Re: [PATCH v6 20/21] selftests: KVM: Test physical counter offsetting

[Andrew Jones <drjones@xxxxxxxxxx>]

On Wed, Aug 04, 2021 at 08:58:18AM +0000, Oliver Upton wrote:
> Test that userspace adjustment of the guest physical counter-timer
> results in the correct view within the guest.
> 
> Cc: Andrew Jones <drjones@xxxxxxxxxx>
> Signed-off-by: Oliver Upton <oupton@xxxxxxxxxx>
> ---
>  .../selftests/kvm/include/aarch64/processor.h | 12 +++++++
>  .../kvm/system_counter_offset_test.c          | 31 +++++++++++++++++--
>  2 files changed, 40 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/include/aarch64/processor.h b/tools/testing/selftests/kvm/include/aarch64/processor.h
> index 3168cdbae6ee..7f53d90e9512 100644
> --- a/tools/testing/selftests/kvm/include/aarch64/processor.h
> +++ b/tools/testing/selftests/kvm/include/aarch64/processor.h
> @@ -141,4 +141,16 @@ static inline uint64_t read_cntvct_ordered(void)
>  	return r;
>  }
>  
> +static inline uint64_t read_cntpct_ordered(void)
> +{
> +	uint64_t r;
> +
> +	__asm__ __volatile__("isb\n\t"
> +			     "mrs %0, cntpct_el0\n\t"
> +			     "isb\n\t"
> +			     : "=r"(r));
> +
> +	return r;
> +}
> +
>  #endif /* SELFTEST_KVM_PROCESSOR_H */
> diff --git a/tools/testing/selftests/kvm/system_counter_offset_test.c b/tools/testing/selftests/kvm/system_counter_offset_test.c
> index ac933db83d03..82d26a45cc48 100644
> --- a/tools/testing/selftests/kvm/system_counter_offset_test.c
> +++ b/tools/testing/selftests/kvm/system_counter_offset_test.c
> @@ -57,6 +57,9 @@ static uint64_t host_read_guest_system_counter(struct test_case *test)
>  
>  enum arch_counter {
>  	VIRTUAL,
> +	PHYSICAL,
> +	/* offset physical, read virtual */
> +	PHYSICAL_READ_VIRTUAL,
>  };
>  
>  struct test_case {
> @@ -68,32 +71,54 @@ static struct test_case test_cases[] = {
>  	{ .counter = VIRTUAL, .offset = 0 },
>  	{ .counter = VIRTUAL, .offset = 180 * NSEC_PER_SEC },
>  	{ .counter = VIRTUAL, .offset = -180 * NSEC_PER_SEC },
> +	{ .counter = PHYSICAL, .offset = 0 },
> +	{ .counter = PHYSICAL, .offset = 180 * NSEC_PER_SEC },
> +	{ .counter = PHYSICAL, .offset = -180 * NSEC_PER_SEC },
> +	{ .counter = PHYSICAL_READ_VIRTUAL, .offset = 0 },
> +	{ .counter = PHYSICAL_READ_VIRTUAL, .offset = 180 * NSEC_PER_SEC },
> +	{ .counter = PHYSICAL_READ_VIRTUAL, .offset = -180 * NSEC_PER_SEC },
>  };
>  
>  static void check_preconditions(struct kvm_vm *vm)
>  {
> -	if (vcpu_has_reg(vm, VCPU_ID, KVM_REG_ARM_TIMER_OFFSET))
> +	if (vcpu_has_reg(vm, VCPU_ID, KVM_REG_ARM_TIMER_OFFSET) &&
> +	    !_vcpu_has_device_attr(vm, VCPU_ID, KVM_ARM_VCPU_TIMER_CTRL,
> +				   KVM_ARM_VCPU_TIMER_OFFSET))
>  		return;
>  
> -	print_skip("KVM_REG_ARM_TIMER_OFFSET not supported; skipping test");
> +	print_skip("KVM_REG_ARM_TIMER_OFFSET|KVM_ARM_VCPU_TIMER_OFFSET not supported; skipping test");
>  	exit(KSFT_SKIP);
>  }
>  
>  static void setup_system_counter(struct kvm_vm *vm, struct test_case *test)
>  {
> +	uint64_t cntvoff, cntpoff;
>  	struct kvm_one_reg reg = {
>  		.id = KVM_REG_ARM_TIMER_OFFSET,
> -		.addr = (__u64)&test->offset,
> +		.addr = (__u64)&cntvoff,
>  	};
>  
> +	if (test->counter == VIRTUAL) {
> +		cntvoff = test->offset;
> +		cntpoff = 0;
> +	} else {
> +		cntvoff = 0;
> +		cntpoff = test->offset;
> +	}
> +
>  	vcpu_set_reg(vm, VCPU_ID, &reg);
> +	vcpu_access_device_attr(vm, VCPU_ID, KVM_ARM_VCPU_TIMER_CTRL,
> +				KVM_ARM_VCPU_TIMER_OFFSET, &cntpoff, true);
>  }
>  
>  static uint64_t guest_read_system_counter(struct test_case *test)
>  {
>  	switch (test->counter) {
>  	case VIRTUAL:
> +	case PHYSICAL_READ_VIRTUAL:
>  		return read_cntvct_ordered();
> +	case PHYSICAL:
> +		return read_cntpct_ordered();
>  	default:
>  		GUEST_ASSERT(0);
>  	}
> -- 
> 2.32.0.605.g8dce9f2422-goog
>

Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>

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