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x86/bugs: Add a separate config for SSB

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Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.

Create an entry for the SSB CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240729164105.554296-10-leitao@debian.org
This commit is contained in:
Breno Leitao 2024-07-29 09:40:57 -07:00 committed by Borislav Petkov (AMD)
parent 72c70f480a
commit b908cdab06
2 changed files with 16 additions and 4 deletions
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10
arch/x86/Kconfig
View File

@ -2741,6 +2741,16 @@ config MITIGATION_SRBDS
using MDS techniques.
See also
<file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst>
config MITIGATION_SSB
bool "Mitigate Speculative Store Bypass (SSB) hardware bug"
default y
help
Enable mitigation for Speculative Store Bypass (SSB). SSB is a
hardware security vulnerability and its exploitation takes advantage
of speculative execution in a similar way to the Meltdown and Spectre
security vulnerabilities.
endif
config ARCH_HAS_ADD_PAGES

10
arch/x86/kernel/cpu/bugs.c
View File

@ -2027,10 +2027,12 @@ static const struct {
static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
{
enum ssb_mitigation_cmd cmd = SPEC_STORE_BYPASS_CMD_AUTO;
enum ssb_mitigation_cmd cmd;
char arg[20];
int ret, i;
cmd = IS_ENABLED(CONFIG_MITIGATION_SSB) ?
SPEC_STORE_BYPASS_CMD_AUTO : SPEC_STORE_BYPASS_CMD_NONE;
if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable") ||
cpu_mitigations_off()) {
return SPEC_STORE_BYPASS_CMD_NONE;
@ -2038,7 +2040,7 @@ static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable",
arg, sizeof(arg));
if (ret < 0)
return SPEC_STORE_BYPASS_CMD_AUTO;
return cmd;
for (i = 0; i < ARRAY_SIZE(ssb_mitigation_options); i++) {
if (!match_option(arg, ret, ssb_mitigation_options[i].option))
@ -2049,8 +2051,8 @@ static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
}
if (i >= ARRAY_SIZE(ssb_mitigation_options)) {
pr_err("unknown option (%s). Switching to AUTO select\n", arg);
return SPEC_STORE_BYPASS_CMD_AUTO;
pr_err("unknown option (%s). Switching to default mode\n", arg);
return cmd;
}
}