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x86/bugs: Add AUTO mitigations for mds/taa/mmio/rfds

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Add AUTO mitigations for mds/taa/mmio/rfds to create consistent vulnerability
handling.  These AUTO mitigations will be turned into the appropriate default
mitigations in the <vuln>_select_mitigation() functions.  Later, these will be
used with the new attack vector controls to help select appropriate
mitigations.

Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250108202515.385902-4-david.kaplan@amd.com
This commit is contained in:
David Kaplan 2025-01-08 14:24:43 -06:00 committed by Borislav Petkov (AMD)
parent 2c93762ec4
commit b8ce25df29
2 changed files with 17 additions and 4 deletions
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1
arch/x86/include/asm/processor.h
View File

@ -757,6 +757,7 @@ extern enum l1tf_mitigations l1tf_mitigation;
enum mds_mitigations {
MDS_MITIGATION_OFF,
MDS_MITIGATION_AUTO,
MDS_MITIGATION_FULL,
MDS_MITIGATION_VMWERV,
};

20
arch/x86/kernel/cpu/bugs.c
View File

@ -238,7 +238,7 @@ static void x86_amd_ssb_disable(void)
/* Default mitigation for MDS-affected CPUs */
static enum mds_mitigations mds_mitigation __ro_after_init =
IS_ENABLED(CONFIG_MITIGATION_MDS) ? MDS_MITIGATION_FULL : MDS_MITIGATION_OFF;
IS_ENABLED(CONFIG_MITIGATION_MDS) ? MDS_MITIGATION_AUTO : MDS_MITIGATION_OFF;
static bool mds_nosmt __ro_after_init = false;
static const char * const mds_strings[] = {
@ -249,6 +249,7 @@ static const char * const mds_strings[] = {
enum taa_mitigations {
TAA_MITIGATION_OFF,
TAA_MITIGATION_AUTO,
TAA_MITIGATION_UCODE_NEEDED,
TAA_MITIGATION_VERW,
TAA_MITIGATION_TSX_DISABLED,
@ -256,27 +257,29 @@ enum taa_mitigations {
/* Default mitigation for TAA-affected CPUs */
static enum taa_mitigations taa_mitigation __ro_after_init =
IS_ENABLED(CONFIG_MITIGATION_TAA) ? TAA_MITIGATION_VERW : TAA_MITIGATION_OFF;
IS_ENABLED(CONFIG_MITIGATION_TAA) ? TAA_MITIGATION_AUTO : TAA_MITIGATION_OFF;
enum mmio_mitigations {
MMIO_MITIGATION_OFF,
MMIO_MITIGATION_AUTO,
MMIO_MITIGATION_UCODE_NEEDED,
MMIO_MITIGATION_VERW,
};
/* Default mitigation for Processor MMIO Stale Data vulnerabilities */
static enum mmio_mitigations mmio_mitigation __ro_after_init =
IS_ENABLED(CONFIG_MITIGATION_MMIO_STALE_DATA) ? MMIO_MITIGATION_VERW : MMIO_MITIGATION_OFF;
IS_ENABLED(CONFIG_MITIGATION_MMIO_STALE_DATA) ? MMIO_MITIGATION_AUTO : MMIO_MITIGATION_OFF;
enum rfds_mitigations {
RFDS_MITIGATION_OFF,
RFDS_MITIGATION_AUTO,
RFDS_MITIGATION_VERW,
RFDS_MITIGATION_UCODE_NEEDED,
};
/* Default mitigation for Register File Data Sampling */
static enum rfds_mitigations rfds_mitigation __ro_after_init =
IS_ENABLED(CONFIG_MITIGATION_RFDS) ? RFDS_MITIGATION_VERW : RFDS_MITIGATION_OFF;
IS_ENABLED(CONFIG_MITIGATION_RFDS) ? RFDS_MITIGATION_AUTO : RFDS_MITIGATION_OFF;
static void __init mds_select_mitigation(void)
{
@ -285,6 +288,9 @@ static void __init mds_select_mitigation(void)
return;
}
if (mds_mitigation == MDS_MITIGATION_AUTO)
mds_mitigation = MDS_MITIGATION_FULL;
if (mds_mitigation == MDS_MITIGATION_FULL) {
if (!boot_cpu_has(X86_FEATURE_MD_CLEAR))
mds_mitigation = MDS_MITIGATION_VMWERV;
@ -514,6 +520,9 @@ static void __init rfds_select_mitigation(void)
if (rfds_mitigation == RFDS_MITIGATION_OFF)
return;
if (rfds_mitigation == RFDS_MITIGATION_AUTO)
rfds_mitigation = RFDS_MITIGATION_VERW;
if (x86_arch_cap_msr & ARCH_CAP_RFDS_CLEAR)
setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF);
else
@ -1979,6 +1988,7 @@ void cpu_bugs_smt_update(void)
switch (mds_mitigation) {
case MDS_MITIGATION_FULL:
case MDS_MITIGATION_AUTO:
case MDS_MITIGATION_VMWERV:
if (sched_smt_active() && !boot_cpu_has(X86_BUG_MSBDS_ONLY))
pr_warn_once(MDS_MSG_SMT);
@ -1990,6 +2000,7 @@ void cpu_bugs_smt_update(void)
switch (taa_mitigation) {
case TAA_MITIGATION_VERW:
case TAA_MITIGATION_AUTO:
case TAA_MITIGATION_UCODE_NEEDED:
if (sched_smt_active())
pr_warn_once(TAA_MSG_SMT);
@ -2001,6 +2012,7 @@ void cpu_bugs_smt_update(void)
switch (mmio_mitigation) {
case MMIO_MITIGATION_VERW:
case MMIO_MITIGATION_AUTO:
case MMIO_MITIGATION_UCODE_NEEDED:
if (sched_smt_active())
pr_warn_once(MMIO_MSG_SMT);