linux/arch/x86/boot
Tom Lendacky 1fec416c03 x86/sev: Evict cache lines during SNP memory validation
Commit 7b306dfa32 upstream.

An SNP cache coherency vulnerability requires a cache line eviction
mitigation when validating memory after a page state change to private.
The specific mitigation is to touch the first and last byte of each 4K
page that is being validated. There is no need to perform the mitigation
when performing a page state change to shared and rescinding validation.

CPUID bit Fn8000001F_EBX[31] defines the COHERENCY_SFW_NO CPUID bit that,
when set, indicates that the software mitigation for this vulnerability is
not needed.

Implement the mitigation and invoke it when validating memory (making it
private) and the COHERENCY_SFW_NO bit is not set, indicating the SNP guest
is vulnerable.

Co-developed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-08-15 12:05:12 +02:00
..
compressed x86/sev: Evict cache lines during SNP memory validation 2025-08-15 12:05:12 +02:00
tools x86/boot: Increase section and file alignment to 4k/512 2024-04-27 17:07:06 +02:00
.gitignore x86/boot: Modernize genimage script; hdimage+EFI support 2021-05-10 12:27:50 +02:00
a20.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 497 2019-06-19 17:09:53 +02:00
apm.c x86/boot: Fix comment spelling 2020-03-17 20:52:52 +01:00
bioscall.S x86/boot: Avoid using Intel mnemonics in AT&T syntax asm 2023-01-18 11:58:22 +01:00
bitops.h x86/boot: Remove superfluous type casting from arch/x86/boot/bitops.h 2022-08-15 19:17:43 +02:00
boot.h - Add a "make x86_debug.config" target which enables a bunch of useful 2022-05-23 18:15:44 -07:00
cmdline.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
copy.S x86/asm: Do not annotate functions with GLOBAL 2019-10-18 11:25:58 +02:00
cpu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 497 2019-06-19 17:09:53 +02:00
cpucheck.c x86/boot: Use MSR read/write helpers instead of inline assembly 2022-04-06 13:02:13 +02:00
cpuflags.c x86/sev: Evict cache lines during SNP memory validation 2025-08-15 12:05:12 +02:00
cpuflags.h x86/tdx: Detect TDX at early kernel decompression time 2022-04-07 08:27:51 -07:00
ctype.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
early_serial_console.c x86: Clean up 'sizeof x' => 'sizeof(x)' 2018-10-29 07:13:28 +01:00
edd.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 497 2019-06-19 17:09:53 +02:00
genimage.sh x86/build: Fix broken copy command in genimage.sh when making isoimage 2025-06-04 14:40:11 +02:00
header.S x86/efistub: Use 1:1 file:memory mapping for PE/COFF .compat section 2024-04-27 17:07:06 +02:00
install.sh kbuild: factor out the common installation code into scripts/install.sh 2022-05-11 21:45:53 +09:00
io.h x86/boot: Port I/O: Allow to hook up alternative helpers 2022-04-07 08:27:52 -07:00
main.c - Add a "make x86_debug.config" target which enables a bunch of useful 2022-05-23 18:15:44 -07:00
Makefile x86/boot: Split off PE/COFF .data section 2024-04-27 17:07:06 +02:00
memory.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 497 2019-06-19 17:09:53 +02:00
mkcpustr.c x86/cpu: Print VMX flags in /proc/cpuinfo using VMX_FEATURES_* 2020-01-13 18:36:02 +01:00
msr.h x86/boot: Introduce helpers for MSR reads/writes 2022-04-06 12:59:17 +02:00
mtools.conf.in x86/boot: Fix make hdimage with older versions of mtools 2021-09-29 11:06:47 +02:00
pm.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 497 2019-06-19 17:09:53 +02:00
pmjump.S x86/asm: Do not annotate functions with GLOBAL 2019-10-18 11:25:58 +02:00
printf.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 497 2019-06-19 17:09:53 +02:00
regs.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 83 2019-05-24 17:37:52 +02:00
setup.ld x86/efistub: Use 1:1 file:memory mapping for PE/COFF .compat section 2024-04-27 17:07:06 +02:00
string.c x86/boot: Add kstrtoul() from lib/ 2020-05-04 15:19:07 +02:00
string.h x86/boot/string: Add missing function prototypes 2021-12-10 19:49:06 +01:00
tty.c treewide: Convert macro and uses of __section(foo) to __section("foo") 2020-10-25 14:51:49 -07:00
version.c kbuild: build init/built-in.a just once 2022-09-29 04:40:15 +09:00
vesa.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 48 2019-05-24 17:27:13 +02:00
video-bios.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 497 2019-06-19 17:09:53 +02:00
video-mode.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 497 2019-06-19 17:09:53 +02:00
video-vesa.c sysfb: Enable boot time VESA graphic mode selection 2022-03-04 20:55:33 +01:00
video-vga.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 497 2019-06-19 17:09:53 +02:00
video.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 497 2019-06-19 17:09:53 +02:00
video.h treewide: Convert macro and uses of __section(foo) to __section("foo") 2020-10-25 14:51:49 -07:00