[V1 PATCH 0/5] Execute hypercalls from guests according to cpu type

[V1 PATCH 0/5] Execute hypercalls from guests according to cpu type

[Vishal Annapurve]

This series is posted in context of the discussion at:
https://lore.kernel.org/lkml/Ywa9T+jKUpaHLu%2Fl@google.com/

Major changes:
1) Move common startup logic to a single common main function in
kvm_util.c
2) Introduce following APIs:
	kvm_arch_main: to perform arch specific common startup.
	kvm_post_vm_load: to update the guest memory state to convey
		common information to guests.
3) For x86, capture cpu type at startup and pass on the cpu type to
guest after guest elf is loaded.
4) Execute hypercall instruction from within guest VMs according to the
cpu type. This will help prevent an extra kvm exit during hypercall
execution.

Vishal Annapurve (5):
  selftests: kvm: move common startup logic to kvm_util.c
  selftests: kvm: Introduce kvm_arch_main and helpers
  selftests: kvm: x86: Execute vmcall/vmmcall according to CPU type
  selftests: kvm: delete svm_vmcall_test
  selftests: kvm: Execute vmcall/vmmcall as per cpu type

 tools/testing/selftests/kvm/.gitignore        |  1 -
 .../selftests/kvm/aarch64/arch_timer.c        |  5 +-
 .../selftests/kvm/aarch64/debug-exceptions.c  |  2 +-
 .../selftests/kvm/aarch64/get-reg-list.c      |  2 +-
 .../selftests/kvm/aarch64/hypercalls.c        |  4 +-
 .../testing/selftests/kvm/aarch64/psci_test.c |  2 +-
 .../selftests/kvm/aarch64/vcpu_width_config.c |  2 +-
 .../testing/selftests/kvm/aarch64/vgic_init.c |  2 +-
 .../testing/selftests/kvm/aarch64/vgic_irq.c  |  5 +-
 .../selftests/kvm/access_tracking_perf_test.c |  4 +-
 .../selftests/kvm/demand_paging_test.c        |  7 +-
 .../selftests/kvm/dirty_log_perf_test.c       |  4 +-
 tools/testing/selftests/kvm/dirty_log_test.c  |  4 +-
 .../selftests/kvm/hardware_disable_test.c     |  2 +-
 .../selftests/kvm/include/kvm_util_base.h     | 15 ++++
 .../selftests/kvm/include/x86_64/processor.h  | 10 +++
 .../selftests/kvm/include/x86_64/vmx.h        |  9 ---
 .../selftests/kvm/kvm_binary_stats_test.c     |  3 +-
 .../selftests/kvm/kvm_create_max_vcpus.c      |  4 +-
 .../selftests/kvm/kvm_page_table_test.c       |  4 +-
 .../selftests/kvm/lib/aarch64/processor.c     |  8 ++
 tools/testing/selftests/kvm/lib/elf.c         |  2 +
 tools/testing/selftests/kvm/lib/kvm_util.c    | 12 +++
 .../selftests/kvm/lib/riscv/processor.c       |  8 ++
 .../selftests/kvm/lib/s390x/processor.c       |  8 ++
 tools/testing/selftests/kvm/lib/sparsebit.c   |  2 +-
 .../selftests/kvm/lib/x86_64/perf_test_util.c |  2 +-
 .../selftests/kvm/lib/x86_64/processor.c      | 38 +++++++++-
 .../selftests/kvm/max_guest_memory_test.c     |  2 +-
 .../kvm/memslot_modification_stress_test.c    |  4 +-
 .../testing/selftests/kvm/memslot_perf_test.c |  9 +--
 tools/testing/selftests/kvm/rseq_test.c       |  7 +-
 tools/testing/selftests/kvm/s390x/memop.c     |  4 +-
 tools/testing/selftests/kvm/s390x/resets.c    |  4 +-
 .../selftests/kvm/s390x/sync_regs_test.c      |  5 +-
 tools/testing/selftests/kvm/s390x/tprot.c     |  2 +-
 .../selftests/kvm/set_memory_region_test.c    |  7 +-
 tools/testing/selftests/kvm/steal_time.c      |  4 +-
 .../kvm/system_counter_offset_test.c          |  2 +-
 tools/testing/selftests/kvm/x86_64/amx_test.c |  2 +-
 .../testing/selftests/kvm/x86_64/cpuid_test.c |  2 +-
 .../kvm/x86_64/cr4_cpuid_sync_test.c          |  6 +-
 .../testing/selftests/kvm/x86_64/debug_regs.c |  4 +-
 .../kvm/x86_64/emulator_error_test.c          |  7 +-
 .../testing/selftests/kvm/x86_64/evmcs_test.c |  2 +-
 .../selftests/kvm/x86_64/fix_hypercall_test.c |  2 +-
 .../kvm/x86_64/get_msr_index_features.c       |  2 +-
 .../selftests/kvm/x86_64/hyperv_clock.c       |  2 +-
 .../selftests/kvm/x86_64/hyperv_cpuid.c       |  7 +-
 .../selftests/kvm/x86_64/hyperv_features.c    |  2 +-
 .../selftests/kvm/x86_64/hyperv_svm_test.c    |  2 +-
 .../selftests/kvm/x86_64/kvm_clock_test.c     |  2 +-
 .../selftests/kvm/x86_64/kvm_pv_test.c        |  2 +-
 .../kvm/x86_64/max_vcpuid_cap_test.c          |  3 +-
 .../selftests/kvm/x86_64/mmio_warning_test.c  |  4 +-
 .../selftests/kvm/x86_64/monitor_mwait_test.c |  3 +-
 .../selftests/kvm/x86_64/nx_huge_pages_test.c |  4 +-
 .../selftests/kvm/x86_64/platform_info_test.c |  7 +-
 .../kvm/x86_64/pmu_event_filter_test.c        |  7 +-
 .../selftests/kvm/x86_64/set_boot_cpu_id.c    |  2 +-
 .../selftests/kvm/x86_64/set_sregs_test.c     |  7 +-
 .../selftests/kvm/x86_64/sev_migrate_tests.c  |  3 +-
 tools/testing/selftests/kvm/x86_64/smm_test.c |  4 +-
 .../testing/selftests/kvm/x86_64/state_test.c | 10 +--
 .../selftests/kvm/x86_64/svm_int_ctl_test.c   |  3 +-
 .../kvm/x86_64/svm_nested_soft_inject_test.c  |  7 +-
 .../selftests/kvm/x86_64/svm_vmcall_test.c    | 74 -------------------
 .../selftests/kvm/x86_64/sync_regs_test.c     |  7 +-
 .../kvm/x86_64/triple_fault_event_test.c      |  2 +-
 .../selftests/kvm/x86_64/tsc_msrs_test.c      |  4 +-
 .../selftests/kvm/x86_64/tsc_scaling_sync.c   |  3 +-
 .../kvm/x86_64/ucna_injection_test.c          |  2 +-
 .../selftests/kvm/x86_64/userspace_io_test.c  |  6 +-
 .../kvm/x86_64/userspace_msr_exit_test.c      |  7 +-
 .../kvm/x86_64/vmx_apic_access_test.c         |  5 +-
 .../kvm/x86_64/vmx_close_while_nested_test.c  |  2 +-
 .../selftests/kvm/x86_64/vmx_dirty_log_test.c |  4 +-
 .../vmx_exception_with_invalid_guest_state.c  |  2 +-
 .../x86_64/vmx_invalid_nested_guest_state.c   |  2 +-
 .../selftests/kvm/x86_64/vmx_msrs_test.c      |  2 +-
 .../kvm/x86_64/vmx_nested_tsc_scaling_test.c  |  5 +-
 .../selftests/kvm/x86_64/vmx_pmu_caps_test.c  |  2 +-
 .../kvm/x86_64/vmx_preemption_timer_test.c    |  4 +-
 .../kvm/x86_64/vmx_set_nested_state_test.c    |  3 +-
 .../kvm/x86_64/vmx_tsc_adjust_test.c          |  5 +-
 .../selftests/kvm/x86_64/xapic_ipi_test.c     |  4 +-
 .../selftests/kvm/x86_64/xapic_state_test.c   |  2 +-
 .../selftests/kvm/x86_64/xen_shinfo_test.c    | 67 +++++++----------
 .../selftests/kvm/x86_64/xen_vmcall_test.c    | 17 +++--
 .../selftests/kvm/x86_64/xss_msr_test.c       |  2 +-
 90 files changed, 223 insertions(+), 339 deletions(-)
 delete mode 100644 tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c

-- 
2.37.2.789.g6183377224-goog

[V1 PATCH 1/5] selftests: kvm: move common startup logic to kvm_util.c

[Vishal Annapurve]

Consolidate common startup logic in one place by implementing a single main
function for all selftests within kvm_util.c.

This allows moving logic like:
	/* Tell stdout not to buffer its content */
        setbuf(stdout, NULL);
to a single file for all selftests.

This will also allow any required setup at entry in future to be done in
common main function.

More context is discussed at:
https://lore.kernel.org/lkml/Ywa9T+jKUpaHLu%2Fl@google.com/

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vishal Annapurve <vannapurve@google.com>
---
 tools/testing/selftests/kvm/aarch64/arch_timer.c       |  5 +----
 tools/testing/selftests/kvm/aarch64/debug-exceptions.c |  2 +-
 tools/testing/selftests/kvm/aarch64/get-reg-list.c     |  2 +-
 tools/testing/selftests/kvm/aarch64/hypercalls.c       |  4 +---
 tools/testing/selftests/kvm/aarch64/psci_test.c        |  2 +-
 .../testing/selftests/kvm/aarch64/vcpu_width_config.c  |  2 +-
 tools/testing/selftests/kvm/aarch64/vgic_init.c        |  2 +-
 tools/testing/selftests/kvm/aarch64/vgic_irq.c         |  5 +----
 .../testing/selftests/kvm/access_tracking_perf_test.c  |  4 +---
 tools/testing/selftests/kvm/demand_paging_test.c       |  7 ++-----
 tools/testing/selftests/kvm/dirty_log_perf_test.c      |  4 +---
 tools/testing/selftests/kvm/dirty_log_test.c           |  4 +---
 tools/testing/selftests/kvm/hardware_disable_test.c    |  2 +-
 tools/testing/selftests/kvm/include/kvm_util_base.h    |  5 +++++
 tools/testing/selftests/kvm/kvm_binary_stats_test.c    |  3 +--
 tools/testing/selftests/kvm/kvm_create_max_vcpus.c     |  4 +---
 tools/testing/selftests/kvm/kvm_page_table_test.c      |  4 +---
 tools/testing/selftests/kvm/lib/kvm_util.c             | 10 ++++++++++
 tools/testing/selftests/kvm/lib/sparsebit.c            |  2 +-
 tools/testing/selftests/kvm/max_guest_memory_test.c    |  2 +-
 .../selftests/kvm/memslot_modification_stress_test.c   |  4 +---
 tools/testing/selftests/kvm/memslot_perf_test.c        |  9 ++-------
 tools/testing/selftests/kvm/rseq_test.c                |  7 +------
 tools/testing/selftests/kvm/s390x/memop.c              |  4 +---
 tools/testing/selftests/kvm/s390x/resets.c             |  4 +---
 tools/testing/selftests/kvm/s390x/sync_regs_test.c     |  5 +----
 tools/testing/selftests/kvm/s390x/tprot.c              |  2 +-
 tools/testing/selftests/kvm/set_memory_region_test.c   |  7 +------
 tools/testing/selftests/kvm/steal_time.c               |  4 +---
 .../testing/selftests/kvm/system_counter_offset_test.c |  2 +-
 tools/testing/selftests/kvm/x86_64/amx_test.c          |  2 +-
 tools/testing/selftests/kvm/x86_64/cpuid_test.c        |  2 +-
 .../testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c |  6 +-----
 tools/testing/selftests/kvm/x86_64/debug_regs.c        |  4 +---
 .../testing/selftests/kvm/x86_64/emulator_error_test.c |  7 +------
 tools/testing/selftests/kvm/x86_64/evmcs_test.c        |  2 +-
 .../testing/selftests/kvm/x86_64/fix_hypercall_test.c  |  2 +-
 .../selftests/kvm/x86_64/get_msr_index_features.c      |  2 +-
 tools/testing/selftests/kvm/x86_64/hyperv_clock.c      |  2 +-
 tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c      |  7 +------
 tools/testing/selftests/kvm/x86_64/hyperv_features.c   |  2 +-
 tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c   |  2 +-
 tools/testing/selftests/kvm/x86_64/kvm_clock_test.c    |  2 +-
 tools/testing/selftests/kvm/x86_64/kvm_pv_test.c       |  2 +-
 .../testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c |  3 +--
 tools/testing/selftests/kvm/x86_64/mmio_warning_test.c |  4 +---
 .../testing/selftests/kvm/x86_64/monitor_mwait_test.c  |  3 +--
 .../testing/selftests/kvm/x86_64/nx_huge_pages_test.c  |  4 +---
 .../testing/selftests/kvm/x86_64/platform_info_test.c  |  7 +------
 .../selftests/kvm/x86_64/pmu_event_filter_test.c       |  7 +------
 tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c   |  2 +-
 tools/testing/selftests/kvm/x86_64/set_sregs_test.c    |  7 +------
 tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c |  3 +--
 tools/testing/selftests/kvm/x86_64/smm_test.c          |  2 +-
 tools/testing/selftests/kvm/x86_64/state_test.c        |  2 +-
 tools/testing/selftests/kvm/x86_64/svm_int_ctl_test.c  |  3 +--
 .../selftests/kvm/x86_64/svm_nested_soft_inject_test.c |  7 +------
 tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c   |  3 +--
 tools/testing/selftests/kvm/x86_64/sync_regs_test.c    |  7 +------
 .../selftests/kvm/x86_64/triple_fault_event_test.c     |  2 +-
 tools/testing/selftests/kvm/x86_64/tsc_msrs_test.c     |  4 +---
 tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c  |  3 +--
 .../testing/selftests/kvm/x86_64/ucna_injection_test.c |  2 +-
 tools/testing/selftests/kvm/x86_64/userspace_io_test.c |  6 +-----
 .../selftests/kvm/x86_64/userspace_msr_exit_test.c     |  7 +------
 .../selftests/kvm/x86_64/vmx_apic_access_test.c        |  3 +--
 .../selftests/kvm/x86_64/vmx_close_while_nested_test.c |  2 +-
 .../testing/selftests/kvm/x86_64/vmx_dirty_log_test.c  |  2 +-
 .../x86_64/vmx_exception_with_invalid_guest_state.c    |  2 +-
 .../kvm/x86_64/vmx_invalid_nested_guest_state.c        |  2 +-
 tools/testing/selftests/kvm/x86_64/vmx_msrs_test.c     |  2 +-
 .../selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c |  3 +--
 tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c |  2 +-
 .../selftests/kvm/x86_64/vmx_preemption_timer_test.c   |  2 +-
 .../selftests/kvm/x86_64/vmx_set_nested_state_test.c   |  3 +--
 .../testing/selftests/kvm/x86_64/vmx_tsc_adjust_test.c |  3 +--
 tools/testing/selftests/kvm/x86_64/xapic_ipi_test.c    |  4 +---
 tools/testing/selftests/kvm/x86_64/xapic_state_test.c  |  2 +-
 tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c   |  3 +--
 tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c   |  3 +--
 tools/testing/selftests/kvm/x86_64/xss_msr_test.c      |  2 +-
 81 files changed, 96 insertions(+), 199 deletions(-)

diff --git a/tools/testing/selftests/kvm/aarch64/arch_timer.c b/tools/testing/selftests/kvm/aarch64/arch_timer.c
index 574eb73f0e90..ecb2e7011b1c 100644
--- a/tools/testing/selftests/kvm/aarch64/arch_timer.c
+++ b/tools/testing/selftests/kvm/aarch64/arch_timer.c
@@ -458,13 +458,10 @@ static bool parse_args(int argc, char *argv[])
 	return false;
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vm *vm;
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	if (!parse_args(argc, argv))
 		exit(KSFT_SKIP);
 
diff --git a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
index 2ee35cf9801e..f0aafa9a7cfc 100644
--- a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
+++ b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
@@ -246,7 +246,7 @@ static int debug_version(struct kvm_vcpu *vcpu)
 	return id_aa64dfr0 & 0xf;
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
diff --git a/tools/testing/selftests/kvm/aarch64/get-reg-list.c b/tools/testing/selftests/kvm/aarch64/get-reg-list.c
index d287dd2cac0a..abae4f44638d 100644
--- a/tools/testing/selftests/kvm/aarch64/get-reg-list.c
+++ b/tools/testing/selftests/kvm/aarch64/get-reg-list.c
@@ -596,7 +596,7 @@ static struct vcpu_config *parse_config(const char *config)
 	return c;
 }
 
-int main(int ac, char **av)
+void __main(int argc, char *argv[])
 {
 	struct vcpu_config *c, *sel = NULL;
 	int i, ret = 0;
diff --git a/tools/testing/selftests/kvm/aarch64/hypercalls.c b/tools/testing/selftests/kvm/aarch64/hypercalls.c
index a39da3fe4952..afa6843c7efa 100644
--- a/tools/testing/selftests/kvm/aarch64/hypercalls.c
+++ b/tools/testing/selftests/kvm/aarch64/hypercalls.c
@@ -304,10 +304,8 @@ static void test_run(void)
 	kvm_vm_free(vm);
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
-	setbuf(stdout, NULL);
-
 	test_run();
 	return 0;
 }
diff --git a/tools/testing/selftests/kvm/aarch64/psci_test.c b/tools/testing/selftests/kvm/aarch64/psci_test.c
index f7621f6e938e..4bdbe22d44aa 100644
--- a/tools/testing/selftests/kvm/aarch64/psci_test.c
+++ b/tools/testing/selftests/kvm/aarch64/psci_test.c
@@ -189,7 +189,7 @@ static void host_test_system_suspend(void)
 	kvm_vm_free(vm);
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_ARM_SYSTEM_SUSPEND));
 
diff --git a/tools/testing/selftests/kvm/aarch64/vcpu_width_config.c b/tools/testing/selftests/kvm/aarch64/vcpu_width_config.c
index 80b74c6f152b..ec9485bbb307 100644
--- a/tools/testing/selftests/kvm/aarch64/vcpu_width_config.c
+++ b/tools/testing/selftests/kvm/aarch64/vcpu_width_config.c
@@ -76,7 +76,7 @@ static int add_2vcpus_init_2vcpus(struct kvm_vcpu_init *init0,
  * The other is running KVM_CREATE_VCPU and KVM_ARM_VCPU_INIT for a vCPU,
  * and then run those commands for another vCPU.
  */
-int main(void)
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu_init init0, init1;
 	struct kvm_vm *vm;
diff --git a/tools/testing/selftests/kvm/aarch64/vgic_init.c b/tools/testing/selftests/kvm/aarch64/vgic_init.c
index e05ecb31823f..3ae1b51ad80b 100644
--- a/tools/testing/selftests/kvm/aarch64/vgic_init.c
+++ b/tools/testing/selftests/kvm/aarch64/vgic_init.c
@@ -687,7 +687,7 @@ void run_tests(uint32_t gic_dev_type)
 	}
 }
 
-int main(int ac, char **av)
+void __main(int argc, char *argv[])
 {
 	int ret;
 	int pa_bits;
diff --git a/tools/testing/selftests/kvm/aarch64/vgic_irq.c b/tools/testing/selftests/kvm/aarch64/vgic_irq.c
index 17417220a083..66943323d6da 100644
--- a/tools/testing/selftests/kvm/aarch64/vgic_irq.c
+++ b/tools/testing/selftests/kvm/aarch64/vgic_irq.c
@@ -810,7 +810,7 @@ static void help(const char *name)
 	exit(1);
 }
 
-int main(int argc, char **argv)
+void __main(int argc, char *argv[])
 {
 	uint32_t nr_irqs = 64;
 	bool default_args = true;
@@ -818,9 +818,6 @@ int main(int argc, char **argv)
 	int opt;
 	bool eoi_split = false;
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	while ((opt = getopt(argc, argv, "hn:e:l:")) != -1) {
 		switch (opt) {
 		case 'n':
diff --git a/tools/testing/selftests/kvm/access_tracking_perf_test.c b/tools/testing/selftests/kvm/access_tracking_perf_test.c
index 1c2749b1481a..3548fc537d8c 100644
--- a/tools/testing/selftests/kvm/access_tracking_perf_test.c
+++ b/tools/testing/selftests/kvm/access_tracking_perf_test.c
@@ -340,7 +340,7 @@ static void help(char *name)
 	exit(0);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct test_params params = {
 		.backing_src = DEFAULT_VM_MEM_SRC,
@@ -382,6 +382,4 @@ int main(int argc, char *argv[])
 	close(page_idle_fd);
 
 	for_each_guest_mode(run_test, &params);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index 779ae54f89c4..dca61fb5c77b 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -393,7 +393,7 @@ static void help(char *name)
 	exit(0);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
 	struct test_params p = {
@@ -447,18 +447,15 @@ int main(int argc, char *argv[])
 	}
 
 	for_each_guest_mode(run_test, &p);
-
-	return 0;
 }
 
 #else /* __NR_userfaultfd */
 
 #warning "missing __NR_userfaultfd definition"
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	print_skip("__NR_userfaultfd must be present for userfaultfd test");
-	return KSFT_SKIP;
 }
 
 #endif /* __NR_userfaultfd */
diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
index f99e39a672d3..87fb7e2cb033 100644
--- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
@@ -387,7 +387,7 @@ static void help(char *name)
 	exit(0);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
 	struct test_params p = {
@@ -460,6 +460,4 @@ int main(int argc, char *argv[])
 	pr_info("Test iterations: %"PRIu64"\n",	p.iterations);
 
 	for_each_guest_mode(run_test, &p);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
index 9c883c94d478..1268741654d8 100644
--- a/tools/testing/selftests/kvm/dirty_log_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_test.c
@@ -838,7 +838,7 @@ static void help(char *name)
 	exit(0);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct test_params p = {
 		.iterations = TEST_HOST_LOOP_N,
@@ -920,6 +920,4 @@ int main(int argc, char *argv[])
 		host_log_mode = host_log_mode_option;
 		for_each_guest_mode(run_test, &p);
 	}
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/hardware_disable_test.c b/tools/testing/selftests/kvm/hardware_disable_test.c
index f5d59b9934f1..919d943e640c 100644
--- a/tools/testing/selftests/kvm/hardware_disable_test.c
+++ b/tools/testing/selftests/kvm/hardware_disable_test.c
@@ -151,7 +151,7 @@ void wait_for_child_setup(pid_t pid)
 	}
 }
 
-int main(int argc, char **argv)
+void __main(int argc, char *argv[])
 {
 	uint32_t i;
 	int s, r;
diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index 24fde97f6121..9e521d1c8afe 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -834,4 +834,9 @@ static inline int __vm_disable_nx_huge_pages(struct kvm_vm *vm)
 	return __vm_enable_cap(vm, KVM_CAP_VM_DISABLE_NX_HUGE_PAGES, 0);
 }
 
+/*
+ * API to be implemented by all the selftests.
+ */
+void __main(int argc, char *argv[]);
+
 #endif /* SELFTEST_KVM_UTIL_BASE_H */
diff --git a/tools/testing/selftests/kvm/kvm_binary_stats_test.c b/tools/testing/selftests/kvm/kvm_binary_stats_test.c
index 0b45ac593387..8ba284006e27 100644
--- a/tools/testing/selftests/kvm/kvm_binary_stats_test.c
+++ b/tools/testing/selftests/kvm/kvm_binary_stats_test.c
@@ -204,7 +204,7 @@ static void vcpu_stats_test(struct kvm_vcpu *vcpu)
  * created for testing.
  */
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	int i, j;
 	struct kvm_vcpu **vcpus;
@@ -250,5 +250,4 @@ int main(int argc, char *argv[])
 	for (i = 0; i < max_vm; ++i)
 		kvm_vm_free(vms[i]);
 	free(vms);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/kvm_create_max_vcpus.c b/tools/testing/selftests/kvm/kvm_create_max_vcpus.c
index 31b3cb24b9a7..d3843606bfbc 100644
--- a/tools/testing/selftests/kvm/kvm_create_max_vcpus.c
+++ b/tools/testing/selftests/kvm/kvm_create_max_vcpus.c
@@ -37,7 +37,7 @@ void test_vcpu_creation(int first_vcpu_id, int num_vcpus)
 	kvm_vm_free(vm);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	int kvm_max_vcpu_id = kvm_check_cap(KVM_CAP_MAX_VCPU_ID);
 	int kvm_max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
@@ -89,6 +89,4 @@ int main(int argc, char *argv[])
 	if (kvm_max_vcpu_id > kvm_max_vcpus)
 		test_vcpu_creation(
 			kvm_max_vcpu_id - kvm_max_vcpus, kvm_max_vcpus);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/kvm_page_table_test.c b/tools/testing/selftests/kvm/kvm_page_table_test.c
index f42c6ac6d71d..895de52fea97 100644
--- a/tools/testing/selftests/kvm/kvm_page_table_test.c
+++ b/tools/testing/selftests/kvm/kvm_page_table_test.c
@@ -438,7 +438,7 @@ static void help(char *name)
 	puts("");
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
 	struct test_params p = {
@@ -476,6 +476,4 @@ int main(int argc, char *argv[])
 	}
 
 	for_each_guest_mode(run_test, &p);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 9889fe0d8919..2e611a021c6e 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1979,3 +1979,13 @@ void __vm_get_stat(struct kvm_vm *vm, const char *stat_name, uint64_t *data,
 		break;
 	}
 }
+
+int main(int argc, char *argv[])
+{
+	/* Tell stdout not to buffer its content */
+	setbuf(stdout, NULL);
+
+	__main(argc, argv);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/kvm/lib/sparsebit.c b/tools/testing/selftests/kvm/lib/sparsebit.c
index 50e0cf41a7dd..6c76507dfc9e 100644
--- a/tools/testing/selftests/kvm/lib/sparsebit.c
+++ b/tools/testing/selftests/kvm/lib/sparsebit.c
@@ -2071,7 +2071,7 @@ uint64_t get64(void)
 	return (x << 8) | get8();
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	s = sparsebit_alloc();
 	for (;;) {
diff --git a/tools/testing/selftests/kvm/max_guest_memory_test.c b/tools/testing/selftests/kvm/max_guest_memory_test.c
index 9a6e4f3ad6b5..72753dadf277 100644
--- a/tools/testing/selftests/kvm/max_guest_memory_test.c
+++ b/tools/testing/selftests/kvm/max_guest_memory_test.c
@@ -153,7 +153,7 @@ static void calc_default_nr_vcpus(void)
 	TEST_ASSERT(nr_vcpus > 0, "Uh, no CPUs?");
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	/*
 	 * Skip the first 4gb and slot0.  slot0 maps <1gb and is used to back
diff --git a/tools/testing/selftests/kvm/memslot_modification_stress_test.c b/tools/testing/selftests/kvm/memslot_modification_stress_test.c
index 6ee7e1dde404..e656c680596f 100644
--- a/tools/testing/selftests/kvm/memslot_modification_stress_test.c
+++ b/tools/testing/selftests/kvm/memslot_modification_stress_test.c
@@ -139,7 +139,7 @@ static void help(char *name)
 	exit(0);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
 	int opt;
@@ -185,6 +185,4 @@ int main(int argc, char *argv[])
 	}
 
 	for_each_guest_mode(run_test, &p);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/memslot_perf_test.c b/tools/testing/selftests/kvm/memslot_perf_test.c
index 44995446d942..f5d630729930 100644
--- a/tools/testing/selftests/kvm/memslot_perf_test.c
+++ b/tools/testing/selftests/kvm/memslot_perf_test.c
@@ -995,7 +995,7 @@ static bool test_loop(const struct test_data *data,
 	return true;
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct test_args targs = {
 		.tfirst = 0,
@@ -1007,11 +1007,8 @@ int main(int argc, char *argv[])
 	struct test_result rbestslottime;
 	int tctr;
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	if (!parse_args(argc, argv, &targs))
-		return -1;
+		exit(-1);
 
 	rbestslottime.slottimens = 0;
 	for (tctr = targs.tfirst; tctr <= targs.tlast; tctr++) {
@@ -1042,6 +1039,4 @@ int main(int argc, char *argv[])
 		pr_info("Best slot setup time for the whole test area was %ld.%.9lds\n",
 			rbestslottime.slot_runtime.tv_sec,
 			rbestslottime.slot_runtime.tv_nsec);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/rseq_test.c b/tools/testing/selftests/kvm/rseq_test.c
index fac248a43666..2803bc82b37a 100644
--- a/tools/testing/selftests/kvm/rseq_test.c
+++ b/tools/testing/selftests/kvm/rseq_test.c
@@ -198,16 +198,13 @@ static void calc_min_max_cpu(void)
 		       "Only one usable CPU, task migration not possible");
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	int r, i, snapshot;
 	struct kvm_vm *vm;
 	struct kvm_vcpu *vcpu;
 	u32 cpu, rseq_cpu;
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	r = sched_getaffinity(0, sizeof(possible_mask), &possible_mask);
 	TEST_ASSERT(!r, "sched_getaffinity failed, errno = %d (%s)", errno,
 		    strerror(errno));
@@ -277,6 +274,4 @@ int main(int argc, char *argv[])
 	kvm_vm_free(vm);
 
 	rseq_unregister_current_thread();
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/s390x/memop.c b/tools/testing/selftests/kvm/s390x/memop.c
index 9113696d5178..ffa2119a9c24 100644
--- a/tools/testing/selftests/kvm/s390x/memop.c
+++ b/tools/testing/selftests/kvm/s390x/memop.c
@@ -754,14 +754,12 @@ struct testdef {
 	},
 };
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	int extension_cap, idx;
 
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_S390_MEM_OP));
 
-	setbuf(stdout, NULL);	/* Tell stdout not to buffer its content */
-
 	ksft_print_header();
 
 	ksft_set_plan(ARRAY_SIZE(testlist));
diff --git a/tools/testing/selftests/kvm/s390x/resets.c b/tools/testing/selftests/kvm/s390x/resets.c
index 19486084eb30..517016169dd7 100644
--- a/tools/testing/selftests/kvm/s390x/resets.c
+++ b/tools/testing/selftests/kvm/s390x/resets.c
@@ -291,13 +291,11 @@ struct testdef {
 	{ "clear", test_clear, true },
 };
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	bool has_s390_vcpu_resets = kvm_check_cap(KVM_CAP_S390_VCPU_RESETS);
 	int idx;
 
-	setbuf(stdout, NULL);	/* Tell stdout not to buffer its content */
-
 	ksft_print_header();
 	ksft_set_plan(ARRAY_SIZE(testlist));
 
diff --git a/tools/testing/selftests/kvm/s390x/sync_regs_test.c b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
index 3fdb6e2598eb..3590159f7849 100644
--- a/tools/testing/selftests/kvm/s390x/sync_regs_test.c
+++ b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
@@ -223,7 +223,7 @@ struct testdef {
 	{ "clear kvm_dirty_regs bits", test_clear_kvm_dirty_regs_bits },
 };
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
@@ -231,9 +231,6 @@ int main(int argc, char *argv[])
 
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_SYNC_REGS));
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	ksft_print_header();
 
 	ksft_set_plan(ARRAY_SIZE(testlist));
diff --git a/tools/testing/selftests/kvm/s390x/tprot.c b/tools/testing/selftests/kvm/s390x/tprot.c
index a9a0b76e5fa4..893eae876906 100644
--- a/tools/testing/selftests/kvm/s390x/tprot.c
+++ b/tools/testing/selftests/kvm/s390x/tprot.c
@@ -201,7 +201,7 @@ static void guest_code(void)
 	ksft_test_result_pass("" #stage "\n");	\
 })
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
index 0d55f508d595..5af62d6eb4dc 100644
--- a/tools/testing/selftests/kvm/set_memory_region_test.c
+++ b/tools/testing/selftests/kvm/set_memory_region_test.c
@@ -386,15 +386,12 @@ static void test_add_max_memory_regions(void)
 	kvm_vm_free(vm);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 #ifdef __x86_64__
 	int i, loops;
 #endif
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 #ifdef __x86_64__
 	/*
 	 * FIXME: the zero-memslot test fails on aarch64 and s390x because
@@ -419,6 +416,4 @@ int main(int argc, char *argv[])
 	for (i = 0; i < loops; i++)
 		test_delete_memory_region();
 #endif
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
index db8967f1a17b..7037d2a08b26 100644
--- a/tools/testing/selftests/kvm/steal_time.c
+++ b/tools/testing/selftests/kvm/steal_time.c
@@ -239,7 +239,7 @@ static void run_vcpu(struct kvm_vcpu *vcpu)
 	}
 }
 
-int main(int ac, char **av)
+void __main(int ac, char *av[])
 {
 	struct kvm_vcpu *vcpus[NR_VCPUS];
 	struct kvm_vm *vm;
@@ -317,6 +317,4 @@ int main(int ac, char **av)
 			steal_time_dump(vm, i);
 		}
 	}
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/system_counter_offset_test.c b/tools/testing/selftests/kvm/system_counter_offset_test.c
index 1c274933912b..bc0a1a652f74 100644
--- a/tools/testing/selftests/kvm/system_counter_offset_test.c
+++ b/tools/testing/selftests/kvm/system_counter_offset_test.c
@@ -114,7 +114,7 @@ static void enter_guest(struct kvm_vcpu *vcpu)
 	}
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c
index dadcbad10a1d..fb4b64d2e68e 100644
--- a/tools/testing/selftests/kvm/x86_64/amx_test.c
+++ b/tools/testing/selftests/kvm/x86_64/amx_test.c
@@ -294,7 +294,7 @@ void guest_nm_handler(struct ex_regs *regs)
 	GUEST_SYNC(9);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_regs regs1, regs2;
 	struct kvm_vcpu *vcpu;
diff --git a/tools/testing/selftests/kvm/x86_64/cpuid_test.c b/tools/testing/selftests/kvm/x86_64/cpuid_test.c
index a6aeee2e62e4..41d27705adee 100644
--- a/tools/testing/selftests/kvm/x86_64/cpuid_test.c
+++ b/tools/testing/selftests/kvm/x86_64/cpuid_test.c
@@ -172,7 +172,7 @@ static void set_cpuid_after_run(struct kvm_vcpu *vcpu)
 	ent->eax = eax;
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	vm_vaddr_t cpuid_gva;
diff --git a/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c b/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c
index 4208487652f8..b5d967a6134f 100644
--- a/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c
+++ b/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c
@@ -47,7 +47,7 @@ static void guest_code(void)
 	GUEST_DONE();
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_run *run;
@@ -57,9 +57,6 @@ int main(int argc, char *argv[])
 
 	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_XSAVE));
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
 	run = vcpu->run;
 
@@ -90,5 +87,4 @@ int main(int argc, char *argv[])
 
 done:
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/debug_regs.c b/tools/testing/selftests/kvm/x86_64/debug_regs.c
index 7ef99c3359a0..40fe07a4f911 100644
--- a/tools/testing/selftests/kvm/x86_64/debug_regs.c
+++ b/tools/testing/selftests/kvm/x86_64/debug_regs.c
@@ -75,7 +75,7 @@ static void vcpu_skip_insn(struct kvm_vcpu *vcpu, int insn_len)
 	vcpu_regs_set(vcpu, &regs);
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	struct kvm_guest_debug debug;
 	unsigned long long target_dr6, target_rip;
@@ -209,6 +209,4 @@ int main(void)
 	TEST_ASSERT(cmd == UCALL_DONE, "UCALL_DONE");
 
 	kvm_vm_free(vm);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/emulator_error_test.c b/tools/testing/selftests/kvm/x86_64/emulator_error_test.c
index 236e11755ba6..6c967f36bbd3 100644
--- a/tools/testing/selftests/kvm/x86_64/emulator_error_test.c
+++ b/tools/testing/selftests/kvm/x86_64/emulator_error_test.c
@@ -148,7 +148,7 @@ static uint64_t process_ucall(struct kvm_vcpu *vcpu)
 	return uc.cmd;
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
@@ -156,9 +156,6 @@ int main(int argc, char *argv[])
 	uint64_t *hva;
 	int rc;
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_SMALLER_MAXPHYADDR));
 
 	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
@@ -188,6 +185,4 @@ int main(int argc, char *argv[])
 	TEST_ASSERT(process_ucall(vcpu) == UCALL_DONE, "Expected UCALL_DONE");
 
 	kvm_vm_free(vm);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/evmcs_test.c b/tools/testing/selftests/kvm/x86_64/evmcs_test.c
index 99bc202243d2..24e02b22e94b 100644
--- a/tools/testing/selftests/kvm/x86_64/evmcs_test.c
+++ b/tools/testing/selftests/kvm/x86_64/evmcs_test.c
@@ -196,7 +196,7 @@ static struct kvm_vcpu *save_restore_vm(struct kvm_vm *vm,
 	return vcpu;
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	vm_vaddr_t vmx_pages_gva = 0;
 
diff --git a/tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c b/tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c
index b1905d280ef5..d85a0be5d106 100644
--- a/tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c
+++ b/tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c
@@ -154,7 +154,7 @@ static void test_fix_hypercall_disabled(void)
 	enter_guest(vcpu);
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	TEST_REQUIRE(kvm_check_cap(KVM_CAP_DISABLE_QUIRKS2) & KVM_X86_QUIRK_FIX_HYPERCALL_INSN);
 
diff --git a/tools/testing/selftests/kvm/x86_64/get_msr_index_features.c b/tools/testing/selftests/kvm/x86_64/get_msr_index_features.c
index d09b3cbcadc6..04c67a250947 100644
--- a/tools/testing/selftests/kvm/x86_64/get_msr_index_features.c
+++ b/tools/testing/selftests/kvm/x86_64/get_msr_index_features.c
@@ -15,7 +15,7 @@
 #include "kvm_util.h"
 #include "processor.h"
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	const struct kvm_msr_list *feature_list;
 	int i;
diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_clock.c b/tools/testing/selftests/kvm/x86_64/hyperv_clock.c
index d576bc8ce823..cece1814098e 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_clock.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_clock.c
@@ -203,7 +203,7 @@ static void host_check_tsc_msr_rdtsc(struct kvm_vcpu *vcpu)
 		    (t2 - t1) * 100, (r2 - r1) * 1000000000 / tsc_freq);
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c b/tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c
index e804eb08dff9..506450541fa8 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c
@@ -128,15 +128,12 @@ void test_hv_cpuid_e2big(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
 		    " it should have: %d %d", !vcpu ? "KVM" : "vCPU", ret, errno);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vm *vm;
 	const struct kvm_cpuid2 *hv_cpuid_entries;
 	struct kvm_vcpu *vcpu;
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_HYPERV_CPUID));
 
 	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
@@ -172,6 +169,4 @@ int main(int argc, char *argv[])
 
 out:
 	kvm_vm_free(vm);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_features.c b/tools/testing/selftests/kvm/x86_64/hyperv_features.c
index 79ab0152d281..c6960281fb85 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_features.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_features.c
@@ -632,7 +632,7 @@ static void guest_test_hcalls_access(void)
 	}
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	pr_info("Testing access to Hyper-V specific MSRs\n");
 	guest_test_msrs_access();
diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c b/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
index a380ad7bb9b3..f54e6f3e8431 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
@@ -117,7 +117,7 @@ static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm)
 	GUEST_DONE();
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	vm_vaddr_t nested_gva = 0;
 
diff --git a/tools/testing/selftests/kvm/x86_64/kvm_clock_test.c b/tools/testing/selftests/kvm/x86_64/kvm_clock_test.c
index 813ce282cf56..f94e77ecb6a9 100644
--- a/tools/testing/selftests/kvm/x86_64/kvm_clock_test.c
+++ b/tools/testing/selftests/kvm/x86_64/kvm_clock_test.c
@@ -171,7 +171,7 @@ static void check_clocksource(void)
 	fclose(fp);
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	vm_vaddr_t pvti_gva;
diff --git a/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c b/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c
index 619655c1a1f3..014ae6dd1482 100644
--- a/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c
+++ b/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c
@@ -136,7 +136,7 @@ static void enter_guest(struct kvm_vcpu *vcpu)
 	}
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
diff --git a/tools/testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c b/tools/testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c
index 3cc4b86832fe..8dbb7a48703b 100644
--- a/tools/testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c
+++ b/tools/testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c
@@ -11,7 +11,7 @@
 
 #define MAX_VCPU_ID	2
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vm *vm;
 	int ret;
@@ -40,5 +40,4 @@ int main(int argc, char *argv[])
 	TEST_ASSERT(ret < 0, "Creating vCPU with ID > MAX_VCPU_ID should fail");
 
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c b/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c
index fb02581953a3..03684a188a81 100644
--- a/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c
+++ b/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c
@@ -89,7 +89,7 @@ int get_warnings_count(void)
 	return warnings;
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	int warnings_before, warnings_after;
 
@@ -116,6 +116,4 @@ int main(void)
 	warnings_after = get_warnings_count();
 	TEST_ASSERT(warnings_before == warnings_after,
 		   "Warnings found in kernel.  Run 'dmesg' to inspect them.");
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c b/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c
index 016070cad36e..cb631d934452 100644
--- a/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c
+++ b/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c
@@ -60,7 +60,7 @@ static void guest_code(void)
 	GUEST_DONE();
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	uint64_t disabled_quirks;
 	struct kvm_vcpu *vcpu;
@@ -127,5 +127,4 @@ int main(int argc, char *argv[])
 
 done:
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
index cc6421716400..3a6756a3eda8 100644
--- a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
+++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
@@ -225,7 +225,7 @@ static void help(char *name)
 	exit(0);
 }
 
-int main(int argc, char **argv)
+void __main(int argc, char *argv[])
 {
 	int reclaim_period_ms = 0, token = 0, opt;
 	bool reboot_permissions = false;
@@ -263,7 +263,5 @@ int main(int argc, char **argv)
 
 	run_test(reclaim_period_ms, false, reboot_permissions);
 	run_test(reclaim_period_ms, true, reboot_permissions);
-
-	return 0;
 }
 
diff --git a/tools/testing/selftests/kvm/x86_64/platform_info_test.c b/tools/testing/selftests/kvm/x86_64/platform_info_test.c
index 76417c7d687b..e32e7bc32d3f 100644
--- a/tools/testing/selftests/kvm/x86_64/platform_info_test.c
+++ b/tools/testing/selftests/kvm/x86_64/platform_info_test.c
@@ -66,15 +66,12 @@ static void test_msr_platform_info_disabled(struct kvm_vcpu *vcpu)
 			exit_reason_str(run->exit_reason));
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
 	uint64_t msr_platform_info;
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_MSR_PLATFORM_INFO));
 
 	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
@@ -87,6 +84,4 @@ int main(int argc, char *argv[])
 	vcpu_set_msr(vcpu, MSR_PLATFORM_INFO, msr_platform_info);
 
 	kvm_vm_free(vm);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
index ea4e259a1e2e..80f58ef7ace4 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
@@ -441,15 +441,12 @@ static bool use_amd_pmu(void)
 		 is_zen3(entry->eax));
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	void (*guest_code)(void);
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_PMU_EVENT_FILTER));
 
 	TEST_REQUIRE(use_intel_pmu() || use_amd_pmu());
@@ -474,6 +471,4 @@ int main(int argc, char *argv[])
 	kvm_vm_free(vm);
 
 	test_pmu_config_disable(guest_code);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c b/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c
index b25d7556b638..4cc460efb2a4 100644
--- a/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c
+++ b/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c
@@ -119,7 +119,7 @@ static void check_set_bsp_busy(void)
 	kvm_vm_free(vm);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_SET_BOOT_CPU_ID));
 
diff --git a/tools/testing/selftests/kvm/x86_64/set_sregs_test.c b/tools/testing/selftests/kvm/x86_64/set_sregs_test.c
index 2bb08bf2125d..a414535d46b2 100644
--- a/tools/testing/selftests/kvm/x86_64/set_sregs_test.c
+++ b/tools/testing/selftests/kvm/x86_64/set_sregs_test.c
@@ -74,7 +74,7 @@ static uint64_t calc_supported_cr4_feature_bits(void)
 	return cr4;
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_sregs sregs;
 	struct kvm_vcpu *vcpu;
@@ -82,9 +82,6 @@ int main(int argc, char *argv[])
 	uint64_t cr4;
 	int rc;
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	/*
 	 * Create a dummy VM, specifically to avoid doing KVM_SET_CPUID2, and
 	 * use it to verify all supported CR4 bits can be set prior to defining
@@ -132,6 +129,4 @@ int main(int argc, char *argv[])
 		    sregs.apic_base);
 
 	kvm_vm_free(vm);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c b/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c
index c7ef97561038..5e7a16a68200 100644
--- a/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c
+++ b/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c
@@ -393,7 +393,7 @@ static void test_sev_move_copy(void)
 	kvm_vm_free(sev_vm);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM));
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_VM_COPY_ENC_CONTEXT_FROM));
@@ -417,5 +417,4 @@ int main(int argc, char *argv[])
 			test_sev_mirror(/* es= */ true);
 		test_sev_mirror_parameters();
 	}
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/smm_test.c b/tools/testing/selftests/kvm/x86_64/smm_test.c
index 1f136a81858e..5f8ebe7795c1 100644
--- a/tools/testing/selftests/kvm/x86_64/smm_test.c
+++ b/tools/testing/selftests/kvm/x86_64/smm_test.c
@@ -126,7 +126,7 @@ void inject_smi(struct kvm_vcpu *vcpu)
 	vcpu_events_set(vcpu, &events);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	vm_vaddr_t nested_gva = 0;
 
diff --git a/tools/testing/selftests/kvm/x86_64/state_test.c b/tools/testing/selftests/kvm/x86_64/state_test.c
index ea578971fb9f..3d42c18d4c5f 100644
--- a/tools/testing/selftests/kvm/x86_64/state_test.c
+++ b/tools/testing/selftests/kvm/x86_64/state_test.c
@@ -151,7 +151,7 @@ static void __attribute__((__flatten__)) guest_code(void *arg)
 	GUEST_DONE();
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	vm_vaddr_t nested_gva = 0;
 
diff --git a/tools/testing/selftests/kvm/x86_64/svm_int_ctl_test.c b/tools/testing/selftests/kvm/x86_64/svm_int_ctl_test.c
index 4a07ba227b99..bd546610e913 100644
--- a/tools/testing/selftests/kvm/x86_64/svm_int_ctl_test.c
+++ b/tools/testing/selftests/kvm/x86_64/svm_int_ctl_test.c
@@ -82,7 +82,7 @@ static void l1_guest_code(struct svm_test_data *svm)
 	GUEST_DONE();
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_run *run;
@@ -123,5 +123,4 @@ int main(int argc, char *argv[])
 	}
 done:
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c b/tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c
index e637d7736012..a990ff4df5aa 100644
--- a/tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c
+++ b/tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c
@@ -192,11 +192,8 @@ static void run_test(bool is_nmi)
 	kvm_vm_free(vm);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SVM));
 
 	TEST_ASSERT(kvm_cpu_has(X86_FEATURE_NRIPS),
@@ -206,6 +203,4 @@ int main(int argc, char *argv[])
 
 	run_test(false);
 	run_test(true);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c b/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c
index c3ac45df7483..95ddc2bff332 100644
--- a/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c
+++ b/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c
@@ -33,7 +33,7 @@ static void l1_guest_code(struct svm_test_data *svm)
 	GUEST_DONE();
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	vm_vaddr_t svm_gva;
@@ -70,5 +70,4 @@ int main(int argc, char *argv[])
 	}
 done:
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/sync_regs_test.c b/tools/testing/selftests/kvm/x86_64/sync_regs_test.c
index 9b6db0b0b13e..cb9eed58031b 100644
--- a/tools/testing/selftests/kvm/x86_64/sync_regs_test.c
+++ b/tools/testing/selftests/kvm/x86_64/sync_regs_test.c
@@ -80,7 +80,7 @@ static void compare_vcpu_events(struct kvm_vcpu_events *left,
 #define TEST_SYNC_FIELDS   (KVM_SYNC_X86_REGS|KVM_SYNC_X86_SREGS|KVM_SYNC_X86_EVENTS)
 #define INVALID_SYNC_FIELD 0x80000000
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
@@ -90,9 +90,6 @@ int main(int argc, char *argv[])
 	struct kvm_vcpu_events events;
 	int rv, cap;
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	cap = kvm_check_cap(KVM_CAP_SYNC_REGS);
 	TEST_REQUIRE((cap & TEST_SYNC_FIELDS) == TEST_SYNC_FIELDS);
 	TEST_REQUIRE(!(cap & INVALID_SYNC_FIELD));
@@ -235,6 +232,4 @@ int main(int argc, char *argv[])
 		    regs.rbx);
 
 	kvm_vm_free(vm);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c b/tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c
index 70b44f0b52fe..d92e1426650b 100644
--- a/tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c
+++ b/tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c
@@ -38,7 +38,7 @@ void l1_guest_code(struct vmx_pages *vmx)
 	GUEST_DONE();
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_run *run;
diff --git a/tools/testing/selftests/kvm/x86_64/tsc_msrs_test.c b/tools/testing/selftests/kvm/x86_64/tsc_msrs_test.c
index 22d366c697f7..8647453df134 100644
--- a/tools/testing/selftests/kvm/x86_64/tsc_msrs_test.c
+++ b/tools/testing/selftests/kvm/x86_64/tsc_msrs_test.c
@@ -86,7 +86,7 @@ static void run_vcpu(struct kvm_vcpu *vcpu, int stage)
 	}
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
@@ -148,6 +148,4 @@ int main(void)
 	ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC_ADJUST), val - HOST_ADJUST);
 
 	kvm_vm_free(vm);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c b/tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c
index 47139aab7408..143881fd223c 100644
--- a/tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c
+++ b/tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c
@@ -91,7 +91,7 @@ static void *run_vcpu(void *_cpu_nr)
 	return (void *)failures;
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_VM_TSC_CONTROL));
 
@@ -114,5 +114,4 @@ int main(int argc, char *argv[])
 	TEST_ASSERT(!failures, "TSC sync failed");
 	pthread_spin_destroy(&create_lock);
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/ucna_injection_test.c b/tools/testing/selftests/kvm/x86_64/ucna_injection_test.c
index a897c7fd8abe..1f466aa6eb26 100644
--- a/tools/testing/selftests/kvm/x86_64/ucna_injection_test.c
+++ b/tools/testing/selftests/kvm/x86_64/ucna_injection_test.c
@@ -275,7 +275,7 @@ static struct kvm_vcpu *create_vcpu_with_mce_cap(struct kvm_vm *vm, uint32_t vcp
 	return vcpu;
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct thread_params params;
 	struct kvm_vm *vm;
diff --git a/tools/testing/selftests/kvm/x86_64/userspace_io_test.c b/tools/testing/selftests/kvm/x86_64/userspace_io_test.c
index 7316521428f8..7bdf6ac4c2b8 100644
--- a/tools/testing/selftests/kvm/x86_64/userspace_io_test.c
+++ b/tools/testing/selftests/kvm/x86_64/userspace_io_test.c
@@ -48,7 +48,7 @@ static void guest_code(void)
 	GUEST_DONE();
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_regs regs;
@@ -56,9 +56,6 @@ int main(int argc, char *argv[])
 	struct kvm_vm *vm;
 	struct ucall uc;
 
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
 	run = vcpu->run;
 
@@ -104,5 +101,4 @@ int main(int argc, char *argv[])
 	}
 
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c b/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c
index a4f06370a245..7bdd2b6872d9 100644
--- a/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c
+++ b/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c
@@ -733,16 +733,11 @@ static void test_msr_permission_bitmap(void)
 	kvm_vm_free(vm);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
 	test_msr_filter_allow();
 
 	test_msr_filter_deny();
 
 	test_msr_permission_bitmap();
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c b/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c
index 5abecf06329e..2d503dce0481 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c
@@ -69,7 +69,7 @@ static void l1_guest_code(struct vmx_pages *vmx_pages, unsigned long high_gpa)
 	GUEST_DONE();
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	unsigned long apic_access_addr = ~0ul;
 	vm_vaddr_t vmx_pages_gva;
@@ -127,5 +127,4 @@ int main(int argc, char *argv[])
 		}
 	}
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_close_while_nested_test.c b/tools/testing/selftests/kvm/x86_64/vmx_close_while_nested_test.c
index d79651b02740..bfaf9efe1fe8 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_close_while_nested_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_close_while_nested_test.c
@@ -45,7 +45,7 @@ static void l1_guest_code(struct vmx_pages *vmx_pages)
 	GUEST_ASSERT(0);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	vm_vaddr_t vmx_pages_gva;
 	struct kvm_vcpu *vcpu;
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c b/tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c
index 2d8c23d639f7..5ab735bcf8ab 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c
@@ -64,7 +64,7 @@ void l1_guest_code(struct vmx_pages *vmx)
 	GUEST_DONE();
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	vm_vaddr_t vmx_pages_gva = 0;
 	struct vmx_pages *vmx;
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_exception_with_invalid_guest_state.c b/tools/testing/selftests/kvm/x86_64/vmx_exception_with_invalid_guest_state.c
index 2641b286b4ed..81ff187a5325 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_exception_with_invalid_guest_state.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_exception_with_invalid_guest_state.c
@@ -106,7 +106,7 @@ static void sigalrm_handler(int sig)
 	}
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_invalid_nested_guest_state.c b/tools/testing/selftests/kvm/x86_64/vmx_invalid_nested_guest_state.c
index 6bfb4bb471ca..ae11ec5402bd 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_invalid_nested_guest_state.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_invalid_nested_guest_state.c
@@ -50,7 +50,7 @@ static void l1_guest_code(struct vmx_pages *vmx_pages)
 	GUEST_DONE();
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	vm_vaddr_t vmx_pages_gva;
 	struct kvm_sregs sregs;
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_msrs_test.c b/tools/testing/selftests/kvm/x86_64/vmx_msrs_test.c
index 322d561b4260..ed34a09a2eeb 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_msrs_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_msrs_test.c
@@ -67,7 +67,7 @@ static void vmx_save_restore_msrs_test(struct kvm_vcpu *vcpu)
 	vmx_fixed1_msr_test(vcpu, MSR_IA32_VMX_VMFUNC, -1ull);
 }
 
-int main(void)
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c b/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
index 465a9434d61c..e3887e08666c 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
@@ -137,7 +137,7 @@ static void stable_tsc_check_supported(void)
 	exit(KSFT_SKIP);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
@@ -227,5 +227,4 @@ int main(int argc, char *argv[])
 
 done:
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c b/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c
index 069589c52f41..fded1964251b 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c
@@ -51,7 +51,7 @@ static void guest_code(void)
 	wrmsr(MSR_IA32_PERF_CAPABILITIES, PMU_CAP_LBR_FMT);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	const struct kvm_cpuid_entry2 *entry_a_0;
 	struct kvm_vm *vm;
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c b/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c
index 0efdc05969a5..629b9c4bd6e4 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c
@@ -151,7 +151,7 @@ void guest_code(struct vmx_pages *vmx_pages)
 	GUEST_DONE();
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	vm_vaddr_t vmx_pages_gva = 0;
 
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c b/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c
index 41ea7028a1f8..4c1cd8910922 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c
@@ -243,7 +243,7 @@ void test_vmx_nested_state(struct kvm_vcpu *vcpu)
 	free(state);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct kvm_vm *vm;
 	struct kvm_nested_state state;
@@ -296,5 +296,4 @@ int main(int argc, char *argv[])
 	test_vmx_nested_state(vcpu);
 
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_tsc_adjust_test.c b/tools/testing/selftests/kvm/x86_64/vmx_tsc_adjust_test.c
index 5943187e8594..da9628db7ee6 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_tsc_adjust_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_tsc_adjust_test.c
@@ -122,7 +122,7 @@ static void report(int64_t val)
 		val, val / TSC_ADJUST_VALUE, val % TSC_ADJUST_VALUE);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	vm_vaddr_t vmx_pages_gva;
 	struct kvm_vcpu *vcpu;
@@ -161,5 +161,4 @@ int main(int argc, char *argv[])
 
 done:
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/xapic_ipi_test.c b/tools/testing/selftests/kvm/x86_64/xapic_ipi_test.c
index 3d272d7f961e..fd0d5fbdeae2 100644
--- a/tools/testing/selftests/kvm/x86_64/xapic_ipi_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xapic_ipi_test.c
@@ -391,7 +391,7 @@ void get_cmdline_args(int argc, char *argv[], int *run_secs,
 	}
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	int r;
 	int wait_secs;
@@ -490,6 +490,4 @@ int main(int argc, char *argv[])
 		data->migrations_attempted, data->migrations_completed);
 
 	kvm_vm_free(vm);
-
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/xapic_state_test.c b/tools/testing/selftests/kvm/x86_64/xapic_state_test.c
index 6f7a5ef66718..750a3cb90b24 100644
--- a/tools/testing/selftests/kvm/x86_64/xapic_state_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xapic_state_test.c
@@ -130,7 +130,7 @@ static void test_icr(struct xapic_vcpu *x)
 	__test_icr(x, -1ull & ~APIC_DM_FIXED_MASK);
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct xapic_vcpu x = {
 		.vcpu = NULL,
diff --git a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
index 8a5cb800f50e..f003c8cc2812 100644
--- a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
@@ -352,7 +352,7 @@ static void handle_alrm(int sig)
 	TEST_FAIL("IRQ delivery timed out");
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	struct timespec min_ts, max_ts, vm_ts;
 	struct kvm_vm *vm;
@@ -876,5 +876,4 @@ int main(int argc, char *argv[])
 			    "runstate times don't add up");
 	}
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c b/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c
index 88914d48c65e..b17f36bd41cc 100644
--- a/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c
@@ -78,7 +78,7 @@ static void guest_code(void)
 	GUEST_DONE();
 }
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	unsigned int xen_caps;
 	struct kvm_vcpu *vcpu;
@@ -141,5 +141,4 @@ int main(int argc, char *argv[])
 	}
 done:
 	kvm_vm_free(vm);
-	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/xss_msr_test.c b/tools/testing/selftests/kvm/x86_64/xss_msr_test.c
index e0ddf47362e7..86cf86361637 100644
--- a/tools/testing/selftests/kvm/x86_64/xss_msr_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xss_msr_test.c
@@ -14,7 +14,7 @@
 
 #define MSR_BITS      64
 
-int main(int argc, char *argv[])
+void __main(int argc, char *argv[])
 {
 	bool xss_in_msr_list;
 	struct kvm_vm *vm;
-- 
2.37.2.789.g6183377224-goog

[V1 PATCH 2/5] selftests: kvm: Introduce kvm_arch_main and helpers

[Vishal Annapurve]

Introduce following APIs:
1) kvm_arch_main : to be called at the startup of each test.
2) kvm_arch_post_vm_load: called after guest elf image is loaded into
   memory to populate any global state in guest memory.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vishal Annapurve <vannapurve@google.com>
---
 tools/testing/selftests/kvm/include/kvm_util_base.h | 10 ++++++++++
 tools/testing/selftests/kvm/lib/aarch64/processor.c |  8 ++++++++
 tools/testing/selftests/kvm/lib/elf.c               |  2 ++
 tools/testing/selftests/kvm/lib/kvm_util.c          |  2 ++
 tools/testing/selftests/kvm/lib/riscv/processor.c   |  8 ++++++++
 tools/testing/selftests/kvm/lib/s390x/processor.c   |  8 ++++++++
 tools/testing/selftests/kvm/lib/x86_64/processor.c  |  8 ++++++++
 7 files changed, 46 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index 9e521d1c8afe..301bef6376a5 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -834,6 +834,16 @@ static inline int __vm_disable_nx_huge_pages(struct kvm_vm *vm)
 	return __vm_enable_cap(vm, KVM_CAP_VM_DISABLE_NX_HUGE_PAGES, 0);
 }
 
+/*
+ * API to execute architecture specific setup before executing selftest logic.
+ */
+void kvm_arch_main(void);
+
+/*
+ * API to execute architecture specific setup after loading VMs.
+ */
+void kvm_arch_post_vm_load(struct kvm_vm *vm);
+
 /*
  * API to be implemented by all the selftests.
  */
diff --git a/tools/testing/selftests/kvm/lib/aarch64/processor.c b/tools/testing/selftests/kvm/lib/aarch64/processor.c
index 6f5551368944..a7ca1947d574 100644
--- a/tools/testing/selftests/kvm/lib/aarch64/processor.c
+++ b/tools/testing/selftests/kvm/lib/aarch64/processor.c
@@ -528,3 +528,11 @@ void smccc_hvc(uint32_t function_id, uint64_t arg0, uint64_t arg1,
 		       [arg4] "r"(arg4), [arg5] "r"(arg5), [arg6] "r"(arg6)
 		     : "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7");
 }
+
+void kvm_arch_main(void)
+{
+}
+
+void kvm_arch_post_vm_load(struct kvm_vm *vm)
+{
+}
diff --git a/tools/testing/selftests/kvm/lib/elf.c b/tools/testing/selftests/kvm/lib/elf.c
index 9f54c098d9d0..f56f9279e703 100644
--- a/tools/testing/selftests/kvm/lib/elf.c
+++ b/tools/testing/selftests/kvm/lib/elf.c
@@ -189,4 +189,6 @@ void kvm_vm_elf_load(struct kvm_vm *vm, const char *filename)
 				phdr.p_filesz);
 		}
 	}
+
+	kvm_arch_post_vm_load(vm);
 }
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 2e611a021c6e..b778dc684e30 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1985,6 +1985,8 @@ int main(int argc, char *argv[])
 	/* Tell stdout not to buffer its content */
 	setbuf(stdout, NULL);
 
+	kvm_arch_main();
+
 	__main(argc, argv);
 
 	return 0;
diff --git a/tools/testing/selftests/kvm/lib/riscv/processor.c b/tools/testing/selftests/kvm/lib/riscv/processor.c
index 604478151212..d992ad5b5771 100644
--- a/tools/testing/selftests/kvm/lib/riscv/processor.c
+++ b/tools/testing/selftests/kvm/lib/riscv/processor.c
@@ -362,3 +362,11 @@ void vcpu_args_set(struct kvm_vcpu *vcpu, unsigned int num, ...)
 void assert_on_unhandled_exception(struct kvm_vcpu *vcpu)
 {
 }
+
+void kvm_arch_main(void)
+{
+}
+
+void kvm_arch_post_vm_load(struct kvm_vm *vm)
+{
+}
diff --git a/tools/testing/selftests/kvm/lib/s390x/processor.c b/tools/testing/selftests/kvm/lib/s390x/processor.c
index 89d7340d9cbd..3a249783b3fe 100644
--- a/tools/testing/selftests/kvm/lib/s390x/processor.c
+++ b/tools/testing/selftests/kvm/lib/s390x/processor.c
@@ -218,3 +218,11 @@ void vcpu_arch_dump(FILE *stream, struct kvm_vcpu *vcpu, uint8_t indent)
 void assert_on_unhandled_exception(struct kvm_vcpu *vcpu)
 {
 }
+
+void kvm_arch_main(void)
+{
+}
+
+void kvm_arch_post_vm_load(struct kvm_vm *vm)
+{
+}
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 2e6e61bbe81b..e22cfc4bf284 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -1311,3 +1311,11 @@ bool vm_is_unrestricted_guest(struct kvm_vm *vm)
 
 	return val == 'Y';
 }
+
+void kvm_arch_main(void)
+{
+}
+
+void kvm_arch_post_vm_load(struct kvm_vm *vm)
+{
+}
-- 
2.37.2.789.g6183377224-goog

[V1 PATCH 3/5] selftests: kvm: x86: Execute vmcall/vmmcall according to CPU type

[Vishal Annapurve]

Modify following APIs for x86 implementation:
1) kvm_arch_main : Query the cpu vendor and cache the value in advance.
2) kvm_arch_post_vm_load: Populate cpu type in the guest memory so that
	guest doesn't need to execute cpuid instruction again.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vishal Annapurve <vannapurve@google.com>
---
 .../testing/selftests/kvm/lib/x86_64/processor.c  | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index e22cfc4bf284..ac104653ab43 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -19,6 +19,7 @@
 #define MAX_NR_CPUID_ENTRIES 100
 
 vm_vaddr_t exception_handlers;
+static int is_cpu_amd = -1;
 
 static void regs_dump(FILE *stream, struct kvm_regs *regs, uint8_t indent)
 {
@@ -1019,7 +1020,7 @@ static bool cpu_vendor_string_is(const char *vendor)
 
 bool is_intel_cpu(void)
 {
-	return cpu_vendor_string_is("GenuineIntel");
+	return (is_cpu_amd == 0);
 }
 
 /*
@@ -1027,7 +1028,7 @@ bool is_intel_cpu(void)
  */
 bool is_amd_cpu(void)
 {
-	return cpu_vendor_string_is("AuthenticAMD");
+	return (is_cpu_amd == 1);
 }
 
 void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits)
@@ -1182,9 +1183,15 @@ uint64_t kvm_hypercall(uint64_t nr, uint64_t a0, uint64_t a1, uint64_t a2,
 {
 	uint64_t r;
 
-	asm volatile("vmcall"
+	if (is_amd_cpu())
+		asm volatile("vmmcall"
 		     : "=a"(r)
 		     : "a"(nr), "b"(a0), "c"(a1), "d"(a2), "S"(a3));
+	else
+		asm volatile("vmcall"
+		     : "=a"(r)
+		     : "a"(nr), "b"(a0), "c"(a1), "d"(a2), "S"(a3));
+
 	return r;
 }
 
@@ -1314,8 +1321,10 @@ bool vm_is_unrestricted_guest(struct kvm_vm *vm)
 
 void kvm_arch_main(void)
 {
+	is_cpu_amd = cpu_vendor_string_is("AuthenticAMD") ? 1 : 0;
 }
 
 void kvm_arch_post_vm_load(struct kvm_vm *vm)
 {
+	sync_global_to_guest(vm, is_cpu_amd);
 }
-- 
2.37.2.789.g6183377224-goog

[V1 PATCH 4/5] selftests: kvm: delete svm_vmcall_test

[Vishal Annapurve]

svm_vmcall_test is superseded by fix_hypercall_test.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vishal Annapurve <vannapurve@google.com>
---
 tools/testing/selftests/kvm/.gitignore        |  1 -
 .../selftests/kvm/x86_64/svm_vmcall_test.c    | 73 -------------------
 2 files changed, 74 deletions(-)
 delete mode 100644 tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index d625a3f83780..22e9a5b5488c 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -36,7 +36,6 @@
 /x86_64/sev_migrate_tests
 /x86_64/smm_test
 /x86_64/state_test
-/x86_64/svm_vmcall_test
 /x86_64/svm_int_ctl_test
 /x86_64/svm_nested_soft_inject_test
 /x86_64/sync_regs_test
diff --git a/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c b/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c
deleted file mode 100644
index 95ddc2bff332..000000000000
--- a/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c
+++ /dev/null
@@ -1,73 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * svm_vmcall_test
- *
- * Copyright (C) 2020, Red Hat, Inc.
- *
- * Nested SVM testing: VMCALL
- */
-
-#include "test_util.h"
-#include "kvm_util.h"
-#include "processor.h"
-#include "svm_util.h"
-
-static void l2_guest_code(struct svm_test_data *svm)
-{
-	__asm__ __volatile__("vmcall");
-}
-
-static void l1_guest_code(struct svm_test_data *svm)
-{
-	#define L2_GUEST_STACK_SIZE 64
-	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
-	struct vmcb *vmcb = svm->vmcb;
-
-	/* Prepare for L2 execution. */
-	generic_svm_setup(svm, l2_guest_code,
-			  &l2_guest_stack[L2_GUEST_STACK_SIZE]);
-
-	run_guest(vmcb, svm->vmcb_gpa);
-
-	GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL);
-	GUEST_DONE();
-}
-
-void __main(int argc, char *argv[])
-{
-	struct kvm_vcpu *vcpu;
-	vm_vaddr_t svm_gva;
-	struct kvm_vm *vm;
-
-	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SVM));
-
-	vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);
-
-	vcpu_alloc_svm(vm, &svm_gva);
-	vcpu_args_set(vcpu, 1, svm_gva);
-
-	for (;;) {
-		volatile struct kvm_run *run = vcpu->run;
-		struct ucall uc;
-
-		vcpu_run(vcpu);
-		TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
-			    "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
-			    run->exit_reason,
-			    exit_reason_str(run->exit_reason));
-
-		switch (get_ucall(vcpu, &uc)) {
-		case UCALL_ABORT:
-			REPORT_GUEST_ASSERT(uc);
-			/* NOT REACHED */
-		case UCALL_SYNC:
-			break;
-		case UCALL_DONE:
-			goto done;
-		default:
-			TEST_FAIL("Unknown ucall 0x%lx.", uc.cmd);
-		}
-	}
-done:
-	kvm_vm_free(vm);
-}
-- 
2.37.2.789.g6183377224-goog

[V1 PATCH 5/5] selftests: kvm: Execute vmcall/vmmcall as per cpu type

[Vishal Annapurve]

Modify existing tests to execute vmcall/vmmcall instructions as per the
cpu type.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vishal Annapurve <vannapurve@google.com>
---
 .../selftests/kvm/include/x86_64/processor.h  | 10 +++
 .../selftests/kvm/include/x86_64/vmx.h        |  9 ---
 .../selftests/kvm/lib/x86_64/perf_test_util.c |  2 +-
 .../selftests/kvm/lib/x86_64/processor.c      | 15 +++++
 tools/testing/selftests/kvm/x86_64/smm_test.c |  2 +-
 .../testing/selftests/kvm/x86_64/state_test.c |  8 +--
 .../kvm/x86_64/vmx_apic_access_test.c         |  2 +-
 .../selftests/kvm/x86_64/vmx_dirty_log_test.c |  2 +-
 .../kvm/x86_64/vmx_nested_tsc_scaling_test.c  |  2 +-
 .../kvm/x86_64/vmx_preemption_timer_test.c    |  2 +-
 .../kvm/x86_64/vmx_tsc_adjust_test.c          |  2 +-
 .../selftests/kvm/x86_64/xen_shinfo_test.c    | 64 +++++++------------
 .../selftests/kvm/x86_64/xen_vmcall_test.c    | 14 ++--
 13 files changed, 70 insertions(+), 64 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 0cbc71b7af50..74893a7a80f8 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -833,6 +833,16 @@ void vm_set_page_table_entry(struct kvm_vm *vm, struct kvm_vcpu *vcpu,
 uint64_t kvm_hypercall(uint64_t nr, uint64_t a0, uint64_t a1, uint64_t a2,
 		       uint64_t a3);
 
+/*
+ * Execute vmcall instruction.
+ */
+static inline void vmcall(void)
+{
+	kvm_hypercall(0, 0, 0, 0, 0);
+}
+
+void nested_guest_vmcall(void);
+
 void __vm_xsave_require_permission(int bit, const char *name);
 
 #define vm_xsave_require_permission(perm)	\
diff --git a/tools/testing/selftests/kvm/include/x86_64/vmx.h b/tools/testing/selftests/kvm/include/x86_64/vmx.h
index 99fa1410964c..d8d4fd3353e5 100644
--- a/tools/testing/selftests/kvm/include/x86_64/vmx.h
+++ b/tools/testing/selftests/kvm/include/x86_64/vmx.h
@@ -480,15 +480,6 @@ static inline int vmresume(void)
 	return ret;
 }
 
-static inline void vmcall(void)
-{
-	/* Currently, L1 destroys our GPRs during vmexits.  */
-	__asm__ __volatile__("push %%rbp; vmcall; pop %%rbp" : : :
-			     "rax", "rbx", "rcx", "rdx",
-			     "rsi", "rdi", "r8", "r9", "r10", "r11", "r12",
-			     "r13", "r14", "r15");
-}
-
 static inline int vmread(uint64_t encoding, uint64_t *value)
 {
 	uint64_t tmp;
diff --git a/tools/testing/selftests/kvm/lib/x86_64/perf_test_util.c b/tools/testing/selftests/kvm/lib/x86_64/perf_test_util.c
index 0f344a7c89c4..b420b35b7f45 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/perf_test_util.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/perf_test_util.c
@@ -18,7 +18,7 @@
 void perf_test_l2_guest_code(uint64_t vcpu_id)
 {
 	perf_test_guest_code(vcpu_id);
-	vmcall();
+	nested_guest_vmcall();
 }
 
 extern char perf_test_l2_guest_entry[];
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index ac104653ab43..5227b2c48a50 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -1195,6 +1195,21 @@ uint64_t kvm_hypercall(uint64_t nr, uint64_t a0, uint64_t a1, uint64_t a2,
 	return r;
 }
 
+void nested_guest_vmcall(void)
+{
+	/* Currently, L1 destroys our GPRs during vmexits.  */
+	if (is_amd_cpu())
+		__asm__ __volatile__("push %%rbp; vmmcall; pop %%rbp" : : :
+			     "rax", "rbx", "rcx", "rdx",
+			     "rsi", "rdi", "r8", "r9", "r10", "r11", "r12",
+			     "r13", "r14", "r15");
+	else
+		__asm__ __volatile__("push %%rbp; vmcall; pop %%rbp" : : :
+			     "rax", "rbx", "rcx", "rdx",
+			     "rsi", "rdi", "r8", "r9", "r10", "r11", "r12",
+			     "r13", "r14", "r15");
+}
+
 const struct kvm_cpuid2 *kvm_get_supported_hv_cpuid(void)
 {
 	static struct kvm_cpuid2 *cpuid;
diff --git a/tools/testing/selftests/kvm/x86_64/smm_test.c b/tools/testing/selftests/kvm/x86_64/smm_test.c
index 5f8ebe7795c1..26db9b18c1ca 100644
--- a/tools/testing/selftests/kvm/x86_64/smm_test.c
+++ b/tools/testing/selftests/kvm/x86_64/smm_test.c
@@ -61,7 +61,7 @@ static void l2_guest_code(void)
 
 	sync_with_host(10);
 
-	vmcall();
+	nested_guest_vmcall();
 }
 
 static void guest_code(void *arg)
diff --git a/tools/testing/selftests/kvm/x86_64/state_test.c b/tools/testing/selftests/kvm/x86_64/state_test.c
index 3d42c18d4c5f..889f73e38af1 100644
--- a/tools/testing/selftests/kvm/x86_64/state_test.c
+++ b/tools/testing/selftests/kvm/x86_64/state_test.c
@@ -26,10 +26,10 @@ void svm_l2_guest_code(void)
 {
 	GUEST_SYNC(4);
 	/* Exit to L1 */
-	vmcall();
+	nested_guest_vmcall();
 	GUEST_SYNC(6);
 	/* Done, exit to L1 and never come back.  */
-	vmcall();
+	nested_guest_vmcall();
 }
 
 static void svm_l1_guest_code(struct svm_test_data *svm)
@@ -57,7 +57,7 @@ void vmx_l2_guest_code(void)
 	GUEST_SYNC(6);
 
 	/* Exit to L1 */
-	vmcall();
+	nested_guest_vmcall();
 
 	/* L1 has now set up a shadow VMCS for us.  */
 	GUEST_ASSERT(vmreadz(GUEST_RIP) == 0xc0ffee);
@@ -70,7 +70,7 @@ void vmx_l2_guest_code(void)
 	GUEST_SYNC(12);
 
 	/* Done, exit to L1 and never come back.  */
-	vmcall();
+	nested_guest_vmcall();
 }
 
 static void vmx_l1_guest_code(struct vmx_pages *vmx_pages)
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c b/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c
index 2d503dce0481..b6caeea02dc3 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c
@@ -31,7 +31,7 @@
 static void l2_guest_code(void)
 {
 	/* Exit to L1 */
-	__asm__ __volatile__("vmcall");
+	vmcall();
 }
 
 static void l1_guest_code(struct vmx_pages *vmx_pages, unsigned long high_gpa)
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c b/tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c
index 5ab735bcf8ab..f8eeb35432f0 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c
@@ -42,7 +42,7 @@ static void l2_guest_code(void)
 	GUEST_SYNC(false);
 
 	/* Exit to L1 and never come back.  */
-	vmcall();
+	nested_guest_vmcall();
 }
 
 void l1_guest_code(struct vmx_pages *vmx)
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c b/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
index e3887e08666c..9ec1b5197193 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
@@ -76,7 +76,7 @@ static void l2_guest_code(void)
 	check_tsc_freq(UCHECK_L2);
 
 	/* exit to L1 */
-	__asm__ __volatile__("vmcall");
+	vmcall();
 }
 
 static void l1_guest_code(struct vmx_pages *vmx_pages)
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c b/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c
index 629b9c4bd6e4..1d5ff49be97d 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c
@@ -38,7 +38,7 @@ void l2_guest_code(void)
 {
 	u64 vmx_pt_delta;
 
-	vmcall();
+	nested_guest_vmcall();
 	l2_vmx_pt_start = (rdtsc() >> vmx_pt_rate) << vmx_pt_rate;
 
 	/*
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_tsc_adjust_test.c b/tools/testing/selftests/kvm/x86_64/vmx_tsc_adjust_test.c
index da9628db7ee6..26cf2554a0a0 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_tsc_adjust_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_tsc_adjust_test.c
@@ -74,7 +74,7 @@ static void l2_guest_code(void)
 	check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
 
 	/* Exit to L1 */
-	__asm__ __volatile__("vmcall");
+	vmcall();
 }
 
 static void l1_guest_code(struct vmx_pages *vmx_pages)
diff --git a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
index f003c8cc2812..4c32c977a98f 100644
--- a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
@@ -145,6 +145,23 @@ static void guest_wait_for_irq(void)
 	guest_saw_irq = false;
 }
 
+static unsigned long vmcall_helper(unsigned long reg_a, unsigned long reg_di,
+	unsigned long reg_si)
+{
+	unsigned long ret;
+
+	if (is_amd_cpu())
+		__asm__ __volatile__ ("vmmcall" :
+			"=a" (ret) :
+			"a" (reg_a), "D" (reg_di), "S" (reg_si));
+	else
+		__asm__ __volatile__ ("vmcall" :
+			"=a" (ret) :
+			"a" (reg_a), "D" (reg_di), "S" (reg_si));
+
+	return ret;
+}
+
 static void guest_code(void)
 {
 	struct vcpu_runstate_info *rs = (void *)RUNSTATE_VADDR;
@@ -217,12 +234,7 @@ static void guest_code(void)
 	 * EVTCHNOP_send hypercall. */
 	unsigned long rax;
 	struct evtchn_send s = { .port = 127 };
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_event_channel_op),
-			      "D" (EVTCHNOP_send),
-			      "S" (&s));
-
+	rax = vmcall_helper(__HYPERVISOR_event_channel_op, EVTCHNOP_send, (unsigned long)&s);
 	GUEST_ASSERT(rax == 0);
 
 	guest_wait_for_irq();
@@ -232,12 +244,7 @@ static void guest_code(void)
 	/* Deliver "outbound" event channel to an eventfd which
 	 * happens to be one of our own irqfds. */
 	s.port = 197;
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_event_channel_op),
-			      "D" (EVTCHNOP_send),
-			      "S" (&s));
-
+	rax = vmcall_helper(__HYPERVISOR_event_channel_op, EVTCHNOP_send, (unsigned long)&s);
 	GUEST_ASSERT(rax == 0);
 
 	guest_wait_for_irq();
@@ -245,10 +252,7 @@ static void guest_code(void)
 	GUEST_SYNC(13);
 
 	/* Set a timer 100ms in the future. */
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_set_timer_op),
-			      "D" (rs->state_entry_time + 100000000));
+	rax = vmcall_helper(__HYPERVISOR_set_timer_op, (rs->state_entry_time + 100000000), 0);
 	GUEST_ASSERT(rax == 0);
 
 	GUEST_SYNC(14);
@@ -271,36 +275,21 @@ static void guest_code(void)
 		.timeout = 0,
 	};
 
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_sched_op),
-			      "D" (SCHEDOP_poll),
-			      "S" (&p));
-
+	rax = vmcall_helper(__HYPERVISOR_sched_op, SCHEDOP_poll, (unsigned long)&p);
 	GUEST_ASSERT(rax == 0);
 
 	GUEST_SYNC(17);
 
 	/* Poll for an unset port and wait for the timeout. */
 	p.timeout = 100000000;
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_sched_op),
-			      "D" (SCHEDOP_poll),
-			      "S" (&p));
-
+	rax = vmcall_helper(__HYPERVISOR_sched_op, SCHEDOP_poll, (unsigned long)&p);
 	GUEST_ASSERT(rax == 0);
 
 	GUEST_SYNC(18);
 
 	/* A timer will wake the masked port we're waiting on, while we poll */
 	p.timeout = 0;
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_sched_op),
-			      "D" (SCHEDOP_poll),
-			      "S" (&p));
-
+	rax = vmcall_helper(__HYPERVISOR_sched_op, SCHEDOP_poll, (unsigned long)&p);
 	GUEST_ASSERT(rax == 0);
 
 	GUEST_SYNC(19);
@@ -309,12 +298,7 @@ static void guest_code(void)
 	 * actual interrupt, while we're polling on a different port. */
 	ports[0]++;
 	p.timeout = 0;
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_sched_op),
-			      "D" (SCHEDOP_poll),
-			      "S" (&p));
-
+	rax = vmcall_helper(__HYPERVISOR_sched_op, SCHEDOP_poll, (unsigned long)&p);
 	GUEST_ASSERT(rax == 0);
 
 	guest_wait_for_irq();
diff --git a/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c b/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c
index b17f36bd41cc..63fca30f085b 100644
--- a/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c
@@ -37,10 +37,16 @@ static void guest_code(void)
 	register unsigned long r9 __asm__("r9") = ARGVALUE(6);
 
 	/* First a direct invocation of 'vmcall' */
-	__asm__ __volatile__("vmcall" :
-			     "=a"(rax) :
-			     "a"(rax), "D"(rdi), "S"(rsi), "d"(rdx),
-			     "r"(r10), "r"(r8), "r"(r9));
+	if (is_amd_cpu())
+		__asm__ __volatile__("vmmcall" :
+			"=a"(rax) :
+			"a"(rax), "D"(rdi), "S"(rsi), "d"(rdx),
+			"r"(r10), "r"(r8), "r"(r9));
+	else
+		__asm__ __volatile__("vmcall" :
+			"=a"(rax) :
+			"a"(rax), "D"(rdi), "S"(rsi), "d"(rdx),
+			"r"(r10), "r"(r8), "r"(r9));
 	GUEST_ASSERT(rax == RETVALUE);
 
 	/* Fill in the Xen hypercall page */
-- 
2.37.2.789.g6183377224-goog

Re: [V1 PATCH 2/5] selftests: kvm: Introduce kvm_arch_main and helpers

[Andrew Jones]

On Sat, Sep 03, 2022 at 01:28:46AM +0000, Vishal Annapurve wrote:
> Introduce following APIs:
> 1) kvm_arch_main : to be called at the startup of each test.

With this, AArch64 can move the content of its constructor,
init_guest_modes(), into kvm_arch_main(). Or, instead of the

 main()
 {
    /* common main stuff */
    kvm_arch_main();
    __main();
 }

approach we could have each arch provide a constructor

 arch_init()
 {
    common_pre_main_stuff();
    /* arch specific pre-main stuff */
 }

I personally prefer the latter.

Thanks,
drew

> 2) kvm_arch_post_vm_load: called after guest elf image is loaded into
>    memory to populate any global state in guest memory.
> 
> Suggested-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Vishal Annapurve <vannapurve@google.com>
> ---
>  tools/testing/selftests/kvm/include/kvm_util_base.h | 10 ++++++++++
>  tools/testing/selftests/kvm/lib/aarch64/processor.c |  8 ++++++++
>  tools/testing/selftests/kvm/lib/elf.c               |  2 ++
>  tools/testing/selftests/kvm/lib/kvm_util.c          |  2 ++
>  tools/testing/selftests/kvm/lib/riscv/processor.c   |  8 ++++++++
>  tools/testing/selftests/kvm/lib/s390x/processor.c   |  8 ++++++++
>  tools/testing/selftests/kvm/lib/x86_64/processor.c  |  8 ++++++++
>  7 files changed, 46 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
> index 9e521d1c8afe..301bef6376a5 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util_base.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
> @@ -834,6 +834,16 @@ static inline int __vm_disable_nx_huge_pages(struct kvm_vm *vm)
>  	return __vm_enable_cap(vm, KVM_CAP_VM_DISABLE_NX_HUGE_PAGES, 0);
>  }
>  
> +/*
> + * API to execute architecture specific setup before executing selftest logic.
> + */
> +void kvm_arch_main(void);
> +
> +/*
> + * API to execute architecture specific setup after loading VMs.
> + */
> +void kvm_arch_post_vm_load(struct kvm_vm *vm);
> +
>  /*
>   * API to be implemented by all the selftests.
>   */
> diff --git a/tools/testing/selftests/kvm/lib/aarch64/processor.c b/tools/testing/selftests/kvm/lib/aarch64/processor.c
> index 6f5551368944..a7ca1947d574 100644
> --- a/tools/testing/selftests/kvm/lib/aarch64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/aarch64/processor.c
> @@ -528,3 +528,11 @@ void smccc_hvc(uint32_t function_id, uint64_t arg0, uint64_t arg1,
>  		       [arg4] "r"(arg4), [arg5] "r"(arg5), [arg6] "r"(arg6)
>  		     : "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7");
>  }
> +
> +void kvm_arch_main(void)
> +{
> +}
> +
> +void kvm_arch_post_vm_load(struct kvm_vm *vm)
> +{
> +}
> diff --git a/tools/testing/selftests/kvm/lib/elf.c b/tools/testing/selftests/kvm/lib/elf.c
> index 9f54c098d9d0..f56f9279e703 100644
> --- a/tools/testing/selftests/kvm/lib/elf.c
> +++ b/tools/testing/selftests/kvm/lib/elf.c
> @@ -189,4 +189,6 @@ void kvm_vm_elf_load(struct kvm_vm *vm, const char *filename)
>  				phdr.p_filesz);
>  		}
>  	}
> +
> +	kvm_arch_post_vm_load(vm);
>  }
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 2e611a021c6e..b778dc684e30 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -1985,6 +1985,8 @@ int main(int argc, char *argv[])
>  	/* Tell stdout not to buffer its content */
>  	setbuf(stdout, NULL);
>  
> +	kvm_arch_main();
> +
>  	__main(argc, argv);
>  
>  	return 0;
> diff --git a/tools/testing/selftests/kvm/lib/riscv/processor.c b/tools/testing/selftests/kvm/lib/riscv/processor.c
> index 604478151212..d992ad5b5771 100644
> --- a/tools/testing/selftests/kvm/lib/riscv/processor.c
> +++ b/tools/testing/selftests/kvm/lib/riscv/processor.c
> @@ -362,3 +362,11 @@ void vcpu_args_set(struct kvm_vcpu *vcpu, unsigned int num, ...)
>  void assert_on_unhandled_exception(struct kvm_vcpu *vcpu)
>  {
>  }
> +
> +void kvm_arch_main(void)
> +{
> +}
> +
> +void kvm_arch_post_vm_load(struct kvm_vm *vm)
> +{
> +}
> diff --git a/tools/testing/selftests/kvm/lib/s390x/processor.c b/tools/testing/selftests/kvm/lib/s390x/processor.c
> index 89d7340d9cbd..3a249783b3fe 100644
> --- a/tools/testing/selftests/kvm/lib/s390x/processor.c
> +++ b/tools/testing/selftests/kvm/lib/s390x/processor.c
> @@ -218,3 +218,11 @@ void vcpu_arch_dump(FILE *stream, struct kvm_vcpu *vcpu, uint8_t indent)
>  void assert_on_unhandled_exception(struct kvm_vcpu *vcpu)
>  {
>  }
> +
> +void kvm_arch_main(void)
> +{
> +}
> +
> +void kvm_arch_post_vm_load(struct kvm_vm *vm)
> +{
> +}
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> index 2e6e61bbe81b..e22cfc4bf284 100644
> --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> @@ -1311,3 +1311,11 @@ bool vm_is_unrestricted_guest(struct kvm_vm *vm)
>  
>  	return val == 'Y';
>  }
> +
> +void kvm_arch_main(void)
> +{
> +}
> +
> +void kvm_arch_post_vm_load(struct kvm_vm *vm)
> +{
> +}
> -- 
> 2.37.2.789.g6183377224-goog
> 

Re: [V1 PATCH 2/5] selftests: kvm: Introduce kvm_arch_main and helpers

[Vishal Annapurve]

On Mon, Sep 5, 2022 at 12:46 AM Andrew Jones <andrew.jones@linux.dev> wrote:
>
> On Sat, Sep 03, 2022 at 01:28:46AM +0000, Vishal Annapurve wrote:
> > Introduce following APIs:
> > 1) kvm_arch_main : to be called at the startup of each test.
>
> With this, AArch64 can move the content of its constructor,
> init_guest_modes(), into kvm_arch_main(). Or, instead of the
>
>  main()
>  {
>     /* common main stuff */
>     kvm_arch_main();
>     __main();
>  }
>
> approach we could have each arch provide a constructor
>
>  arch_init()
>  {
>     common_pre_main_stuff();
>     /* arch specific pre-main stuff */
>  }
>
> I personally prefer the latter.
>

I agree with your suggestion of using constructors here. This will
help avoid changes in all the selftests.
Maybe I can add a common constructor that can invoke arch specific
init. I will add this change in the next series.

Thanks,
Vishal

> Thanks,
> drew
>
> > 2) kvm_arch_post_vm_load: called after guest elf image is loaded into
> >    memory to populate any global state in guest memory.
> >
> > Suggested-by: Sean Christopherson <seanjc@google.com>
> > Signed-off-by: Vishal Annapurve <vannapurve@google.com>
> > ---
> >  tools/testing/selftests/kvm/include/kvm_util_base.h | 10 ++++++++++
> >  tools/testing/selftests/kvm/lib/aarch64/processor.c |  8 ++++++++
> >  tools/testing/selftests/kvm/lib/elf.c               |  2 ++
> >  tools/testing/selftests/kvm/lib/kvm_util.c          |  2 ++
> >  tools/testing/selftests/kvm/lib/riscv/processor.c   |  8 ++++++++
> >  tools/testing/selftests/kvm/lib/s390x/processor.c   |  8 ++++++++
> >  tools/testing/selftests/kvm/lib/x86_64/processor.c  |  8 ++++++++
> >  7 files changed, 46 insertions(+)
> >
> > diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
> > index 9e521d1c8afe..301bef6376a5 100644
> > --- a/tools/testing/selftests/kvm/include/kvm_util_base.h
> > +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
> > @@ -834,6 +834,16 @@ static inline int __vm_disable_nx_huge_pages(struct kvm_vm *vm)
> >       return __vm_enable_cap(vm, KVM_CAP_VM_DISABLE_NX_HUGE_PAGES, 0);
> >  }
> >
> > +/*
> > + * API to execute architecture specific setup before executing selftest logic.
> > + */
> > +void kvm_arch_main(void);
> > +
> > +/*
> > + * API to execute architecture specific setup after loading VMs.
> > + */
> > +void kvm_arch_post_vm_load(struct kvm_vm *vm);
> > +
> >  /*
> >   * API to be implemented by all the selftests.
> >   */
> > diff --git a/tools/testing/selftests/kvm/lib/aarch64/processor.c b/tools/testing/selftests/kvm/lib/aarch64/processor.c
> > index 6f5551368944..a7ca1947d574 100644
> > --- a/tools/testing/selftests/kvm/lib/aarch64/processor.c
> > +++ b/tools/testing/selftests/kvm/lib/aarch64/processor.c
> > @@ -528,3 +528,11 @@ void smccc_hvc(uint32_t function_id, uint64_t arg0, uint64_t arg1,
> >                      [arg4] "r"(arg4), [arg5] "r"(arg5), [arg6] "r"(arg6)
> >                    : "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7");
> >  }
> > +
> > +void kvm_arch_main(void)
> > +{
> > +}
> > +
> > +void kvm_arch_post_vm_load(struct kvm_vm *vm)
> > +{
> > +}
> > diff --git a/tools/testing/selftests/kvm/lib/elf.c b/tools/testing/selftests/kvm/lib/elf.c
> > index 9f54c098d9d0..f56f9279e703 100644
> > --- a/tools/testing/selftests/kvm/lib/elf.c
> > +++ b/tools/testing/selftests/kvm/lib/elf.c
> > @@ -189,4 +189,6 @@ void kvm_vm_elf_load(struct kvm_vm *vm, const char *filename)
> >                               phdr.p_filesz);
> >               }
> >       }
> > +
> > +     kvm_arch_post_vm_load(vm);
> >  }
> > diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> > index 2e611a021c6e..b778dc684e30 100644
> > --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> > +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> > @@ -1985,6 +1985,8 @@ int main(int argc, char *argv[])
> >       /* Tell stdout not to buffer its content */
> >       setbuf(stdout, NULL);
> >
> > +     kvm_arch_main();
> > +
> >       __main(argc, argv);
> >
> >       return 0;
> > diff --git a/tools/testing/selftests/kvm/lib/riscv/processor.c b/tools/testing/selftests/kvm/lib/riscv/processor.c
> > index 604478151212..d992ad5b5771 100644
> > --- a/tools/testing/selftests/kvm/lib/riscv/processor.c
> > +++ b/tools/testing/selftests/kvm/lib/riscv/processor.c
> > @@ -362,3 +362,11 @@ void vcpu_args_set(struct kvm_vcpu *vcpu, unsigned int num, ...)
> >  void assert_on_unhandled_exception(struct kvm_vcpu *vcpu)
> >  {
> >  }
> > +
> > +void kvm_arch_main(void)
> > +{
> > +}
> > +
> > +void kvm_arch_post_vm_load(struct kvm_vm *vm)
> > +{
> > +}
> > diff --git a/tools/testing/selftests/kvm/lib/s390x/processor.c b/tools/testing/selftests/kvm/lib/s390x/processor.c
> > index 89d7340d9cbd..3a249783b3fe 100644
> > --- a/tools/testing/selftests/kvm/lib/s390x/processor.c
> > +++ b/tools/testing/selftests/kvm/lib/s390x/processor.c
> > @@ -218,3 +218,11 @@ void vcpu_arch_dump(FILE *stream, struct kvm_vcpu *vcpu, uint8_t indent)
> >  void assert_on_unhandled_exception(struct kvm_vcpu *vcpu)
> >  {
> >  }
> > +
> > +void kvm_arch_main(void)
> > +{
> > +}
> > +
> > +void kvm_arch_post_vm_load(struct kvm_vm *vm)
> > +{
> > +}
> > diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> > index 2e6e61bbe81b..e22cfc4bf284 100644
> > --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
> > +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> > @@ -1311,3 +1311,11 @@ bool vm_is_unrestricted_guest(struct kvm_vm *vm)
> >
> >       return val == 'Y';
> >  }
> > +
> > +void kvm_arch_main(void)
> > +{
> > +}
> > +
> > +void kvm_arch_post_vm_load(struct kvm_vm *vm)
> > +{
> > +}
> > --
> > 2.37.2.789.g6183377224-goog
> >

Re: [V1 PATCH 1/5] selftests: kvm: move common startup logic to kvm_util.c

[David Matlack]

On Sat, Sep 03, 2022 at 01:28:45AM +0000, Vishal Annapurve wrote:
[...]
> --- a/tools/testing/selftests/kvm/demand_paging_test.c
> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> @@ -393,7 +393,7 @@ static void help(char *name)
>  	exit(0);
>  }
>  
> -int main(int argc, char *argv[])
> +void __main(int argc, char *argv[])
>  {
>  	int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
>  	struct test_params p = {
> @@ -447,18 +447,15 @@ int main(int argc, char *argv[])
>  	}
>  
>  	for_each_guest_mode(run_test, &p);
> -
> -	return 0;
>  }
>  
>  #else /* __NR_userfaultfd */
>  
>  #warning "missing __NR_userfaultfd definition"
>  
> -int main(void)
> +void __main(int argc, char *argv[])
>  {
>  	print_skip("__NR_userfaultfd must be present for userfaultfd test");
> -	return KSFT_SKIP;

exit(KSFT_SKIP) to preserve the test behavior.

Re: [V1 PATCH 2/5] selftests: kvm: Introduce kvm_arch_main and helpers

[David Matlack]

On Tue, Sep 06, 2022 at 03:46:20PM -0700, Vishal Annapurve wrote:
> On Mon, Sep 5, 2022 at 12:46 AM Andrew Jones <andrew.jones@linux.dev> wrote:
> >
> > On Sat, Sep 03, 2022 at 01:28:46AM +0000, Vishal Annapurve wrote:
> > > Introduce following APIs:
> > > 1) kvm_arch_main : to be called at the startup of each test.
> >
> > With this, AArch64 can move the content of its constructor,
> > init_guest_modes(), into kvm_arch_main(). Or, instead of the
> >
> >  main()
> >  {
> >     /* common main stuff */
> >     kvm_arch_main();
> >     __main();
> >  }
> >
> > approach we could have each arch provide a constructor
> >
> >  arch_init()
> >  {
> >     common_pre_main_stuff();
> >     /* arch specific pre-main stuff */
> >  }
> >
> > I personally prefer the latter.
> >
> 
> I agree with your suggestion of using constructors here. This will
> help avoid changes in all the selftests.
> Maybe I can add a common constructor that can invoke arch specific
> init. I will add this change in the next series.

In case anyone else is confused like me: "constructor" refers to
__attribute__ ((constructor)), which causes the function to run before
main().

I have a slight preference for having as few constructors as possible,
since they are somewhat subtle. So how about one constructor for all
selftests, e.g.:

void __attribute__ ((constructor)) kvm_selftest_init(void)
{
        /* Tell stdout not to buffer its content. */
        setbuf(stdout, NULL);

        kvm_selftest_arch_init();
}

Per-arch:

void kvm_selftest_arch_init(void)
{
        /* arch-specific pre-main stuff */
}

Re: [V1 PATCH 2/5] selftests: kvm: Introduce kvm_arch_main and helpers

[David Matlack]

On Sat, Sep 03, 2022 at 01:28:46AM +0000, Vishal Annapurve wrote:
> Introduce following APIs:
> 1) kvm_arch_main : to be called at the startup of each test.
> 2) kvm_arch_post_vm_load: called after guest elf image is loaded into
>    memory to populate any global state in guest memory.

nit: Can you throw the post_vm_load in a separate commit? It's a
logically distinct change. Also suggest naming it
kvm_arch_post_vm_elf_load() to make it obvious it runs after
kvm_vm_elf_load().

Re: [V1 PATCH 3/5] selftests: kvm: x86: Execute vmcall/vmmcall according to CPU type

[David Matlack]

Please use "KVM: selftest: ..." for the shortlog.

On Sat, Sep 03, 2022 at 01:28:47AM +0000, Vishal Annapurve wrote:
> Modify following APIs for x86 implementation:
> 1) kvm_arch_main : Query the cpu vendor and cache the value in advance.
> 2) kvm_arch_post_vm_load: Populate cpu type in the guest memory so that
> 	guest doesn't need to execute cpuid instruction again.

This commit message only describes a subset of the changes in this
commit, and does not provide any context on why the changes are being
made (other than a clue about avoiding CPUID).

I also think this could be split up into 2 separate commits.

I would suggest first patch changes is_{intel,amd}_cpu() to return a cached
result. e.g.

  KVM: selftests: Precompute the result for is_{intel,amd}_cpu()

  Cache the vendor CPU type in a global variable so that multiple calls
  to is_intel_cpu() do not need to re-execute CPUID. This will be useful
  in a follow-up commit to check if running on AMD or Intel from within
  a selftest guest where executing CPUID requires a VM-exit.

Then add support for AMD to kvm_hypercall():

  KVM: selftests: Add AMD support to kvm_hypercall()

  Add support for AMD hypercalls to kvm_hypercall() so that it can be
  used in selftests running on Intel or AMD hosts. This will be used in
  a follow up commit to ...

  As part of this change, sync the global variable is_cpu_amd into the
  guest so the guest can determine which hypercall instruction to use
  without needing to re-execute CPUID for every hypercall.

> 
> Suggested-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Vishal Annapurve <vannapurve@google.com>
> ---
>  .../testing/selftests/kvm/lib/x86_64/processor.c  | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> index e22cfc4bf284..ac104653ab43 100644
> --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> @@ -19,6 +19,7 @@
>  #define MAX_NR_CPUID_ENTRIES 100
>  
>  vm_vaddr_t exception_handlers;
> +static int is_cpu_amd = -1;

Should this just be a bool? Since you are initializing it before main(),
there is really no way for any code to observe it's pre-initialized
value. And nothing even checks if is_cpu_amd -1, it just silently
returns false from is_intel_cpu() and is_amd_cpu().

>  
>  static void regs_dump(FILE *stream, struct kvm_regs *regs, uint8_t indent)
>  {
> @@ -1019,7 +1020,7 @@ static bool cpu_vendor_string_is(const char *vendor)
>  
>  bool is_intel_cpu(void)
>  {
> -	return cpu_vendor_string_is("GenuineIntel");
> +	return (is_cpu_amd == 0);
>  }
>  
>  /*
> @@ -1027,7 +1028,7 @@ bool is_intel_cpu(void)
>   */
>  bool is_amd_cpu(void)
>  {
> -	return cpu_vendor_string_is("AuthenticAMD");
> +	return (is_cpu_amd == 1);
>  }
>  
>  void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits)
> @@ -1182,9 +1183,15 @@ uint64_t kvm_hypercall(uint64_t nr, uint64_t a0, uint64_t a1, uint64_t a2,
>  {
>  	uint64_t r;
>  
> -	asm volatile("vmcall"
> +	if (is_amd_cpu())
> +		asm volatile("vmmcall"
>  		     : "=a"(r)
>  		     : "a"(nr), "b"(a0), "c"(a1), "d"(a2), "S"(a3));
> +	else
> +		asm volatile("vmcall"
> +		     : "=a"(r)
> +		     : "a"(nr), "b"(a0), "c"(a1), "d"(a2), "S"(a3));
> +
>  	return r;
>  }
>  
> @@ -1314,8 +1321,10 @@ bool vm_is_unrestricted_guest(struct kvm_vm *vm)
>  
>  void kvm_arch_main(void)
>  {
> +	is_cpu_amd = cpu_vendor_string_is("AuthenticAMD") ? 1 : 0;
>  }
>  
>  void kvm_arch_post_vm_load(struct kvm_vm *vm)
>  {
> +	sync_global_to_guest(vm, is_cpu_amd);
>  }
> -- 
> 2.37.2.789.g6183377224-goog
> 

Re: [V1 PATCH 3/5] selftests: kvm: x86: Execute vmcall/vmmcall according to CPU type

[David Matlack]

On Thu, Sep 08, 2022 at 03:54:41PM -0700, David Matlack wrote:
> Please use "KVM: selftest: ..." for the shortlog.

Doh. "KVM: selftests: ..."

Re: [V1 PATCH 2/5] selftests: kvm: Introduce kvm_arch_main and helpers

[Andrew Jones]

On Thu, Sep 08, 2022 at 02:21:52PM -0700, David Matlack wrote:
> On Tue, Sep 06, 2022 at 03:46:20PM -0700, Vishal Annapurve wrote:
> > On Mon, Sep 5, 2022 at 12:46 AM Andrew Jones <andrew.jones@linux.dev> wrote:
> > >
> > > On Sat, Sep 03, 2022 at 01:28:46AM +0000, Vishal Annapurve wrote:
> > > > Introduce following APIs:
> > > > 1) kvm_arch_main : to be called at the startup of each test.
> > >
> > > With this, AArch64 can move the content of its constructor,
> > > init_guest_modes(), into kvm_arch_main(). Or, instead of the
> > >
> > >  main()
> > >  {
> > >     /* common main stuff */
> > >     kvm_arch_main();
> > >     __main();
> > >  }
> > >
> > > approach we could have each arch provide a constructor
> > >
> > >  arch_init()
> > >  {
> > >     common_pre_main_stuff();
> > >     /* arch specific pre-main stuff */
> > >  }
> > >
> > > I personally prefer the latter.
> > >
> > 
> > I agree with your suggestion of using constructors here. This will
> > help avoid changes in all the selftests.
> > Maybe I can add a common constructor that can invoke arch specific
> > init. I will add this change in the next series.
> 
> In case anyone else is confused like me: "constructor" refers to
> __attribute__ ((constructor)), which causes the function to run before
> main().
> 
> I have a slight preference for having as few constructors as possible,
> since they are somewhat subtle. So how about one constructor for all
> selftests, e.g.:
> 
> void __attribute__ ((constructor)) kvm_selftest_init(void)
> {
>         /* Tell stdout not to buffer its content. */
>         setbuf(stdout, NULL);
> 
>         kvm_selftest_arch_init();
> }
> 
> Per-arch:
> 
> void kvm_selftest_arch_init(void)
> {
>         /* arch-specific pre-main stuff */
> }

WFM and I think that's what Vishal was suggesting as well.

Thanks,
drew

Re: [V1 PATCH 1/5] selftests: kvm: move common startup logic to kvm_util.c

[Vishal Annapurve]

On Thu, Sep 8, 2022 at 2:09 PM David Matlack <dmatlack@google.com> wrote:
>
...
> >       print_skip("__NR_userfaultfd must be present for userfaultfd test");
> > -     return KSFT_SKIP;
>
> exit(KSFT_SKIP) to preserve the test behavior.

Ack, though this change should go away in the next series with common
selftest init using constructor attribute.

Regards,
Vishal

Re: [V1 PATCH 3/5] selftests: kvm: x86: Execute vmcall/vmmcall according to CPU type

[Vishal Annapurve]

On Thu, Sep 8, 2022 at 3:54 PM David Matlack <dmatlack@google.com> wrote:
>
> Please use "KVM: selftest: ..." for the shortlog.
>

Ack.

> On Sat, Sep 03, 2022 at 01:28:47AM +0000, Vishal Annapurve wrote:
> > Modify following APIs for x86 implementation:
> > 1) kvm_arch_main : Query the cpu vendor and cache the value in advance.
> > 2) kvm_arch_post_vm_load: Populate cpu type in the guest memory so that
> >       guest doesn't need to execute cpuid instruction again.
>
> This commit message only describes a subset of the changes in this
> commit, and does not provide any context on why the changes are being
> made (other than a clue about avoiding CPUID).
>
> I also think this could be split up into 2 separate commits.
>

Ack, will add more details to the commit log. Though since
is_amd_cpu/is_intel_cpu is used by both selftest VMM and selftest
guest logic, I would prefer to not split this change into two. For
now, I will upload the series with this change being a single patch.
We can discuss again if this split is really needed.

Regards,
Vishal

> I would suggest first patch changes is_{intel,amd}_cpu() to return a cached
> result. e.g.
>
>   KVM: selftests: Precompute the result for is_{intel,amd}_cpu()
>
>   Cache the vendor CPU type in a global variable so that multiple calls
>   to is_intel_cpu() do not need to re-execute CPUID. This will be useful
>   in a follow-up commit to check if running on AMD or Intel from within
>   a selftest guest where executing CPUID requires a VM-exit.
>
> Then add support for AMD to kvm_hypercall():
>
>   KVM: selftests: Add AMD support to kvm_hypercall()
>
>   Add support for AMD hypercalls to kvm_hypercall() so that it can be
>   used in selftests running on Intel or AMD hosts. This will be used in
>   a follow up commit to ...
>
>   As part of this change, sync the global variable is_cpu_amd into the
>   guest so the guest can determine which hypercall instruction to use
>   without needing to re-execute CPUID for every hypercall.
>

Re: [V1 PATCH 2/5] selftests: kvm: Introduce kvm_arch_main and helpers

[Vishal Annapurve]

On Fri, Sep 9, 2022 at 12:01 AM Andrew Jones <andrew.jones@linux.dev> wrote:
...
> >
> > void __attribute__ ((constructor)) kvm_selftest_init(void)
> > {
> >         /* Tell stdout not to buffer its content. */
> >         setbuf(stdout, NULL);
> >
> >         kvm_selftest_arch_init();
> > }
> >
> > Per-arch:
> >
> > void kvm_selftest_arch_init(void)
> > {
> >         /* arch-specific pre-main stuff */
> > }
>
> WFM and I think that's what Vishal was suggesting as well.
>

Yes, this matches with what I was suggesting. Planning to post this
update in the next series.

- Vishal

> Thanks,
> drew