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Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0p5i-0002GA-PO; Wed, 29 Jul 2020 16:38:06 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0p5g-0002Fm-Pu for linux-arm-kernel@lists.infradead.org; Wed, 29 Jul 2020 16:38:05 +0000 Received: from gaia (unknown [95.146.230.158]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D80AF206D8; Wed, 29 Jul 2020 16:38:02 +0000 (UTC) Date: Wed, 29 Jul 2020 17:38:00 +0100 From: Catalin Marinas To: Rob Herring Subject: Re: [PATCH v3 3/3] arm64: Add workaround for Arm Cortex-A77 erratum 1508412 Message-ID: <20200729163800.GA24572@gaia> References: <20200717205233.903344-1-robh@kernel.org> <20200717205233.903344-4-robh@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200717205233.903344-4-robh@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200729_123805_120205_52BA2C53 X-CRM114-Status: GOOD ( 18.12 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Suzuki K Poulose , Marc Zyngier , James Morse , linux-arm-kernel@lists.infradead.org, Will Deacon , kvmarm@lists.cs.columbia.edu, Julien Thierry Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jul 17, 2020 at 02:52:33PM -0600, Rob Herring wrote: > 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). > 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? > 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