---

yaml
---
r: 329159
b: refs/heads/master
c: 488f046
h: refs/heads/master
i:
  329157: 3e9a9f7
  329155: 955ec5a
  329151: 6064570
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: caaf9ecf16feffa4f1a5a0d617bc78906a114514
+refs/heads/master: 488f046df922af992c1a718eff276529c0510885

trunk/arch/x86/xen/mmu.c

@@ -1708,7 +1708,20 @@ static void convert_pfn_mfn(void *v)
 	for (i = 0; i < PTRS_PER_PTE; i++)
 		pte[i] = xen_make_pte(pte[i].pte);
 }
-
+static void __init check_pt_base(unsigned long *pt_base, unsigned long *pt_end,
+				 unsigned long addr)
+{
+	if (*pt_base == PFN_DOWN(__pa(addr))) {
+		set_page_prot((void *)addr, PAGE_KERNEL);
+		clear_page((void *)addr);
+		(*pt_base)++;
+	}
+	if (*pt_end == PFN_DOWN(__pa(addr))) {
+		set_page_prot((void *)addr, PAGE_KERNEL);
+		clear_page((void *)addr);
+		(*pt_end)--;
+	}
+}
 /*
  * Set up the initial kernel pagetable.
  *
@@ -1724,13 +1737,19 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
 {
 	pud_t *l3;
 	pmd_t *l2;
+	unsigned long addr[3];
+	unsigned long pt_base, pt_end;
+	unsigned i;
 
 	/* max_pfn_mapped is the last pfn mapped in the initial memory
 	 * mappings. Considering that on Xen after the kernel mappings we
 	 * have the mappings of some pages that don't exist in pfn space, we
 	 * set max_pfn_mapped to the last real pfn mapped. */
 	max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->mfn_list));
 
+	pt_base = PFN_DOWN(__pa(xen_start_info->pt_base));
+	pt_end = pt_base + xen_start_info->nr_pt_frames;
+
 	/* Zap identity mapping */
 	init_level4_pgt[0] = __pgd(0);
 
@@ -1749,6 +1768,9 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
 	l3 = m2v(pgd[pgd_index(__START_KERNEL_map)].pgd);
 	l2 = m2v(l3[pud_index(__START_KERNEL_map)].pud);
 
+	addr[0] = (unsigned long)pgd;
+	addr[1] = (unsigned long)l3;
+	addr[2] = (unsigned long)l2;
 	/* Graft it onto L4[272][0]. Note that we creating an aliasing problem:
 	 * Both L4[272][0] and L4[511][511] have entries that point to the same
 	 * L2 (PMD) tables. Meaning that if you modify it in __va space
@@ -1782,20 +1804,26 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
 	/* Unpin Xen-provided one */
 	pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
 
-	/* Switch over */
-	pgd = init_level4_pgt;
-
 	/*
 	 * At this stage there can be no user pgd, and no page
 	 * structure to attach it to, so make sure we just set kernel
 	 * pgd.
 	 */
 	xen_mc_batch();
-	__xen_write_cr3(true, __pa(pgd));
+	__xen_write_cr3(true, __pa(init_level4_pgt));
 	xen_mc_issue(PARAVIRT_LAZY_CPU);
 
-	memblock_reserve(__pa(xen_start_info->pt_base),
-			 xen_start_info->nr_pt_frames * PAGE_SIZE);
+	/* We can't that easily rip out L3 and L2, as the Xen pagetables are
+	 * set out this way: [L4], [L1], [L2], [L3], [L1], [L1] ...  for
+	 * the initial domain. For guests using the toolstack, they are in:
+	 * [L4], [L3], [L2], [L1], [L1], order .. So for dom0 we can only
+	 * rip out the [L4] (pgd), but for guests we shave off three pages.
+	 */
+	for (i = 0; i < ARRAY_SIZE(addr); i++)
+		check_pt_base(&pt_base, &pt_end, addr[i]);
+
+	/* Our (by three pages) smaller Xen pagetable that we are using */
+	memblock_reserve(PFN_PHYS(pt_base), (pt_end - pt_base) * PAGE_SIZE);
 }
 #else	/* !CONFIG_X86_64 */
 static RESERVE_BRK_ARRAY(pmd_t, initial_kernel_pmd, PTRS_PER_PMD);