Re: [PATCH v4 16/16] KVM: selftests: Handle memory fault exits in demand_paging_test

[Robert Hoo <robert.hoo.linux@xxxxxxxxx>]

On 6/3/2023 12:19 AM, Anish Moorthy wrote:
[...]
>   static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)
>   {
>   	struct kvm_vcpu *vcpu = vcpu_args->vcpu;
>   	int vcpu_idx = vcpu_args->vcpu_idx;
>   	struct kvm_run *run = vcpu->run;
> -	struct timespec start;
> -	struct timespec ts_diff;
> +	struct timespec last_start;
> +	struct timespec total_runtime = {};
>   	int ret;
>   
> -	clock_gettime(CLOCK_MONOTONIC, &start);
>   
> -	/* Let the guest access its memory */
> -	ret = _vcpu_run(vcpu);
> -	TEST_ASSERT(ret == 0, "vcpu_run failed: %d\n", ret);
> -	if (get_ucall(vcpu, NULL) != UCALL_SYNC) {
> -		TEST_ASSERT(false,
> -			    "Invalid guest sync status: exit_reason=%s\n",
> -			    exit_reason_str(run->exit_reason));
> -	}
> +	while (true) {
> +		clock_gettime(CLOCK_MONOTONIC, &last_start);
> +		/* Let the guest access its memory */
> +		ret = _vcpu_run(vcpu);
> +		TEST_ASSERT(ret == 0
> +			    || (errno == EFAULT
> +				&& run->exit_reason == KVM_EXIT_MEMORY_FAULT),
> +			    "vcpu_run failed: %d\n", ret);
>   
> -	ts_diff = timespec_elapsed(start);
> +		total_runtime = timespec_add(total_runtime,
> +					     timespec_elapsed(last_start));
> +		if (ret != 0 && get_ucall(vcpu, NULL) != UCALL_SYNC) {
> +
> +			if (run->exit_reason == KVM_EXIT_MEMORY_FAULT) {
> +				ready_page(run->memory_fault.gpa);
> +				continue;
> +			}
> +
> +			TEST_ASSERT(false,
> +				    "Invalid guest sync status: exit_reason=%s\n",
> +				    exit_reason_str(run->exit_reason));
> +		}
> +		break;
> +	}
>   	PER_VCPU_DEBUG("vCPU %d execution time: %ld.%.9lds\n", vcpu_idx,
> -		       ts_diff.tv_sec, ts_diff.tv_nsec);
> +			total_runtime.tv_sec, total_runtime.tv_nsec);
>   }

Can include number of #PF handled by vcpu worker in PER_VCPU_DEBUG output.

diff --git a/tools/testing/selftests/kvm/demand_paging_test.c 
b/tools/testing/selftests/kvm/demand_paging_test.c
index 4b79c88cb22d..8841150b0e2b 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -91,7 +91,7 @@ static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)
        struct timespec last_start;
        struct timespec total_runtime = {};
        int ret;
-
+       int pages = 0;

        while (true) {
                clock_gettime(CLOCK_MONOTONIC, &last_start);
@@ -108,6 +108,7 @@ static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)

                        if (run->exit_reason == KVM_EXIT_MEMORY_FAULT) {
                                ready_page(run->memory_fault.gpa);
+                               pages++;
                                continue;
                        }

@@ -117,8 +118,8 @@ static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)
                }
                break;
        }
-       PER_VCPU_DEBUG("vCPU %d execution time: %ld.%.9lds\n", vcpu_idx,
-                       total_runtime.tv_sec, total_runtime.tv_nsec);
+       PER_VCPU_DEBUG("vCPU %d execution time: %ld.%.9lds, %d page faults 
handled\n", vcpu_idx,
+                       total_runtime.tv_sec, total_runtime.tv_nsec, pages);
 }