On Tue, May 22, 2018 at 04:06:37PM +0100, Marc Zyngier wrote: > In a heterogeneous system, we can end up with both affected and > unaffected CPUs. Let's check their status before calling into the > firmware. > > Signed-off-by: Marc Zyngier <marc.zyng...@arm.com>
Ah, I guess this may fix the issue I noted with the prior patch, assuming we only set arm64_ssbd_callback_required for a CPU when the FW supports the mitigation. If so, if you fold this together with the prior patch: Reviewed-by: Mark Rutland <mark.rutl...@arm.com> Thanks, Mark. > --- > arch/arm64/kernel/cpu_errata.c | 2 ++ > arch/arm64/kernel/entry.S | 11 +++++++---- > 2 files changed, 9 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c > index 46b3aafb631a..0288d6cf560e 100644 > --- a/arch/arm64/kernel/cpu_errata.c > +++ b/arch/arm64/kernel/cpu_errata.c > @@ -233,6 +233,8 @@ enable_smccc_arch_workaround_1(const struct > arm64_cpu_capabilities *entry) > #endif /* CONFIG_HARDEN_BRANCH_PREDICTOR */ > > #ifdef CONFIG_ARM64_SSBD > +DEFINE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required); > + > void __init arm64_update_smccc_conduit(struct alt_instr *alt, > __le32 *origptr, __le32 *updptr, > int nr_inst) > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index f33e6aed3037..29ad672a6abd 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -140,8 +140,10 @@ alternative_else_nop_endif > > // This macro corrupts x0-x3. It is the caller's duty > // to save/restore them if required. > - .macro apply_ssbd, state > + .macro apply_ssbd, state, targ, tmp1, tmp2 > #ifdef CONFIG_ARM64_SSBD > + ldr_this_cpu \tmp2, arm64_ssbd_callback_required, \tmp1 > + cbz \tmp2, \targ > mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2 > mov w1, #\state > alternative_cb arm64_update_smccc_conduit > @@ -176,12 +178,13 @@ alternative_cb_end > ldr x19, [tsk, #TSK_TI_FLAGS] // since we can unmask debug > disable_step_tsk x19, x20 // exceptions when scheduling. > > - apply_ssbd 1 > + apply_ssbd 1, 1f, x22, x23 > > #ifdef CONFIG_ARM64_SSBD > ldp x0, x1, [sp, #16 * 0] > ldp x2, x3, [sp, #16 * 1] > #endif > +1: > > mov x29, xzr // fp pointed to user-space > .else > @@ -323,8 +326,8 @@ alternative_if ARM64_WORKAROUND_845719 > alternative_else_nop_endif > #endif > 3: > - apply_ssbd 0 > - > + apply_ssbd 0, 5f, x0, x1 > +5: > .endif > > msr elr_el1, x21 // set up the return data > -- > 2.14.2 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-ker...@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
