KVM: selftests: Add aarch64/debug-exceptions test

Covers fundamental tests for debug exceptions. The guest installs and
handle its debug exceptions itself, without KVM_SET_GUEST_DEBUG.
Signed-off-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210611011020.3420067-7-ricarkol@google.com

tools/testing/selftests/kvm/.gitignore

 # SPDX-License-Identifier: GPL-2.0-only
+/aarch64/debug-exceptions
 /aarch64/get-reg-list
 /aarch64/get-reg-list-sve
 /aarch64/vgic_init

tools/testing/selftests/kvm/Makefile

@@ -78,6 +78,7 @@ TEST_GEN_PROGS_x86_64 += memslot_perf_test
 TEST_GEN_PROGS_x86_64 += set_memory_region_test
 TEST_GEN_PROGS_x86_64 += steal_time
 
+TEST_GEN_PROGS_aarch64 += aarch64/debug-exceptions
 TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list
 TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list-sve
 TEST_GEN_PROGS_aarch64 += aarch64/vgic_init

tools/testing/selftests/kvm/aarch64/debug-exceptions.c

+// SPDX-License-Identifier: GPL-2.0
+#include <test_util.h>
+#include <kvm_util.h>
+#include <processor.h>
+
+#define VCPU_ID 0
+
+#define MDSCR_KDE	(1 << 13)
+#define MDSCR_MDE	(1 << 15)
+#define MDSCR_SS	(1 << 0)
+
+#define DBGBCR_LEN8	(0xff << 5)
+#define DBGBCR_EXEC	(0x0 << 3)
+#define DBGBCR_EL1	(0x1 << 1)
+#define DBGBCR_E	(0x1 << 0)
+
+#define DBGWCR_LEN8	(0xff << 5)
+#define DBGWCR_RD	(0x1 << 3)
+#define DBGWCR_WR	(0x2 << 3)
+#define DBGWCR_EL1	(0x1 << 1)
+#define DBGWCR_E	(0x1 << 0)
+
+#define SPSR_D		(1 << 9)
+#define SPSR_SS		(1 << 21)
+
+extern unsigned char sw_bp, hw_bp, bp_svc, bp_brk, hw_wp, ss_start;
+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;
+static volatile uint64_t ss_addr[4], ss_idx;
+#define  PC(v)  ((uint64_t)&(v))
+
+static void reset_debug_state(void)
+{
+	asm volatile("msr daifset, #8");
+
+	write_sysreg(osdlr_el1, 0);
+	write_sysreg(oslar_el1, 0);
+	isb();
+
+	write_sysreg(mdscr_el1, 0);
+	/* This test only uses the first bp and wp slot. */
+	write_sysreg(dbgbvr0_el1, 0);
+	write_sysreg(dbgbcr0_el1, 0);
+	write_sysreg(dbgwcr0_el1, 0);
+	write_sysreg(dbgwvr0_el1, 0);
+	isb();
+}
+
+static void install_wp(uint64_t addr)
+{
+	uint32_t wcr;
+	uint32_t mdscr;
+
+	wcr = DBGWCR_LEN8 | DBGWCR_RD | DBGWCR_WR | DBGWCR_EL1 | DBGWCR_E;
+	write_sysreg(dbgwcr0_el1, wcr);
+	write_sysreg(dbgwvr0_el1, addr);
+	isb();
+
+	asm volatile("msr daifclr, #8");
+
+	mdscr = read_sysreg(mdscr_el1) | MDSCR_KDE | MDSCR_MDE;
+	write_sysreg(mdscr_el1, mdscr);
+	isb();
+}
+
+static void install_hw_bp(uint64_t addr)
+{
+	uint32_t bcr;
+	uint32_t mdscr;
+
+	bcr = DBGBCR_LEN8 | DBGBCR_EXEC | DBGBCR_EL1 | DBGBCR_E;
+	write_sysreg(dbgbcr0_el1, bcr);
+	write_sysreg(dbgbvr0_el1, addr);
+	isb();
+
+	asm volatile("msr daifclr, #8");
+
+	mdscr = read_sysreg(mdscr_el1) | MDSCR_KDE | MDSCR_MDE;
+	write_sysreg(mdscr_el1, mdscr);
+	isb();
+}
+
+static void install_ss(void)
+{
+	uint32_t mdscr;
+
+	asm volatile("msr daifclr, #8");
+
+	mdscr = read_sysreg(mdscr_el1) | MDSCR_KDE | MDSCR_SS;
+	write_sysreg(mdscr_el1, mdscr);
+	isb();
+}
+
+static volatile char write_data;
+
+static void guest_code(void)
+{
+	GUEST_SYNC(0);
+
+	/* Software-breakpoint */
+	asm volatile("sw_bp: brk #0");
+	GUEST_ASSERT_EQ(sw_bp_addr, PC(sw_bp));
+
+	GUEST_SYNC(1);
+
+	/* Hardware-breakpoint */
+	reset_debug_state();
+	install_hw_bp(PC(hw_bp));
+	asm volatile("hw_bp: nop");
+	GUEST_ASSERT_EQ(hw_bp_addr, PC(hw_bp));
+
+	GUEST_SYNC(2);
+
+	/* Hardware-breakpoint + svc */
+	reset_debug_state();
+	install_hw_bp(PC(bp_svc));
+	asm volatile("bp_svc: svc #0");
+	GUEST_ASSERT_EQ(hw_bp_addr, PC(bp_svc));
+	GUEST_ASSERT_EQ(svc_addr, PC(bp_svc) + 4);
+
+	GUEST_SYNC(3);
+
+	/* Hardware-breakpoint + software-breakpoint */
+	reset_debug_state();
+	install_hw_bp(PC(bp_brk));
+	asm volatile("bp_brk: brk #0");
+	GUEST_ASSERT_EQ(sw_bp_addr, PC(bp_brk));
+	GUEST_ASSERT_EQ(hw_bp_addr, PC(bp_brk));
+
+	GUEST_SYNC(4);
+
+	/* Watchpoint */
+	reset_debug_state();
+	install_wp(PC(write_data));
+	write_data = 'x';
+	GUEST_ASSERT_EQ(write_data, 'x');
+	GUEST_ASSERT_EQ(wp_data_addr, PC(write_data));
+
+	GUEST_SYNC(5);
+
+	/* Single-step */
+	reset_debug_state();
+	install_ss();
+	ss_idx = 0;
+	asm volatile("ss_start:\n"
+		     "mrs x0, esr_el1\n"
+		     "add x0, x0, #1\n"
+		     "msr daifset, #8\n"
+		     : : : "x0");
+	GUEST_ASSERT_EQ(ss_addr[0], PC(ss_start));
+	GUEST_ASSERT_EQ(ss_addr[1], PC(ss_start) + 4);
+	GUEST_ASSERT_EQ(ss_addr[2], PC(ss_start) + 8);
+
+	GUEST_DONE();
+}
+
+static void guest_sw_bp_handler(struct ex_regs *regs)
+{
+	sw_bp_addr = regs->pc;
+	regs->pc += 4;
+}
+
+static void guest_hw_bp_handler(struct ex_regs *regs)
+{
+	hw_bp_addr = regs->pc;
+	regs->pstate |= SPSR_D;
+}
+
+static void guest_wp_handler(struct ex_regs *regs)
+{
+	wp_data_addr = read_sysreg(far_el1);
+	wp_addr = regs->pc;
+	regs->pstate |= SPSR_D;
+}
+
+static void guest_ss_handler(struct ex_regs *regs)
+{
+	GUEST_ASSERT_1(ss_idx < 4, ss_idx);
+	ss_addr[ss_idx++] = regs->pc;
+	regs->pstate |= SPSR_SS;
+}
+
+static void guest_svc_handler(struct ex_regs *regs)
+{
+	svc_addr = regs->pc;
+}
+
+static int debug_version(struct kvm_vm *vm)
+{
+	uint64_t id_aa64dfr0;
+
+	get_reg(vm, VCPU_ID, ARM64_SYS_REG(ID_AA64DFR0_EL1), &id_aa64dfr0);
+	return id_aa64dfr0 & 0xf;
+}
+
+int main(int argc, char *argv[])
+{
+	struct kvm_vm *vm;
+	struct ucall uc;
+	int stage;
+
+	vm = vm_create_default(VCPU_ID, 0, guest_code);
+	ucall_init(vm, NULL);
+
+	vm_init_descriptor_tables(vm);
+	vcpu_init_descriptor_tables(vm, VCPU_ID);
+
+	if (debug_version(vm) < 6) {
+		print_skip("Armv8 debug architecture not supported.");
+		kvm_vm_free(vm);
+		exit(KSFT_SKIP);
+	}
+
+	vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,
+				ESR_EC_BRK_INS, guest_sw_bp_handler);
+	vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,
+				ESR_EC_HW_BP_CURRENT, guest_hw_bp_handler);
+	vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,
+				ESR_EC_WP_CURRENT, guest_wp_handler);
+	vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,
+				ESR_EC_SSTEP_CURRENT, guest_ss_handler);
+	vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,
+				ESR_EC_SVC64, guest_svc_handler);
+
+	for (stage = 0; stage < 7; stage++) {
+		vcpu_run(vm, VCPU_ID);
+
+		switch (get_ucall(vm, VCPU_ID, &uc)) {
+		case UCALL_SYNC:
+			TEST_ASSERT(uc.args[1] == stage,
+				"Stage %d: Unexpected sync ucall, got %lx",
+				stage, (ulong)uc.args[1]);
+			break;
+		case UCALL_ABORT:
+			TEST_FAIL("%s at %s:%ld\n\tvalues: %#lx, %#lx",
+				(const char *)uc.args[0],
+				__FILE__, uc.args[1], uc.args[2], uc.args[3]);
+			break;
+		case UCALL_DONE:
+			goto done;
+		default:
+			TEST_FAIL("Unknown ucall %lu", uc.cmd);
+		}
+	}
+
+done:
+	kvm_vm_free(vm);
+	return 0;
+}

tools/testing/selftests/kvm/include/aarch64/processor.h

@@ -14,12 +14,14 @@
 #define ARM64_CORE_REG(x) (KVM_REG_ARM64 | KVM_REG_SIZE_U64 | \
 			   KVM_REG_ARM_CORE | KVM_REG_ARM_CORE_REG(x))
 
-#define CPACR_EL1	3, 0,  1, 0, 2
-#define TCR_EL1		3, 0,  2, 0, 2
-#define MAIR_EL1	3, 0, 10, 2, 0
-#define TTBR0_EL1	3, 0,  2, 0, 0
-#define SCTLR_EL1	3, 0,  1, 0, 0
-#define VBAR_EL1	3, 0, 12, 0, 0
+#define CPACR_EL1               3, 0,  1, 0, 2
+#define TCR_EL1                 3, 0,  2, 0, 2
+#define MAIR_EL1                3, 0, 10, 2, 0
+#define TTBR0_EL1               3, 0,  2, 0, 0
+#define SCTLR_EL1               3, 0,  1, 0, 0
+#define VBAR_EL1                3, 0, 12, 0, 0
+
+#define ID_AA64DFR0_EL1         3, 0,  0, 5, 0
 
 /*
  * Default MAIR
@@ -98,6 +100,12 @@ enum {
 #define ESR_EC_SHIFT		26
 #define ESR_EC_MASK		(ESR_EC_NUM - 1)
 
+#define ESR_EC_SVC64		0x15
+#define ESR_EC_HW_BP_CURRENT	0x31
+#define ESR_EC_SSTEP_CURRENT	0x33
+#define ESR_EC_WP_CURRENT	0x35
+#define ESR_EC_BRK_INS		0x3c
+
 void vm_init_descriptor_tables(struct kvm_vm *vm);
 void vcpu_init_descriptor_tables(struct kvm_vm *vm, uint32_t vcpuid);
 
@@ -119,4 +127,6 @@ void vm_install_sync_handler(struct kvm_vm *vm,
 	val;								  \
 })
 
+#define isb()	asm volatile("isb" : : : "memory")
+
 #endif /* SELFTEST_KVM_PROCESSOR_H */