tests/ioctl_kvm_run_common.c - platform/external/strace - Git at Google

 /*
  * Check decoding of KVM_* commands of ioctl syscall using /dev/kvm API.
  * Based on kvmtest.c from https://lwn.net/Articles/658512/
  *
  * kvmtest.c author: Josh Triplett <josh@joshtriplett.org>
  * Copyright (c) 2015 Intel Corporation
  * Copyright (c) 2017-2018 The strace developers.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to
  * deal in the Software without restriction, including without limitation the
  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  * sell copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  * IN THE SOFTWARE.
  */

 #include "tests.h"

 #if defined HAVE_LINUX_KVM_H				\
  && defined HAVE_STRUCT_KVM_CPUID2			\
  && defined HAVE_STRUCT_KVM_REGS			\
  && defined HAVE_STRUCT_KVM_SREGS			\
  && defined HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION	\
  &&(defined __x86_64__ || defined __i386__)

 # include <fcntl.h>
 # include <stdint.h>
 # include <stdio.h>
 # include <stdlib.h>
 # include <string.h>
 # include <sys/ioctl.h>
 # include <sys/mman.h>
 # include <unistd.h>
 # include <linux/kvm.h>

 # ifndef KVM_MAX_CPUID_ENTRIES
 #  define KVM_MAX_CPUID_ENTRIES 80
 # endif

 #include "xlat.h"
 #include "xlat/kvm_cpuid_flags.h"

 static int
 kvm_ioctl(int fd, unsigned long cmd, const char *cmd_str, void *arg)
 {
 	int rc = ioctl(fd, cmd, arg);
 	if (rc < 0)
 		perror_msg_and_skip("%s", cmd_str);
 	return rc;
 }

 #define KVM_IOCTL(fd_, cmd_, arg_)	\
 	kvm_ioctl((fd_), (cmd_), #cmd_, (arg_))

 static const char dev[] = "/dev/kvm";
 static const char vm_dev[] = "anon_inode:kvm-vm";
 static char vcpu_dev[] = "anon_inode:kvm-vcpu:0";
 static size_t page_size;

 extern const char code[];
 extern const unsigned short code_size;

 __asm__(
 	".type code, @object		\n"
 	"code:				\n"
 	"	mov $0xd80003f8, %edx	\n"
 	"	mov $'\n', %al		\n"
 	"	out %al, (%dx)		\n"
 	"	hlt			\n"
 	".size code, . - code		\n"
 	".type code_size, @object	\n"
 	"code_size:			\n"
 	"	.short . - code		\n"
 	".size code_size, . - code_size	\n"
 	);

 static void
 print_kvm_segment(const struct kvm_segment *seg)
 {
 	printf("{base=%#jx, limit=%u, selector=%u, type=%u, present=%u, "
 	       "dpl=%u, db=%u, s=%u, l=%u, g=%u, avl=%u}",
 	       (uintmax_t) seg->base, seg->limit, seg->selector, seg->type,
 	       seg->present, seg->dpl, seg->db, seg->s, seg->l, seg->g,
 	       seg->avl);
 }

 static void
 print_kvm_sregs(const struct kvm_sregs *sregs)
 {
 	printf("{cs=");
 	print_kvm_segment(&sregs->cs);
 #if VERBOSE
 	printf(", ds=");
 	print_kvm_segment(&sregs->ds);
 	printf(", es=");
 	print_kvm_segment(&sregs->es);
 	printf(", fs=");
 	print_kvm_segment(&sregs->fs);
 	printf(", gs=");
 	print_kvm_segment(&sregs->gs);
 	printf(", ss=");
 	print_kvm_segment(&sregs->ss);
 	printf(", tr=");
 	print_kvm_segment(&sregs->tr);
 	printf(", ldt=");
 	print_kvm_segment(&sregs->ldt);
 	printf(", gdt={base=%#jx, limit=%u}, idt={base=%#jx, limit=%u}, "
 	      "cr0=%llu, cr2=%llu, cr3=%llu, cr4=%llu, cr8=%llu, efer=%llu, "
 	      "apic_base=%#jx", (uintmax_t) sregs->gdt.base, sregs->gdt.limit,
 	      (uintmax_t) sregs->idt.base, sregs->idt.limit, sregs->cr0,
 	      sregs->cr2, sregs->cr3, sregs->cr4, sregs->cr8, sregs->efer,
 	      (uintmax_t)sregs->apic_base);
 	printf(", interrupt_bitmap=[");
 	for (size_t i = 0; i < ARRAY_SIZE(sregs->interrupt_bitmap); i++) {
 		if (i)
 			printf(", ");
 		printf("%#jx", (uintmax_t) sregs->interrupt_bitmap[i]);
 	}
 	printf("]");
 #else
 	printf(", ...");
 #endif
 	printf("}");
 }

 static void
 print_kvm_regs(const struct kvm_regs *regs)
 {
 	printf("{rax=%#jx", (uintmax_t) regs->rax);
 #if VERBOSE
 	printf(", rbx=%#jx, rcx=%#jx, rdx=%#jx, rsi=%#jx, rdi=%#jx",
 	       (uintmax_t) regs->rbx, (uintmax_t) regs->rcx,
 	       (uintmax_t) regs->rdx, (uintmax_t) regs->rsi,
 	       (uintmax_t) regs->rdi);
 #else
 	printf(", ...");
 #endif
 	printf(", rsp=%#jx, rbp=%#jx", (uintmax_t) regs->rsp,
 	       (uintmax_t) regs->rbp);
 #if VERBOSE
 	printf(", r8=%#jx, r9=%#jx, r10=%#jx, r11=%#jx, r12=%#jx, r13=%#jx"
 	       ", r14=%#jx, r15=%#jx",
 	       (uintmax_t) regs->r8, (uintmax_t) regs->r9,
 	       (uintmax_t) regs->r10, (uintmax_t) regs->r11,
 	       (uintmax_t) regs->r12, (uintmax_t) regs->r13,
 	       (uintmax_t) regs->r14, (uintmax_t) regs->r15);
 #else
 	printf(", ...");
 #endif
 	printf(", rip=%#jx, rflags=%#jx}", (uintmax_t) regs->rip,
 	       (uintmax_t) regs->rflags);
 }

 # define need_print_KVM_RUN 1

 static void
 print_KVM_RUN(const int fd, const char *const dev, const unsigned int reason);

 static void
 run_kvm(const int vcpu_fd, struct kvm_run *const run, const size_t mmap_size,
 	void *const mem)
 {
 	/* Initialize CS to point at 0, via a read-modify-write of sregs. */
 	struct kvm_sregs sregs;
 	KVM_IOCTL(vcpu_fd, KVM_GET_SREGS, &sregs);
 	printf("ioctl(%d<%s>, KVM_GET_SREGS, ", vcpu_fd, vcpu_dev);
 	print_kvm_sregs(&sregs);
 	printf(") = 0\n");

 	sregs.cs.base = 0;
 	sregs.cs.selector = 0;
 	KVM_IOCTL(vcpu_fd, KVM_SET_SREGS, &sregs);
 	printf("ioctl(%d<%s>, KVM_SET_SREGS, ", vcpu_fd, vcpu_dev);
 	print_kvm_sregs(&sregs);
 	printf(") = 0\n");

 	/*
 	 * Initialize registers: instruction pointer for our code, addends,
 	 * and initial flags required by x86 architecture.
 	 */
 	struct kvm_regs regs = {
 		.rip = page_size,
 		.rax = 2,
 		.rbx = 2,
 		.rflags = 0x2,
 	};
 	KVM_IOCTL(vcpu_fd, KVM_SET_REGS, &regs);
 	printf("ioctl(%d<%s>, KVM_SET_REGS, ", vcpu_fd, vcpu_dev);
 	print_kvm_regs(&regs);
 	printf(") = 0\n");

 	/* Copy the code */
 	memcpy(mem, code, code_size);

 	const char *p = "\n";

 	/* Repeatedly run code and handle VM exits. */
 	for (;;) {
 		KVM_IOCTL(vcpu_fd, KVM_RUN, NULL);
 		print_KVM_RUN(vcpu_fd, vcpu_dev, run->exit_reason);

 		switch (run->exit_reason) {
 		case KVM_EXIT_HLT:
 			if (p)
 				error_msg_and_fail("premature KVM_EXIT_HLT");
 			return;
 		case KVM_EXIT_IO:
 			if (run->io.direction == KVM_EXIT_IO_OUT
 			    && run->io.size == 1
 			    && run->io.port == 0x03f8
 			    && run->io.count == 1
 			    && run->io.data_offset < mmap_size
 			    && p && *p == ((char *) run)[run->io.data_offset])
 				p = NULL;
 			else
 				error_msg_and_fail("unhandled KVM_EXIT_IO");
 			break;
 		case KVM_EXIT_MMIO:
 			error_msg_and_fail("Got an unexpected MMIO exit:"
 					   " phys_addr %#llx,"
 					   " data %02x %02x %02x %02x"
 						" %02x %02x %02x %02x,"
 					   " len %u, is_write %hhu",
 					   (unsigned long long) run->mmio.phys_addr,
 					   run->mmio.data[0], run->mmio.data[1],
 					   run->mmio.data[2], run->mmio.data[3],
 					   run->mmio.data[4], run->mmio.data[5],
 					   run->mmio.data[6], run->mmio.data[7],
 					   run->mmio.len, run->mmio.is_write);

 		default:
 			error_msg_and_fail("exit_reason = %#x",
 					   run->exit_reason);
 		}
 	}
 }

 static int
 vcpu_dev_should_have_cpuid(int fd)
 {
 	int r = 0;
 	char *filename = NULL;
 	char buf[sizeof(vcpu_dev)];

 	if (asprintf(&filename, "/proc/%d/fd/%d", getpid(), fd) < 0)
 		error_msg_and_fail("asprintf");

 	if (readlink(filename, buf, sizeof(buf)) == sizeof(buf) - 1
 	    && (memcmp(buf, vcpu_dev, sizeof(buf) - 1) == 0))
 		r = 1;
 	free(filename);
 	return r;
 }

 static void
 print_cpuid_ioctl(int fd, const char *fd_dev,
 		  const char *ioctl_name, const struct kvm_cpuid2 *cpuid)
 {
 	printf("ioctl(%d<%s>, %s, {nent=%u, entries=[",
 	       fd, fd_dev, ioctl_name, cpuid->nent);
 #if VERBOSE
 	for (size_t i = 0; i < cpuid->nent; i++) {
 		if (i)
 			printf(", ");
 		printf("{function=%#x, index=%#x, flags=",
 		       cpuid->entries[i].function, cpuid->entries[i].index);
 		printflags(kvm_cpuid_flags, cpuid->entries[i].flags,
 			   "KVM_CPUID_FLAG_???");
 		printf(", eax=%#x, ebx=%#x, ecx=%#x, edx=%#x}",
 		       cpuid->entries[i].eax, cpuid->entries[i].ebx,
 		       cpuid->entries[i].ecx, cpuid->entries[i].edx);
 	}
 #else
 	if (cpuid->nent)
 		printf("...");
 #endif
 	printf("]}) = 0\n");
 }

 int
 main(void)
 {
 	skip_if_unavailable("/proc/self/fd/");

 	int kvm = open(dev, O_RDWR);
 	if (kvm < 0)
 		perror_msg_and_skip("open: %s", dev);

 	/* Make sure we have the stable version of the API */
 	int ret = KVM_IOCTL(kvm, KVM_GET_API_VERSION, 0);
 	if (ret != KVM_API_VERSION)
 		error_msg_and_skip("KVM_GET_API_VERSION returned %d"
 				   ", KVM_API_VERSION is %d",
 				   kvm, KVM_API_VERSION);
 	printf("ioctl(%d<%s>, KVM_GET_API_VERSION, 0) = %d\n",
 	       kvm, dev, ret);

 	ret = KVM_IOCTL(kvm, KVM_CHECK_EXTENSION,
 			(void *) (uintptr_t) KVM_CAP_USER_MEMORY);
 	printf("ioctl(%d<%s>, KVM_CHECK_EXTENSION, KVM_CAP_USER_MEMORY) = %d\n",
 	       kvm, dev, ret);

 	int vm_fd = KVM_IOCTL(kvm, KVM_CREATE_VM, 0);
 	printf("ioctl(%d<%s>, KVM_CREATE_VM, 0) = %d<%s>\n",
 	       kvm, dev, vm_fd, vm_dev);

 	/* Allocate one aligned page of guest memory to hold the code. */
 	page_size = get_page_size();
 	void *const mem = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
 				  MAP_SHARED | MAP_ANONYMOUS, -1, 0);
 	if (mem == MAP_FAILED)
 		perror_msg_and_fail("mmap page");

 	/* Map it to the second page frame (to avoid the real-mode IDT at 0). */
 	struct kvm_userspace_memory_region region = {
 		.slot = 0,
 		.guest_phys_addr = page_size,
 		.memory_size = page_size,
 		.userspace_addr = (uintptr_t) mem,
 	};
 	KVM_IOCTL(vm_fd, KVM_SET_USER_MEMORY_REGION, &region);
 	printf("ioctl(%d<%s>, KVM_SET_USER_MEMORY_REGION"
 	       ", {slot=0, flags=0, guest_phys_addr=%#lx, memory_size=%lu"
 	       ", userspace_addr=%p}) = 0\n", vm_fd, vm_dev,
 	       (unsigned long) page_size, (unsigned long) page_size, mem);

 	int vcpu_fd = KVM_IOCTL(vm_fd, KVM_CREATE_VCPU, NULL);
 	if (!vcpu_dev_should_have_cpuid(vcpu_fd)) {
 		/*
 		 * This is an older kernel that doesn't place a cpuid
 		 * at the end of the dentry associated with vcpu_fd.
 		 * Trim the cpuid part of vcpu_dev like:
 		 * "anon_inode:kvm-vcpu:0" -> "anon_inode:kvm-vcpu"
 		 */
 		vcpu_dev[strlen (vcpu_dev) - 2] = '\0';
 #ifdef KVM_NO_CPUID_CALLBACK
 		KVM_NO_CPUID_CALLBACK;
 #endif
 	}

 	printf("ioctl(%d<%s>, KVM_CREATE_VCPU, 0) = %d<%s>\n",
 	       vm_fd, vm_dev, vcpu_fd, vcpu_dev);

 	/* Map the shared kvm_run structure and following data. */
 	ret = KVM_IOCTL(kvm, KVM_GET_VCPU_MMAP_SIZE, NULL);
 	struct kvm_run *run;
 	if (ret < (int) sizeof(*run))
 		error_msg_and_fail("KVM_GET_VCPU_MMAP_SIZE returned %d < %d",
 				   ret, (int) sizeof(*run));
 	printf("ioctl(%d<%s>, KVM_GET_VCPU_MMAP_SIZE, 0) = %d\n",
 	       kvm, dev, ret);

 	const size_t mmap_size = (ret + page_size - 1) & -page_size;
 	run = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
 		   MAP_SHARED, vcpu_fd, 0);
 	if (run == MAP_FAILED)
 		perror_msg_and_fail("mmap vcpu");

 	size_t cpuid_nent = KVM_MAX_CPUID_ENTRIES;
 	struct kvm_cpuid2 *cpuid = tail_alloc(sizeof(*cpuid) +
 					      cpuid_nent *
 					      sizeof(*cpuid->entries));

 	cpuid->nent = 0;
 	ioctl(kvm, KVM_GET_SUPPORTED_CPUID, cpuid);
 	printf("ioctl(%d<%s>, KVM_GET_SUPPORTED_CPUID, %p) = -1 E2BIG (%m)\n",
 	       kvm, dev, cpuid);

 	cpuid->nent = cpuid_nent;

 	KVM_IOCTL(kvm, KVM_GET_SUPPORTED_CPUID, cpuid);
 	print_cpuid_ioctl(kvm, dev, "KVM_GET_SUPPORTED_CPUID", cpuid);

 	struct kvm_cpuid2 cpuid_tmp = { .nent = 0 };
 	KVM_IOCTL(vcpu_fd, KVM_SET_CPUID2, &cpuid_tmp);
 	printf("ioctl(%d<%s>, KVM_SET_CPUID2, {nent=%u, entries=[]}) = 0\n",
 	       vcpu_fd, vcpu_dev, cpuid_tmp.nent);

 	KVM_IOCTL(vcpu_fd, KVM_SET_CPUID2, cpuid);
 	print_cpuid_ioctl(vcpu_fd, vcpu_dev, "KVM_SET_CPUID2", cpuid);

 	ioctl(vcpu_fd, KVM_SET_CPUID2, NULL);
 	printf("ioctl(%d<%s>, KVM_SET_CPUID2, NULL) = -1 EFAULT (%m)\n",
 	       vcpu_fd, vcpu_dev);

 	run_kvm(vcpu_fd, run, mmap_size, mem);

 	puts("+++ exited with 0 +++");
 	return 0;
 }

 #else /* !HAVE_LINUX_KVM_H */

 SKIP_MAIN_UNDEFINED("HAVE_LINUX_KVM_H && HAVE_STRUCT_KVM_CPUID2 && "
 		    "HAVE_STRUCT_KVM_REGS && HAVE_STRUCT_KVM_SREGS && "
 		    "HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION && "
 		    "(__x86_64__ || __i386__)")

 # define need_print_KVM_RUN 0

 #endif
	/*
	* Check decoding of KVM_* commands of ioctl syscall using /dev/kvm API.
	* Based on kvmtest.c from https://lwn.net/Articles/658512/
	*
	* kvmtest.c author: Josh Triplett <josh@joshtriplett.org>
	* Copyright (c) 2015 Intel Corporation
	* Copyright (c) 2017-2018 The strace developers.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to
	* deal in the Software without restriction, including without limitation the
	* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
	* sell copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
	* IN THE SOFTWARE.
	*/

	#include "tests.h"

	#if defined HAVE_LINUX_KVM_H \
	&& defined HAVE_STRUCT_KVM_CPUID2 \
	&& defined HAVE_STRUCT_KVM_REGS \
	&& defined HAVE_STRUCT_KVM_SREGS \
	&& defined HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION \
	&&(defined __x86_64__ \|\| defined __i386__)

	# include <fcntl.h>
	# include <stdint.h>
	# include <stdio.h>
	# include <stdlib.h>
	# include <string.h>
	# include <sys/ioctl.h>
	# include <sys/mman.h>
	# include <unistd.h>
	# include <linux/kvm.h>

	# ifndef KVM_MAX_CPUID_ENTRIES
	# define KVM_MAX_CPUID_ENTRIES 80
	# endif

	#include "xlat.h"
	#include "xlat/kvm_cpuid_flags.h"

	static int
	kvm_ioctl(int fd, unsigned long cmd, const char cmd_str, void arg)
	{
	int rc = ioctl(fd, cmd, arg);
	if (rc < 0)
	perror_msg_and_skip("%s", cmd_str);
	return rc;
	}

	#define KVM_IOCTL(fd_, cmd_, arg_) \
	kvm_ioctl((fd_), (cmd_), #cmd_, (arg_))

	static const char dev[] = "/dev/kvm";
	static const char vm_dev[] = "anon_inode:kvm-vm";
	static char vcpu_dev[] = "anon_inode:kvm-vcpu:0";
	static size_t page_size;

	extern const char code[];
	extern const unsigned short code_size;

	__asm__(
	".type code, @object \n"
	"code: \n"
	" mov $0xd80003f8, %edx \n"
	" mov $'\n', %al \n"
	" out %al, (%dx) \n"
	" hlt \n"
	".size code, . - code \n"
	".type code_size, @object \n"
	"code_size: \n"
	" .short . - code \n"
	".size code_size, . - code_size \n"
	);

	static void
	print_kvm_segment(const struct kvm_segment *seg)
	{
	printf("{base=%#jx, limit=%u, selector=%u, type=%u, present=%u, "
	"dpl=%u, db=%u, s=%u, l=%u, g=%u, avl=%u}",
	(uintmax_t) seg->base, seg->limit, seg->selector, seg->type,
	seg->present, seg->dpl, seg->db, seg->s, seg->l, seg->g,
	seg->avl);
	}

	static void
	print_kvm_sregs(const struct kvm_sregs *sregs)
	{
	printf("{cs=");
	print_kvm_segment(&sregs->cs);
	#if VERBOSE
	printf(", ds=");
	print_kvm_segment(&sregs->ds);
	printf(", es=");
	print_kvm_segment(&sregs->es);
	printf(", fs=");
	print_kvm_segment(&sregs->fs);
	printf(", gs=");
	print_kvm_segment(&sregs->gs);
	printf(", ss=");
	print_kvm_segment(&sregs->ss);
	printf(", tr=");
	print_kvm_segment(&sregs->tr);
	printf(", ldt=");
	print_kvm_segment(&sregs->ldt);
	printf(", gdt={base=%#jx, limit=%u}, idt={base=%#jx, limit=%u}, "
	"cr0=%llu, cr2=%llu, cr3=%llu, cr4=%llu, cr8=%llu, efer=%llu, "
	"apic_base=%#jx", (uintmax_t) sregs->gdt.base, sregs->gdt.limit,
	(uintmax_t) sregs->idt.base, sregs->idt.limit, sregs->cr0,
	sregs->cr2, sregs->cr3, sregs->cr4, sregs->cr8, sregs->efer,
	(uintmax_t)sregs->apic_base);
	printf(", interrupt_bitmap=[");
	for (size_t i = 0; i < ARRAY_SIZE(sregs->interrupt_bitmap); i++) {
	if (i)
	printf(", ");
	printf("%#jx", (uintmax_t) sregs->interrupt_bitmap[i]);
	}
	printf("]");
	#else
	printf(", ...");
	#endif
	printf("}");
	}

	static void
	print_kvm_regs(const struct kvm_regs *regs)
	{
	printf("{rax=%#jx", (uintmax_t) regs->rax);
	#if VERBOSE
	printf(", rbx=%#jx, rcx=%#jx, rdx=%#jx, rsi=%#jx, rdi=%#jx",
	(uintmax_t) regs->rbx, (uintmax_t) regs->rcx,
	(uintmax_t) regs->rdx, (uintmax_t) regs->rsi,
	(uintmax_t) regs->rdi);
	#else
	printf(", ...");
	#endif
	printf(", rsp=%#jx, rbp=%#jx", (uintmax_t) regs->rsp,
	(uintmax_t) regs->rbp);
	#if VERBOSE
	printf(", r8=%#jx, r9=%#jx, r10=%#jx, r11=%#jx, r12=%#jx, r13=%#jx"
	", r14=%#jx, r15=%#jx",
	(uintmax_t) regs->r8, (uintmax_t) regs->r9,
	(uintmax_t) regs->r10, (uintmax_t) regs->r11,
	(uintmax_t) regs->r12, (uintmax_t) regs->r13,
	(uintmax_t) regs->r14, (uintmax_t) regs->r15);
	#else
	printf(", ...");
	#endif
	printf(", rip=%#jx, rflags=%#jx}", (uintmax_t) regs->rip,
	(uintmax_t) regs->rflags);
	}

	# define need_print_KVM_RUN 1

	static void
	print_KVM_RUN(const int fd, const char *const dev, const unsigned int reason);

	static void
	run_kvm(const int vcpu_fd, struct kvm_run *const run, const size_t mmap_size,
	void *const mem)
	{
	/* Initialize CS to point at 0, via a read-modify-write of sregs. */
	struct kvm_sregs sregs;
	KVM_IOCTL(vcpu_fd, KVM_GET_SREGS, &sregs);
	printf("ioctl(%d<%s>, KVM_GET_SREGS, ", vcpu_fd, vcpu_dev);
	print_kvm_sregs(&sregs);
	printf(") = 0\n");

	sregs.cs.base = 0;
	sregs.cs.selector = 0;
	KVM_IOCTL(vcpu_fd, KVM_SET_SREGS, &sregs);
	printf("ioctl(%d<%s>, KVM_SET_SREGS, ", vcpu_fd, vcpu_dev);
	print_kvm_sregs(&sregs);
	printf(") = 0\n");

	/*
	* Initialize registers: instruction pointer for our code, addends,
	* and initial flags required by x86 architecture.
	*/
	struct kvm_regs regs = {
	.rip = page_size,
	.rax = 2,
	.rbx = 2,
	.rflags = 0x2,
	};
	KVM_IOCTL(vcpu_fd, KVM_SET_REGS, &regs);
	printf("ioctl(%d<%s>, KVM_SET_REGS, ", vcpu_fd, vcpu_dev);
	print_kvm_regs(&regs);
	printf(") = 0\n");

	/* Copy the code */
	memcpy(mem, code, code_size);

	const char *p = "\n";

	/* Repeatedly run code and handle VM exits. */
	for (;;) {
	KVM_IOCTL(vcpu_fd, KVM_RUN, NULL);
	print_KVM_RUN(vcpu_fd, vcpu_dev, run->exit_reason);

	switch (run->exit_reason) {
	case KVM_EXIT_HLT:
	if (p)
	error_msg_and_fail("premature KVM_EXIT_HLT");
	return;
	case KVM_EXIT_IO:
	if (run->io.direction == KVM_EXIT_IO_OUT
	&& run->io.size == 1
	&& run->io.port == 0x03f8
	&& run->io.count == 1
	&& run->io.data_offset < mmap_size
	&& p && p == ((char ) run)[run->io.data_offset])
	p = NULL;
	else
	error_msg_and_fail("unhandled KVM_EXIT_IO");
	break;
	case KVM_EXIT_MMIO:
	error_msg_and_fail("Got an unexpected MMIO exit:"
	" phys_addr %#llx,"
	" data %02x %02x %02x %02x"
	" %02x %02x %02x %02x,"
	" len %u, is_write %hhu",
	(unsigned long long) run->mmio.phys_addr,
	run->mmio.data[0], run->mmio.data[1],
	run->mmio.data[2], run->mmio.data[3],
	run->mmio.data[4], run->mmio.data[5],
	run->mmio.data[6], run->mmio.data[7],
	run->mmio.len, run->mmio.is_write);

	default:
	error_msg_and_fail("exit_reason = %#x",
	run->exit_reason);
	}
	}
	}

	static int
	vcpu_dev_should_have_cpuid(int fd)
	{
	int r = 0;
	char *filename = NULL;
	char buf[sizeof(vcpu_dev)];

	if (asprintf(&filename, "/proc/%d/fd/%d", getpid(), fd) < 0)
	error_msg_and_fail("asprintf");

	if (readlink(filename, buf, sizeof(buf)) == sizeof(buf) - 1
	&& (memcmp(buf, vcpu_dev, sizeof(buf) - 1) == 0))
	r = 1;
	free(filename);
	return r;
	}

	static void
	print_cpuid_ioctl(int fd, const char *fd_dev,
	const char ioctl_name, const struct kvm_cpuid2 cpuid)
	{
	printf("ioctl(%d<%s>, %s, {nent=%u, entries=[",
	fd, fd_dev, ioctl_name, cpuid->nent);
	#if VERBOSE
	for (size_t i = 0; i < cpuid->nent; i++) {
	if (i)
	printf(", ");
	printf("{function=%#x, index=%#x, flags=",
	cpuid->entries[i].function, cpuid->entries[i].index);
	printflags(kvm_cpuid_flags, cpuid->entries[i].flags,
	"KVM_CPUID_FLAG_???");
	printf(", eax=%#x, ebx=%#x, ecx=%#x, edx=%#x}",
	cpuid->entries[i].eax, cpuid->entries[i].ebx,
	cpuid->entries[i].ecx, cpuid->entries[i].edx);
	}
	#else
	if (cpuid->nent)
	printf("...");
	#endif
	printf("]}) = 0\n");
	}

	int
	main(void)
	{
	skip_if_unavailable("/proc/self/fd/");

	int kvm = open(dev, O_RDWR);
	if (kvm < 0)
	perror_msg_and_skip("open: %s", dev);

	/* Make sure we have the stable version of the API */
	int ret = KVM_IOCTL(kvm, KVM_GET_API_VERSION, 0);
	if (ret != KVM_API_VERSION)
	error_msg_and_skip("KVM_GET_API_VERSION returned %d"
	", KVM_API_VERSION is %d",
	kvm, KVM_API_VERSION);
	printf("ioctl(%d<%s>, KVM_GET_API_VERSION, 0) = %d\n",
	kvm, dev, ret);

	ret = KVM_IOCTL(kvm, KVM_CHECK_EXTENSION,
	(void *) (uintptr_t) KVM_CAP_USER_MEMORY);
	printf("ioctl(%d<%s>, KVM_CHECK_EXTENSION, KVM_CAP_USER_MEMORY) = %d\n",
	kvm, dev, ret);

	int vm_fd = KVM_IOCTL(kvm, KVM_CREATE_VM, 0);
	printf("ioctl(%d<%s>, KVM_CREATE_VM, 0) = %d<%s>\n",
	kvm, dev, vm_fd, vm_dev);

	/* Allocate one aligned page of guest memory to hold the code. */
	page_size = get_page_size();
	void *const mem = mmap(NULL, page_size, PROT_READ \| PROT_WRITE,
	MAP_SHARED \| MAP_ANONYMOUS, -1, 0);
	if (mem == MAP_FAILED)
	perror_msg_and_fail("mmap page");

	/* Map it to the second page frame (to avoid the real-mode IDT at 0). */
	struct kvm_userspace_memory_region region = {
	.slot = 0,
	.guest_phys_addr = page_size,
	.memory_size = page_size,
	.userspace_addr = (uintptr_t) mem,
	};
	KVM_IOCTL(vm_fd, KVM_SET_USER_MEMORY_REGION, &region);
	printf("ioctl(%d<%s>, KVM_SET_USER_MEMORY_REGION"
	", {slot=0, flags=0, guest_phys_addr=%#lx, memory_size=%lu"
	", userspace_addr=%p}) = 0\n", vm_fd, vm_dev,
	(unsigned long) page_size, (unsigned long) page_size, mem);

	int vcpu_fd = KVM_IOCTL(vm_fd, KVM_CREATE_VCPU, NULL);
	if (!vcpu_dev_should_have_cpuid(vcpu_fd)) {
	/*
	* This is an older kernel that doesn't place a cpuid
	* at the end of the dentry associated with vcpu_fd.
	* Trim the cpuid part of vcpu_dev like:
	* "anon_inode:kvm-vcpu:0" -> "anon_inode:kvm-vcpu"
	*/
	vcpu_dev[strlen (vcpu_dev) - 2] = '\0';
	#ifdef KVM_NO_CPUID_CALLBACK
	KVM_NO_CPUID_CALLBACK;
	#endif
	}

	printf("ioctl(%d<%s>, KVM_CREATE_VCPU, 0) = %d<%s>\n",
	vm_fd, vm_dev, vcpu_fd, vcpu_dev);

	/* Map the shared kvm_run structure and following data. */
	ret = KVM_IOCTL(kvm, KVM_GET_VCPU_MMAP_SIZE, NULL);
	struct kvm_run *run;
	if (ret < (int) sizeof(*run))
	error_msg_and_fail("KVM_GET_VCPU_MMAP_SIZE returned %d < %d",
	ret, (int) sizeof(*run));
	printf("ioctl(%d<%s>, KVM_GET_VCPU_MMAP_SIZE, 0) = %d\n",
	kvm, dev, ret);

	const size_t mmap_size = (ret + page_size - 1) & -page_size;
	run = mmap(NULL, mmap_size, PROT_READ \| PROT_WRITE,
	MAP_SHARED, vcpu_fd, 0);
	if (run == MAP_FAILED)
	perror_msg_and_fail("mmap vcpu");

	size_t cpuid_nent = KVM_MAX_CPUID_ENTRIES;
	struct kvm_cpuid2 cpuid = tail_alloc(sizeof(cpuid) +
	cpuid_nent *
	sizeof(*cpuid->entries));

	cpuid->nent = 0;
	ioctl(kvm, KVM_GET_SUPPORTED_CPUID, cpuid);
	printf("ioctl(%d<%s>, KVM_GET_SUPPORTED_CPUID, %p) = -1 E2BIG (%m)\n",
	kvm, dev, cpuid);

	cpuid->nent = cpuid_nent;

	KVM_IOCTL(kvm, KVM_GET_SUPPORTED_CPUID, cpuid);
	print_cpuid_ioctl(kvm, dev, "KVM_GET_SUPPORTED_CPUID", cpuid);

	struct kvm_cpuid2 cpuid_tmp = { .nent = 0 };
	KVM_IOCTL(vcpu_fd, KVM_SET_CPUID2, &cpuid_tmp);
	printf("ioctl(%d<%s>, KVM_SET_CPUID2, {nent=%u, entries=[]}) = 0\n",
	vcpu_fd, vcpu_dev, cpuid_tmp.nent);

	KVM_IOCTL(vcpu_fd, KVM_SET_CPUID2, cpuid);
	print_cpuid_ioctl(vcpu_fd, vcpu_dev, "KVM_SET_CPUID2", cpuid);

	ioctl(vcpu_fd, KVM_SET_CPUID2, NULL);
	printf("ioctl(%d<%s>, KVM_SET_CPUID2, NULL) = -1 EFAULT (%m)\n",
	vcpu_fd, vcpu_dev);

	run_kvm(vcpu_fd, run, mmap_size, mem);

	puts("+++ exited with 0 +++");
	return 0;
	}

	#else /* !HAVE_LINUX_KVM_H */

	SKIP_MAIN_UNDEFINED("HAVE_LINUX_KVM_H && HAVE_STRUCT_KVM_CPUID2 && "
	"HAVE_STRUCT_KVM_REGS && HAVE_STRUCT_KVM_SREGS && "
	"HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION && "
	"(__x86_64__ \|\| __i386__)")

	# define need_print_KVM_RUN 0

	#endif