From: Marc Zyngier <marc.zyngier@xxxxxxx>
[ Upstream commit 517953c2c47f9c00a002f588ac856a5bc70cede3 ]
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@xxxxxxx>
Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Tested-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
arch/arm64/kernel/cpu_errata.c | 32 ++++++++++++++------
1 file changed, 23 insertions(+), 9 deletions(-)
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index a9ad932160cc..c623b58a7e2b 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -198,22 +198,36 @@ 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:
--
2.20.1
