ARM: KVM: report support for SMCCC_ARCH_WORKAROUND_1

Report support for SMCCC_ARCH_WORKAROUND_1 to KVM guests for affected
CPUs.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Boot-tested-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm/include/asm/kvm_host.h

@@ -21,6 +21,7 @@
 
 #include <linux/types.h>
 #include <linux/kvm_types.h>
+#include <asm/cputype.h>
 #include <asm/kvm.h>
 #include <asm/kvm_asm.h>
 #include <asm/kvm_mmio.h>
@@ -311,8 +312,17 @@ static inline void kvm_arm_vhe_guest_exit(void) {}
 
 static inline bool kvm_arm_harden_branch_predictor(void)
 {
-	/* No way to detect it yet, pretend it is not there. */
-	return false;
+	switch(read_cpuid_part()) {
+#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
+	case ARM_CPU_PART_BRAHMA_B15:
+	case ARM_CPU_PART_CORTEX_A12:
+	case ARM_CPU_PART_CORTEX_A15:
+	case ARM_CPU_PART_CORTEX_A17:
+		return true;
+#endif
+	default:
+		return false;
+	}
 }
 
 #endif /* __ARM_KVM_HOST_H__ */