Re: [LTP] [PATCH 1/2] KVM test infrastructure

[Richard Palethorpe <rpalethorpe@suse.de>]

Hi Martin,

Martin Doucha <mdoucha@suse.cz> writes:

> Implement LTP infrastructure for tests which require executing a special
> program inside KVM virtual machine. The infrastructure is split into two parts:
> the host library and the guest library.
>
> The host library provides functions for setting up and running virtual machines
> with test payload built from test sources.
>
> The guest library provides CPU bootstrap code and basic implementation of
> some C and LTP library functions as well as functions for accessing low-level
> arch features like special registers, interrupt tables or memory mapping tables.
>
> The test sources will contain both guest-side payload code and host-side setup
> code separated by preprocessor switch. The files get compiled twice with
> different compiler options. Once to build the VM payload, once to build
> the main program that will create the VM and execute the payload
> inside it.

This is great!

Due to its size I'll just comment as I get chance to read it.

> diff --git a/testcases/kernel/kvm/lib_host.c b/testcases/kernel/kvm/lib_host.c
> new file mode 100644
> index 000000000..d070c8106
> --- /dev/null
> +++ b/testcases/kernel/kvm/lib_host.c
> @@ -0,0 +1,215 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2021 SUSE LLC <mdoucha@suse.cz>
> + *
> + * KVM host library for setting up and running virtual machine tests.
> + */
> +
> +#include <stdlib.h>
> +#include <errno.h>
> +
> +#define TST_NO_DEFAULT_MAIN
> +#include "tst_test.h"
> +#include "kvm_host.h"
> +
> +static struct tst_kvm_instance test_vm = { .vm_fd = -1 };
> +
> +const unsigned char tst_kvm_reset_code[VM_RESET_CODE_SIZE] = {
> +	0xea, 0x00, 0x10, 0x00, 0x00	/* JMP 0x1000 */
> +};
> +
> +void tst_kvm_validate_result(int value)
> +{
> +	int ttype, valid_result[] = {TPASS, TFAIL, TBROK, TWARN, TINFO, TCONF};
> +	size_t i;
> +
> +	if (value == KVM_TNONE)
> +		tst_brk(TBROK, "KVM test did not return any result");
> +
> +	ttype = TTYPE_RESULT(value);
> +
> +	for (i = 0; i < ARRAY_SIZE(valid_result); i++) {
> +		if (ttype == valid_result[i])
> +			return;
> +	}
> +
> +	tst_brk(TBROK, "KVM test returned invalid result value %d", value);
> +}
> +
> +void tst_kvm_print_result(const struct tst_kvm_result *result)
> +{
> +	int ttype;
> +
> +	tst_kvm_validate_result(result->result);
> +	ttype = TTYPE_RESULT(result->result);
> +
> +	if (ttype == TBROK)
> +		tst_brk(ttype, "%s", result->message);
> +	else
> +		tst_res(ttype, "%s", result->message);
> +}

Could you please pass the file and lineno from the test?

> +
> +void *tst_kvm_alloc_memory(int vm, unsigned int slot, uint64_t baseaddr,
> +	size_t size, unsigned int flags)
> +{
> +	size_t pagesize;
> +	void *ret;
> +	struct kvm_userspace_memory_region memslot = {
> +		.slot = slot,
> +		.flags = flags
> +	};
> +
> +	pagesize = SAFE_SYSCONF(_SC_PAGESIZE);
> +	size += (baseaddr % pagesize) + pagesize - 1;
> +	baseaddr -= baseaddr % pagesize;
> +	size -= size % pagesize;
> +	ret = tst_alloc(size);
> +
> +	memslot.guest_phys_addr = baseaddr;
> +	memslot.memory_size = size;
> +	memslot.userspace_addr = (uintptr_t)ret;
> +	SAFE_IOCTL(vm, KVM_SET_USER_MEMORY_REGION, &memslot);
> +	return ret;
> +}
> +
> +struct kvm_cpuid2 *tst_kvm_get_cpuid(int sysfd)
> +{
> +	unsigned int count;
> +	int result;
> +	struct kvm_cpuid2 *ret;
> +
> +	if (!SAFE_IOCTL(sysfd, KVM_CHECK_EXTENSION, KVM_CAP_EXT_CPUID))
> +		return NULL;
> +
> +	for (count = 8; count < 1 << 30; count *= 2) {
> +		ret = SAFE_MALLOC(sizeof(struct kvm_cpuid2) +
> +			count * sizeof(struct kvm_cpuid_entry2));
> +		ret->nent = count;
> +		errno = 0;
> +		result = ioctl(sysfd, KVM_GET_SUPPORTED_CPUID, ret);
> +
> +		if (!result)
> +			return ret;
> +
> +		free(ret);
> +
> +		if (errno != E2BIG)
> +			break;
> +	}
> +
> +	tst_brk(TBROK | TERRNO, "ioctl(KVM_GET_SUPPORTED_CPUID) failed");
> +	return NULL;
> +}
> +
> +void tst_kvm_create_instance(struct tst_kvm_instance *inst, size_t ram_size)
> +{
> +	int sys_fd;
> +	size_t pagesize, result_pageaddr = KVM_RESULT_BASEADDR;
> +	char *vm_result, *reset_ptr;
> +	struct kvm_cpuid2 *cpuid_data;
> +	const size_t payload_size = kvm_payload_end - kvm_payload_start;
> +
> +	memset(inst, 0, sizeof(struct tst_kvm_instance));
> +	inst->vm_fd = -1;
> +	inst->vcpu_fd = -1;
> +	inst->vcpu_info = MAP_FAILED;
> +
> +	pagesize = SAFE_SYSCONF(_SC_PAGESIZE);
> +	result_pageaddr -= result_pageaddr % pagesize;
> +
> +	if (payload_size + MIN_FREE_RAM > ram_size - VM_KERNEL_BASEADDR) {
> +		ram_size = payload_size + MIN_FREE_RAM + VM_KERNEL_BASEADDR;
> +		ram_size += 1024 * 1024 - 1;
> +		ram_size -= ram_size % (1024 * 1024);
> +		tst_res(TWARN, "RAM size increased to %zu bytes", ram_size);
> +	}
> +
> +	if (ram_size > result_pageaddr) {
> +		ram_size = result_pageaddr;
> +		tst_res(TWARN, "RAM size truncated to %zu bytes", ram_size);
> +	}
> +
> +	/* Create VM */

These comments are pretty redundant when we have ioctl's like
KVM_CREATE_VM and KVM_CREATE_VCPU. There are much harder things to
understand in this patchset.

> +	sys_fd = SAFE_OPEN("/dev/kvm", O_RDWR);
> +	inst->vcpu_info_size = SAFE_IOCTL(sys_fd, KVM_GET_VCPU_MMAP_SIZE, 0);
> +	inst->vm_fd = SAFE_IOCTL(sys_fd, KVM_CREATE_VM, 0);
> +	cpuid_data = tst_kvm_get_cpuid(sys_fd);
> +	SAFE_CLOSE(sys_fd);
> +
> +	/* Create virtual CPU */
> +	inst->vcpu_fd = SAFE_IOCTL(inst->vm_fd, KVM_CREATE_VCPU, 0);
> +
> +	if (cpuid_data) {
> +		SAFE_IOCTL(inst->vcpu_fd, KVM_SET_CPUID2, cpuid_data);
> +		free(cpuid_data);
> +	}
> +
> +	inst->vcpu_info = SAFE_MMAP(NULL, inst->vcpu_info_size,
> +		PROT_READ | PROT_WRITE, MAP_SHARED, inst->vcpu_fd, 0);
> +
> +	/* Set VM memory banks and install test program */
> +	inst->ram = tst_kvm_alloc_memory(inst->vm_fd, 0, 0, ram_size, 0);
> +	vm_result = tst_kvm_alloc_memory(inst->vm_fd, 1, KVM_RESULT_BASEADDR,
> +		KVM_RESULT_SIZE, 0);
> +	memset(vm_result, 0, KVM_RESULT_SIZE);
> +	memcpy(inst->ram + VM_KERNEL_BASEADDR, kvm_payload_start, payload_size);
> +
> +	reset_ptr = vm_result + (VM_RESET_BASEADDR % pagesize);
> +	memcpy(reset_ptr, tst_kvm_reset_code, sizeof(tst_kvm_reset_code));
> +	inst->result = (struct tst_kvm_result *)(vm_result +
> +		(KVM_RESULT_BASEADDR % pagesize));
> +	inst->result->result = KVM_TNONE;
> +	inst->result->message[0] = '\0';
> +}
> +
> +void tst_kvm_run_instance(struct tst_kvm_instance *inst)
> +{
> +	struct kvm_regs regs;
> +
> +	while (1) {
> +		inst->result->result = KVM_TNONE;
> +		inst->result->message[0] = '\0';
> +		SAFE_IOCTL(inst->vcpu_fd, KVM_RUN, 0);
> +
> +		if (inst->vcpu_info->exit_reason != KVM_EXIT_HLT) {
> +			SAFE_IOCTL(inst->vcpu_fd, KVM_GET_REGS, &regs);
> +			tst_brk(TBROK,
> +				"Unexpected VM exit, RIP=0x%llx, reason=%u",
> +				regs.rip, inst->vcpu_info->exit_reason);
> +		}
> +
> +		if (inst->result->result == KVM_TEXIT)
> +			break;
> +
> +		tst_kvm_print_result(inst->result);
> +	}
> +}
> +
> +void tst_kvm_destroy_instance(struct tst_kvm_instance *inst)
> +{
> +	if (inst->vm_fd < 0)
> +		return;
> +
> +	if (inst->vcpu_info != MAP_FAILED)
> +		SAFE_MUNMAP(inst->vcpu_info, inst->vcpu_info_size);
> +
> +	if (inst->vcpu_fd >= 0)
> +		SAFE_CLOSE(inst->vcpu_fd);
> +
> +	SAFE_CLOSE(inst->vm_fd);
> +}
> +
> +void tst_kvm_setup(void)
> +{
> +	tst_kvm_create_instance(&test_vm, DEFAULT_RAM_SIZE);
> +}
> +
> +void tst_kvm_run(void)
> +{
> +	tst_kvm_run_instance(&test_vm);
> +}
> +
> +void tst_kvm_cleanup(void)
> +{
> +	tst_kvm_destroy_instance(&test_vm);
> +}

-- 
Thank you,
Richard.

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