linux-kernel - [PATCH 10/13] xen: check pre-allocated page tables for conflict with memory map

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Date:	Wed, 18 Feb 2015 07:52:03 +0100
From:	Juergen Gross <jgross@...e.com>
To:	linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
	konrad.wilk@...cle.com, david.vrabel@...rix.com,
	boris.ostrovsky@...cle.com
Cc:	Juergen Gross <jgross@...e.com>
Subject: [PATCH 10/13] xen: check pre-allocated page tables for conflict with memory map

Check whether the page tables built by the domain builder are at
memory addresses which are in conflict with the target memory map.
If this is the case just panic instead of running into problems
later.

Signed-off-by: Juergen Gross <jgross@...e.com>
---
 arch/x86/xen/mmu.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 1ca5197..6641459 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1863,6 +1863,12 @@ void __init xen_setup_machphys_mapping(void)
 #endif
 }
 
+static int __init xen_pt_memory_conflict(phys_addr_t start, phys_addr_t size)
+{
+	panic("page tables are located at position conflicting with E820 map!\n");
+	return 0;
+}
+
 #ifdef CONFIG_X86_64
 static void __init convert_pfn_mfn(void *v)
 {
@@ -1998,7 +2004,9 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
 		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);
+	xen_add_reserved_area(PFN_PHYS(pt_base),
+			      (pt_end - pt_base) * PAGE_SIZE,
+			      xen_pt_memory_conflict, 1);
 	/* protect xen_start_info */
 	memblock_reserve(__pa(xen_start_info), PAGE_SIZE);
 	/* Revector the xen_start_info */
@@ -2074,8 +2082,9 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
 			  PFN_DOWN(__pa(initial_page_table)));
 	xen_write_cr3(__pa(initial_page_table));
 
-	memblock_reserve(__pa(xen_start_info->pt_base),
-			 xen_start_info->nr_pt_frames * PAGE_SIZE);
+	xen_add_reserved_area(__pa(xen_start_info->pt_base),
+			      xen_start_info->nr_pt_frames * PAGE_SIZE,
+			      xen_pt_memory_conflict, 1);
 }
 #endif	/* CONFIG_X86_64 */
 
-- 
2.1.4

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