Re: [PATCH 4/4] selftests: kvm: add get_emulated_cpuid test

[Vitaly Kuznetsov <vkuznets@redhat.com>]

Emanuele Giuseppe Esposito <eesposit@redhat.com> writes:

> Introduce a new selftest for the KVM_GET_EMULATED_CPUID
> ioctl. Since the behavior and functionality is similar to
> get_cpuid_test, the test checks:
>
> 1) checks for corner case in the nent field of the struct kvm_cpuid2.
> 2) sets and gets it as cpuid from the guest VM
>
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
> ---
>  tools/testing/selftests/kvm/.gitignore        |   1 +
>  tools/testing/selftests/kvm/Makefile          |   1 +
>  .../selftests/kvm/x86_64/get_emulated_cpuid.c | 183 ++++++++++++++++++
>  3 files changed, 185 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/x86_64/get_emulated_cpuid.c
>
> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
> index 7bd7e776c266..f1523f3bfd04 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -8,6 +8,7 @@
>  /x86_64/debug_regs
>  /x86_64/evmcs_test
>  /x86_64/get_cpuid_test
> +x86_64/get_emulated_cpuid
>  /x86_64/get_msr_index_features
>  /x86_64/kvm_pv_test
>  /x86_64/hyperv_clock
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 67eebb53235f..0d8d3bd5a7c7 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -40,6 +40,7 @@ LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c lib/s390x/diag318_test_ha
>  
>  TEST_GEN_PROGS_x86_64 = x86_64/cr4_cpuid_sync_test
>  TEST_GEN_PROGS_x86_64 += x86_64/get_msr_index_features
> +TEST_GEN_PROGS_x86_64 += x86_64/get_emulated_cpuid
>  TEST_GEN_PROGS_x86_64 += x86_64/evmcs_test
>  TEST_GEN_PROGS_x86_64 += x86_64/get_cpuid_test
>  TEST_GEN_PROGS_x86_64 += x86_64/hyperv_clock
> diff --git a/tools/testing/selftests/kvm/x86_64/get_emulated_cpuid.c b/tools/testing/selftests/kvm/x86_64/get_emulated_cpuid.c
> new file mode 100644
> index 000000000000..f5294dc4b8ff
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/x86_64/get_emulated_cpuid.c
> @@ -0,0 +1,183 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2021, Red Hat Inc.
> + *
> + * Generic tests for KVM CPUID set/get ioctls
> + */
> +#include <asm/kvm_para.h>
> +#include <linux/kvm_para.h>
> +#include <stdint.h>
> +
> +#include "test_util.h"
> +#include "kvm_util.h"
> +#include "processor.h"
> +
> +#define VCPU_ID 0
> +#define MAX_NENT 1000
> +
> +/* CPUIDs known to differ */
> +struct {
> +	u32 function;
> +	u32 index;
> +} mangled_cpuids[] = {
> +	{.function = 0xd, .index = 0},
> +};
> +
> +static void guest_main(void)
> +{
> +
> +}
> +
> +static bool is_cpuid_mangled(struct kvm_cpuid_entry2 *entrie)
> +{
> +	int i;
> +
> +	for (i = 0; i < sizeof(mangled_cpuids); i++) {
> +		if (mangled_cpuids[i].function == entrie->function &&
> +		    mangled_cpuids[i].index == entrie->index)
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
> +static void check_cpuid(struct kvm_cpuid2 *cpuid, struct kvm_cpuid_entry2 *entrie)
> +{
> +	int i;
> +
> +	for (i = 0; i < cpuid->nent; i++) {
> +		if (cpuid->entries[i].function == entrie->function &&
> +		    cpuid->entries[i].index == entrie->index) {
> +			if (is_cpuid_mangled(entrie))
> +				return;
> +
> +			TEST_ASSERT(cpuid->entries[i].eax == entrie->eax &&
> +				    cpuid->entries[i].ebx == entrie->ebx &&
> +				    cpuid->entries[i].ecx == entrie->ecx &&
> +				    cpuid->entries[i].edx == entrie->edx,
> +				    "CPUID 0x%x.%x differ: 0x%x:0x%x:0x%x:0x%x vs 0x%x:0x%x:0x%x:0x%x",
> +				    entrie->function, entrie->index,
> +				    cpuid->entries[i].eax, cpuid->entries[i].ebx,
> +				    cpuid->entries[i].ecx, cpuid->entries[i].edx,
> +				    entrie->eax, entrie->ebx, entrie->ecx, entrie->edx);
> +			return;
> +		}
> +	}
> +
> +	TEST_ASSERT(false, "CPUID 0x%x.%x not found", entrie->function, entrie->index);
> +}
> +
> +static void compare_cpuids(struct kvm_cpuid2 *cpuid1,
> +						   struct kvm_cpuid2 *cpuid2)
> +{
> +	int i;
> +
> +	for (i = 0; i < cpuid1->nent; i++)
> +		check_cpuid(cpuid2, &cpuid1->entries[i]);
> +
> +	for (i = 0; i < cpuid2->nent; i++)
> +		check_cpuid(cpuid1, &cpuid2->entries[i]);
> +}

CPUID comparison here seems to be borrowed from get_cpuid_test.c, I
think we can either put it to a library or (my preference) just merge
these two selftests together. 'get_cpuid_test' name is generic enough to
be used for KVM_GET_EMULATED_CPUID too.

> +
> +struct kvm_cpuid2 *vcpu_alloc_cpuid(struct kvm_vm *vm, vm_vaddr_t *p_gva, struct kvm_cpuid2 *cpuid)
> +{
> +	int size = sizeof(*cpuid) + cpuid->nent * sizeof(cpuid->entries[0]);
> +	vm_vaddr_t gva = vm_vaddr_alloc(vm, size,
> +					getpagesize(), 0, 0);
> +	struct kvm_cpuid2 *guest_cpuids = addr_gva2hva(vm, gva);
> +
> +	memcpy(guest_cpuids, cpuid, size);
> +
> +	*p_gva = gva;
> +	return guest_cpuids;
> +}
> +
> +static struct kvm_cpuid2 *alloc_custom_kvm_cpuid2(int nent)
> +{
> +	struct kvm_cpuid2 *cpuid;
> +	size_t size;
> +
> +	size = sizeof(*cpuid);
> +	size += nent * sizeof(struct kvm_cpuid_entry2);
> +	cpuid = calloc(1, size);
> +	if (!cpuid) {
> +		perror("malloc");
> +		abort();
> +	}
> +
> +	cpuid->nent = nent;
> +
> +	return cpuid;
> +}
> +
> +static void test_emulated_entries(struct kvm_vm *vm)
> +{
> +	int res, right_nent;
> +	struct kvm_cpuid2 *cpuid;
> +
> +	cpuid = alloc_custom_kvm_cpuid2(MAX_NENT);
> +
> +	/* 0 nent, return E2BIG */
> +	cpuid->nent = 0;
> +	res = _kvm_ioctl(vm, KVM_GET_EMULATED_CPUID, cpuid);
> +	TEST_ASSERT(res == -1 && errno == E2BIG,
> +				"KVM_GET_EMULATED_CPUID should fail E2BIG with nent=0");
> +
> +	/* high nent, set the entries and adjust */
> +	cpuid->nent = MAX_NENT;
> +	res = _kvm_ioctl(vm, KVM_GET_EMULATED_CPUID, cpuid);
> +	printf("%d %d\n", res, errno);
> +	TEST_ASSERT(res == 0,
> +			"KVM_GET_EMULATED_CPUID should not fail with nent > actual nent");
> +	right_nent = cpuid->nent;
> +
> +	/* high nent, set the entries and adjust */
> +	cpuid->nent++;
> +	res = _kvm_ioctl(vm, KVM_GET_EMULATED_CPUID, cpuid);
> +	TEST_ASSERT(res == 0,
> +			"KVM_GET_EMULATED_CPUID should not fail with nent > actual nent");
> +	TEST_ASSERT(right_nent == cpuid->nent,
> +				"KVM_GET_EMULATED_CPUID nent should be always the same");
> +
> +	/* low nent, return E2BIG */
> +	if (right_nent > 1) {
> +		cpuid->nent = 1;
> +		res = _kvm_ioctl(vm, KVM_GET_EMULATED_CPUID, cpuid);
> +		TEST_ASSERT(res == -1 && errno == E2BIG,
> +					"KVM_GET_EMULATED_CPUID should fail with nent=1");
> +	}
> +
> +	/* exact nent */
> +	cpuid->nent = right_nent;
> +	res = _kvm_ioctl(vm, KVM_GET_EMULATED_CPUID, cpuid);
> +	TEST_ASSERT(res == 0,
> +			"KVM_GET_EMULATED_CPUID should not fail with nent == actual nent");
> +	TEST_ASSERT(cpuid->nent == right_nent,
> +			"KVM_GET_EMULATED_CPUID should be invaried when nent is exact");
> +
> +	free(cpuid);
> +}
> +
> +// emulated is all emulated
> +// supported is only hw + kvm

/*
 * ...
 */

comments please

> +int main(void)
> +{
> +	struct kvm_cpuid2 *emul_cpuid, *cpuid2;
> +	struct kvm_vm *vm;
> +
> +	if (!kvm_check_cap(KVM_CAP_EXT_EMUL_CPUID)) {
> +		print_skip("KVM_GET_EMULATED_CPUID not available");
> +		return 0;
> +	}
> +
> +	vm = vm_create_default(VCPU_ID, 0, guest_main);
> +
> +	emul_cpuid = kvm_get_emulated_cpuid();
> +	vcpu_set_cpuid(vm, VCPU_ID, emul_cpuid);
> +	cpuid2 = vcpu_get_cpuid(vm, VCPU_ID);
> +
> +	test_emulated_entries(vm);
> +	compare_cpuids(emul_cpuid, cpuid2);
> +
> +	kvm_vm_free(vm);
> +}

-- 
Vitaly