arm64: ssbd: Add global mitigation state accessor

We're about to need the mitigation state in various parts of the
kernel in order to do the right thing for userspace and guests.

Let's expose an accessor that will let other subsystems know
about the state.

Reviewed-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index b50650f3e496b2c37399712121fea3e850e797d1..b0fc3224ce8ae10ae6444668f3990ce837aa4bba 100644 (file)
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -543,6 +543,16 @@ static inline u64 read_zcr_features(void)
 #define ARM64_SSBD_FORCE_ENABLE                2
 #define ARM64_SSBD_MITIGATED           3
 
+static inline int arm64_get_ssbd_state(void)
+{
+#ifdef CONFIG_ARM64_SSBD
+       extern int ssbd_state;
+       return ssbd_state;
+#else
+       return ARM64_SSBD_UNKNOWN;
+#endif
+}
+
 #endif /* __ASSEMBLY__ */
 
 #endif