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arm64: Delay initialisation of cpuinfo_arm64::reg_{zcr,smcr}

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Even if we are now able to tell the kernel to avoid exposing SVE/SME
from the command line, we still have a couple of places where we
unconditionally access the ZCR_EL1 (resp. SMCR_EL1) registers.

On systems with broken firmwares, this results in a crash even if
arm64.nosve (resp. arm64.nosme) was passed on the command-line.

To avoid this, only update cpuinfo_arm64::reg_{zcr,smcr} once
we have computed the sanitised version for the corresponding
feature registers (ID_AA64PFR0 for SVE, and ID_AA64PFR1 for
SME). This results in some minor refactoring.

Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Peter Collingbourne <pcc@google.com>
Tested-by: Peter Collingbourne <pcc@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220720105219.1755096-1-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Marc Zyngier 2022-07-20 11:52:19 +01:00 committed by Will Deacon
parent f96d67a8af
commit 892f7237b3
2 changed files with 29 additions and 28 deletions
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41
arch/arm64/kernel/cpufeature.c
View file

@ -1001,15 +1001,24 @@ void __init init_cpu_features(struct cpuinfo_arm64 *info)
if (id_aa64pfr0_32bit_el0(info->reg_id_aa64pfr0))
init_32bit_cpu_features(&info->aarch32);
if (id_aa64pfr0_sve(info->reg_id_aa64pfr0)) {
if (IS_ENABLED(CONFIG_ARM64_SVE) &&
id_aa64pfr0_sve(read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1))) {
info->reg_zcr = read_zcr_features();
init_cpu_ftr_reg(SYS_ZCR_EL1, info->reg_zcr);
vec_init_vq_map(ARM64_VEC_SVE);
}
if (id_aa64pfr1_sme(info->reg_id_aa64pfr1)) {
if (IS_ENABLED(CONFIG_ARM64_SME) &&
id_aa64pfr1_sme(read_sanitised_ftr_reg(SYS_ID_AA64PFR1_EL1))) {
info->reg_smcr = read_smcr_features();
/*
* We mask out SMPS since even if the hardware
* supports priorities the kernel does not at present
* and we block access to them.
*/
info->reg_smidr = read_cpuid(SMIDR_EL1) & ~SMIDR_EL1_SMPS;
init_cpu_ftr_reg(SYS_SMCR_EL1, info->reg_smcr);
if (IS_ENABLED(CONFIG_ARM64_SME))
vec_init_vq_map(ARM64_VEC_SME);
vec_init_vq_map(ARM64_VEC_SME);
}
if (id_aa64pfr1_mte(info->reg_id_aa64pfr1))
@ -1241,23 +1250,31 @@ void update_cpu_features(int cpu,
taint |= check_update_ftr_reg(SYS_ID_AA64SMFR0_EL1, cpu,
info->reg_id_aa64smfr0, boot->reg_id_aa64smfr0);
if (id_aa64pfr0_sve(info->reg_id_aa64pfr0)) {
if (IS_ENABLED(CONFIG_ARM64_SVE) &&
id_aa64pfr0_sve(read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1))) {
info->reg_zcr = read_zcr_features();
taint |= check_update_ftr_reg(SYS_ZCR_EL1, cpu,
info->reg_zcr, boot->reg_zcr);
/* Probe vector lengths, unless we already gave up on SVE */
if (id_aa64pfr0_sve(read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1)) &&
!system_capabilities_finalized())
/* Probe vector lengths */
if (!system_capabilities_finalized())
vec_update_vq_map(ARM64_VEC_SVE);
}
if (id_aa64pfr1_sme(info->reg_id_aa64pfr1)) {
if (IS_ENABLED(CONFIG_ARM64_SME) &&
id_aa64pfr1_sme(read_sanitised_ftr_reg(SYS_ID_AA64PFR1_EL1))) {
info->reg_smcr = read_smcr_features();
/*
* We mask out SMPS since even if the hardware
* supports priorities the kernel does not at present
* and we block access to them.
*/
info->reg_smidr = read_cpuid(SMIDR_EL1) & ~SMIDR_EL1_SMPS;
taint |= check_update_ftr_reg(SYS_SMCR_EL1, cpu,
info->reg_smcr, boot->reg_smcr);
/* Probe vector lengths, unless we already gave up on SME */
if (id_aa64pfr1_sme(read_sanitised_ftr_reg(SYS_ID_AA64PFR1_EL1)) &&
!system_capabilities_finalized())
/* Probe vector lengths */
if (!system_capabilities_finalized())
vec_update_vq_map(ARM64_VEC_SME);
}

16
arch/arm64/kernel/cpuinfo.c
View file

@ -439,22 +439,6 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info)
if (id_aa64pfr0_32bit_el0(info->reg_id_aa64pfr0))
__cpuinfo_store_cpu_32bit(&info->aarch32);
if (IS_ENABLED(CONFIG_ARM64_SVE) &&
id_aa64pfr0_sve(info->reg_id_aa64pfr0))
info->reg_zcr = read_zcr_features();
if (IS_ENABLED(CONFIG_ARM64_SME) &&
id_aa64pfr1_sme(info->reg_id_aa64pfr1)) {
info->reg_smcr = read_smcr_features();
/*
* We mask out SMPS since even if the hardware
* supports priorities the kernel does not at present
* and we block access to them.
*/
info->reg_smidr = read_cpuid(SMIDR_EL1) & ~SMIDR_EL1_SMPS;
}
cpuinfo_detect_icache_policy(info);
}