At times, such as when in the interrupt handler, the guest wants to
get the vCPU-id that it's running on. As a result, introduce
get_vcpuid() that parses the MPIDR_EL1 and returns the vcpuid to the
requested caller.

Signed-off-by: Raghavendra Rao Ananta <[email protected]>
---
 .../selftests/kvm/include/aarch64/processor.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/aarch64/processor.h 
b/tools/testing/selftests/kvm/include/aarch64/processor.h
index ae7a079ae180..e9342e63d05d 100644
--- a/tools/testing/selftests/kvm/include/aarch64/processor.h
+++ b/tools/testing/selftests/kvm/include/aarch64/processor.h
@@ -248,4 +248,23 @@ static inline void local_irq_disable(void)
        asm volatile("msr daifset, #3" : : : "memory");
 }
 
+#define MPIDR_LEVEL_BITS 8
+#define MPIDR_LEVEL_SHIFT(level) (MPIDR_LEVEL_BITS * level)
+#define MPIDR_LEVEL_MASK ((1 << MPIDR_LEVEL_BITS) - 1)
+#define MPIDR_AFFINITY_LEVEL(mpidr, level) \
+       ((mpidr >> MPIDR_LEVEL_SHIFT(level)) & MPIDR_LEVEL_MASK)
+
+static inline uint32_t get_vcpuid(void)
+{
+       uint32_t vcpuid = 0;
+       uint64_t mpidr = read_sysreg(mpidr_el1);
+
+       /* KVM limits only 16 vCPUs at level 0 */
+       vcpuid = mpidr & 0x0f;
+       vcpuid |= MPIDR_AFFINITY_LEVEL(mpidr, 1) << 4;
+       vcpuid |= MPIDR_AFFINITY_LEVEL(mpidr, 2) << 12;
+
+       return vcpuid;
+}
+
 #endif /* SELFTEST_KVM_PROCESSOR_H */
-- 
2.33.0.rc1.237.g0d66db33f3-goog

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