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 <james.morse@xxxxxxx>
Reviewed-by: Punit Agrawal <punit.agrawal@xxxxxxx>
Tested-by: Tyler Baicar <tbaicar@xxxxxxxxxxxxxx>
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
CC: Xie XiuQi <xiexiuqi@xxxxxxxxxx>
CC: gengdongjiu <gengdongjiu@xxxxxxxxxx>
---
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 <linux/init.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
+#include <linux/irq_work.h>
#include <linux/memblock.h>
#include <linux/of_fdt.h>
#include <linux/smp.h>
@@ -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;
--
2.20.1
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