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KVM: arm64: selftests: Add a test case for KVM_GUESTDBG_SINGLESTEP

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Add a test case for KVM_GUESTDBG_SINGLESTEP to the debug-exceptions test.
The test enables single-step execution from userspace, and check if the
exit to userspace occurs for each instruction that is stepped.
Set the default number of the test iterations to a number of iterations
sufficient to always reproduce the problem that the previous patch fixes
on an Ampere Altra machine.

Signed-off-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220917010600.532642-5-reijiw@google.com
This commit is contained in:
Reiji Watanabe 2022-09-16 18:06:00 -07:00 committed by Marc Zyngier
parent ff00e73709
commit b18e4d4aeb
1 changed files with 131 additions and 0 deletions
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131
tools/testing/selftests/kvm/aarch64/debug-exceptions.c
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@ -22,6 +22,7 @@
#define SPSR_SS (1 << 21)
extern unsigned char sw_bp, sw_bp2, hw_bp, hw_bp2, bp_svc, bp_brk, hw_wp, ss_start;
extern unsigned char iter_ss_begin, iter_ss_end;
static volatile uint64_t sw_bp_addr, hw_bp_addr;
static volatile uint64_t wp_addr, wp_data_addr;
static volatile uint64_t svc_addr;
@ -238,6 +239,46 @@ static void guest_svc_handler(struct ex_regs *regs)
svc_addr = regs->pc;
}
enum single_step_op {
SINGLE_STEP_ENABLE = 0,
SINGLE_STEP_DISABLE = 1,
};
static void guest_code_ss(int test_cnt)
{
uint64_t i;
uint64_t bvr, wvr, w_bvr, w_wvr;
for (i = 0; i < test_cnt; i++) {
/* Bits [1:0] of dbg{b,w}vr are RES0 */
w_bvr = i << 2;
w_wvr = i << 2;
/* Enable Single Step execution */
GUEST_SYNC(SINGLE_STEP_ENABLE);
/*
* The userspace will veriry that the pc is as expected during
* single step execution between iter_ss_begin and iter_ss_end.
*/
asm volatile("iter_ss_begin:nop\n");
write_sysreg(w_bvr, dbgbvr0_el1);
write_sysreg(w_wvr, dbgwvr0_el1);
bvr = read_sysreg(dbgbvr0_el1);
wvr = read_sysreg(dbgwvr0_el1);
asm volatile("iter_ss_end:\n");
/* Disable Single Step execution */
GUEST_SYNC(SINGLE_STEP_DISABLE);
GUEST_ASSERT(bvr == w_bvr);
GUEST_ASSERT(wvr == w_wvr);
}
GUEST_DONE();
}
static int debug_version(struct kvm_vcpu *vcpu)
{
uint64_t id_aa64dfr0;
@ -293,16 +334,106 @@ done:
kvm_vm_free(vm);
}
void test_single_step_from_userspace(int test_cnt)
{
struct kvm_vcpu *vcpu;
struct kvm_vm *vm;
struct ucall uc;
struct kvm_run *run;
uint64_t pc, cmd;
uint64_t test_pc = 0;
bool ss_enable = false;
struct kvm_guest_debug debug = {};
vm = vm_create_with_one_vcpu(&vcpu, guest_code_ss);
ucall_init(vm, NULL);
run = vcpu->run;
vcpu_args_set(vcpu, 1, test_cnt);
while (1) {
vcpu_run(vcpu);
if (run->exit_reason != KVM_EXIT_DEBUG) {
cmd = get_ucall(vcpu, &uc);
if (cmd == UCALL_ABORT) {
REPORT_GUEST_ASSERT(uc);
/* NOT REACHED */
} else if (cmd == UCALL_DONE) {
break;
}
TEST_ASSERT(cmd == UCALL_SYNC,
"Unexpected ucall cmd 0x%lx", cmd);
if (uc.args[1] == SINGLE_STEP_ENABLE) {
debug.control = KVM_GUESTDBG_ENABLE |
KVM_GUESTDBG_SINGLESTEP;
ss_enable = true;
} else {
debug.control = SINGLE_STEP_DISABLE;
ss_enable = false;
}
vcpu_guest_debug_set(vcpu, &debug);
continue;
}
TEST_ASSERT(ss_enable, "Unexpected KVM_EXIT_DEBUG");
/* Check if the current pc is expected. */
vcpu_get_reg(vcpu, ARM64_CORE_REG(regs.pc), &pc);
TEST_ASSERT(!test_pc || pc == test_pc,
"Unexpected pc 0x%lx (expected 0x%lx)",
pc, test_pc);
/*
* If the current pc is between iter_ss_bgin and
* iter_ss_end, the pc for the next KVM_EXIT_DEBUG should
* be the current pc + 4.
*/
if ((pc >= (uint64_t)&iter_ss_begin) &&
(pc < (uint64_t)&iter_ss_end))
test_pc = pc + 4;
else
test_pc = 0;
}
kvm_vm_free(vm);
}
static void help(char *name)
{
puts("");
printf("Usage: %s [-h] [-i iterations of the single step test]\n", name);
puts("");
exit(0);
}
int main(int argc, char *argv[])
{
struct kvm_vcpu *vcpu;
struct kvm_vm *vm;
int opt;
int ss_iteration = 10000;
vm = vm_create_with_one_vcpu(&vcpu, guest_code);
__TEST_REQUIRE(debug_version(vcpu) >= 6,
"Armv8 debug architecture not supported.");
kvm_vm_free(vm);
while ((opt = getopt(argc, argv, "i:")) != -1) {
switch (opt) {
case 'i':
ss_iteration = atoi(optarg);
break;
case 'h':
default:
help(argv[0]);
break;
}
}
test_guest_debug_exceptions();
test_single_step_from_userspace(ss_iteration);
return 0;
}