Re: [PATCH v3 3/3] arm64: Add workaround for Arm Cortex-A77 erratum 1508412
From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2020-07-29 16:39:50
Also in:
kvmarm
On Fri, Jul 17, 2020 at 02:52:33PM -0600, Rob Herring wrote:
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h index ce3080834bfa..ce5b0d9b12bf 100644 --- a/arch/arm64/include/asm/kvm_hyp.h +++ b/arch/arm64/include/asm/kvm_hyp.h@@ -46,6 +46,17 @@ #define read_sysreg_el2(r) read_sysreg_elx(r, _EL2, _EL1) #define write_sysreg_el2(v,r) write_sysreg_elx(v, r, _EL2, _EL1) +static inline u64 __hyp_text read_sysreg_par(void) +{ + u64 par; + if (cpus_have_const_cap(ARM64_WORKAROUND_1508412)) + dmb(sy); + par = read_sysreg(par_el1); + if (cpus_have_const_cap(ARM64_WORKAROUND_1508412)) + dmb(sy); + return par; +}
Even if that's not always called on a critical path, I agree with Andrew that we could use alternatives here for dmb(sy).
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index baf5ce9225ce..3f798e0f1419 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c@@ -94,10 +94,16 @@ static bool __vcpu_read_sys_reg_from_cpu(int reg, u64 *val) case TPIDR_EL1: *val = read_sysreg_s(SYS_TPIDR_EL1); break; case AMAIR_EL1: *val = read_sysreg_s(SYS_AMAIR_EL12); break; case CNTKCTL_EL1: *val = read_sysreg_s(SYS_CNTKCTL_EL12); break; - case PAR_EL1: *val = read_sysreg_s(SYS_PAR_EL1); break; case DACR32_EL2: *val = read_sysreg_s(SYS_DACR32_EL2); break; case IFSR32_EL2: *val = read_sysreg_s(SYS_IFSR32_EL2); break; case DBGVCR32_EL2: *val = read_sysreg_s(SYS_DBGVCR32_EL2); break; + case PAR_EL1: + if (cpus_have_const_cap(ARM64_WORKAROUND_1508412)) + dmb(sy); + *val = read_sysreg_s(SYS_PAR_EL1); + if (cpus_have_const_cap(ARM64_WORKAROUND_1508412)) + dmb(sy); + break; default: return false; }
Can't we use read_sysreg_par() directly here?
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 8afb238ff335..98609532e61a 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c@@ -260,7 +260,17 @@ static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr, local_irq_save(flags); asm volatile("at s1e1r, %0" :: "r" (addr)); isb(); + /* + * Arm Erratum 1508412 requires dmb(sy) before and after reads of + * PAR_EL1. + * As this location is not a hot path, just condition it on the config + * option. + */ + if (IS_ENABLED(CONFIG_ARM64_ERRATUM_1508412)) + dmb(sy); par = read_sysreg(par_el1); + if (IS_ENABLED(CONFIG_ARM64_ERRATUM_1508412)) + dmb(sy); local_irq_restore(flags);
Why not read_sysreg_par()? -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel