[PATCH 3/3] KVM: selftests: Add KVM_SET_GUEST_DEBUG test

Peter Xu
2020-05-05T20:50:22Z

Covers fundamental tests for KVM_SET_GUEST_DEBUG. It is very close to the debug
test in kvm-unit-test, but doing it from outside the guest.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
tools/testing/selftests/kvm/Makefile | 1 +
.../testing/selftests/kvm/include/kvm_util.h | 2 +
tools/testing/selftests/kvm/lib/kvm_util.c | 9 +
.../testing/selftests/kvm/x86_64/debug_regs.c | 180 ++++++++++++++++++
4 files changed, 192 insertions(+)
create mode 100644 tools/testing/selftests/kvm/x86_64/debug_regs.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 712a2ddd2a27..44b6ef513164 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -28,6 +28,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_dirty_log_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test
TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
+TEST_GEN_PROGS_x86_64 += x86_64/debug_regs
TEST_GEN_PROGS_x86_64 += clear_dirty_log_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/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index a99b875f50d2..92e184a422ee 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -143,6 +143,8 @@ struct kvm_run *vcpu_state(struct kvm_vm *vm, uint32_t vcpuid);
void vcpu_run(struct kvm_vm *vm, uint32_t vcpuid);
int _vcpu_run(struct kvm_vm *vm, uint32_t vcpuid);
void vcpu_run_complete_io(struct kvm_vm *vm, uint32_t vcpuid);
+void vcpu_set_guest_debug(struct kvm_vm *vm, uint32_t vcpuid,
+ struct kvm_guest_debug *debug);
void vcpu_set_mp_state(struct kvm_vm *vm, uint32_t vcpuid,
struct kvm_mp_state *mp_state);
void vcpu_regs_get(struct kvm_vm *vm, uint32_t vcpuid, struct kvm_regs *regs);
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 8a3523d4434f..9622431069bc 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1201,6 +1201,15 @@ void vcpu_run_complete_io(struct kvm_vm *vm, uint32_t vcpuid)
ret, errno);
}

+void vcpu_set_guest_debug(struct kvm_vm *vm, uint32_t vcpuid,
+ struct kvm_guest_debug *debug)
+{
+ struct vcpu *vcpu = vcpu_find(vm, vcpuid);
+ int ret = ioctl(vcpu->fd, KVM_SET_GUEST_DEBUG, debug);
+
+ TEST_ASSERT(ret == 0, "KVM_SET_GUEST_DEBUG failed: %d", ret);
+}
+
/*
* VM VCPU Set MP State
*
diff --git a/tools/testing/selftests/kvm/x86_64/debug_regs.c b/tools/testing/selftests/kvm/x86_64/debug_regs.c
new file mode 100644
index 000000000000..2b7187db061d
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/debug_regs.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KVM guest debug register tests
+ *
+ * Copyright (C) 2020, Red Hat, Inc.
+ */
+#include <stdio.h>
+#include <string.h>
+#include "kvm_util.h"
+#include "processor.h"
+
+#define VCPU_ID 0
+
+/* For testing data access debug BP */
+uint32_t guest_value;
+
+extern unsigned char sw_bp, hw_bp, write_data, ss_start;
+
+static void guest_code(void)
+{
+ /*
+ * Software BP tests.
+ *
+ * NOTE: sw_bp need to be before the cmd here, because int3 is an
+ * exception rather than a normal trap for KVM_SET_GUEST_DEBUG (we
+ * capture it using the vcpu exception bitmap).
+ */
+ asm volatile("sw_bp: int3");
+
+ /* Hardware instruction BP test */
+ asm volatile("hw_bp: nop");
+
+ /* Hardware data BP test */
+ asm volatile("mov $1234,%%rax;\n\t"
+ "mov %%rax,%0;\n\t write_data:"
+ : "=m" (guest_value) : : "rax");
+
+ /* Single step test, covers 2 basic commands and 2 emulated */
+ asm volatile("ss_start: "
+ "xor %%rax,%%rax\n\t"
+ "cpuid\n\t"
+ "movl $0x1a0,%%ecx\n\t"
+ "rdmsr\n\t"
+ : : : "rax", "ecx");
+
+ GUEST_DONE();
+}
+
+#define CLEAR_DEBUG() memset(&debug, 0, sizeof(debug))
+#define APPLY_DEBUG() vcpu_set_guest_debug(vm, VCPU_ID, &debug)
+#define CAST_TO_RIP(v) ((unsigned long long)&(v))
+#define SET_RIP(v) do { \
+ vcpu_regs_get(vm, VCPU_ID, &regs); \
+ regs.rip = (v); \
+ vcpu_regs_set(vm, VCPU_ID, &regs); \
+ } while (0)
+#define MOVE_RIP(v) SET_RIP(regs.rip + (v));
+
+int main(void)
+{
+ struct kvm_guest_debug debug;
+ unsigned long long target_dr6, target_rip;
+ struct kvm_regs regs;
+ struct kvm_run *run;
+ struct kvm_vm *vm;
+ struct ucall uc;
+ uint64_t cmd;
+ int i;
+ /* Corresponds to commands starts with ss_start */
+ int ss_size[4] = {
+ 3, /* xor */
+ 2, /* cpuid */
+ 5, /* mov */
+ 2, /* rdmsr */
+ };
+
+ if (!kvm_check_cap(KVM_CAP_SET_GUEST_DEBUG)) {
+ print_skip("KVM_CAP_SET_GUEST_DEBUG not supported");
+ return 0;
+ }
+
+ vm = vm_create_default(VCPU_ID, 0, guest_code);
+ vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
+ run = vcpu_state(vm, VCPU_ID);
+
+ /* Test software BPs - int3 */
+ CLEAR_DEBUG();
+ debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP;
+ APPLY_DEBUG();
+ vcpu_run(vm, VCPU_ID);
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG &&
+ run->debug.arch.exception == BP_VECTOR &&
+ run->debug.arch.pc == CAST_TO_RIP(sw_bp),
+ "INT3: exit %d exception %d rip 0x%llx (should be 0x%llx)",
+ run->exit_reason, run->debug.arch.exception,
+ run->debug.arch.pc, CAST_TO_RIP(sw_bp));
+ MOVE_RIP(1);
+
+ /* Test instruction HW BP over DR[0-3] */
+ for (i = 0; i < 4; i++) {
+ CLEAR_DEBUG();
+ debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP;
+ debug.arch.debugreg[i] = CAST_TO_RIP(hw_bp);
+ debug.arch.debugreg[7] = 0x400 | (1UL << (2*i+1));
+ APPLY_DEBUG();
+ vcpu_run(vm, VCPU_ID);
+ target_dr6 = 0xffff0ff0 | (1UL << i);
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG &&
+ run->debug.arch.exception == DB_VECTOR &&
+ run->debug.arch.pc == CAST_TO_RIP(hw_bp) &&
+ run->debug.arch.dr6 == target_dr6,
+ "INS_HW_BP (DR%d): exit %d exception %d rip 0x%llx "
+ "(should be 0x%llx) dr6 0x%llx (should be 0x%llx)",
+ i, run->exit_reason, run->debug.arch.exception,
+ run->debug.arch.pc, CAST_TO_RIP(hw_bp),
+ run->debug.arch.dr6, target_dr6);
+ }
+ /* Skip "nop" */
+ MOVE_RIP(1);
+
+ /* Test data access HW BP over DR[0-3] */
+ for (i = 0; i < 4; i++) {
+ CLEAR_DEBUG();
+ debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP;
+ debug.arch.debugreg[i] = CAST_TO_RIP(guest_value);
+ debug.arch.debugreg[7] = 0x00000400 | (1UL << (2*i+1)) |
+ (0x000d0000UL << (4*i));
+ APPLY_DEBUG();
+ vcpu_run(vm, VCPU_ID);
+ target_dr6 = 0xffff0ff0 | (1UL << i);
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG &&
+ run->debug.arch.exception == DB_VECTOR &&
+ run->debug.arch.pc == CAST_TO_RIP(write_data) &&
+ run->debug.arch.dr6 == target_dr6,
+ "DATA_HW_BP (DR%d): exit %d exception %d rip 0x%llx "
+ "(should be 0x%llx) dr6 0x%llx (should be 0x%llx)",
+ i, run->exit_reason, run->debug.arch.exception,
+ run->debug.arch.pc, CAST_TO_RIP(write_data),
+ run->debug.arch.dr6, target_dr6);
+ /* Rollback the 4-bytes "mov" */
+ MOVE_RIP(-7);
+ }
+ /* Skip the 4-bytes "mov" */
+ MOVE_RIP(7);
+
+ /* Test single step */
+ target_rip = CAST_TO_RIP(ss_start);
+ target_dr6 = 0xffff4ff0ULL;
+ vcpu_regs_get(vm, VCPU_ID, &regs);
+ for (i = 0; i < (sizeof(ss_size) / sizeof(ss_size[0])); i++) {
+ target_rip += ss_size[i];
+ CLEAR_DEBUG();
+ debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP;
+ debug.arch.debugreg[7] = 0x00000400;
+ APPLY_DEBUG();
+ vcpu_run(vm, VCPU_ID);
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG &&
+ run->debug.arch.exception == DB_VECTOR &&
+ run->debug.arch.pc == target_rip &&
+ run->debug.arch.dr6 == target_dr6,
+ "SINGLE_STEP[%d]: exit %d exception %d rip 0x%llx "
+ "(should be 0x%llx) dr6 0x%llx (should be 0x%llx)",
+ i, run->exit_reason, run->debug.arch.exception,
+ run->debug.arch.pc, target_rip, run->debug.arch.dr6,
+ target_dr6);
+ }
+
+ /* Disable all debug controls, run to the end */
+ CLEAR_DEBUG();
+ APPLY_DEBUG();
+
+ vcpu_run(vm, VCPU_ID);
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_IO, "KVM_EXIT_IO");
+ cmd = get_ucall(vm, VCPU_ID, &uc);
+ TEST_ASSERT(cmd == UCALL_DONE, "UCALL_DONE");
+
+ kvm_vm_free(vm);
+
+ return 0;
+}
--
2.26.2