// 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"
#include "apic.h"
#define DR6_BD (1 << 13)
#define DR7_GD (1 << 13)
#define IRQ_VECTOR 0xAA
/* For testing data access debug BP */
uint32_t guest_value;
extern unsigned char sw_bp, hw_bp, write_data, ss_start, bd_start;
static void guest_code(void)
{
/* Create a pending interrupt on current vCPU */
x2apic_enable();
x2apic_write_reg(APIC_ICR, APIC_DEST_SELF | APIC_INT_ASSERT |
APIC_DM_FIXED | IRQ_VECTOR);
/*
* 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 instructions and 2 emulated
*
* Enable interrupts during the single stepping to see that pending
* interrupt we raised is not handled due to KVM_GUESTDBG_BLOCKIRQ.
*
* Write MSR_IA32_TSC_DEADLINE to verify that KVM's fastpath handler
* exits to userspace due to single-step being enabled.
*/
asm volatile("ss_start: "
"sti\n\t"
"xor %%eax,%%eax\n\t"
"cpuid\n\t"
"movl $" __stringify(MSR_IA32_TSC_DEADLINE) ", %%ecx\n\t"
"wrmsr\n\t"
"cli\n\t"
: : : "eax", "ebx", "ecx", "edx");
/* DR6.BD test */
asm volatile("bd_start: mov %%dr0, %%rax" : : : "rax");
GUEST_DONE();
}
#define CAST_TO_RIP(v) ((unsigned long long)&(v))
static void vcpu_skip_insn(struct kvm_vcpu *vcpu, int insn_len)
{
struct kvm_regs regs;
vcpu_regs_get(vcpu, ®s);
regs.rip += insn_len;
vcpu_regs_set(vcpu, ®s);
}
int main(void)
{
struct kvm_guest_debug debug;
unsigned long long target_dr6, target_rip;
struct kvm_vcpu *vcpu;
struct kvm_run *run;
struct kvm_vm *vm;
struct ucall uc;
uint64_t cmd;
int i;
/* Instruction lengths starting at ss_start */
int ss_size[6] = {
1, /* sti*/
2, /* xor */
2, /* cpuid */
5, /* mov */
2, /* rdmsr */
1, /* cli */
};
TEST_REQUIRE(kvm_has_cap(KVM_CAP_SET_GUEST_DEBUG));
vm = vm_create_with_one_vcpu(&vcpu, guest_code);
run = vcpu->run;
/* Test software BPs - int3 */
memset(&debug, 0, sizeof(debug));
debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP;
vcpu_guest_debug_set(vcpu, &debug);
vcpu_run(vcpu);
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));
vcpu_skip_insn(vcpu, 1);
/* Test instruction HW BP over DR[0-3] */
for (i = 0; i < 4; i++) {
memset(&debug, 0, sizeof(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));
vcpu_guest_debug_set(vcpu, &debug);
vcpu_run(vcpu);
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" */
vcpu_skip_insn(vcpu, 1);
/* Test data access HW BP over DR[0-3] */
for (i = 0; i < 4; i++) {
memset(&debug, 0, sizeof(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));
vcpu_guest_debug_set(vcpu, &debug);
vcpu_run(vcpu);
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" */
vcpu_skip_insn(vcpu, -7);
}
/* Skip the 4-bytes "mov" */
vcpu_skip_insn(vcpu, 7);
/* Test single step */
target_rip = CAST_TO_RIP(ss_start);
target_dr6 = 0xffff4ff0ULL;
for (i = 0; i < (sizeof(ss_size) / sizeof(ss_size[0])); i++) {
target_rip += ss_size[i];
memset(&debug, 0, sizeof(debug));
debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP |
KVM_GUESTDBG_BLOCKIRQ;
debug.arch.debugreg[7] = 0x00000400;
vcpu_guest_debug_set(vcpu, &debug);
vcpu_run(vcpu);
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);
}
/* Finally test global disable */
memset(&debug, 0, sizeof(debug));
debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP;
debug.arch.debugreg[7] = 0x400 | DR7_GD;
vcpu_guest_debug_set(vcpu, &debug);
vcpu_run(vcpu);
target_dr6 = 0xffff0ff0 | DR6_BD;
TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG &&
run->debug.arch.exception == DB_VECTOR &&
run->debug.arch.pc == CAST_TO_RIP(bd_start) &&
run->debug.arch.dr6 == target_dr6,
"DR7.GD: exit %d exception %d rip 0x%llx "
"(should be 0x%llx) dr6 0x%llx (should be 0x%llx)",
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 */
memset(&debug, 0, sizeof(debug));
vcpu_guest_debug_set(vcpu, &debug);
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
cmd = get_ucall(vcpu, &uc);
TEST_ASSERT(cmd == UCALL_DONE, "UCALL_DONE");
kvm_vm_free(vm);
return 0;
}
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