Commit 05c9324d authored by Oliver Upton's avatar Oliver Upton Committed by Marc Zyngier
Browse files

selftests: KVM: Test OS lock behavior 



KVM now correctly handles the OS Lock for its guests. When set, KVM
blocks all debug exceptions originating from the guest. Add test cases
to the debug-exceptions test to assert that software breakpoint,
hardware breakpoint, watchpoint, and single-step exceptions are in fact
blocked.

Signed-off-by: default avatarOliver Upton <oupton@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220203174159.2887882-7-oupton@google.com
parent d1349988

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

+56 −2
Original line number Diff line number Diff line
@@ -23,7 +23,7 @@ 
#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;

extern unsigned char sw_bp, sw_bp2, hw_bp, hw_bp2, 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;
@@ -47,6 +47,14 @@ static void reset_debug_state(void) 
	isb();

}



static void enable_os_lock(void)

{

	write_sysreg(1, oslar_el1);

	isb();



	GUEST_ASSERT(read_sysreg(oslsr_el1) & 2);

}



static void install_wp(uint64_t addr)

{

	uint32_t wcr;
@@ -99,6 +107,7 @@ static void guest_code(void) 
	GUEST_SYNC(0);



	/* Software-breakpoint */

	reset_debug_state();

	asm volatile("sw_bp: brk #0");

	GUEST_ASSERT_EQ(sw_bp_addr, PC(sw_bp));
@@ -152,6 +161,51 @@ static void guest_code(void) 
	GUEST_ASSERT_EQ(ss_addr[1], PC(ss_start) + 4);

	GUEST_ASSERT_EQ(ss_addr[2], PC(ss_start) + 8);



	GUEST_SYNC(6);



	/* OS Lock does not block software-breakpoint */

	reset_debug_state();

	enable_os_lock();

	sw_bp_addr = 0;

	asm volatile("sw_bp2: brk #0");

	GUEST_ASSERT_EQ(sw_bp_addr, PC(sw_bp2));



	GUEST_SYNC(7);



	/* OS Lock blocking hardware-breakpoint */

	reset_debug_state();

	enable_os_lock();

	install_hw_bp(PC(hw_bp2));

	hw_bp_addr = 0;

	asm volatile("hw_bp2: nop");

	GUEST_ASSERT_EQ(hw_bp_addr, 0);



	GUEST_SYNC(8);



	/* OS Lock blocking watchpoint */

	reset_debug_state();

	enable_os_lock();

	write_data = '\0';

	wp_data_addr = 0;

	install_wp(PC(write_data));

	write_data = 'x';

	GUEST_ASSERT_EQ(write_data, 'x');

	GUEST_ASSERT_EQ(wp_data_addr, 0);



	GUEST_SYNC(9);



	/* OS Lock blocking single-step */

	reset_debug_state();

	enable_os_lock();

	ss_addr[0] = 0;

	install_ss();

	ss_idx = 0;

	asm volatile("mrs x0, esr_el1\n\t"

		     "add x0, x0, #1\n\t"

		     "msr daifset, #8\n\t"

		     : : : "x0");

	GUEST_ASSERT_EQ(ss_addr[0], 0);



	GUEST_DONE();

}
@@ -223,7 +277,7 @@ int main(int argc, char *argv[]) 
	vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,

				ESR_EC_SVC64, guest_svc_handler);



	for (stage = 0; stage < 7; stage++) {

	for (stage = 0; stage < 11; stage++) {

		vcpu_run(vm, VCPU_ID);



		switch (get_ucall(vm, VCPU_ID, &uc)) {