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selftests: KVM: Test OS lock behavior

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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: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220203174159.2887882-7-oupton@google.com
This commit is contained in:
Oliver Upton 2022-02-03 17:41:59 +00:00 committed by Marc Zyngier
parent d134998838
commit 05c9324de1
1 changed files with 56 additions and 2 deletions
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58
tools/testing/selftests/kvm/aarch64/debug-exceptions.c
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@ -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)) {