linux-kernel - Re: [PATCH] selftests: kvm: Check whether SIDA memop fails for normal guests

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Message-ID: <801aa4ea-ca26-7561-95f3-162b0f680929@linux.ibm.com>
Date:   Tue, 15 Feb 2022 10:54:55 +0100
From:   Janis Schoetterl-Glausch <scgl@...ux.ibm.com>
To:     Thomas Huth <thuth@...hat.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>, kvm@...r.kernel.org
Cc:     David Hildenbrand <david@...hat.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] selftests: kvm: Check whether SIDA memop fails for normal
 guests

On 2/15/22 08:48, Thomas Huth wrote:
> Commit 2c212e1baedc ("KVM: s390: Return error on SIDA memop on normal
> guest") fixed the behavior of the SIDA memops for normal guests. It
> would be nice to have a way to test whether the current kernel has
> the fix applied or not. Thus add a check to the KVM selftests for
> these two memops.
> 
> Signed-off-by: Thomas Huth <thuth@...hat.com>
> ---
>  tools/testing/selftests/kvm/s390x/memop.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/s390x/memop.c b/tools/testing/selftests/kvm/s390x/memop.c
> index 9f49ead380ab..d19c3ffdea3f 100644
> --- a/tools/testing/selftests/kvm/s390x/memop.c
> +++ b/tools/testing/selftests/kvm/s390x/memop.c
> @@ -160,6 +160,21 @@ int main(int argc, char *argv[])
>  	run->psw_mask &= ~(3UL << (63 - 17));   /* Disable AR mode */
>  	vcpu_run(vm, VCPU_ID);                  /* Run to sync new state */
> 
> +	/* Check that the SIDA calls are rejected for non-protected guests */
> +	ksmo.gaddr = 0;
> +	ksmo.flags = 0;
> +	ksmo.size = 8;
> +	ksmo.op = KVM_S390_MEMOP_SIDA_READ;
> +	ksmo.buf = (uintptr_t)mem1;
> +	ksmo.sida_offset = 0x1c0;

What is the rational for that constant?
Any would do, as long as size + offset < PAGE_SIZE, correct?

> +	rv = _vcpu_ioctl(vm, VCPU_ID, KVM_S390_MEM_OP, &ksmo);
> +	TEST_ASSERT(rv == -1 && errno == EINVAL,
> +		    "ioctl does not reject SIDA_READ in non-protected mode");
> +	ksmo.op = KVM_S390_MEMOP_SIDA_WRITE;
> +	rv = _vcpu_ioctl(vm, VCPU_ID, KVM_S390_MEM_OP, &ksmo);
> +	TEST_ASSERT(rv == -1 && errno == EINVAL,
> +		    "ioctl does not reject SIDA_WRITE in non-protected mode");
> +
>  	kvm_vm_free(vm);
> 
>  	return 0;