On Fri, 25 Jan 2019 12:07:08 -0600 Jeremy Linton <[email protected]> wrote:
> From: Marc Zyngier <[email protected]> > > 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 <[email protected]> > Signed-off-by: Jeremy Linton <[email protected]> Yes, I stumbled over this in the firmware spec as well: Reviewed-by: Andre Przywara <[email protected]> Cheers, Andre. > --- > 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 4d23b4d4cfa8..024c83ffff99 100644 > --- a/arch/arm64/kernel/cpu_errata.c > +++ b/arch/arm64/kernel/cpu_errata.c > @@ -217,22 +217,36 @@ 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:
