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Juergen Gross 6705a2ab8a x86/xen: Set MTRR state when running as Xen PV initial domain 
[ Upstream commit a153f254e5 ]

When running as Xen PV initial domain (aka dom0), MTRRs are disabled
by the hypervisor, but the system should nevertheless use correct
cache memory types. This has always kind of worked, as disabled MTRRs
resulted in disabled PAT, too, so that the kernel avoided code paths
resulting in inconsistencies. This bypassed all of the sanity checks
the kernel is doing with enabled MTRRs in order to avoid memory
mappings with conflicting memory types.

This has been changed recently, leading to PAT being accepted to be
enabled, while MTRRs stayed disabled. The result is that
mtrr_type_lookup() no longer is accepting all memory type requests,
but started to return WB even if UC- was requested. This led to
driver failures during initialization of some devices.

In reality MTRRs are still in effect, but they are under complete
control of the Xen hypervisor. It is possible, however, to retrieve
the MTRR settings from the hypervisor.

In order to fix those problems, overwrite the MTRR state via
mtrr_overwrite_state() with the MTRR data from the hypervisor, if the
system is running as a Xen dom0.

Fixes: 72cbc8f04f ("x86/PAT: Have pat_enabled() properly reflect state when running on Xen")
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20230502120931.20719-6-jgross@suse.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-07-19 16:35:18 +02:00
arch x86/xen: Set MTRR state when running as Xen PV initial domain 2023-07-19 16:35:18 +02:00
block blk-mq: don't insert passthrough request into sw queue 2023-07-19 16:35:14 +02:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto KEYS: asymmetric: Copy sig and digest in public_key_verify_signature() 2023-06-02 15:36:23 +02:00
Documentation dt-bindings: iio: ad7192: Add mandatory reference voltage source 2023-07-19 16:35:05 +02:00
drivers thermal/drivers/qoriq: Only enable supported sensors 2023-07-19 16:35:16 +02:00
fs btrfs: fix file_offset for REQ_BTRFS_ONE_ORDERED bios that get split 2023-07-19 16:35:13 +02:00
include drivers/perf: apple_m1: Force 63bit counters for M2 CPUs 2023-07-19 16:35:14 +02:00
init start_kernel: Add __no_stack_protector function attribute 2023-07-19 16:35:05 +02:00
io_uring io_uring/net: use the correct msghdr union member in io_sendmsg_copy_hdr 2023-06-21 07:34:17 -06:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel rcu/rcuscale: Stop kfree_scale_thread thread(s) after unloading rcuscale 2023-07-19 16:35:17 +02:00
lib maple_tree: fix potential out-of-bounds access in mas_wr_end_piv() 2023-07-01 13:12:38 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm splice: Fix filemap_splice_read() to use the correct inode 2023-07-19 16:35:07 +02:00
net svcrdma: Prevent page release when nothing was received 2023-07-19 16:35:11 +02:00
rust Rust changes for v6.4 2023-04-30 11:20:22 -07:00
samples samples/bpf: Drop unnecessary fallthrough 2023-05-16 19:44:05 +02:00
scripts scripts/tags.sh: Resolve gtags empty index generation 2023-07-05 18:30:30 +01:00
security selinux: don't use make's grouped targets feature yet 2023-06-01 13:56:13 -04:00
sound ASoC: Fix for v6.4 2023-06-21 15:23:23 +02:00
tools rcutorture: Correct name of use_softirq module parameter 2023-07-19 16:35:17 +02:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Avoid illegal stage2 mapping on invalid memory slot 2023-06-22 15:14:57 -04:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: add entries for Ben Dooks 2023-06-19 13:19:35 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 6.4-rc8, including fixes from ipsec, bpf, 2023-06-22 17:59:51 -07:00
Makefile Linux 6.4.3 2023-07-11 06:31:05 +02:00
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.