Re: [PATCH v2 2/5] KVM: selftests: Introduce UCALL_UNHANDLED for unhandled vector reporting

From: Andrew Jones <drjones@redhat.com>
To: Ricardo Koller <ricarkol@google.com>
Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
	pbonzini@redhat.com, maz@kernel.org, alexandru.elisei@arm.com,
	eric.auger@redhat.com
Subject: Re: [PATCH v2 2/5] KVM: selftests: Introduce UCALL_UNHANDLED for unhandled vector reporting
Date: Mon, 3 May 2021 13:09:09 +0200	[thread overview]
Message-ID: <20210503110909.n7chjg2run6gaeq3@gator.home> (raw)
In-Reply-To: <20210430232408.2707420-3-ricarkol@google.com>

On Fri, Apr 30, 2021 at 04:24:04PM -0700, Ricardo Koller wrote:
> x86, the only arch implementing exception handling, reports unhandled
> vectors using port IO at a specific port number. This replicates what
> ucall already does.
> 
> Introduce a new ucall type, UCALL_UNHANDLED, for guests to report
> unhandled exceptions. Then replace the x86 unhandled vector exception
> reporting to use it instead of port IO.  This new ucall type will be
> used in the next commits by arm64 to report unhandled vectors as well.
> 
> Tested: Forcing a page fault in the ./x86_64/xapic_ipi_test
> 	halter_guest_code() shows this:
> 
> 	$ ./x86_64/xapic_ipi_test
> 	...
> 	  Unexpected vectored event in guest (vector:0xe)
> 
> Signed-off-by: Ricardo Koller <ricarkol@google.com>
> ---
>  tools/testing/selftests/kvm/include/kvm_util.h    |  1 +
>  .../selftests/kvm/include/x86_64/processor.h      |  2 --
>  .../testing/selftests/kvm/lib/x86_64/processor.c  | 15 ++++++---------
>  3 files changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index bea4644d645d..7880929ea548 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -347,6 +347,7 @@ enum {
>  	UCALL_SYNC,
>  	UCALL_ABORT,
>  	UCALL_DONE,
> +	UCALL_UNHANDLED,
>  };
>  
>  #define UCALL_MAX_ARGS 6
> diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
> index 12889d3e8948..ff4da2f95b13 100644
> --- a/tools/testing/selftests/kvm/include/x86_64/processor.h
> +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
> @@ -53,8 +53,6 @@
>  #define CPUID_PKU		(1ul << 3)
>  #define CPUID_LA57		(1ul << 16)
>  
> -#define UNEXPECTED_VECTOR_PORT 0xfff0u
> -
>  /* General Registers in 64-Bit Mode */
>  struct gpr64_regs {
>  	u64 rax;
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> index e156061263a6..96e2bd9d66eb 100644
> --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> @@ -1207,7 +1207,7 @@ static void set_idt_entry(struct kvm_vm *vm, int vector, unsigned long addr,
>  
>  void kvm_exit_unexpected_vector(uint32_t value)
>  {
> -	outl(UNEXPECTED_VECTOR_PORT, value);
> +	ucall(UCALL_UNHANDLED, 1, value);
>  }
>  
>  void route_exception(struct ex_regs *regs)
> @@ -1260,16 +1260,13 @@ void vm_install_vector_handler(struct kvm_vm *vm, int vector,
>  
>  void assert_on_unhandled_exception(struct kvm_vm *vm, uint32_t vcpuid)
>  {
> -	if (vcpu_state(vm, vcpuid)->exit_reason == KVM_EXIT_IO
> -		&& vcpu_state(vm, vcpuid)->io.port == UNEXPECTED_VECTOR_PORT
> -		&& vcpu_state(vm, vcpuid)->io.size == 4) {
> -		/* Grab pointer to io data */
> -		uint32_t *data = (void *)vcpu_state(vm, vcpuid)
> -			+ vcpu_state(vm, vcpuid)->io.data_offset;
> +	struct ucall uc;
>  
> +	if (get_ucall(vm, vcpuid, &uc) == UCALL_UNHANDLED) {
> +		uint64_t vector = uc.args[0];
>  		TEST_ASSERT(false,
> -			    "Unexpected vectored event in guest (vector:0x%x)",
> -			    *data);
> +			    "Unexpected vectored event in guest (vector:0x%lx)",
> +			    vector);

nit: Could have changed this TEST_ASSERT(false, ...) to TEST_FAIL while
touching it.

>  	}
>  }
>  
> -- 
> 2.31.1.527.g47e6f16901-goog
>

Reviewed-by: Andrew Jones <drjones@redhat.com>

Thanks,
drew