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[217.140.101.70]) by mx.google.com with ESMTP id j30si2157551edc.365.2019.01.29.10.50.49 for ; Tue, 29 Jan 2019 10:50:49 -0800 (PST) Received-SPF: pass (google.com: domain of james.morse@arm.com designates 217.140.101.70 as permitted sender) client-ip=217.140.101.70; Authentication-Results: mx.google.com; spf=pass (google.com: domain of james.morse@arm.com designates 217.140.101.70 as permitted sender) smtp.mailfrom=james.morse@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D427E1650; Tue, 29 Jan 2019 10:50:48 -0800 (PST) Received: from eglon.cambridge.arm.com (eglon.cambridge.arm.com [10.1.196.105]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 327F33F557; Tue, 29 Jan 2019 10:50:46 -0800 (PST) From: James Morse To: linux-acpi@vger.kernel.org Cc: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, Borislav Petkov , Marc Zyngier , Christoffer Dall , Will Deacon , Catalin Marinas , Naoya Horiguchi , Rafael Wysocki , Len Brown , Tony Luck , Dongjiu Geng , Xie XiuQi , james.morse@arm.com Subject: [PATCH v8 24/26] arm64: acpi: Make apei_claim_sea() synchronise with APEI's irq work Date: Tue, 29 Jan 2019 18:49:00 +0000 Message-Id: <20190129184902.102850-25-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190129184902.102850-1-james.morse@arm.com> References: <20190129184902.102850-1-james.morse@arm.com> MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP APEI is unable to do all of its error handling work in nmi-context, so it defers non-fatal work onto the irq_work queue. arch_irq_work_raise() sends an IPI to the calling cpu, but this is not guaranteed to be taken before returning to user-space. Unless the exception interrupted a context with irqs-masked, irq_work_run() can run immediately. Otherwise return -EINPROGRESS to indicate ghes_notify_sea() found some work to do, but it hasn't finished yet. With this apei_claim_sea() returning '0' means this external-abort was also notification of a firmware-first RAS error, and that APEI has processed the CPER records. Signed-off-by: James Morse Reviewed-by: Punit Agrawal Tested-by: Tyler Baicar Acked-by: Catalin Marinas CC: Xie XiuQi CC: gengdongjiu Reviewed-by: Julien Thierry --- Changes since v7: * Added Catalin's ack, then: * Added __irq_enter()/exit() calls so if we interrupted preemptible code, the preempt count matches what other irq-work expects. * Changed the 'if (!arch_irqs_disabled_flags(interrupted_flags))' test to be safe before/after Julien's PMR series. Changes since v6: * Added pr_warn() for the EINPROGRESS case so panic-tracebacks show 'APEI was here'. * Tinkered with the commit message Changes since v2: * Removed IS_ENABLED() check, done by the caller unless we have a dummy definition. --- arch/arm64/kernel/acpi.c | 23 +++++++++++++++++++++++ arch/arm64/mm/fault.c | 9 ++++----- 2 files changed, 27 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index 803f0494dd3e..8288ae0c8f3b 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include #include @@ -268,12 +269,17 @@ pgprot_t __acpi_get_mem_attribute(phys_addr_t addr) int apei_claim_sea(struct pt_regs *regs) { int err = -ENOENT; + bool return_to_irqs_enabled; unsigned long current_flags; if (!IS_ENABLED(CONFIG_ACPI_APEI_GHES)) return err; current_flags = arch_local_save_flags(); + return_to_irqs_enabled = !irqs_disabled_flags(current_flags); + + if (regs) + return_to_irqs_enabled = interrupts_enabled(regs); /* * SEA can interrupt SError, mask it and describe this as an NMI so @@ -283,6 +289,23 @@ int apei_claim_sea(struct pt_regs *regs) nmi_enter(); err = ghes_notify_sea(); nmi_exit(); + + /* + * APEI NMI-like notifications are deferred to irq_work. Unless + * we interrupted irqs-masked code, we can do that now. + */ + if (!err) { + if (return_to_irqs_enabled) { + local_daif_restore(DAIF_PROCCTX_NOIRQ); + __irq_enter(); + irq_work_run(); + __irq_exit(); + } else { + pr_warn("APEI work queued but not completed"); + err = -EINPROGRESS; + } + } + local_daif_restore(current_flags); return err; diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index e1c84c2e1cab..1611714f8333 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -642,11 +642,10 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs) inf = esr_to_fault_info(esr); - /* - * Return value ignored as we rely on signal merging. - * Future patches will make this more robust. - */ - apei_claim_sea(regs); + if (apei_claim_sea(regs) == 0) { + /* APEI claimed this as a firmware-first notification */ + return 0; + } if (esr & ESR_ELx_FnV) siaddr = NULL;