[PATCH v6 07/18] arm64: KVM/mm: Move SEA handling behind a single 'claim' interface
From: bp@alien8.de (Borislav Petkov)
Date: 2018-10-12 10:02:15
Also in:
kvmarm, linux-acpi, linux-mm
On Fri, Sep 21, 2018 at 11:16:54PM +0100, James Morse wrote:
To split up APEIs in_nmi() path, we need the nmi-like callers 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. We can then go on to see if (a future) kernel-first mechanism wants to claim the notification, before falling through to the existing default behaviour. The NOTIFY_SEA code was merged before we had multiple, possibly interacting, NMI-like notifications and the need to consider kernel first in the future. Make the 'claiming' behaviour explicit. As we're restructuring the APEI code to allow multiple NMI-like notifications, any notification that might interrupt interrupts-masked code must always be wrapped in nmi_enter()/nmi_exit(). This allows APEI to use in_nmi() to use the right fixmap entries. We 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 <redacted> Tested-by: Tyler Baicar <redacted>
...
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index ed46dc188b22..a9b8bba014b5 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c@@ -28,8 +28,10 @@ #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>@@ -257,3 +259,30 @@ 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 = arch_local_save_flags(); + + if (!IS_ENABLED(CONFIG_ACPI_APEI_SEA)) + return err;
I don't know what side effects arch_local_save_flags() has on ARM but if
we return here, it looks to me like useless work.
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Regards/Gruss,
Boris.
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