Re: [PATCH v3 01/12] KVM: arm64: selftests: Add MMIO readl/writel support

Define the readl() and writel() functions for the guests to
access (4-byte) the MMIO region.

The routines, and their dependents, are inspired from the kernel's
arch/arm64/include/asm/io.h and arch/arm64/include/asm/barrier.h.

Signed-off-by: Raghavendra Rao Ananta <redacted>
---
 .../selftests/kvm/include/aarch64/processor.h | 45 ++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/include/aarch64/processor.h b/tools/testing/selftests/kvm/include/aarch64/processor.h
index c0273aefa63d..3cbaf5c1e26b 100644
--- a/tools/testing/selftests/kvm/include/aarch64/processor.h
+++ b/tools/testing/selftests/kvm/include/aarch64/processor.h

@@ -130,6 +130,49 @@ void vm_install_sync_handler(struct kvm_vm *vm,
 	val;								  \
 })
 
-#define isb()	asm volatile("isb" : : : "memory")
+#define isb()		asm volatile("isb" : : : "memory")
+#define dsb(opt)	asm volatile("dsb " #opt : : : "memory")
+#define dmb(opt)	asm volatile("dmb " #opt : : : "memory")
+
+#define dma_wmb()	dmb(oshst)
+#define __iowmb()	dma_wmb()
+
+#define dma_rmb()	dmb(oshld)
+
+#define __iormb(v)							\
+({									\
+	unsigned long tmp;						\
+									\
+	dma_rmb();							\
+									\
+	/*								\
+	 * Courtesy of arch/arm64/include/asm/io.h:			\
+	 * Create a dummy control dependency from the IO read to any	\
+	 * later instructions. This ensures that a subsequent call	\
+	 * to udelay() will be ordered due to the ISB in __delay().	\

+	 */								\
+	asm volatile("eor	%0, %1, %1\n"				\
+		     "cbnz	%0, ."					\
+		     : "=r" (tmp) : "r" ((unsigned long)(v))		\
+		     : "memory");					\
+})
+
+static __always_inline void __raw_writel(u32 val, volatile void *addr)
+{
+	asm volatile("str %w0, [%1]" : : "rZ" (val), "r" (addr));
+}
+
+static __always_inline u32 __raw_readl(const volatile void *addr)
+{
+	u32 val;
+	asm volatile("ldr %w0, [%1]" : "=r" (val) : "r" (addr));
+	return val;
+}
+
+#define writel_relaxed(v,c)	((void)__raw_writel((__force u32)cpu_to_le32(v),(c)))
+#define readl_relaxed(c)	({ u32 __r = le32_to_cpu((__force __le32)__raw_readl(c)); __r; })