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authorJames Morse <james.morse@arm.com>2019-01-29 18:48:50 +0000
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2019-02-07 23:10:45 +0100
commitd44f1b8dd7e66d80cc4205809e5ace866bd851da (patch)
tree102c993327b0f620c9d1aefcc95ad3d7819fd68c /arch/arm64/kernel
parent0db5e0223035b2c84e6186831fc27511270af812 (diff)
downloadlinux-d44f1b8dd7e66d80cc4205809e5ace866bd851da.tar.bz2
arm64: KVM/mm: Move SEA handling behind a single 'claim' interface
To split up APEIs in_nmi() path, the caller needs to always be in_nmi(). Add a helper to do the work and claim the notification. When KVM or the arch code takes an exception that might be a RAS notification, it asks the APEI firmware-first code whether it wants to claim the exception. A future kernel-first mechanism may be queried afterwards, and claim the notification, otherwise we fall through to the existing default behaviour. The NOTIFY_SEA code was merged before considering multiple, possibly interacting, NMI-like notifications and the need to consider kernel first in the future. Make the 'claiming' behaviour explicit. Restructuring the APEI code to allow multiple NMI-like notifications means any notification that might interrupt interrupts-masked code must always be wrapped in nmi_enter()/nmi_exit(). This will allow APEI to use in_nmi() to use the right fixmap entries. Mask SError over this window to prevent an asynchronous RAS error arriving and tripping 'nmi_enter()'s BUG_ON(in_nmi()). Signed-off-by: James Morse <james.morse@arm.com> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Tested-by: Tyler Baicar <tbaicar@codeaurora.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'arch/arm64/kernel')
-rw-r--r--arch/arm64/kernel/acpi.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index 44e3c351e1ea..803f0494dd3e 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -27,8 +27,10 @@
#include <linux/smp.h>
#include <linux/serial_core.h>
+#include <acpi/ghes.h>
#include <asm/cputype.h>
#include <asm/cpu_ops.h>
+#include <asm/daifflags.h>
#include <asm/pgtable.h>
#include <asm/smp_plat.h>
@@ -256,3 +258,32 @@ pgprot_t __acpi_get_mem_attribute(phys_addr_t addr)
return __pgprot(PROT_NORMAL_NC);
return __pgprot(PROT_DEVICE_nGnRnE);
}
+
+/*
+ * Claim Synchronous External Aborts as a firmware first notification.
+ *
+ * Used by KVM and the arch do_sea handler.
+ * @regs may be NULL when called from process context.
+ */
+int apei_claim_sea(struct pt_regs *regs)
+{
+ int err = -ENOENT;
+ unsigned long current_flags;
+
+ if (!IS_ENABLED(CONFIG_ACPI_APEI_GHES))
+ return err;
+
+ current_flags = arch_local_save_flags();
+
+ /*
+ * SEA can interrupt SError, mask it and describe this as an NMI so
+ * that APEI defers the handling.
+ */
+ local_daif_restore(DAIF_ERRCTX);
+ nmi_enter();
+ err = ghes_notify_sea();
+ nmi_exit();
+ local_daif_restore(current_flags);
+
+ return err;
+}