Re: [PATCH v2] KVM: selftests: Add a test for the KVM_S390_MEM_OP ioctl

[David Hildenbrand]

On 29.08.19 14:14, Thomas Huth wrote:
> Check that we can write and read the guest memory with this s390x
> ioctl, and that some error cases are handled correctly.
> 
> Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
> ---
>  v2: Check the ioctl also with "size" set to 0
> 
>  tools/testing/selftests/kvm/Makefile      |   1 +
>  tools/testing/selftests/kvm/s390x/memop.c | 165 ++++++++++++++++++++++
>  2 files changed, 166 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/s390x/memop.c
> 
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 1b48a94b4350..62c591f87dab 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -32,6 +32,7 @@ TEST_GEN_PROGS_aarch64 += clear_dirty_log_test
>  TEST_GEN_PROGS_aarch64 += dirty_log_test
>  TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
>  
> +TEST_GEN_PROGS_s390x = s390x/memop
>  TEST_GEN_PROGS_s390x += s390x/sync_regs_test
>  TEST_GEN_PROGS_s390x += dirty_log_test
>  TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
> diff --git a/tools/testing/selftests/kvm/s390x/memop.c b/tools/testing/selftests/kvm/s390x/memop.c
> new file mode 100644
> index 000000000000..e6a65f9e48ca
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/s390x/memop.c
> @@ -0,0 +1,165 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Test for s390x KVM_S390_MEM_OP
> + *
> + * Copyright (C) 2019, Red Hat, Inc.
> + */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/ioctl.h>
> +
> +#include "test_util.h"
> +#include "kvm_util.h"
> +
> +#define VCPU_ID 1
> +
> +static uint8_t mem1[65536];
> +static uint8_t mem2[65536];
> +
> +static void guest_code(void)
> +{
> +	int i;
> +
> +	for (;;) {
> +		for (i = 0; i < sizeof(mem2); i++)
> +			mem2[i] = mem1[i];
> +		GUEST_SYNC(0);
> +	}
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	struct kvm_vm *vm;
> +	struct kvm_run *run;
> +	struct kvm_s390_mem_op ksmo;
> +	int rv, i, maxsize;
> +
> +	setbuf(stdout, NULL);	/* Tell stdout not to buffer its content */
> +
> +	maxsize = kvm_check_cap(KVM_CAP_S390_MEM_OP);
> +	if (!maxsize) {
> +		fprintf(stderr, "CAP_S390_MEM_OP not supported -> skip test\n");
> +		exit(KSFT_SKIP);
> +	}
> +	if (maxsize > sizeof(mem1))
> +		maxsize = sizeof(mem1);
> +
> +	/* Create VM */
> +	vm = vm_create_default(VCPU_ID, 0, guest_code);
> +	run = vcpu_state(vm, VCPU_ID);
> +
> +	for (i = 0; i < sizeof(mem1); i++)
> +		mem1[i] = i * i + i;
> +
> +	/* Set the first array */
> +	ksmo.gaddr = addr_gva2gpa(vm, (uintptr_t)mem1);
> +	ksmo.flags = 0;
> +	ksmo.size = maxsize;
> +	ksmo.op = KVM_S390_MEMOP_LOGICAL_WRITE;
> +	ksmo.buf = (uintptr_t)mem1;
> +	ksmo.ar = 0;
> +	vcpu_ioctl(vm, VCPU_ID, KVM_S390_MEM_OP, &ksmo);
> +
> +	/* Let the guest code copy the first array to the second */
> +	vcpu_run(vm, VCPU_ID);
> +	TEST_ASSERT(run->exit_reason == KVM_EXIT_S390_SIEIC,
> +		    "Unexpected exit reason: %u (%s)\n",
> +		    run->exit_reason,
> +		    exit_reason_str(run->exit_reason));
> +
> +	memset(mem2, 0xaa, sizeof(mem2));
> +
> +	/* Get the second array */
> +	ksmo.gaddr = (uintptr_t)mem2;
> +	ksmo.flags = 0;
> +	ksmo.size = maxsize;
> +	ksmo.op = KVM_S390_MEMOP_LOGICAL_READ;
> +	ksmo.buf = (uintptr_t)mem2;
> +	ksmo.ar = 0;
> +	vcpu_ioctl(vm, VCPU_ID, KVM_S390_MEM_OP, &ksmo);
> +
> +	TEST_ASSERT(!memcmp(mem1, mem2, maxsize),
> +		    "Memory contents do not match!");
> +
> +	/* Check error conditions - first bad size: */
> +	ksmo.gaddr = (uintptr_t)mem1;
> +	ksmo.flags = 0;
> +	ksmo.size = -1;
> +	ksmo.op = KVM_S390_MEMOP_LOGICAL_WRITE;
> +	ksmo.buf = (uintptr_t)mem1;
> +	ksmo.ar = 0;
> +	rv = _vcpu_ioctl(vm, VCPU_ID, KVM_S390_MEM_OP, &ksmo);
> +	TEST_ASSERT(rv == -1 && errno == E2BIG, "ioctl allows insane sizes");
> +
> +	/* Zero size: */
> +	ksmo.gaddr = (uintptr_t)mem1;
> +	ksmo.flags = 0;
> +	ksmo.size = 0;
> +	ksmo.op = KVM_S390_MEMOP_LOGICAL_WRITE;
> +	ksmo.buf = (uintptr_t)mem1;
> +	ksmo.ar = 0;
> +	rv = _vcpu_ioctl(vm, VCPU_ID, KVM_S390_MEM_OP, &ksmo);
> +	TEST_ASSERT(rv == -1, "ioctl allows 0 as size");
> +
> +	/* Bad flags: */
> +	ksmo.gaddr = (uintptr_t)mem1;
> +	ksmo.flags = -1;
> +	ksmo.size = maxsize;
> +	ksmo.op = KVM_S390_MEMOP_LOGICAL_WRITE;
> +	ksmo.buf = (uintptr_t)mem1;
> +	ksmo.ar = 0;
> +	rv = _vcpu_ioctl(vm, VCPU_ID, KVM_S390_MEM_OP, &ksmo);
> +	TEST_ASSERT(rv == -1 && errno == EINVAL, "ioctl allows all flags?");
> +
> +	/* Bad operation: */
> +	ksmo.gaddr = (uintptr_t)mem1;
> +	ksmo.flags = 0;
> +	ksmo.size = maxsize;
> +	ksmo.op = -1;
> +	ksmo.buf = (uintptr_t)mem1;
> +	ksmo.ar = 0;
> +	rv = _vcpu_ioctl(vm, VCPU_ID, KVM_S390_MEM_OP, &ksmo);
> +	TEST_ASSERT(rv == -1 && errno == EINVAL, "ioctl allows all flags?");
> +
> +	/* Bad guest address: */
> +	ksmo.gaddr = ~0xfffUL;
> +	ksmo.flags = KVM_S390_MEMOP_F_CHECK_ONLY;
> +	ksmo.size = maxsize;
> +	ksmo.op = KVM_S390_MEMOP_LOGICAL_WRITE;
> +	ksmo.buf = (uintptr_t)mem1;
> +	ksmo.ar = 0;
> +	rv = _vcpu_ioctl(vm, VCPU_ID, KVM_S390_MEM_OP, &ksmo);
> +	TEST_ASSERT(rv > 0, "ioctl does not report bad guest memory access");
> +
> +	/* Bad host address: */
> +	ksmo.gaddr = (uintptr_t)mem1;
> +	ksmo.flags = 0;
> +	ksmo.size = maxsize;
> +	ksmo.op = KVM_S390_MEMOP_LOGICAL_WRITE;
> +	ksmo.buf = 0;
> +	ksmo.ar = 0;
> +	rv = _vcpu_ioctl(vm, VCPU_ID, KVM_S390_MEM_OP, &ksmo);
> +	TEST_ASSERT(rv == -1 && errno == EFAULT,
> +		    "ioctl does not report bad host memory address");
> +
> +	/* Bad access register: */
> +	run->psw_mask &= ~(3UL << (63 - 17));
> +	run->psw_mask |= 1UL << (63 - 17);  /* Enable AR mode */
> +	vcpu_run(vm, VCPU_ID);              /* To sync new state to SIE block */
> +	ksmo.gaddr = (uintptr_t)mem1;
> +	ksmo.flags = 0;
> +	ksmo.size = maxsize;
> +	ksmo.op = KVM_S390_MEMOP_LOGICAL_WRITE;
> +	ksmo.buf = (uintptr_t)mem1;
> +	ksmo.ar = 17;
> +	rv = _vcpu_ioctl(vm, VCPU_ID, KVM_S390_MEM_OP, &ksmo);
> +	TEST_ASSERT(rv == -1 && errno == EINVAL, "ioctl allows ARs > 15");
> +	run->psw_mask &= ~(3UL << (63 - 17));   /* Disable AR mode */
> +	vcpu_run(vm, VCPU_ID);                  /* Run to sync new state */
> +
> +	kvm_vm_free(vm);
> +
> +	return 0;
> +}
> 

Had a quick glimpse and besides the two things Janosch mentioned,
nothing jumped at me.

-- 

Thanks,

David / dhildenb