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arm64: Use firmware to detect CPUs that are not affected by Spectre-v2 

The SMCCC ARCH_WORKAROUND_1 service can indicate that although the
firmware knows about the Spectre-v2 mitigation, this particular
CPU is not vulnerable, and it is thus not necessary to call
the firmware on this CPU.

Let's use this information to our benefit.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
hifive-unleashed-5.2
Marc Zyngier 2019-04-15 16:21:24 -05:00 committed by Will Deacon
parent 73f3816609
commit 517953c2c4
1 changed files with 23 additions and 9 deletions
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32
arch/arm64/kernel/cpu_errata.c
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@ -230,22 +230,36 @@ static int detect_harden_bp_fw(void)
case PSCI_CONDUIT_HVC:
arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
ARM_SMCCC_ARCH_WORKAROUND_1, &res);
if ((int)res.a0 < 0)
switch ((int)res.a0) {
case 1:
/* Firmware says we're just fine */
return 0;
case 0:
cb = call_hvc_arch_workaround_1;
/* This is a guest, no need to patch KVM vectors */
smccc_start = NULL;
smccc_end = NULL;
break;
default:
return -1;
cb = call_hvc_arch_workaround_1;
/* This is a guest, no need to patch KVM vectors */
smccc_start = NULL;
smccc_end = NULL;
}
break;
case PSCI_CONDUIT_SMC:
arm_smccc_1_1_smc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
ARM_SMCCC_ARCH_WORKAROUND_1, &res);
if ((int)res.a0 < 0)
switch ((int)res.a0) {
case 1:
/* Firmware says we're just fine */
return 0;
case 0:
cb = call_smc_arch_workaround_1;
smccc_start = __smccc_workaround_1_smc_start;
smccc_end = __smccc_workaround_1_smc_end;
break;
default:
return -1;
cb = call_smc_arch_workaround_1;
smccc_start = __smccc_workaround_1_smc_start;
smccc_end = __smccc_workaround_1_smc_end;
}
break;
default: