1 files changed, 292 insertions, 78 deletions

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 2e555163c2fe..af7216128d93 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -29,6 +29,7 @@
 #include <xen/features.h>
 #include "xen-ops.h"
 #include "vdso.h"
+#include "p2m.h"
 
 /* These are code, but not functions.  Defined in entry.S */
 extern const char xen_hypervisor_callback[];
@@ -46,6 +47,9 @@ struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
 /* Number of pages released from the initial allocation. */
 unsigned long xen_released_pages;
 
+/* Buffer used to remap identity mapped pages */
+unsigned long xen_remap_buf[P2M_PER_PAGE] __initdata;
+
 /* 
  * The maximum amount of extra memory compared to the base size.  The
  * main scaling factor is the size of struct page.  At extreme ratios
@@ -151,107 +155,325 @@ static unsigned long __init xen_do_chunk(unsigned long start,
 	return len;
 }
 
-static unsigned long __init xen_release_chunk(unsigned long start,
-					      unsigned long end)
-{
-	return xen_do_chunk(start, end, true);
-}
-
-static unsigned long __init xen_populate_chunk(
+/*
+ * Finds the next RAM pfn available in the E820 map after min_pfn.
+ * This function updates min_pfn with the pfn found and returns
+ * the size of that range or zero if not found.
+ */
+static unsigned long __init xen_find_pfn_range(
 	const struct e820entry *list, size_t map_size,
-	unsigned long max_pfn, unsigned long *last_pfn,
-	unsigned long credits_left)
+	unsigned long *min_pfn)
 {
 	const struct e820entry *entry;
 	unsigned int i;
 	unsigned long done = 0;
-	unsigned long dest_pfn;
 
 	for (i = 0, entry = list; i < map_size; i++, entry++) {
 		unsigned long s_pfn;
 		unsigned long e_pfn;
-		unsigned long pfns;
-		long capacity;
-
-		if (credits_left <= 0)
-			break;
 
 		if (entry->type != E820_RAM)
 			continue;
 
 		e_pfn = PFN_DOWN(entry->addr + entry->size);
 
-		/* We only care about E820 after the xen_start_info->nr_pages */
-		if (e_pfn <= max_pfn)
+		/* We only care about E820 after this */
+		if (e_pfn < *min_pfn)
 			continue;
 
 		s_pfn = PFN_UP(entry->addr);
-		/* If the E820 falls within the nr_pages, we want to start
-		 * at the nr_pages PFN.
-		 * If that would mean going past the E820 entry, skip it
+
+		/* If min_pfn falls within the E820 entry, we want to start
+		 * at the min_pfn PFN.
 		 */
-		if (s_pfn <= max_pfn) {
-			capacity = e_pfn - max_pfn;
-			dest_pfn = max_pfn;
+		if (s_pfn <= *min_pfn) {
+			done = e_pfn - *min_pfn;
 		} else {
-			capacity = e_pfn - s_pfn;
-			dest_pfn = s_pfn;
+			done = e_pfn - s_pfn;
+			*min_pfn = s_pfn;
 		}
+		break;
+	}
 
-		if (credits_left < capacity)
-			capacity = credits_left;
+	return done;
+}
 
-		pfns = xen_do_chunk(dest_pfn, dest_pfn + capacity, false);
-		done += pfns;
-		*last_pfn = (dest_pfn + pfns);
-		if (pfns < capacity)
-			break;
-		credits_left -= pfns;
+/*
+ * This releases a chunk of memory and then does the identity map. It's used as
+ * as a fallback if the remapping fails.
+ */
+static void __init xen_set_identity_and_release_chunk(unsigned long start_pfn,
+	unsigned long end_pfn, unsigned long nr_pages, unsigned long *identity,
+	unsigned long *released)
+{
+	WARN_ON(start_pfn > end_pfn);
+
+	/* Need to release pages first */
+	*released += xen_do_chunk(start_pfn, min(end_pfn, nr_pages), true);
+	*identity += set_phys_range_identity(start_pfn, end_pfn);
+}
+
+/*
+ * Helper function to update both the p2m and m2p tables.
+ */
+static unsigned long __init xen_update_mem_tables(unsigned long pfn,
+						  unsigned long mfn)
+{
+	struct mmu_update update = {
+		.ptr = ((unsigned long long)mfn << PAGE_SHIFT) | MMU_MACHPHYS_UPDATE,
+		.val = pfn
+	};
+
+	/* Update p2m */
+	if (!early_set_phys_to_machine(pfn, mfn)) {
+		WARN(1, "Failed to set p2m mapping for pfn=%ld mfn=%ld\n",
+		     pfn, mfn);
+		return false;
 	}
-	return done;
+
+	/* Update m2p */
+	if (HYPERVISOR_mmu_update(&update, 1, NULL, DOMID_SELF) < 0) {
+		WARN(1, "Failed to set m2p mapping for mfn=%ld pfn=%ld\n",
+		     mfn, pfn);
+		return false;
+	}
+
+	return true;
 }
 
-static void __init xen_set_identity_and_release_chunk(
-	unsigned long start_pfn, unsigned long end_pfn, unsigned long nr_pages,
-	unsigned long *released, unsigned long *identity)
+/*
+ * This function updates the p2m and m2p tables with an identity map from
+ * start_pfn to start_pfn+size and remaps the underlying RAM of the original
+ * allocation at remap_pfn. It must do so carefully in P2M_PER_PAGE sized blocks
+ * to not exhaust the reserved brk space. Doing it in properly aligned blocks
+ * ensures we only allocate the minimum required leaf pages in the p2m table. It
+ * copies the existing mfns from the p2m table under the 1:1 map, overwrites
+ * them with the identity map and then updates the p2m and m2p tables with the
+ * remapped memory.
+ */
+static unsigned long __init xen_do_set_identity_and_remap_chunk(
+        unsigned long start_pfn, unsigned long size, unsigned long remap_pfn)
 {
-	unsigned long pfn;
+	unsigned long ident_pfn_iter, remap_pfn_iter;
+	unsigned long ident_start_pfn_align, remap_start_pfn_align;
+	unsigned long ident_end_pfn_align, remap_end_pfn_align;
+	unsigned long ident_boundary_pfn, remap_boundary_pfn;
+	unsigned long ident_cnt = 0;
+	unsigned long remap_cnt = 0;
+	unsigned long left = size;
+	unsigned long mod;
+	int i;
+
+	WARN_ON(size == 0);
+
+	BUG_ON(xen_feature(XENFEAT_auto_translated_physmap));
 
 	/*
-	 * If the PFNs are currently mapped, clear the mappings
-	 * (except for the ISA region which must be 1:1 mapped) to
-	 * release the refcounts (in Xen) on the original frames.
+	 * Determine the proper alignment to remap memory in P2M_PER_PAGE sized
+	 * blocks. We need to keep track of both the existing pfn mapping and
+	 * the new pfn remapping.
 	 */
-	for (pfn = start_pfn; pfn <= max_pfn_mapped && pfn < end_pfn; pfn++) {
-		pte_t pte = __pte_ma(0);
+	mod = start_pfn % P2M_PER_PAGE;
+	ident_start_pfn_align =
+		mod ? (start_pfn - mod + P2M_PER_PAGE) : start_pfn;
+	mod = remap_pfn % P2M_PER_PAGE;
+	remap_start_pfn_align =
+		mod ? (remap_pfn - mod + P2M_PER_PAGE) : remap_pfn;
+	mod = (start_pfn + size) % P2M_PER_PAGE;
+	ident_end_pfn_align = start_pfn + size - mod;
+	mod = (remap_pfn + size) % P2M_PER_PAGE;
+	remap_end_pfn_align = remap_pfn + size - mod;
+
+	/* Iterate over each p2m leaf node in each range */
+	for (ident_pfn_iter = ident_start_pfn_align, remap_pfn_iter = remap_start_pfn_align;
+	     ident_pfn_iter < ident_end_pfn_align && remap_pfn_iter < remap_end_pfn_align;
+	     ident_pfn_iter += P2M_PER_PAGE, remap_pfn_iter += P2M_PER_PAGE) {
+		/* Check we aren't past the end */
+		BUG_ON(ident_pfn_iter + P2M_PER_PAGE > start_pfn + size);
+		BUG_ON(remap_pfn_iter + P2M_PER_PAGE > remap_pfn + size);
+
+		/* Save p2m mappings */
+		for (i = 0; i < P2M_PER_PAGE; i++)
+			xen_remap_buf[i] = pfn_to_mfn(ident_pfn_iter + i);
+
+		/* Set identity map which will free a p2m leaf */
+		ident_cnt += set_phys_range_identity(ident_pfn_iter,
+			ident_pfn_iter + P2M_PER_PAGE);
+
+#ifdef DEBUG
+		/* Helps verify a p2m leaf has been freed */
+		for (i = 0; i < P2M_PER_PAGE; i++) {
+			unsigned int pfn = ident_pfn_iter + i;
+			BUG_ON(pfn_to_mfn(pfn) != pfn);
+		}
+#endif
+		/* Now remap memory */
+		for (i = 0; i < P2M_PER_PAGE; i++) {
+			unsigned long mfn = xen_remap_buf[i];
+
+			/* This will use the p2m leaf freed above */
+			if (!xen_update_mem_tables(remap_pfn_iter + i, mfn)) {
+				WARN(1, "Failed to update mem mapping for pfn=%ld mfn=%ld\n",
+					remap_pfn_iter + i, mfn);
+				return 0;
+			}
+
+			remap_cnt++;
+		}
 
-		if (pfn < PFN_UP(ISA_END_ADDRESS))
-			pte = mfn_pte(pfn, PAGE_KERNEL_IO);
+		left -= P2M_PER_PAGE;
+	}
 
-		(void)HYPERVISOR_update_va_mapping(
-			(unsigned long)__va(pfn << PAGE_SHIFT), pte, 0);
+	/* Max boundary space possible */
+	BUG_ON(left > (P2M_PER_PAGE - 1) * 2);
+
+	/* Now handle the boundary conditions */
+	ident_boundary_pfn = start_pfn;
+	remap_boundary_pfn = remap_pfn;
+	for (i = 0; i < left; i++) {
+		unsigned long mfn;
+
+		/* These two checks move from the start to end boundaries */
+		if (ident_boundary_pfn == ident_start_pfn_align)
+			ident_boundary_pfn = ident_pfn_iter;
+		if (remap_boundary_pfn == remap_start_pfn_align)
+			remap_boundary_pfn = remap_pfn_iter;
+
+		/* Check we aren't past the end */
+		BUG_ON(ident_boundary_pfn >= start_pfn + size);
+		BUG_ON(remap_boundary_pfn >= remap_pfn + size);
+
+		mfn = pfn_to_mfn(ident_boundary_pfn);
+
+		if (!xen_update_mem_tables(remap_boundary_pfn, mfn)) {
+			WARN(1, "Failed to update mem mapping for pfn=%ld mfn=%ld\n",
+				remap_pfn_iter + i, mfn);
+			return 0;
+		}
+		remap_cnt++;
+
+		ident_boundary_pfn++;
+		remap_boundary_pfn++;
 	}
 
-	if (start_pfn < nr_pages)
-		*released += xen_release_chunk(
-			start_pfn, min(end_pfn, nr_pages));
+	/* Finish up the identity map */
+	if (ident_start_pfn_align >= ident_end_pfn_align) {
+		/*
+                 * In this case we have an identity range which does not span an
+                 * aligned block so everything needs to be identity mapped here.
+                 * If we didn't check this we might remap too many pages since
+                 * the align boundaries are not meaningful in this case.
+	         */
+		ident_cnt += set_phys_range_identity(start_pfn,
+			start_pfn + size);
+	} else {
+		/* Remapped above so check each end of the chunk */
+		if (start_pfn < ident_start_pfn_align)
+			ident_cnt += set_phys_range_identity(start_pfn,
+				ident_start_pfn_align);
+		if (start_pfn + size > ident_pfn_iter)
+			ident_cnt += set_phys_range_identity(ident_pfn_iter,
+				start_pfn + size);
+	}
 
-	*identity += set_phys_range_identity(start_pfn, end_pfn);
+	BUG_ON(ident_cnt != size);
+	BUG_ON(remap_cnt != size);
+
+	return size;
 }
 
-static unsigned long __init xen_set_identity_and_release(
-	const struct e820entry *list, size_t map_size, unsigned long nr_pages)
+/*
+ * This function takes a contiguous pfn range that needs to be identity mapped
+ * and:
+ *
+ *  1) Finds a new range of pfns to use to remap based on E820 and remap_pfn.
+ *  2) Calls the do_ function to actually do the mapping/remapping work.
+ *
+ * The goal is to not allocate additional memory but to remap the existing
+ * pages. In the case of an error the underlying memory is simply released back
+ * to Xen and not remapped.
+ */
+static unsigned long __init xen_set_identity_and_remap_chunk(
+        const struct e820entry *list, size_t map_size, unsigned long start_pfn,
+	unsigned long end_pfn, unsigned long nr_pages, unsigned long remap_pfn,
+	unsigned long *identity, unsigned long *remapped,
+	unsigned long *released)
+{
+	unsigned long pfn;
+	unsigned long i = 0;
+	unsigned long n = end_pfn - start_pfn;
+
+	while (i < n) {
+		unsigned long cur_pfn = start_pfn + i;
+		unsigned long left = n - i;
+		unsigned long size = left;
+		unsigned long remap_range_size;
+
+		/* Do not remap pages beyond the current allocation */
+		if (cur_pfn >= nr_pages) {
+			/* Identity map remaining pages */
+			*identity += set_phys_range_identity(cur_pfn,
+				cur_pfn + size);
+			break;
+		}
+		if (cur_pfn + size > nr_pages)
+			size = nr_pages - cur_pfn;
+
+		remap_range_size = xen_find_pfn_range(list, map_size,
+						      &remap_pfn);
+		if (!remap_range_size) {
+			pr_warning("Unable to find available pfn range, not remapping identity pages\n");
+			xen_set_identity_and_release_chunk(cur_pfn,
+				cur_pfn + left, nr_pages, identity, released);
+			break;
+		}
+		/* Adjust size to fit in current e820 RAM region */
+		if (size > remap_range_size)
+			size = remap_range_size;
+
+		if (!xen_do_set_identity_and_remap_chunk(cur_pfn, size, remap_pfn)) {
+			WARN(1, "Failed to remap 1:1 memory cur_pfn=%ld size=%ld remap_pfn=%ld\n",
+				cur_pfn, size, remap_pfn);
+			xen_set_identity_and_release_chunk(cur_pfn,
+				cur_pfn + left, nr_pages, identity, released);
+			break;
+		}
+
+		/* Update variables to reflect new mappings. */
+		i += size;
+		remap_pfn += size;
+		*identity += size;
+		*remapped += size;
+	}
+
+	/*
+	 * If the PFNs are currently mapped, the VA mapping also needs
+	 * to be updated to be 1:1.
+	 */
+	for (pfn = start_pfn; pfn <= max_pfn_mapped && pfn < end_pfn; pfn++)
+		(void)HYPERVISOR_update_va_mapping(
+			(unsigned long)__va(pfn << PAGE_SHIFT),
+			mfn_pte(pfn, PAGE_KERNEL_IO), 0);
+
+	return remap_pfn;
+}
+
+static unsigned long __init xen_set_identity_and_remap(
+	const struct e820entry *list, size_t map_size, unsigned long nr_pages,
+	unsigned long *released)
 {
 	phys_addr_t start = 0;
-	unsigned long released = 0;
 	unsigned long identity = 0;
+	unsigned long remapped = 0;
+	unsigned long last_pfn = nr_pages;
 	const struct e820entry *entry;
+	unsigned long num_released = 0;
 	int i;
 
 	/*
 	 * Combine non-RAM regions and gaps until a RAM region (or the
 	 * end of the map) is reached, then set the 1:1 map and
-	 * release the pages (if available) in those non-RAM regions.
+	 * remap the memory in those non-RAM regions.
 	 *
 	 * The combined non-RAM regions are rounded to a whole number
 	 * of pages so any partial pages are accessible via the 1:1
@@ -269,22 +491,24 @@ static unsigned long __init xen_set_identity_and_release(
 				end_pfn = PFN_UP(entry->addr);
 
 			if (start_pfn < end_pfn)
-				xen_set_identity_and_release_chunk(
-					start_pfn, end_pfn, nr_pages,
-					&released, &identity);
-
+				last_pfn = xen_set_identity_and_remap_chunk(
+						list, map_size, start_pfn,
+						end_pfn, nr_pages, last_pfn,
+						&identity, &remapped,
+						&num_released);
 			start = end;
 		}
 	}
 
-	if (released)
-		printk(KERN_INFO "Released %lu pages of unused memory\n", released);
-	if (identity)
-		printk(KERN_INFO "Set %ld page(s) to 1-1 mapping\n", identity);
+	*released = num_released;
 
-	return released;
-}
+	pr_info("Set %ld page(s) to 1-1 mapping\n", identity);
+	pr_info("Remapped %ld page(s), last_pfn=%ld\n", remapped,
+		last_pfn);
+	pr_info("Released %ld page(s)\n", num_released);
 
+	return last_pfn;
+}
 static unsigned long __init xen_get_max_pages(void)
 {
 	unsigned long max_pages = MAX_DOMAIN_PAGES;
@@ -347,7 +571,6 @@ char * __init xen_memory_setup(void)
 	unsigned long max_pages;
 	unsigned long last_pfn = 0;
 	unsigned long extra_pages = 0;
-	unsigned long populated;
 	int i;
 	int op;
 
@@ -392,20 +615,11 @@ char * __init xen_memory_setup(void)
 		extra_pages += max_pages - max_pfn;
 
 	/*
-	 * Set P2M for all non-RAM pages and E820 gaps to be identity
-	 * type PFNs.  Any RAM pages that would be made inaccesible by
-	 * this are first released.
+	 * Set identity map on non-RAM pages and remap the underlying RAM.
 	 */
-	xen_released_pages = xen_set_identity_and_release(
-		map, memmap.nr_entries, max_pfn);
-
-	/*
-	 * Populate back the non-RAM pages and E820 gaps that had been
-	 * released. */
-	populated = xen_populate_chunk(map, memmap.nr_entries,
-			max_pfn, &last_pfn, xen_released_pages);
+	last_pfn = xen_set_identity_and_remap(map, memmap.nr_entries, max_pfn,
+					      &xen_released_pages);
 
-	xen_released_pages -= populated;
 	extra_pages += xen_released_pages;
 
 	if (last_pfn > max_pfn) {