Re: [PATCH v3 6/6] KVM: s390: selftests: Add selftest for single-stepping

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Mon, 24 Jul 2023 11:44:12 +0200
Ilya Leoshkevich <iii@linux.ibm.com> wrote:

> Test different variations of single-stepping into interrupts:
> 
> - SVC and PGM interrupts;
> - Interrupts generated by ISKE;
> - Interrupts generated by instructions emulated by KVM;
> - Interrupts generated by instructions emulated by userspace.

thank you for writing this selftest!

> 
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

> ---
>  tools/testing/selftests/kvm/Makefile          |   1 +
>  .../testing/selftests/kvm/s390x/debug_test.c  | 160 ++++++++++++++++++
>  2 files changed, 161 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/s390x/debug_test.c
> 
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index c692cc86e7da..f3306eaa7031 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -166,6 +166,7 @@ TEST_GEN_PROGS_s390x += s390x/resets
>  TEST_GEN_PROGS_s390x += s390x/sync_regs_test
>  TEST_GEN_PROGS_s390x += s390x/tprot
>  TEST_GEN_PROGS_s390x += s390x/cmma_test
> +TEST_GEN_PROGS_s390x += s390x/debug_test
>  TEST_GEN_PROGS_s390x += demand_paging_test
>  TEST_GEN_PROGS_s390x += dirty_log_test
>  TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
> diff --git a/tools/testing/selftests/kvm/s390x/debug_test.c b/tools/testing/selftests/kvm/s390x/debug_test.c
> new file mode 100644
> index 000000000000..a8fa9fe93b3c
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/s390x/debug_test.c
> @@ -0,0 +1,160 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Test KVM debugging features. */
> +#include "kvm_util.h"
> +#include "test_util.h"
> +
> +#include <linux/kvm.h>
> +
> +#define __LC_SVC_NEW_PSW 0x1c0
> +#define __LC_PGM_NEW_PSW 0x1d0
> +#define ICPT_INSTRUCTION 0x04
> +#define IPA0_DIAG 0x8300
> +#define PGM_SPECIFICATION 0x06
> +
> +/* Common code for testing single-stepping interruptions. */
> +extern char int_handler[];
> +asm("int_handler:\n"
> +    "j .\n");
> +
> +static struct kvm_vm *test_step_int_1(struct kvm_vcpu **vcpu, void *guest_code,
> +				      size_t new_psw_off, uint64_t *new_psw)
> +{
> +	struct kvm_guest_debug debug = {};
> +	struct kvm_regs regs;
> +	struct kvm_vm *vm;
> +	char *lowcore;
> +
> +	vm = vm_create_with_one_vcpu(vcpu, guest_code);
> +	lowcore = addr_gpa2hva(vm, 0);
> +	new_psw[0] = (*vcpu)->run->psw_mask;
> +	new_psw[1] = (uint64_t)int_handler;
> +	memcpy(lowcore + new_psw_off, new_psw, 16);
> +	vcpu_regs_get(*vcpu, &regs);
> +	regs.gprs[2] = -1;
> +	vcpu_regs_set(*vcpu, &regs);
> +	debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP;
> +	vcpu_guest_debug_set(*vcpu, &debug);
> +	vcpu_run(*vcpu);
> +
> +	return vm;
> +}
> +
> +static void test_step_int(void *guest_code, size_t new_psw_off)
> +{
> +	struct kvm_vcpu *vcpu;
> +	uint64_t new_psw[2];
> +	struct kvm_vm *vm;
> +
> +	vm = test_step_int_1(&vcpu, guest_code, new_psw_off, new_psw);
> +	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_DEBUG);
> +	ASSERT_EQ(vcpu->run->psw_mask, new_psw[0]);
> +	ASSERT_EQ(vcpu->run->psw_addr, new_psw[1]);
> +	kvm_vm_free(vm);
> +}
> +
> +/* Test single-stepping "boring" program interruptions. */
> +extern char test_step_pgm_guest_code[];
> +asm("test_step_pgm_guest_code:\n"
> +    ".insn rr,0x1d00,%r1,%r0 /* dr %r1,%r0 */\n"
> +    "j .\n");
> +
> +static void test_step_pgm(void)
> +{
> +	test_step_int(test_step_pgm_guest_code, __LC_PGM_NEW_PSW);
> +}
> +
> +/*
> + * Test single-stepping program interruptions caused by DIAG.
> + * Userspace emulation must not interfere with single-stepping.
> + */
> +extern char test_step_pgm_diag_guest_code[];
> +asm("test_step_pgm_diag_guest_code:\n"
> +    "diag %r0,%r0,0\n"
> +    "j .\n");
> +
> +static void test_step_pgm_diag(void)
> +{
> +	struct kvm_s390_irq irq = {
> +		.type = KVM_S390_PROGRAM_INT,
> +		.u.pgm.code = PGM_SPECIFICATION,
> +	};
> +	struct kvm_vcpu *vcpu;
> +	uint64_t new_psw[2];
> +	struct kvm_vm *vm;
> +
> +	vm = test_step_int_1(&vcpu, test_step_pgm_diag_guest_code,
> +			     __LC_PGM_NEW_PSW, new_psw);
> +	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_S390_SIEIC);
> +	ASSERT_EQ(vcpu->run->s390_sieic.icptcode, ICPT_INSTRUCTION);
> +	ASSERT_EQ(vcpu->run->s390_sieic.ipa & 0xff00, IPA0_DIAG);
> +	vcpu_ioctl(vcpu, KVM_S390_IRQ, &irq);
> +	vcpu_run(vcpu);
> +	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_DEBUG);
> +	ASSERT_EQ(vcpu->run->psw_mask, new_psw[0]);
> +	ASSERT_EQ(vcpu->run->psw_addr, new_psw[1]);
> +	kvm_vm_free(vm);
> +}
> +
> +/*
> + * Test single-stepping program interruptions caused by ISKE.
> + * CPUSTAT_KSS handling must not interfere with single-stepping.
> + */
> +extern char test_step_pgm_iske_guest_code[];
> +asm("test_step_pgm_iske_guest_code:\n"
> +    "iske %r2,%r2\n"
> +    "j .\n");
> +
> +static void test_step_pgm_iske(void)
> +{
> +	test_step_int(test_step_pgm_iske_guest_code, __LC_PGM_NEW_PSW);
> +}
> +
> +/*
> + * Test single-stepping program interruptions caused by LCTL.
> + * KVM emulation must not interfere with single-stepping.
> + */
> +extern char test_step_pgm_lctl_guest_code[];
> +asm("test_step_pgm_lctl_guest_code:\n"
> +    "lctl %c0,%c0,1\n"
> +    "j .\n");
> +
> +static void test_step_pgm_lctl(void)
> +{
> +	test_step_int(test_step_pgm_lctl_guest_code, __LC_PGM_NEW_PSW);
> +}
> +
> +/* Test single-stepping supervisor-call interruptions. */
> +extern char test_step_svc_guest_code[];
> +asm("test_step_svc_guest_code:\n"
> +    "svc 0\n"
> +    "j .\n");
> +
> +static void test_step_svc(void)
> +{
> +	test_step_int(test_step_svc_guest_code, __LC_SVC_NEW_PSW);
> +}
> +
> +/* Run all tests above. */
> +static struct testdef {
> +	const char *name;
> +	void (*test)(void);
> +} testlist[] = {
> +	{ "single-step pgm", test_step_pgm },
> +	{ "single-step pgm caused by diag", test_step_pgm_diag },
> +	{ "single-step pgm caused by iske", test_step_pgm_iske },
> +	{ "single-step pgm caused by lctl", test_step_pgm_lctl },
> +	{ "single-step svc", test_step_svc },
> +};
> +
> +int main(int argc, char *argv[])
> +{
> +	int idx;
> +
> +	ksft_print_header();
> +	ksft_set_plan(ARRAY_SIZE(testlist));
> +	for (idx = 0; idx < ARRAY_SIZE(testlist); idx++) {
> +		testlist[idx].test();
> +		ksft_test_result_pass("%s\n", testlist[idx].name);
> +	}
> +	ksft_finished();
> +}