefetchable memory behind bridge: 0000380000800000-0000380000bfffff

Previously, when the kernel assigned resource addresses (with the
pci=realloc command line parameter, for example) it could clear the struct
resource corresponding to the BAR.  When this happened, lspci would report
this BAR as "ignored":

   Region 0: Memory at <ignored> (32-bit, non-prefetchable) [size=256K]

This is because the kernel reports a zero start address and zero flags
in the corresponding sysfs resource file and in /proc/bus/pci/devices.
Investigation with 'lspci -x', however, shows the BIOS-assigned address
will still be programmed in the device's BAR registers.

It's clearly a bug that the kernel lost track of the BAR value, but in most
cases, this still won't result in a visible issue because nothing uses the
memory, so nothing is affected.  However, when an IOMMU is in use, it will
not reserve this space in the IOVA because the kernel no longer thinks the
range is valid.  (See dmar_init_reserved_ranges() for the Intel
implementation of this.)

Without the proper reserved range, a DMA mapping may allocate an IOVA that
matches a bridge BAR, which results in DMA accesses going to the BAR
instead of the intended RAM.

The problem was in pci_assign_unassigned_root_bus_resources().  When any
resource from a bridge device fails to get assigned, the code set the
resource's flags to zero.  This makes sense for bridge windows, as they
will be re-enabled later, but for regular BARs, it makes the kernel
permanently lose track of the fact that they decode address space.

Change pci_assign_unassigned_root_bus_resources() and
pci_assign_unassigned_bridge_resources() so they only clear "res->flags"
for bridge *windows*, not bridge BARs.

Fixes: da7822e5ad ("PCI: update bridge resources to get more big ranges when allocating space (again)")
Link: https://lore.kernel.org/r/20200108213208.4612-1-logang@deltatee.com
[bhelgaas: commit log, check for pci_is_bridge()]
Reported-by: Kit Chow <kchow@gigaio.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2020-02-14 16:52:57 -05:00
arch compat: ARM64: always include asm-generic/compat.h 2020-02-11 04:37:30 -08:00
block compat: scsi: sg: fix v3 compat read/write interface 2020-02-11 04:37:17 -08:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto crypto: api - Fix race condition in crypto_spawn_alg 2020-02-11 04:37:01 -08:00
Documentation PM / devfreq: Add new name attribute for sysfs 2020-02-04 18:18:01 +00:00
drivers PCI: Don't disable bridge BARs when assigning bus resources 2020-02-14 16:52:57 -05:00
fs io_uring: prevent potential eventfd recursion on poll 2020-02-11 04:37:28 -08:00
include RDMA/uverbs: Verify MR access flags 2020-02-14 16:52:56 -05:00
init Revert "um: Enable CONFIG_CONSTRUCTORS" 2020-02-01 09:33:00 +00:00
ipc ipc/msg.c: consolidate all xxxctl_down() functions 2020-02-11 04:36:39 -08:00
kernel perf/cgroups: Install cgroup events to correct cpuctx 2020-02-11 04:37:28 -08:00
lib lib/test_kasan.c: fix memory leak in kmalloc_oob_krealloc_more() 2020-02-11 04:36:45 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/mmu_gather: invalidate TLB correctly on batch allocation failure and flush 2020-02-11 04:37:14 -08:00
net rxrpc: Fix service call disconnection 2020-02-11 04:37:29 -08:00
samples samples/bpf: Reintroduce missed build targets 2020-02-11 04:37:00 -08:00
scripts scripts/find-unused-docs: Fix massive false positives 2020-02-11 04:36:53 -08:00
security broken ping to ipv6 linklocal addresses on debian buster 2020-02-11 04:37:16 -08:00
sound ASoC: Intel: skl_hda_dsp_common: Fix global-out-of-bounds bug 2020-02-11 04:37:21 -08:00
tools libbpf: Extract and generalize CPU mask parsing logic 2020-02-11 04:37:22 -08:00
usr gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-04 00:00:48 +09:00
virt KVM: Play nice with read-only memslots when querying host page size 2020-02-11 04:37:29 -08:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap MAINTAINERS: update my email address 2020-01-11 14:33:39 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Linux 5.4-rc4 2019-10-29 04:43:29 -06:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS: correct entries for ISDN/mISDN section 2020-02-11 04:36:38 -08:00
Makefile Linux 5.5.3 2020-02-11 04:37:31 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.