KVM: LoongArch: selftests: Add time counter test case

With time counter test, it is to verify that time count starts from 0
and always grows up then.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Author: bibo-mao

tools/testing/selftests/kvm/lib/loongarch/processor.c

@@ -3,6 +3,7 @@
 #include <assert.h>
 #include <linux/compiler.h>
 
+#include <asm/kvm.h>
 #include "kvm_util.h"
 #include "processor.h"
 #include "ucall_common.h"
@@ -245,6 +246,11 @@ void vcpu_args_set(struct kvm_vcpu *vcpu, unsigned int num, ...)
 	vcpu_regs_set(vcpu, &regs);
 }
 
+static void loongarch_set_reg(struct kvm_vcpu *vcpu, uint64_t id, uint64_t val)
+{
+	__vcpu_set_reg(vcpu, id, val);
+}
+
 static void loongarch_get_csr(struct kvm_vcpu *vcpu, uint64_t id, void *addr)
 {
 	uint64_t csrid;
@@ -285,7 +291,10 @@ static void loongarch_vcpu_setup(struct kvm_vcpu *vcpu)
 	loongarch_set_csr(vcpu, LOONGARCH_CSR_TCFG, 0);
 	loongarch_set_csr(vcpu, LOONGARCH_CSR_ASID, 1);
 
+	/* time count start from 0 */
 	val = 0;
+	loongarch_set_reg(vcpu, KVM_REG_LOONGARCH_COUNTER, val);
+
 	width = vm->page_shift - 3;
 
 	switch (vm->pgtable_levels) {

tools/testing/selftests/kvm/loongarch/arch_timer.c

@@ -136,10 +136,40 @@ static void guest_test_emulate_timer(uint32_t cpu)
 	local_irq_enable();
 }
 
+static void guest_time_count_test(uint32_t cpu)
+{
+	uint32_t config_iter;
+	unsigned long start, end, prev, us;
+
+	/* Assuming that test case starts to run in 1 second */
+	start = timer_get_cycles();
+	us = msec_to_cycles(1000);
+	__GUEST_ASSERT(start <= us,
+			"start = 0x%lx, us = 0x%lx.\n",
+			start, us);
+
+	us = msec_to_cycles(test_args.timer_period_ms);
+	for (config_iter = 0; config_iter < test_args.nr_iter; config_iter++) {
+		start = timer_get_cycles();
+		end = start + us;
+		/* test time count growing up always */
+		while (start < end) {
+			prev = start;
+			start = timer_get_cycles();
+			__GUEST_ASSERT(prev <= start,
+					"prev = 0x%lx, start = 0x%lx.\n",
+					prev, start);
+		}
+	}
+}
+
 static void guest_code(void)
 {
 	uint32_t cpu = guest_get_vcpuid();
 
+	/* must run at first */
+	guest_time_count_test(cpu);
+
 	timer_irq_enable();
 	local_irq_enable();
 	guest_test_period_timer(cpu);