Re: [PATCH v6 09/13] KVM: selftests: aarch64: Add aarch64/page_fault_test

[Ricardo Koller <ricarkol@google.com>]

On Sat, Sep 17, 2022 at 09:58:28PM +0000, Oliver Upton wrote:
> On Tue, Sep 06, 2022 at 06:09:26PM +0000, Ricardo Koller wrote:
> > Add a new test for stage 2 faults when using different combinations of
> > guest accesses (e.g., write, S1PTW), backing source type (e.g., anon)
> > and types of faults (e.g., read on hugetlbfs with a hole). The next
> > commits will add different handling methods and more faults (e.g., uffd
> > and dirty logging). This first commit starts by adding two sanity checks
> > for all types of accesses: AF setting by the hw, and accessing memslots
> > with holes.
> > 
> > Signed-off-by: Ricardo Koller <ricarkol@google.com>
> 
> Hey Ricardo,
> 
> You'll need to update .gitignore for this patch. Additionally, building
> this test throws the following compiler warning:
> 
> In function ‘load_exec_code_for_test’,
>     inlined from ‘run_test’ at aarch64/page_fault_test.c:745:2:
> aarch64/page_fault_test.c:545:9: warning: array subscript ‘long unsigned int[0]’ is partly outside array bounds of ‘unsigned char[1]’ [-Warray-bounds]
>   545 |         memcpy(code, c, 8);
>       |         ^~~~~~~~~~~~~~~~~~
> 
> I've fixed both of these in the appended diff, feel free to squash.

Thanks, will do that.

> 
> --
> Thanks,
> Oliver
> 
> From 0a5d3710b9043ae8fe5a9d7cc48eb854d1b7b746 Mon Sep 17 00:00:00 2001
> From: Oliver Upton <oliver.upton@linux.dev>
> Date: Sat, 17 Sep 2022 21:38:11 +0000
> Subject: [PATCH] fixup! KVM: selftests: aarch64: Add aarch64/page_fault_test
> 
> ---
>  tools/testing/selftests/kvm/.gitignore               |  1 +
>  .../testing/selftests/kvm/aarch64/page_fault_test.c  | 12 +++---------
>  2 files changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
> index d625a3f83780..7a9022cfa033 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -3,6 +3,7 @@
>  /aarch64/debug-exceptions
>  /aarch64/get-reg-list
>  /aarch64/hypercalls
> +/aarch64/page_fault_test
>  /aarch64/psci_test
>  /aarch64/vcpu_width_config
>  /aarch64/vgic_init
> diff --git a/tools/testing/selftests/kvm/aarch64/page_fault_test.c b/tools/testing/selftests/kvm/aarch64/page_fault_test.c
> index 60a6a8a45fa4..5ef2a7b941ec 100644
> --- a/tools/testing/selftests/kvm/aarch64/page_fault_test.c
> +++ b/tools/testing/selftests/kvm/aarch64/page_fault_test.c
> @@ -512,7 +512,7 @@ void fail_vcpu_run_mmio_no_syndrome_handler(int ret)
>  	events.fail_vcpu_runs += 1;
>  }
>  
> -extern unsigned char __exec_test;
> +extern uint64_t __exec_test;
>  
>  void noinline __return_0x77(void)
>  {
> @@ -526,7 +526,7 @@ void noinline __return_0x77(void)
>   */
>  static void load_exec_code_for_test(struct kvm_vm *vm)
>  {
> -	uint64_t *code, *c;
> +	uint64_t *code;
>  	struct userspace_mem_region *region;
>  	void *hva;
>  
> @@ -536,13 +536,7 @@ static void load_exec_code_for_test(struct kvm_vm *vm)
>  	assert(TEST_EXEC_GVA - TEST_GVA);
>  	code = hva + 8;
>  
> -	/*
> -	 * We need the cast to be separate in order for the compiler to not
> -	 * complain with: "‘memcpy’ forming offset [1, 7] is out of the bounds
> -	 * [0, 1] of object ‘__exec_test’ with type ‘unsigned char’"
> -	 */
> -	c = (uint64_t *)&__exec_test;
> -	memcpy(code, c, 8);
> +	*code = __exec_test;

I remember trying many ways of getting the compiler to not complain, I
must have tried this (wonder what happened). Anyway, gcc and clang are
happy with it.

>  }
>  
>  static void setup_abort_handlers(struct kvm_vm *vm, struct kvm_vcpu *vcpu,
> -- 
> 2.37.3.968.ga6b4b080e4-goog
>