Re: [RFC PATCH v4 7/7] KVM: selftests: Add tests for VM and vCPU cap KVM_CAP_X86_DISABLE_EXITS

["Huang, Shaoqin" <shaoqin.huang@intel.com>]

On 6/22/2022 8:49 AM, Kechen Lu wrote:
> Add tests for KVM cap KVM_CAP_X86_DISABLE_EXITS overriding flags
> in VM and vCPU scope both works as expected.
> 
> Suggested-by: Chao Gao <chao.gao@intel.com>
> Signed-off-by: Kechen Lu <kechenl@nvidia.com>
> ---
>   tools/testing/selftests/kvm/.gitignore        |   1 +
>   tools/testing/selftests/kvm/Makefile          |   1 +
>   .../selftests/kvm/include/x86_64/svm_util.h   |   1 +
>   .../selftests/kvm/x86_64/disable_exits_test.c | 145 ++++++++++++++++++
>   4 files changed, 148 insertions(+)
>   create mode 100644 tools/testing/selftests/kvm/x86_64/disable_exits_test.c
> 
> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
> index 4509a3a7eeae..2b50170db9b2 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -15,6 +15,7 @@
>   /x86_64/cpuid_test
>   /x86_64/cr4_cpuid_sync_test
>   /x86_64/debug_regs
> +/x86_64/disable_exits_test
>   /x86_64/evmcs_test
>   /x86_64/emulator_error_test
>   /x86_64/fix_hypercall_test
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 22423c871ed6..de11d1f95700 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -115,6 +115,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/xen_shinfo_test
>   TEST_GEN_PROGS_x86_64 += x86_64/xen_vmcall_test
>   TEST_GEN_PROGS_x86_64 += x86_64/sev_migrate_tests
>   TEST_GEN_PROGS_x86_64 += x86_64/amx_test
> +TEST_GEN_PROGS_x86_64 += x86_64/disable_exits_test
>   TEST_GEN_PROGS_x86_64 += access_tracking_perf_test
>   TEST_GEN_PROGS_x86_64 += demand_paging_test
>   TEST_GEN_PROGS_x86_64 += dirty_log_test
> diff --git a/tools/testing/selftests/kvm/include/x86_64/svm_util.h b/tools/testing/selftests/kvm/include/x86_64/svm_util.h
> index a25aabd8f5e7..d8cad1cff578 100644
> --- a/tools/testing/selftests/kvm/include/x86_64/svm_util.h
> +++ b/tools/testing/selftests/kvm/include/x86_64/svm_util.h
> @@ -17,6 +17,7 @@
>   #define CPUID_SVM		BIT_ULL(CPUID_SVM_BIT)
>   
>   #define SVM_EXIT_MSR		0x07c
> +#define SVM_EXIT_HLT		0x078

There has other people add the SVM_EXIT_HLT in the kvm/queue, so you may 
not need to add it here.

>   #define SVM_EXIT_VMMCALL	0x081
>   
>   struct svm_test_data {
> diff --git a/tools/testing/selftests/kvm/x86_64/disable_exits_test.c b/tools/testing/selftests/kvm/x86_64/disable_exits_test.c
> new file mode 100644
> index 000000000000..2811b07e8885
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/x86_64/disable_exits_test.c
> @@ -0,0 +1,145 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Test per-VM and per-vCPU disable exits cap
> + *
> + */
> +
> +#define _GNU_SOURCE /* for program_invocation_short_name */
> +#include <sys/ioctl.h>
> +
> +#include "test_util.h"
> +#include "kvm_util.h"
> +#include "svm_util.h"
> +#include "vmx.h"
> +#include "processor.h"
> +
> +#define VCPU_ID_1 0
> +#define VCPU_ID_2 1
> +
> +static void guest_code_exits(void) {
> +	asm volatile("sti; hlt; cli");
> +}
> +
> +/* Set debug control for trapped instruction exiting to userspace */
> +static void vcpu_set_debug_exit_userspace(struct kvm_vm *vm, int vcpu_id) {

nit: you should make the code style consistent, please use the format:
function()
{

}

> +	struct kvm_guest_debug debug;
> +	memset(&debug, 0, sizeof(debug));
> +	debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_EXIT_USERSPACE;
> +	vcpu_set_guest_debug(vm, vcpu_id, &debug);
> +}
> +
> +static void test_vm_cap_disable_exits(void) {
> +	struct kvm_enable_cap cap = {
> +		.cap = KVM_CAP_X86_DISABLE_EXITS,
> +		.args[0] = KVM_X86_DISABLE_EXITS_HLT|KVM_X86_DISABLE_EXITS_OVERRIDE,
						    ^
			nit: a space is much more clear here

> +	};
> +	struct kvm_vm *vm;
> +	struct kvm_run *run;
> +
> +	/* Create VM */
> +	vm = vm_create_without_vcpus(VM_MODE_DEFAULT, DEFAULT_GUEST_PHY_PAGES);
> +
> +	/* Test Case #1
> +	 * Default without disabling HLT exits in VM scope
> +	 */
> +	vm_vcpu_add_default(vm, VCPU_ID_1, (void *)guest_code_exits);
> +	vcpu_set_debug_exit_userspace(vm, VCPU_ID_1);
> +	run = vcpu_state(vm, VCPU_ID_1);
> +	vcpu_run(vm, VCPU_ID_1);
> +	/* Exit reason should be HLT */
> +	if (is_amd_cpu())
> +		TEST_ASSERT(run->hw.hardware_exit_reason == SVM_EXIT_HLT,
> +			"Got exit_reason other than HLT: 0x%llx\n",
> +			run->hw.hardware_exit_reason);
> +	else
> +		TEST_ASSERT(run->hw.hardware_exit_reason == EXIT_REASON_HLT,
> +			"Got exit_reason other than HLT: 0x%llx\n",
> +			run->hw.hardware_exit_reason);
> +
> +	/* Test Case #2
> +	 * Disabling HLT exits in VM scope
> +	 */
> +	vm_vcpu_add_default(vm, VCPU_ID_2, (void *)guest_code_exits);
> +	vcpu_set_debug_exit_userspace(vm, VCPU_ID_2);
> +	run = vcpu_state(vm, VCPU_ID_2);

I think you can add more vcpu here to make sure after disabling HLT 
exits in VM scope here, every vcpu will not exit due to the HLT.

> +	/* Set VM scoped cap arg
> +	 * KVM_X86_DISABLE_EXITS_HLT|KVM_X86_DISABLE_EXITS_OVERRIDE
> +	 * after vCPUs creation so requiring override flag
> +	 */
> +	TEST_ASSERT(!vm_enable_cap(vm, &cap), "Failed to set KVM_CAP_X86_DISABLE_EXITS");
> +	vcpu_run(vm, VCPU_ID_2);
> +	/* Exit reason should not be HLT, would finish the guest
> +	 * running and exit (e.g. SVM_EXIT_SHUTDOWN)
> +	 */
> +	if (is_amd_cpu())
> +		TEST_ASSERT(run->hw.hardware_exit_reason != SVM_EXIT_HLT,
> +			"Got exit_reason as HLT: 0x%llx\n",
> +			run->hw.hardware_exit_reason);
> +	else
> +		TEST_ASSERT(run->hw.hardware_exit_reason != EXIT_REASON_HLT,
> +			"Got exit_reason as HLT: 0x%llx\n",
> +			run->hw.hardware_exit_reason);
> +
> +	kvm_vm_free(vm);
> +}
> +
> +static void test_vcpu_cap_disable_exits(void) {
> +	struct kvm_enable_cap cap = {
> +		.cap = KVM_CAP_X86_DISABLE_EXITS,
> +		.args[0] = KVM_X86_DISABLE_EXITS_HLT|KVM_X86_DISABLE_EXITS_OVERRIDE,
> +	};
> +	struct kvm_vm *vm;
> +	struct kvm_run *run;
> +
> +	/* Create VM */
> +	vm = vm_create_without_vcpus(VM_MODE_DEFAULT, DEFAULT_GUEST_PHY_PAGES);
> +	vm_vcpu_add_default(vm, VCPU_ID_1, (void *)guest_code_exits);
> +	vcpu_set_debug_exit_userspace(vm, VCPU_ID_1);
> +	vm_vcpu_add_default(vm, VCPU_ID_2, (void *)guest_code_exits);
> +	vcpu_set_debug_exit_userspace(vm, VCPU_ID_2);
> +	/* Set vCPU 2 scoped cap arg
> +	 * KVM_X86_DISABLE_EXITS_HLT|KVM_X86_DISABLE_EXITS_OVERRIDE
> +	 */
> +	TEST_ASSERT(!vcpu_enable_cap(vm, VCPU_ID_2, &cap), "Failed to set KVM_CAP_X86_DISABLE_EXITS");
> +
> +	/* Test Case #3
> +	 * Default without disabling HLT exits in this vCPU 1
> +	 */
> +	run = vcpu_state(vm, VCPU_ID_1);
> +	vcpu_run(vm, VCPU_ID_1);
> +	/* Exit reason should be HLT */
> +	if (is_amd_cpu())
> +		TEST_ASSERT(run->hw.hardware_exit_reason == SVM_EXIT_HLT,
> +			"Got exit_reason other than HLT: 0x%llx\n",
> +			run->hw.hardware_exit_reason);
> +	else
> +		TEST_ASSERT(run->hw.hardware_exit_reason == EXIT_REASON_HLT,
> +			"Got exit_reason other than HLT: 0x%llx\n",
> +			run->hw.hardware_exit_reason);
> +
> +	/* Test Case #4
> +	 * Disabling HLT exits in vCPU 2
> +	 */
> +	run = vcpu_state(vm, VCPU_ID_2);
> +	vcpu_run(vm, VCPU_ID_2);
> +	/* Exit reason should not be HLT, would finish the guest
> +	 * running and exit (e.g. SVM_EXIT_SHUTDOWN)
> +	 */
> +	if (is_amd_cpu())
> +		TEST_ASSERT(run->hw.hardware_exit_reason != SVM_EXIT_HLT,
> +			"Got exit_reason as HLT: 0x%llx\n",
> +			run->hw.hardware_exit_reason);
> +	else
> +		TEST_ASSERT(run->hw.hardware_exit_reason != EXIT_REASON_HLT,
> +			"Got exit_reason as HLT: 0x%llx\n",
> +			run->hw.hardware_exit_reason);
> +
> +	kvm_vm_free(vm);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	test_vm_cap_disable_exits();
> +	test_vcpu_cap_disable_exits();
> +	return 0;
> +}