[PATCH] arm64: acpi: fix DAIF manipulation with pNMI

[PATCH] arm64: acpi: fix DAIF manipulation with pNMI

[Mark Rutland]

Since commit:

  d44f1b8dd7e66d80 ("arm64: KVM/mm: Move SEA handling behind a single 'claim' interface")

... the top-level APEI SEA handler has the shape:

1. current_flags = arch_local_save_flags()
2. local_daif_restore(DAIF_ERRCTX)
3. <GHES handler>
4. local_daif_restore(current_flags)

However, since commit:

  4a503217ce37e1f4 ("arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking")

... when pMIs are in use, arch_local_save_flags() will save the PMR
value rather than the DAIF flags.

The combination of these two commits means that the APEI SEA handler
will erroneously attempt to restore the PMR value into DAIF. Fix this by
factoring local_daif_save_flags() out of local_daif_save(), so that we
can consistently save DAIF in step #1, regardless of whether pNMIs are
in use.

Both commits were introduced concurrently in v5.0.

Fixes: 4a503217ce37e1f4 ("arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking")
Fixes: d44f1b8dd7e66d80 ("arm64: KVM/mm: Move SEA handling behind a single 'claim' interface")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Julien Thierry <julien.thierry.kdev@gmail.com>
Cc: Will Deacon <will@kernel.org>
---
 arch/arm64/include/asm/daifflags.h | 11 ++++++++++-
 arch/arm64/kernel/acpi.c           |  2 +-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/daifflags.h b/arch/arm64/include/asm/daifflags.h
index 72acd2db167f..ec213b4a1650 100644
--- a/arch/arm64/include/asm/daifflags.h
+++ b/arch/arm64/include/asm/daifflags.h
@@ -38,7 +38,7 @@ static inline void local_daif_mask(void)
 	trace_hardirqs_off();
 }
 
-static inline unsigned long local_daif_save(void)
+static inline unsigned long local_daif_save_flags(void)
 {
 	unsigned long flags;
 
@@ -50,6 +50,15 @@ static inline unsigned long local_daif_save(void)
 			flags |= PSR_I_BIT;
 	}
 
+	return flags;
+}
+
+static inline unsigned long local_daif_save(void)
+{
+	unsigned long flags;
+
+	flags = local_daif_save_flags();
+
 	local_daif_mask();
 
 	return flags;
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index 3a58e9db5cfe..a100483b47c4 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -274,7 +274,7 @@ int apei_claim_sea(struct pt_regs *regs)
 	if (!IS_ENABLED(CONFIG_ACPI_APEI_GHES))
 		return err;
 
-	current_flags = arch_local_save_flags();
+	current_flags = local_daif_save_flags();
 
 	/*
 	 * SEA can interrupt SError, mask it and describe this as an NMI so
-- 
2.11.0


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