KVM: arm64: selftests: Add arch_timer_edge_cases selftest

Add a new arch_timer_edge_cases selftests that validates:

* timers above the max TVAL value
* timers in the past
* moving counters ahead and behind pending timers
* reprograming timers
* timers fired multiple times
* masking/unmasking using the timer control mask

These are intentionally unusual scenarios to stress compliance with
the arm architecture.
Co-developed-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Colton Lewis <coltonlewis@google.com>
Link: https://lore.kernel.org/r/20240823175836.2798235-3-coltonlewis@google.comSigned-off-by: Marc Zyngier <maz@kernel.org>

tools/testing/selftests/kvm/Makefile

@@ -152,6 +152,7 @@ TEST_GEN_PROGS_x86_64 += pre_fault_memory_test
 TEST_GEN_PROGS_EXTENDED_x86_64 += x86_64/nx_huge_pages_test
 
 TEST_GEN_PROGS_aarch64 += aarch64/aarch32_id_regs
+TEST_GEN_PROGS_aarch64 += aarch64/arch_timer_edge_cases
 TEST_GEN_PROGS_aarch64 += aarch64/debug-exceptions
 TEST_GEN_PROGS_aarch64 += aarch64/hypercalls
 TEST_GEN_PROGS_aarch64 += aarch64/page_fault_test

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

@@ -79,7 +79,7 @@ static inline uint64_t timer_get_cval(enum arch_timer timer)
 	return 0;
 }
 
-static inline void timer_set_tval(enum arch_timer timer, uint32_t tval)
+static inline void timer_set_tval(enum arch_timer timer, int32_t tval)
 {
 	switch (timer) {
 	case VIRTUAL:
@@ -95,6 +95,22 @@ static inline void timer_set_tval(enum arch_timer timer, uint32_t tval)
 	isb();
 }
 
+static inline int32_t timer_get_tval(enum arch_timer timer)
+{
+	isb();
+	switch (timer) {
+	case VIRTUAL:
+		return read_sysreg(cntv_tval_el0);
+	case PHYSICAL:
+		return read_sysreg(cntp_tval_el0);
+	default:
+		GUEST_FAIL("Could not get timer %d\n", timer);
+	}
+
+	/* We should not reach here */
+	return 0;
+}
+
 static inline void timer_set_ctl(enum arch_timer timer, uint32_t ctl)
 {
 	switch (timer) {