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@suse.com>
Acked-by: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index c04e14e6b301881c6d3b2bf6cda8ac3b29b6800a..1982617fa9c71e01c17f35a5d9f3063d7b8f51be 100644 (file)
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -116,6 +116,7 @@ static pud_t level3_user_vsyscall[PTRS_PER_PUD] __page_aligned_bss;
 DEFINE_PER_CPU(unsigned long, xen_cr3);         /* cr3 stored as physaddr */
 DEFINE_PER_CPU(unsigned long, xen_current_cr3);         /* actual vcpu cr3 */
 
+static phys_addr_t xen_pt_base, xen_pt_size __initdata;
 
 /*
  * Just beyond the highest usermode address.  STACK_TOP_MAX has a
@@ -1998,7 +1999,9 @@ 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_pt_base = PFN_PHYS(pt_base);
+       xen_pt_size = (pt_end - pt_base) * PAGE_SIZE;
+       memblock_reserve(xen_pt_base, xen_pt_size);
        /* protect xen_start_info */
        memblock_reserve(__pa(xen_start_info), PAGE_SIZE);
        /* Revector the xen_start_info */
@@ -2074,11 +2077,21 @@ 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_pt_base = __pa(xen_start_info->pt_base);
+       xen_pt_size = xen_start_info->nr_pt_frames * PAGE_SIZE;
+
+       memblock_reserve(xen_pt_base, xen_pt_size);
 }
 #endif /* CONFIG_X86_64 */
 
+void __init xen_pt_check_e820(void)
+{
+       if (xen_is_e820_reserved(xen_pt_base, xen_pt_size)) {
+               xen_raw_console_write("Xen hypervisor allocated page table memory conflicts with E820 map\n");
+               BUG();
+       }
+}
+
 static unsigned char dummy_mapping[PAGE_SIZE] __page_aligned_bss;
 
 static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 9bd3f358f3d9963195fcde74d3622505b92f3ada..3fca9c114828d02c9a32dad17240c566ae427763 100644 (file)
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -802,6 +802,12 @@ char * __init xen_memory_setup(void)
                BUG();
        }
 
+       /*
+        * Check for a conflict of the hypervisor supplied page tables with
+        * the target E820 map.
+        */
+       xen_pt_check_e820();
+
        xen_reserve_xen_mfnlist();
 
        /*

diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index c4c3c23597a56079846e42468b93af65bab5a885..9038a0f1d5a1fc6e09c0d1895ea4b1a237449b57 100644 (file)
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -35,6 +35,7 @@ void xen_build_mfn_list_list(void);
 void xen_setup_machphys_mapping(void);
 void xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn);
 void xen_reserve_top(void);
+void __init xen_pt_check_e820(void);
 
 void xen_mm_pin_all(void);
 void xen_mm_unpin_all(void);