KVM: arm64: selftests: Add support to disable and enable local IRQs

Add functions local_irq_enable() and local_irq_disable() to
enable and disable the IRQs from the guest, respectively.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211007233439.1826892-9-rananta@google.com

tools/testing/selftests/kvm/include/aarch64/processor.h

@@ -172,4 +172,14 @@ static __always_inline u32 __raw_readl(const volatile void *addr)
 #define writel(v,c)		({ __iowmb(); writel_relaxed((v),(c));})
 #define readl(c)		({ u32 __v = readl_relaxed(c); __iormb(__v); __v; })
 
+static inline void local_irq_enable(void)
+{
+	asm volatile("msr daifclr, #3" : : : "memory");
+}
+
+static inline void local_irq_disable(void)
+{
+	asm volatile("msr daifset, #3" : : : "memory");
+}
+
 #endif /* SELFTEST_KVM_PROCESSOR_H */