privcmd.c 14 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630
/******************************************************************************
 * privcmd.c
 *
 * Interface to privileged domain-0 commands.
 *
 * Copyright (c) 2002-2004, K A Fraser, B Dragovic
 */

#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/uaccess.h>
#include <linux/swap.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/seq_file.h>
#include <linux/miscdevice.h>

#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/tlb.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>

#include <xen/xen.h>
#include <xen/privcmd.h>
#include <xen/interface/xen.h>
#include <xen/features.h>
#include <xen/page.h>
#include <xen/xen-ops.h>
#include <xen/balloon.h>

#include "privcmd.h"

MODULE_LICENSE("GPL");

#define PRIV_VMA_LOCKED ((void *)1)

static int privcmd_vma_range_is_mapped(
               struct vm_area_struct *vma,
               unsigned long addr,
               unsigned long nr_pages);

static long privcmd_ioctl_hypercall(void __user *udata)
{
	struct privcmd_hypercall hypercall;
	long ret;

	if (copy_from_user(&hypercall, udata, sizeof(hypercall)))
		return -EFAULT;

	ret = privcmd_call(hypercall.op,
			   hypercall.arg[0], hypercall.arg[1],
			   hypercall.arg[2], hypercall.arg[3],
			   hypercall.arg[4]);

	return ret;
}

static void free_page_list(struct list_head *pages)
{
	struct page *p, *n;

	list_for_each_entry_safe(p, n, pages, lru)
		__free_page(p);

	INIT_LIST_HEAD(pages);
}

/*
 * Given an array of items in userspace, return a list of pages
 * containing the data.  If copying fails, either because of memory
 * allocation failure or a problem reading user memory, return an
 * error code; its up to the caller to dispose of any partial list.
 */
static int gather_array(struct list_head *pagelist,
			unsigned nelem, size_t size,
			const void __user *data)
{
	unsigned pageidx;
	void *pagedata;
	int ret;

	if (size > PAGE_SIZE)
		return 0;

	pageidx = PAGE_SIZE;
	pagedata = NULL;	/* quiet, gcc */
	while (nelem--) {
		if (pageidx > PAGE_SIZE-size) {
			struct page *page = alloc_page(GFP_KERNEL);

			ret = -ENOMEM;
			if (page == NULL)
				goto fail;

			pagedata = page_address(page);

			list_add_tail(&page->lru, pagelist);
			pageidx = 0;
		}

		ret = -EFAULT;
		if (copy_from_user(pagedata + pageidx, data, size))
			goto fail;

		data += size;
		pageidx += size;
	}

	ret = 0;

fail:
	return ret;
}

/*
 * Call function "fn" on each element of the array fragmented
 * over a list of pages.
 */
static int traverse_pages(unsigned nelem, size_t size,
			  struct list_head *pos,
			  int (*fn)(void *data, void *state),
			  void *state)
{
	void *pagedata;
	unsigned pageidx;
	int ret = 0;

	BUG_ON(size > PAGE_SIZE);

	pageidx = PAGE_SIZE;
	pagedata = NULL;	/* hush, gcc */

	while (nelem--) {
		if (pageidx > PAGE_SIZE-size) {
			struct page *page;
			pos = pos->next;
			page = list_entry(pos, struct page, lru);
			pagedata = page_address(page);
			pageidx = 0;
		}

		ret = (*fn)(pagedata + pageidx, state);
		if (ret)
			break;
		pageidx += size;
	}

	return ret;
}

struct mmap_mfn_state {
	unsigned long va;
	struct vm_area_struct *vma;
	domid_t domain;
};

static int mmap_mfn_range(void *data, void *state)
{
	struct privcmd_mmap_entry *msg = data;
	struct mmap_mfn_state *st = state;
	struct vm_area_struct *vma = st->vma;
	int rc;

	/* Do not allow range to wrap the address space. */
	if ((msg->npages > (LONG_MAX >> PAGE_SHIFT)) ||
	    ((unsigned long)(msg->npages << PAGE_SHIFT) >= -st->va))
		return -EINVAL;

	/* Range chunks must be contiguous in va space. */
	if ((msg->va != st->va) ||
	    ((msg->va+(msg->npages<<PAGE_SHIFT)) > vma->vm_end))
		return -EINVAL;

	rc = xen_remap_domain_mfn_range(vma,
					msg->va & PAGE_MASK,
					msg->mfn, msg->npages,
					vma->vm_page_prot,
					st->domain, NULL);
	if (rc < 0)
		return rc;

	st->va += msg->npages << PAGE_SHIFT;

	return 0;
}

static long privcmd_ioctl_mmap(void __user *udata)
{
	struct privcmd_mmap mmapcmd;
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	int rc;
	LIST_HEAD(pagelist);
	struct mmap_mfn_state state;

	/* We only support privcmd_ioctl_mmap_batch for auto translated. */
	if (xen_feature(XENFEAT_auto_translated_physmap))
		return -ENOSYS;

	if (copy_from_user(&mmapcmd, udata, sizeof(mmapcmd)))
		return -EFAULT;

	rc = gather_array(&pagelist,
			  mmapcmd.num, sizeof(struct privcmd_mmap_entry),
			  mmapcmd.entry);

	if (rc || list_empty(&pagelist))
		goto out;

	down_write(&mm->mmap_sem);

	{
		struct page *page = list_first_entry(&pagelist,
						     struct page, lru);
		struct privcmd_mmap_entry *msg = page_address(page);

		vma = find_vma(mm, msg->va);
		rc = -EINVAL;

		if (!vma || (msg->va != vma->vm_start) || vma->vm_private_data)
			goto out_up;
		vma->vm_private_data = PRIV_VMA_LOCKED;
	}

	state.va = vma->vm_start;
	state.vma = vma;
	state.domain = mmapcmd.dom;

	rc = traverse_pages(mmapcmd.num, sizeof(struct privcmd_mmap_entry),
			    &pagelist,
			    mmap_mfn_range, &state);


out_up:
	up_write(&mm->mmap_sem);

out:
	free_page_list(&pagelist);

	return rc;
}

struct mmap_batch_state {
	domid_t domain;
	unsigned long va;
	struct vm_area_struct *vma;
	int index;
	/* A tristate:
	 *      0 for no errors
	 *      1 if at least one error has happened (and no
	 *          -ENOENT errors have happened)
	 *      -ENOENT if at least 1 -ENOENT has happened.
	 */
	int global_error;
	int version;

	/* User-space mfn array to store errors in the second pass for V1. */
	xen_pfn_t __user *user_mfn;
	/* User-space int array to store errors in the second pass for V2. */
	int __user *user_err;
};

/* auto translated dom0 note: if domU being created is PV, then mfn is
 * mfn(addr on bus). If it's auto xlated, then mfn is pfn (input to HAP).
 */
static int mmap_batch_fn(void *data, void *state)
{
	xen_pfn_t *mfnp = data;
	struct mmap_batch_state *st = state;
	struct vm_area_struct *vma = st->vma;
	struct page **pages = vma->vm_private_data;
	struct page *cur_page = NULL;
	int ret;

	if (xen_feature(XENFEAT_auto_translated_physmap))
		cur_page = pages[st->index++];

	ret = xen_remap_domain_mfn_range(st->vma, st->va & PAGE_MASK, *mfnp, 1,
					 st->vma->vm_page_prot, st->domain,
					 &cur_page);

	/* Store error code for second pass. */
	if (st->version == 1) {
		if (ret < 0) {
			/*
			 * V1 encodes the error codes in the 32bit top nibble of the
			 * mfn (with its known limitations vis-a-vis 64 bit callers).
			 */
			*mfnp |= (ret == -ENOENT) ?
						PRIVCMD_MMAPBATCH_PAGED_ERROR :
						PRIVCMD_MMAPBATCH_MFN_ERROR;
		}
	} else { /* st->version == 2 */
		*((int *) mfnp) = ret;
	}

	/* And see if it affects the global_error. */
	if (ret < 0) {
		if (ret == -ENOENT)
			st->global_error = -ENOENT;
		else {
			/* Record that at least one error has happened. */
			if (st->global_error == 0)
				st->global_error = 1;
		}
	}
	st->va += PAGE_SIZE;

	return 0;
}

static int mmap_return_errors(void *data, void *state)
{
	struct mmap_batch_state *st = state;

	if (st->version == 1) {
		xen_pfn_t mfnp = *((xen_pfn_t *) data);
		if (mfnp & PRIVCMD_MMAPBATCH_MFN_ERROR)
			return __put_user(mfnp, st->user_mfn++);
		else
			st->user_mfn++;
	} else { /* st->version == 2 */
		int err = *((int *) data);
		if (err)
			return __put_user(err, st->user_err++);
		else
			st->user_err++;
	}

	return 0;
}

/* Allocate pfns that are then mapped with gmfns from foreign domid. Update
 * the vma with the page info to use later.
 * Returns: 0 if success, otherwise -errno
 */
static int alloc_empty_pages(struct vm_area_struct *vma, int numpgs)
{
	int rc;
	struct page **pages;

	pages = kcalloc(numpgs, sizeof(pages[0]), GFP_KERNEL);
	if (pages == NULL)
		return -ENOMEM;

	rc = alloc_xenballooned_pages(numpgs, pages, 0);
	if (rc != 0) {
		pr_warn("%s Could not alloc %d pfns rc:%d\n", __func__,
			numpgs, rc);
		kfree(pages);
		return -ENOMEM;
	}
	BUG_ON(vma->vm_private_data != NULL);
	vma->vm_private_data = pages;

	return 0;
}

static struct vm_operations_struct privcmd_vm_ops;

static long privcmd_ioctl_mmap_batch(void __user *udata, int version)
{
	int ret;
	struct privcmd_mmapbatch_v2 m;
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned long nr_pages;
	LIST_HEAD(pagelist);
	struct mmap_batch_state state;

	switch (version) {
	case 1:
		if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch)))
			return -EFAULT;
		/* Returns per-frame error in m.arr. */
		m.err = NULL;
		if (!access_ok(VERIFY_WRITE, m.arr, m.num * sizeof(*m.arr)))
			return -EFAULT;
		break;
	case 2:
		if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch_v2)))
			return -EFAULT;
		/* Returns per-frame error code in m.err. */
		if (!access_ok(VERIFY_WRITE, m.err, m.num * (sizeof(*m.err))))
			return -EFAULT;
		break;
	default:
		return -EINVAL;
	}

	nr_pages = m.num;
	if ((m.num <= 0) || (nr_pages > (LONG_MAX >> PAGE_SHIFT)))
		return -EINVAL;

	ret = gather_array(&pagelist, m.num, sizeof(xen_pfn_t), m.arr);

	if (ret)
		goto out;
	if (list_empty(&pagelist)) {
		ret = -EINVAL;
		goto out;
	}

	if (version == 2) {
		/* Zero error array now to only copy back actual errors. */
		if (clear_user(m.err, sizeof(int) * m.num)) {
			ret = -EFAULT;
			goto out;
		}
	}

	down_write(&mm->mmap_sem);

	vma = find_vma(mm, m.addr);
	if (!vma ||
	    vma->vm_ops != &privcmd_vm_ops) {
		ret = -EINVAL;
		goto out_unlock;
	}

	/*
	 * Caller must either:
	 *
	 * Map the whole VMA range, which will also allocate all the
	 * pages required for the auto_translated_physmap case.
	 *
	 * Or
	 *
	 * Map unmapped holes left from a previous map attempt (e.g.,
	 * because those foreign frames were previously paged out).
	 */
	if (vma->vm_private_data == NULL) {
		if (m.addr != vma->vm_start ||
		    m.addr + (nr_pages << PAGE_SHIFT) != vma->vm_end) {
			ret = -EINVAL;
			goto out_unlock;
		}
		if (xen_feature(XENFEAT_auto_translated_physmap)) {
			ret = alloc_empty_pages(vma, m.num);
			if (ret < 0)
				goto out_unlock;
		} else
			vma->vm_private_data = PRIV_VMA_LOCKED;
	} else {
		if (m.addr < vma->vm_start ||
		    m.addr + (nr_pages << PAGE_SHIFT) > vma->vm_end) {
			ret = -EINVAL;
			goto out_unlock;
		}
		if (privcmd_vma_range_is_mapped(vma, m.addr, nr_pages)) {
			ret = -EINVAL;
			goto out_unlock;
		}
	}

	state.domain        = m.dom;
	state.vma           = vma;
	state.va            = m.addr;
	state.index         = 0;
	state.global_error  = 0;
	state.version       = version;

	/* mmap_batch_fn guarantees ret == 0 */
	BUG_ON(traverse_pages(m.num, sizeof(xen_pfn_t),
			     &pagelist, mmap_batch_fn, &state));

	up_write(&mm->mmap_sem);

	if (state.global_error) {
		/* Write back errors in second pass. */
		state.user_mfn = (xen_pfn_t *)m.arr;
		state.user_err = m.err;
		ret = traverse_pages(m.num, sizeof(xen_pfn_t),
							 &pagelist, mmap_return_errors, &state);
	} else
		ret = 0;

	/* If we have not had any EFAULT-like global errors then set the global
	 * error to -ENOENT if necessary. */
	if ((ret == 0) && (state.global_error == -ENOENT))
		ret = -ENOENT;

out:
	free_page_list(&pagelist);
	return ret;

out_unlock:
	up_write(&mm->mmap_sem);
	goto out;
}

static long privcmd_ioctl(struct file *file,
			  unsigned int cmd, unsigned long data)
{
	int ret = -ENOSYS;
	void __user *udata = (void __user *) data;

	switch (cmd) {
	case IOCTL_PRIVCMD_HYPERCALL:
		ret = privcmd_ioctl_hypercall(udata);
		break;

	case IOCTL_PRIVCMD_MMAP:
		ret = privcmd_ioctl_mmap(udata);
		break;

	case IOCTL_PRIVCMD_MMAPBATCH:
		ret = privcmd_ioctl_mmap_batch(udata, 1);
		break;

	case IOCTL_PRIVCMD_MMAPBATCH_V2:
		ret = privcmd_ioctl_mmap_batch(udata, 2);
		break;

	default:
		ret = -EINVAL;
		break;
	}

	return ret;
}

static void privcmd_close(struct vm_area_struct *vma)
{
	struct page **pages = vma->vm_private_data;
	int numpgs = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
	int rc;

	if (!xen_feature(XENFEAT_auto_translated_physmap) || !numpgs || !pages)
		return;

	rc = xen_unmap_domain_mfn_range(vma, numpgs, pages);
	if (rc == 0)
		free_xenballooned_pages(numpgs, pages);
	else
		pr_crit("unable to unmap MFN range: leaking %d pages. rc=%d\n",
			numpgs, rc);
	kfree(pages);
}

static int privcmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	printk(KERN_DEBUG "privcmd_fault: vma=%p %lx-%lx, pgoff=%lx, uv=%p\n",
	       vma, vma->vm_start, vma->vm_end,
	       vmf->pgoff, vmf->virtual_address);

	return VM_FAULT_SIGBUS;
}

static struct vm_operations_struct privcmd_vm_ops = {
	.close = privcmd_close,
	.fault = privcmd_fault
};

static int privcmd_mmap(struct file *file, struct vm_area_struct *vma)
{
	/* DONTCOPY is essential for Xen because copy_page_range doesn't know
	 * how to recreate these mappings */
	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTCOPY |
			 VM_DONTEXPAND | VM_DONTDUMP;
	vma->vm_ops = &privcmd_vm_ops;
	vma->vm_private_data = NULL;

	return 0;
}

/*
 * For MMAPBATCH*. This allows asserting the singleshot mapping
 * on a per pfn/pte basis. Mapping calls that fail with ENOENT
 * can be then retried until success.
 */
static int is_mapped_fn(pte_t *pte, struct page *pmd_page,
	                unsigned long addr, void *data)
{
	return pte_none(*pte) ? 0 : -EBUSY;
}

static int privcmd_vma_range_is_mapped(
	           struct vm_area_struct *vma,
	           unsigned long addr,
	           unsigned long nr_pages)
{
	return apply_to_page_range(vma->vm_mm, addr, nr_pages << PAGE_SHIFT,
				   is_mapped_fn, NULL) != 0;
}

const struct file_operations xen_privcmd_fops = {
	.owner = THIS_MODULE,
	.unlocked_ioctl = privcmd_ioctl,
	.mmap = privcmd_mmap,
};
EXPORT_SYMBOL_GPL(xen_privcmd_fops);

static struct miscdevice privcmd_dev = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "xen/privcmd",
	.fops = &xen_privcmd_fops,
};

static int __init privcmd_init(void)
{
	int err;

	if (!xen_domain())
		return -ENODEV;

	err = misc_register(&privcmd_dev);
	if (err != 0) {
		pr_err("Could not register Xen privcmd device\n");
		return err;
	}
	return 0;
}

static void __exit privcmd_exit(void)
{
	misc_deregister(&privcmd_dev);
}

module_init(privcmd_init);
module_exit(privcmd_exit);