xen: Delay invalidating extra memory

When the physical memory configuration is initialized the p2m entries
for not pouplated memory pages are set to "invalid". As those pages
are beyond the hypervisor built p2m list the p2m tree has to be
extended.

This patch delays processing the extra memory related p2m entries
during the boot process until some more basic memory management
functions are callable. This removes the need to create new p2m
entries until virtual memory management is available.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

1 files changed, 73 insertions, 25 deletions

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index e0b6912f9cad..12cd199e4c9a 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -76,7 +76,6 @@ static unsigned long xen_remap_mfn __initdata = INVALID_P2M_ENTRY;
 
 static void __init xen_add_extra_mem(u64 start, u64 size)
 {
-	unsigned long pfn;
 	int i;
 
 	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
@@ -96,17 +95,75 @@ static void __init xen_add_extra_mem(u64 start, u64 size)
 		printk(KERN_WARNING "Warning: not enough extra memory regions\n");
 
 	memblock_reserve(start, size);
+}
 
-	xen_max_p2m_pfn = PFN_DOWN(start + size);
-	for (pfn = PFN_DOWN(start); pfn < xen_max_p2m_pfn; pfn++) {
-		unsigned long mfn = pfn_to_mfn(pfn);
+static void __init xen_del_extra_mem(u64 start, u64 size)
+{
+	int i;
+	u64 start_r, size_r;
 
-		if (WARN_ONCE(mfn == pfn, "Trying to over-write 1-1 mapping (pfn: %lx)\n", pfn))
-			continue;
-		WARN_ONCE(mfn != INVALID_P2M_ENTRY, "Trying to remove %lx which has %lx mfn!\n",
-			  pfn, mfn);
+	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
+		start_r = xen_extra_mem[i].start;
+		size_r = xen_extra_mem[i].size;
+
+		/* Start of region. */
+		if (start_r == start) {
+			BUG_ON(size > size_r);
+			xen_extra_mem[i].start += size;
+			xen_extra_mem[i].size -= size;
+			break;
+		}
+		/* End of region. */
+		if (start_r + size_r == start + size) {
+			BUG_ON(size > size_r);
+			xen_extra_mem[i].size -= size;
+			break;
+		}
+		/* Mid of region. */
+		if (start > start_r && start < start_r + size_r) {
+			BUG_ON(start + size > start_r + size_r);
+			xen_extra_mem[i].size = start - start_r;
+			/* Calling memblock_reserve() again is okay. */
+			xen_add_extra_mem(start + size, start_r + size_r -
+					  (start + size));
+			break;
+		}
+	}
+	memblock_free(start, size);
+}
+
+/*
+ * Called during boot before the p2m list can take entries beyond the
+ * hypervisor supplied p2m list. Entries in extra mem are to be regarded as
+ * invalid.
+ */
+unsigned long __ref xen_chk_extra_mem(unsigned long pfn)
+{
+	int i;
+	unsigned long addr = PFN_PHYS(pfn);
 
-		__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
+	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
+		if (addr >= xen_extra_mem[i].start &&
+		    addr < xen_extra_mem[i].start + xen_extra_mem[i].size)
+			return INVALID_P2M_ENTRY;
+	}
+
+	return IDENTITY_FRAME(pfn);
+}
+
+/*
+ * Mark all pfns of extra mem as invalid in p2m list.
+ */
+void __init xen_inv_extra_mem(void)
+{
+	unsigned long pfn, pfn_s, pfn_e;
+	int i;
+
+	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
+		pfn_s = PFN_DOWN(xen_extra_mem[i].start);
+		pfn_e = PFN_UP(xen_extra_mem[i].start + xen_extra_mem[i].size);
+		for (pfn = pfn_s; pfn < pfn_e; pfn++)
+			set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
 	}
 }
 
@@ -268,9 +325,6 @@ static void __init xen_do_set_identity_and_remap_chunk(
 
 	BUG_ON(xen_feature(XENFEAT_auto_translated_physmap));
 
-	/* Don't use memory until remapped */
-	memblock_reserve(PFN_PHYS(remap_pfn), PFN_PHYS(size));
-
 	mfn_save = virt_to_mfn(buf);
 
 	for (ident_pfn_iter = start_pfn, remap_pfn_iter = remap_pfn;
@@ -314,7 +368,7 @@ static void __init xen_do_set_identity_and_remap_chunk(
  * 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(
+static unsigned long 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 *released)
@@ -371,7 +425,7 @@ static unsigned long __init xen_set_identity_and_remap_chunk(
 	return remap_pfn;
 }
 
-static unsigned long __init xen_set_identity_and_remap(
+static void __init xen_set_identity_and_remap(
 	const struct e820entry *list, size_t map_size, unsigned long nr_pages,
 	unsigned long *released)
 {
@@ -415,8 +469,6 @@ static unsigned long __init xen_set_identity_and_remap(
 
 	pr_info("Set %ld page(s) to 1-1 mapping\n", identity);
 	pr_info("Released %ld page(s)\n", num_released);
-
-	return last_pfn;
 }
 
 /*
@@ -456,7 +508,7 @@ void __init xen_remap_memory(void)
 		} else if (pfn_s + len == xen_remap_buf.target_pfn) {
 			len += xen_remap_buf.size;
 		} else {
-			memblock_free(PFN_PHYS(pfn_s), PFN_PHYS(len));
+			xen_del_extra_mem(PFN_PHYS(pfn_s), PFN_PHYS(len));
 			pfn_s = xen_remap_buf.target_pfn;
 			len = xen_remap_buf.size;
 		}
@@ -466,7 +518,7 @@ void __init xen_remap_memory(void)
 	}
 
 	if (pfn_s != ~0UL && len)
-		memblock_free(PFN_PHYS(pfn_s), PFN_PHYS(len));
+		xen_del_extra_mem(PFN_PHYS(pfn_s), PFN_PHYS(len));
 
 	set_pte_mfn(buf, mfn_save, PAGE_KERNEL);
 
@@ -533,7 +585,6 @@ char * __init xen_memory_setup(void)
 	int rc;
 	struct xen_memory_map memmap;
 	unsigned long max_pages;
-	unsigned long last_pfn = 0;
 	unsigned long extra_pages = 0;
 	int i;
 	int op;
@@ -583,15 +634,11 @@ char * __init xen_memory_setup(void)
 	 * Set identity map on non-RAM pages and prepare remapping the
 	 * underlying RAM.
 	 */
-	last_pfn = xen_set_identity_and_remap(map, memmap.nr_entries, max_pfn,
-					      &xen_released_pages);
+	xen_set_identity_and_remap(map, memmap.nr_entries, max_pfn,
+				   &xen_released_pages);
 
 	extra_pages += xen_released_pages;
 
-	if (last_pfn > max_pfn) {
-		max_pfn = min(MAX_DOMAIN_PAGES, last_pfn);
-		mem_end = PFN_PHYS(max_pfn);
-	}
 	/*
 	 * Clamp the amount of extra memory to a EXTRA_MEM_RATIO
 	 * factor the base size.  On non-highmem systems, the base
@@ -618,6 +665,7 @@ char * __init xen_memory_setup(void)
 				size = min(size, (u64)extra_pages * PAGE_SIZE);
 				extra_pages -= size / PAGE_SIZE;
 				xen_add_extra_mem(addr, size);
+				xen_max_p2m_pfn = PFN_DOWN(addr + size);
 			} else
 				type = E820_UNUSABLE;
 		}