tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Test for x86 KVM_CAP_HYPERV_CPUID
 *
 * Copyright (C) 2018, Red Hat, Inc.
 *
 * This work is licensed under the terms of the GNU GPL, version 2.
 *
 */

#define _GNU_SOURCE /* for program_invocation_short_name */
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>

#include "test_util.h"
#include "kvm_util.h"
#include "processor.h"
#include "vmx.h"

#define VCPU_ID 0

static void guest_code(void)
{
}

static bool smt_possible(void)
{
	char buf[16];
	FILE *f;
	bool res = true;

	f = fopen("/sys/devices/system/cpu/smt/control", "r");
	if (f) {
		if (fread(buf, sizeof(*buf), sizeof(buf), f) > 0) {
			if (!strncmp(buf, "forceoff", 8) ||
			    !strncmp(buf, "notsupported", 12))
				res = false;
		}
		fclose(f);
	}

	return res;
}

static void test_hv_cpuid(struct kvm_cpuid2 *hv_cpuid_entries,
			  bool evmcs_enabled)
{
	int i;
	int nent = 9;
	u32 test_val;

	if (evmcs_enabled)
		nent += 1; /* 0x4000000A */

	TEST_ASSERT(hv_cpuid_entries->nent == nent,
		    "KVM_GET_SUPPORTED_HV_CPUID should return %d entries"
		    " with evmcs=%d (returned %d)",
		    nent, evmcs_enabled, hv_cpuid_entries->nent);

	for (i = 0; i < hv_cpuid_entries->nent; i++) {
		struct kvm_cpuid_entry2 *entry = &hv_cpuid_entries->entries[i];

		TEST_ASSERT((entry->function >= 0x40000000) &&
			    (entry->function <= 0x40000082),
			    "function %x is our of supported range",
			    entry->function);

		TEST_ASSERT(evmcs_enabled || (entry->function != 0x4000000A),
			    "0x4000000A leaf should not be reported");

		TEST_ASSERT(entry->index == 0,
			    ".index field should be zero");

		TEST_ASSERT(entry->flags == 0,
			    ".flags field should be zero");

		TEST_ASSERT(!entry->padding[0] && !entry->padding[1] &&
			    !entry->padding[2], "padding should be zero");

		switch (entry->function) {
		case 0x40000000:
			test_val = 0x40000082;

			TEST_ASSERT(entry->eax == test_val,
				    "Wrong max leaf report in 0x40000000.EAX: %x"
				    " (evmcs=%d)",
				    entry->eax, evmcs_enabled
				);
			break;
		case 0x40000004:
			test_val = entry->eax & (1UL << 18);

			TEST_ASSERT(!!test_val == !smt_possible(),
				    "NoNonArchitecturalCoreSharing bit"
				    " doesn't reflect SMT setting");
			break;
		}

		/*
		 * If needed for debug:
		 * fprintf(stdout,
		 *	"CPUID%lx EAX=0x%lx EBX=0x%lx ECX=0x%lx EDX=0x%lx\n",
		 *	entry->function, entry->eax, entry->ebx, entry->ecx,
		 *	entry->edx);
		 */
	}

}

void test_hv_cpuid_e2big(struct kvm_vm *vm)
{
	static struct kvm_cpuid2 cpuid = {.nent = 0};
	int ret;

	ret = _vcpu_ioctl(vm, VCPU_ID, KVM_GET_SUPPORTED_HV_CPUID, &cpuid);

	TEST_ASSERT(ret == -1 && errno == E2BIG,
		    "KVM_GET_SUPPORTED_HV_CPUID didn't fail with -E2BIG when"
		    " it should have: %d %d", ret, errno);
}


struct kvm_cpuid2 *kvm_get_supported_hv_cpuid(struct kvm_vm *vm)
{
	int nent = 20; /* should be enough */
	static struct kvm_cpuid2 *cpuid;

	cpuid = malloc(sizeof(*cpuid) + nent * sizeof(struct kvm_cpuid_entry2));

	if (!cpuid) {
		perror("malloc");
		abort();
	}

	cpuid->nent = nent;

	vcpu_ioctl(vm, VCPU_ID, KVM_GET_SUPPORTED_HV_CPUID, cpuid);

	return cpuid;
}


int main(int argc, char *argv[])
{
	struct kvm_vm *vm;
	int rv, stage;
	struct kvm_cpuid2 *hv_cpuid_entries;
	bool evmcs_enabled;

	/* Tell stdout not to buffer its content */
	setbuf(stdout, NULL);

	rv = kvm_check_cap(KVM_CAP_HYPERV_CPUID);
	if (!rv) {
		print_skip("KVM_CAP_HYPERV_CPUID not supported");
		exit(KSFT_SKIP);
	}

	for (stage = 0; stage < 3; stage++) {
		evmcs_enabled = false;

		vm = vm_create_default(VCPU_ID, 0, guest_code);
		switch (stage) {
		case 0:
			test_hv_cpuid_e2big(vm);
			continue;
		case 1:
			break;
		case 2:
			if (!nested_vmx_supported() ||
			    !kvm_check_cap(KVM_CAP_HYPERV_ENLIGHTENED_VMCS)) {
				print_skip("Enlightened VMCS is unsupported");
				continue;
			}
			vcpu_enable_evmcs(vm, VCPU_ID);
			evmcs_enabled = true;
			break;
		}

		hv_cpuid_entries = kvm_get_supported_hv_cpuid(vm);
		test_hv_cpuid(hv_cpuid_entries, evmcs_enabled);
		free(hv_cpuid_entries);
		kvm_vm_free(vm);
	}

	return 0;
}