Revision - 694556d - KVM: arm/arm64: Clean dcache to PoC when changing PTE due to CoW - origin: https://github.com/torvalds/linux

visit type:

https://github.com/torvalds/linux

13 August 2024, 17:29:01 UTC

Revision 694556d54f354d3fe43bb2e61fd6103cca2638a4 authored by Marc Zyngier on 23 August 2018, 08:58:27 UTC, committed by Christoffer Dall on 07 September 2018, 13:05:40 UTC

KVM: arm/arm64: Clean dcache to PoC when changing PTE due to CoW

When triggering a CoW, we unmap the RO page via an MMU notifier
(invalidate_range_start), and then populate the new PTE using another
one (change_pte). In the meantime, we'll have copied the old page
into the new one.

The problem is that the data for the new page is sitting in the
cache, and should the guest have an uncached mapping to that page
(or its MMU off), following accesses will bypass the cache.

In a way, this is similar to what happens on a translation fault:
We need to clean the page to the PoC before mapping it. So let's just
do that.

This fixes a KVM unit test regression observed on a HiSilicon platform,
and subsequently reproduced on Seattle.

Fixes: a9c0e12ebee5 ("KVM: arm/arm64: Only clean the dcache on translation fault")
Cc: stable@vger.kernel.org # v4.16+
Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>

1 parent 5b394b2

Files
Changes

Permalinks

Tip revision: 694556d54f354d3fe43bb2e61fd6103cca2638a4 authored by Marc Zyngier on 23 August 2018, 08:58:27 UTC
KVM: arm/arm64: Clean dcache to PoC when changing PTE due to CoW

Tip revision: 694556d

File	Mode	Size
Documentation
LICENSES
arch
block
certs
crypto
drivers
firmware
fs
include
init
ipc
kernel
lib
mm
net
samples
scripts
security
sound
tools
usr
virt
.clang-format	-rw-r--r--	12.8 KB
.cocciconfig	-rw-r--r--	59 bytes
.get_maintainer.ignore	-rw-r--r--	31 bytes
.gitattributes	-rw-r--r--	30 bytes
.gitignore	-rw-r--r--	1.5 KB
.mailmap	-rw-r--r--	9.7 KB
COPYING	-rw-r--r--	423 bytes
CREDITS	-rw-r--r--	96.4 KB
Kbuild	-rw-r--r--	2.2 KB
Kconfig	-rw-r--r--	563 bytes
MAINTAINERS	-rw-r--r--	458.4 KB
Makefile	-rw-r--r--	59.0 KB
README	-rw-r--r--	800 bytes

Showing with 0 additions and 0 deletions (0 / 0 diffs computed)

Computing file changes ...

https://github.com/torvalds/linux

KVM: arm/arm64: Clean dcache to PoC when changing PTE due to CoW

README