4.9-stable review patch. If anyone has any objections, please let me know.
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From: Marc Zyngier marc.zyngier@arm.com
[ Upstream commit e21da1c992007594d391e7b301779cf30f438691 ]
A recent update to the ARM SMCCC ARCH_WORKAROUND_1 specification allows firmware to return a non zero, positive value to describe that although the mitigation is implemented at the higher exception level, the CPU on which the call is made is not affected.
Let's relax the check on the return value from ARCH_WORKAROUND_1 so that we only error out if the returned value is negative.
Fixes: b092201e0020 ("arm64: Add ARM_SMCCC_ARCH_WORKAROUND_1 BP hardening support") Signed-off-by: Marc Zyngier marc.zyngier@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/kernel/cpu_errata.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -160,7 +160,7 @@ static int enable_smccc_arch_workaround_ case PSCI_CONDUIT_HVC: arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, ARM_SMCCC_ARCH_WORKAROUND_1, &res); - if (res.a0) + if ((int)res.a0 < 0) return 0; cb = call_hvc_arch_workaround_1; smccc_start = __smccc_workaround_1_hvc_start; @@ -170,7 +170,7 @@ static int enable_smccc_arch_workaround_ case PSCI_CONDUIT_SMC: arm_smccc_1_1_smc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, ARM_SMCCC_ARCH_WORKAROUND_1, &res); - if (res.a0) + if ((int)res.a0 < 0) return 0; cb = call_smc_arch_workaround_1; smccc_start = __smccc_workaround_1_smc_start;