Пример #1
0
int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
			    struct gnttab_map_grant_ref *kmap_ops,
			    struct page **pages, unsigned int count)
{
	int i, ret = 0;
	bool lazy = false;
	pte_t *pte;

	if (xen_feature(XENFEAT_auto_translated_physmap))
		return 0;

	if (kmap_ops &&
	    !in_interrupt() &&
	    paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
		arch_enter_lazy_mmu_mode();
		lazy = true;
	}

	for (i = 0; i < count; i++) {
		unsigned long mfn, pfn;

		/* Do not add to override if the map failed. */
		if (map_ops[i].status)
			continue;

		if (map_ops[i].flags & GNTMAP_contains_pte) {
			pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
				(map_ops[i].host_addr & ~PAGE_MASK));
			mfn = pte_mfn(*pte);
		} else {
			mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
		}
		pfn = page_to_pfn(pages[i]);

		WARN_ON(PagePrivate(pages[i]));
		SetPagePrivate(pages[i]);
		set_page_private(pages[i], mfn);
		pages[i]->index = pfn_to_mfn(pfn);

		if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
			ret = -ENOMEM;
			goto out;
		}

		if (kmap_ops) {
			ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]);
			if (ret)
				goto out;
		}
	}

out:
	if (lazy)
		arch_leave_lazy_mmu_mode();

	return ret;
}
Пример #2
0
/* Add an MFN override for a particular page */
static int m2p_add_override(unsigned long mfn, struct page *page,
			    struct gnttab_map_grant_ref *kmap_op)
{
	unsigned long flags;
	unsigned long pfn;
	unsigned long uninitialized_var(address);
	unsigned level;
	pte_t *ptep = NULL;

	pfn = page_to_pfn(page);
	if (!PageHighMem(page)) {
		address = (unsigned long)__va(pfn << PAGE_SHIFT);
		ptep = lookup_address(address, &level);
		if (WARN(ptep == NULL || level != PG_LEVEL_4K,
			 "m2p_add_override: pfn %lx not mapped", pfn))
			return -EINVAL;
	}

	if (kmap_op != NULL) {
		if (!PageHighMem(page)) {
			struct multicall_space mcs =
				xen_mc_entry(sizeof(*kmap_op));

			MULTI_grant_table_op(mcs.mc,
					GNTTABOP_map_grant_ref, kmap_op, 1);

			xen_mc_issue(PARAVIRT_LAZY_MMU);
		}
	}
	spin_lock_irqsave(&m2p_override_lock, flags);
	list_add(&page->lru,  &m2p_overrides[mfn_hash(mfn)]);
	spin_unlock_irqrestore(&m2p_override_lock, flags);

	/* p2m(m2p(mfn)) == mfn: the mfn is already present somewhere in
	 * this domain. Set the FOREIGN_FRAME_BIT in the p2m for the other
	 * pfn so that the following mfn_to_pfn(mfn) calls will return the
	 * pfn from the m2p_override (the backend pfn) instead.
	 * We need to do this because the pages shared by the frontend
	 * (xen-blkfront) can be already locked (lock_page, called by
	 * do_read_cache_page); when the userspace backend tries to use them
	 * with direct_IO, mfn_to_pfn returns the pfn of the frontend, so
	 * do_blockdev_direct_IO is going to try to lock the same pages
	 * again resulting in a deadlock.
	 * As a side effect get_user_pages_fast might not be safe on the
	 * frontend pages while they are being shared with the backend,
	 * because mfn_to_pfn (that ends up being called by GUPF) will
	 * return the backend pfn rather than the frontend pfn. */
	pfn = mfn_to_pfn_no_overrides(mfn);
	if (__pfn_to_mfn(pfn) == mfn)
		set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));

	return 0;
}
Пример #3
0
int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
			    struct gnttab_map_grant_ref *kmap_ops,
			    struct page **pages, unsigned int count)
{
	int i, ret = 0;
	pte_t *pte;

	if (xen_feature(XENFEAT_auto_translated_physmap))
		return 0;

	if (kmap_ops) {
		ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
						kmap_ops, count);
		if (ret)
			goto out;
	}

	for (i = 0; i < count; i++) {
		unsigned long mfn, pfn;

		/* Do not add to override if the map failed. */
		if (map_ops[i].status)
			continue;

		if (map_ops[i].flags & GNTMAP_contains_pte) {
			pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
				(map_ops[i].host_addr & ~PAGE_MASK));
			mfn = pte_mfn(*pte);
		} else {
			mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
		}
		pfn = page_to_pfn(pages[i]);

		WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned");

		if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
			ret = -ENOMEM;
			goto out;
		}
	}

out:
	return ret;
}
Пример #4
0
int m2p_remove_override(struct page *page, bool clear_pte)
{
	unsigned long flags;
	unsigned long mfn;
	unsigned long pfn;
	unsigned long uninitialized_var(address);
	unsigned level;
	pte_t *ptep = NULL;
	int ret = 0;

	pfn = page_to_pfn(page);
	mfn = get_phys_to_machine(pfn);
	if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
		return -EINVAL;

	if (!PageHighMem(page)) {
		address = (unsigned long)__va(pfn << PAGE_SHIFT);
		ptep = lookup_address(address, &level);

		if (WARN(ptep == NULL || level != PG_LEVEL_4K,
					"m2p_remove_override: pfn %lx not mapped", pfn))
			return -EINVAL;
	}

	spin_lock_irqsave(&m2p_override_lock, flags);
	list_del(&page->lru);
	spin_unlock_irqrestore(&m2p_override_lock, flags);
	WARN_ON(!PagePrivate(page));
	ClearPagePrivate(page);

	if (clear_pte) {
		struct gnttab_map_grant_ref *map_op =
			(struct gnttab_map_grant_ref *) page->index;
		set_phys_to_machine(pfn, map_op->dev_bus_addr);
		if (!PageHighMem(page)) {
			struct multicall_space mcs;
			struct gnttab_unmap_grant_ref *unmap_op;

			/*
			 * It might be that we queued all the m2p grant table
			 * hypercalls in a multicall, then m2p_remove_override
			 * get called before the multicall has actually been
			 * issued. In this case handle is going to -1 because
			 * it hasn't been modified yet.
			 */
			if (map_op->handle == -1)
				xen_mc_flush();
			/*
			 * Now if map_op->handle is negative it means that the
			 * hypercall actually returned an error.
			 */
			if (map_op->handle == GNTST_general_error) {
				printk(KERN_WARNING "m2p_remove_override: "
						"pfn %lx mfn %lx, failed to modify kernel mappings",
						pfn, mfn);
				return -1;
			}

			mcs = xen_mc_entry(
					sizeof(struct gnttab_unmap_grant_ref));
			unmap_op = mcs.args;
			unmap_op->host_addr = map_op->host_addr;
			unmap_op->handle = map_op->handle;
			unmap_op->dev_bus_addr = 0;

			MULTI_grant_table_op(mcs.mc,
					GNTTABOP_unmap_grant_ref, unmap_op, 1);

			xen_mc_issue(PARAVIRT_LAZY_MMU);

			set_pte_at(&init_mm, address, ptep,
					pfn_pte(pfn, PAGE_KERNEL));
			__flush_tlb_single(address);
			map_op->host_addr = 0;
		}
	} else
		set_phys_to_machine(pfn, page->index);

	/* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present
	 * somewhere in this domain, even before being added to the
	 * m2p_override (see comment above in m2p_add_override).
	 * If there are no other entries in the m2p_override corresponding
	 * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for
	 * the original pfn (the one shared by the frontend): the backend
	 * cannot do any IO on this page anymore because it has been
	 * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of
	 * the original pfn causes mfn_to_pfn(mfn) to return the frontend
	 * pfn again. */
	mfn &= ~FOREIGN_FRAME_BIT;
	ret = __get_user(pfn, &machine_to_phys_mapping[mfn]);
	if (ret == 0 && get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) &&
			m2p_find_override(mfn) == NULL)
		set_phys_to_machine(pfn, mfn);

	return 0;
}
Пример #5
0
static int m2p_remove_override(struct page *page,
			       struct gnttab_map_grant_ref *kmap_op,
			       unsigned long mfn)
{
	unsigned long flags;
	unsigned long pfn;
	unsigned long uninitialized_var(address);
	unsigned level;
	pte_t *ptep = NULL;

	pfn = page_to_pfn(page);

	if (!PageHighMem(page)) {
		address = (unsigned long)__va(pfn << PAGE_SHIFT);
		ptep = lookup_address(address, &level);

		if (WARN(ptep == NULL || level != PG_LEVEL_4K,
			 "m2p_remove_override: pfn %lx not mapped", pfn))
			return -EINVAL;
	}

	spin_lock_irqsave(&m2p_override_lock, flags);
	list_del(&page->lru);
	spin_unlock_irqrestore(&m2p_override_lock, flags);

	if (kmap_op != NULL) {
		if (!PageHighMem(page)) {
			struct multicall_space mcs;
			struct gnttab_unmap_and_replace *unmap_op;
			struct page *scratch_page = get_balloon_scratch_page();
			unsigned long scratch_page_address = (unsigned long)
				__va(page_to_pfn(scratch_page) << PAGE_SHIFT);

			/*
			 * It might be that we queued all the m2p grant table
			 * hypercalls in a multicall, then m2p_remove_override
			 * get called before the multicall has actually been
			 * issued. In this case handle is going to -1 because
			 * it hasn't been modified yet.
			 */
			if (kmap_op->handle == -1)
				xen_mc_flush();
			/*
			 * Now if kmap_op->handle is negative it means that the
			 * hypercall actually returned an error.
			 */
			if (kmap_op->handle == GNTST_general_error) {
				pr_warn("m2p_remove_override: pfn %lx mfn %lx, failed to modify kernel mappings",
					pfn, mfn);
				put_balloon_scratch_page();
				return -1;
			}

			xen_mc_batch();

			mcs = __xen_mc_entry(
				sizeof(struct gnttab_unmap_and_replace));
			unmap_op = mcs.args;
			unmap_op->host_addr = kmap_op->host_addr;
			unmap_op->new_addr = scratch_page_address;
			unmap_op->handle = kmap_op->handle;

			MULTI_grant_table_op(mcs.mc,
				GNTTABOP_unmap_and_replace, unmap_op, 1);

			mcs = __xen_mc_entry(0);
			MULTI_update_va_mapping(mcs.mc, scratch_page_address,
					pfn_pte(page_to_pfn(scratch_page),
					PAGE_KERNEL_RO), 0);

			xen_mc_issue(PARAVIRT_LAZY_MMU);

			kmap_op->host_addr = 0;
			put_balloon_scratch_page();
		}
	}

	/* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present
	 * somewhere in this domain, even before being added to the
	 * m2p_override (see comment above in m2p_add_override).
	 * If there are no other entries in the m2p_override corresponding
	 * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for
	 * the original pfn (the one shared by the frontend): the backend
	 * cannot do any IO on this page anymore because it has been
	 * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of
	 * the original pfn causes mfn_to_pfn(mfn) to return the frontend
	 * pfn again. */
	mfn &= ~FOREIGN_FRAME_BIT;
	pfn = mfn_to_pfn_no_overrides(mfn);
	if (__pfn_to_mfn(pfn) == FOREIGN_FRAME(mfn) &&
			m2p_find_override(mfn) == NULL)
		set_phys_to_machine(pfn, mfn);

	return 0;
}