KVM: selftests: Allow specify physical cpu list in demand paging test

Mimic the dirty log test and allow the user to pin demand paging test
tasks to physical CPUs.

Put the help message into a general helper as suggested by Sean.
Signed-off-by: Peter Xu <peterx@redhat.com>
[sean: rebase, tweak arg ordering, add "print" to helper, print program name]
Link: https://lore.kernel.org/r/20230607001226.1398889-1-seanjc@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>

tools/testing/selftests/kvm/demand_paging_test.c

@@ -208,10 +208,11 @@ static void help(char *name)
 {
 	puts("");
 	printf("usage: %s [-h] [-m vm_mode] [-u uffd_mode] [-d uffd_delay_usec]\n"
-	       "          [-b memory] [-s type] [-v vcpus] [-o]\n", name);
+	       "          [-b memory] [-s type] [-v vcpus] [-c cpu_list] [-o]\n", name);
 	guest_modes_help();
 	printf(" -u: use userfaultfd to handle vCPU page faults. Mode is a\n"
 	       "     UFFD registration mode: 'MISSING' or 'MINOR'.\n");
+	kvm_print_vcpu_pinning_help();
 	printf(" -d: add a delay in usec to the User Fault\n"
 	       "     FD handler to simulate demand paging\n"
 	       "     overheads. Ignored without -u.\n");
@@ -229,6 +230,7 @@ static void help(char *name)
 int main(int argc, char *argv[])
 {
 	int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
+	const char *cpulist = NULL;
 	struct test_params p = {
 		.src_type = DEFAULT_VM_MEM_SRC,
 		.partition_vcpu_memory_access = true,
@@ -237,7 +239,7 @@ int main(int argc, char *argv[])
 
 	guest_modes_append_default();
 
-	while ((opt = getopt(argc, argv, "hm:u:d:b:s:v:o")) != -1) {
+	while ((opt = getopt(argc, argv, "hm:u:d:b:s:v:c:o")) != -1) {
 		switch (opt) {
 		case 'm':
 			guest_modes_cmdline(optarg);
@@ -264,6 +266,9 @@ int main(int argc, char *argv[])
 			TEST_ASSERT(nr_vcpus <= max_vcpus,
 				    "Invalid number of vcpus, must be between 1 and %d", max_vcpus);
 			break;
+		case 'c':
+			cpulist = optarg;
+			break;
 		case 'o':
 			p.partition_vcpu_memory_access = false;
 			break;
@@ -279,6 +284,12 @@ int main(int argc, char *argv[])
 		TEST_FAIL("userfaultfd MINOR mode requires shared memory; pick a different -s");
 	}
 
+	if (cpulist) {
+		kvm_parse_vcpu_pinning(cpulist, memstress_args.vcpu_to_pcpu,
+				       nr_vcpus);
+		memstress_args.pin_vcpus = true;
+	}
+
 	for_each_guest_mode(run_test, &p);
 
 	return 0;

tools/testing/selftests/kvm/dirty_log_perf_test.c

@@ -332,17 +332,7 @@ static void help(char *name)
 	       "     so -w X means each page has an X%% chance of writing\n"
 	       "     and a (100-X)%% chance of reading.\n"
 	       "     (default: 100 i.e. all pages are written to.)\n");
-	printf(" -c: Pin tasks to physical CPUs.  Takes a list of comma separated\n"
-	       "     values (target pCPU), one for each vCPU, plus an optional\n"
-	       "     entry for the main application task (specified via entry\n"
-	       "     <nr_vcpus + 1>).  If used, entries must be provided for all\n"
-	       "     vCPUs, i.e. pinning vCPUs is all or nothing.\n\n"
-	       "     E.g. to create 3 vCPUs, pin vCPU0=>pCPU22, vCPU1=>pCPU23,\n"
-	       "     vCPU2=>pCPU24, and pin the application task to pCPU50:\n\n"
-	       "         ./dirty_log_perf_test -v 3 -c 22,23,24,50\n\n"
-	       "     To leave the application task unpinned, drop the final entry:\n\n"
-	       "         ./dirty_log_perf_test -v 3 -c 22,23,24\n\n"
-	       "     (default: no pinning)\n");
+	kvm_print_vcpu_pinning_help();
 	puts("");
 	exit(0);
 }

tools/testing/selftests/kvm/include/kvm_util_base.h

@@ -733,6 +733,7 @@ static inline struct kvm_vm *vm_create_with_one_vcpu(struct kvm_vcpu **vcpu,
 struct kvm_vcpu *vm_recreate_with_one_vcpu(struct kvm_vm *vm);
 
 void kvm_pin_this_task_to_pcpu(uint32_t pcpu);
+void kvm_print_vcpu_pinning_help(void);
 void kvm_parse_vcpu_pinning(const char *pcpus_string, uint32_t vcpu_to_pcpu[],
 			    int nr_vcpus);
 

tools/testing/selftests/kvm/lib/kvm_util.c

@@ -494,6 +494,23 @@ static uint32_t parse_pcpu(const char *cpu_str, const cpu_set_t *allowed_mask)
 	return pcpu;
 }
 
+void kvm_print_vcpu_pinning_help(void)
+{
+	const char *name = program_invocation_name;
+
+	printf(" -c: Pin tasks to physical CPUs.  Takes a list of comma separated\n"
+	       "     values (target pCPU), one for each vCPU, plus an optional\n"
+	       "     entry for the main application task (specified via entry\n"
+	       "     <nr_vcpus + 1>).  If used, entries must be provided for all\n"
+	       "     vCPUs, i.e. pinning vCPUs is all or nothing.\n\n"
+	       "     E.g. to create 3 vCPUs, pin vCPU0=>pCPU22, vCPU1=>pCPU23,\n"
+	       "     vCPU2=>pCPU24, and pin the application task to pCPU50:\n\n"
+	       "         %s -v 3 -c 22,23,24,50\n\n"
+	       "     To leave the application task unpinned, drop the final entry:\n\n"
+	       "         %s -v 3 -c 22,23,24\n\n"
+	       "     (default: no pinning)\n", name, name);
+}
+
 void kvm_parse_vcpu_pinning(const char *pcpus_string, uint32_t vcpu_to_pcpu[],
 			    int nr_vcpus)
 {