Re: [PATCH v2 6/6] selftests: KVM: Test OS lock behavior

[Ricardo Koller <ricarkol@google.com>]

On Tue, Nov 02, 2021 at 09:46:51AM +0000, Oliver Upton wrote:
> 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>
> ---
>  .../selftests/kvm/aarch64/debug-exceptions.c  | 58 ++++++++++++++++++-
>  1 file changed, 56 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
> index e5e6c92b60da..6b6ff81cdd23 100644
> --- a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
> +++ b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
> @@ -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, 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(oslar_el1, 1);

should be: write_sysreg(val, reg);

> +	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 blocking software-breakpoint */
> +	reset_debug_state();
> +	enable_os_lock();
> +	sw_bp_addr = 0;
> +	asm volatile("brk #0");
> +	GUEST_ASSERT_EQ(sw_bp_addr, 0);
> +
> +	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)) {
> -- 
> 2.33.1.1089.g2158813163f-goog
> 
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