[Xen-devel] [PATCH] xen/setup: Don't relocate p2m/initrd over existing one

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

When relocating the p2m/initrd, take special care not to relocate it so
that is overlaps with the current location of the p2m/initrd. This is
needed since the full extent of the current location is not marked as a
reserved region in the e820 (and it shouldn't be since it is about to be
moved).

This was seen to happen to a dom0 with a large initial p2m and a small
reserved region in the middle of the initial p2m.

Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
---
 arch/x86/xen/mmu.c     |  4 ++--
 arch/x86/xen/setup.c   | 16 ++++++++++------
 arch/x86/xen/xen-ops.h |  5 +++--
 3 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 7d5afdb..bc40325 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -2074,7 +2074,7 @@ static phys_addr_t __init xen_early_virt_to_phys(unsigned 
long vaddr)
  * Find a new area for the hypervisor supplied p2m list and relocate the p2m to
  * this area.
  */
-void __init xen_relocate_p2m(void)
+void __init xen_relocate_p2m(phys_addr_t cur_start, phys_addr_t cur_size)
 {
        phys_addr_t size, new_area, pt_phys, pmd_phys, pud_phys;
        unsigned long p2m_pfn, p2m_pfn_end, n_frames, pfn, pfn_end;
@@ -2092,7 +2092,7 @@ void __init xen_relocate_p2m(void)
        n_pud = roundup(size, PGDIR_SIZE) >> PGDIR_SHIFT;
        n_frames = n_pte + n_pt + n_pmd + n_pud;
 
-       new_area = xen_find_free_area(PFN_PHYS(n_frames));
+       new_area = xen_find_free_area(PFN_PHYS(n_frames), cur_start, cur_size);
        if (!new_area) {
                xen_raw_console_write("Can't find new memory area for p2m 
needed due to E820 map conflict\n");
                BUG();
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index f8960fc..513c48b 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -634,14 +634,15 @@ bool __init xen_is_e820_reserved(phys_addr_t start, 
phys_addr_t size)
 }
 
 /*
- * Find a free area in physical memory not yet reserved and compliant with
- * E820 map.
+ * Find a free area in physical memory not yet reserved, compliant with the
+ * E820 map and not overlapping with the pre-allocated area.
  * Used to relocate pre-allocated areas like initrd or p2m list which are in
  * conflict with the to be used E820 map.
  * In case no area is found, return 0. Otherwise return the physical address
  * of the area which is already reserved for convenience.
  */
-phys_addr_t __init xen_find_free_area(phys_addr_t size)
+phys_addr_t __init xen_find_free_area(phys_addr_t size, phys_addr_t cur_start,
+                                     phys_addr_t cur_size)
 {
        unsigned mapcnt;
        phys_addr_t addr, start;
@@ -652,7 +653,8 @@ phys_addr_t __init xen_find_free_area(phys_addr_t size)
                        continue;
                start = entry->addr;
                for (addr = start; addr < start + size; addr += PAGE_SIZE) {
-                       if (!memblock_is_reserved(addr))
+                       if (!memblock_is_reserved(addr) &&
+                           (addr < cur_start || addr >= cur_start + cur_size))
                                continue;
                        start = addr + PAGE_SIZE;
                        if (start + size > entry->addr + entry->size)
@@ -726,7 +728,7 @@ static void __init xen_reserve_xen_mfnlist(void)
        xen_raw_console_write("Xen hypervisor allocated p2m list conflicts with 
E820 map\n");
        BUG();
 #else
-       xen_relocate_p2m();
+       xen_relocate_p2m(start, size);
 #endif
 }
 
@@ -887,7 +889,9 @@ char * __init xen_memory_setup(void)
                                 boot_params.hdr.ramdisk_size)) {
                phys_addr_t new_area, start, size;
 
-               new_area = xen_find_free_area(boot_params.hdr.ramdisk_size);
+               new_area = xen_find_free_area(boot_params.hdr.ramdisk_size,
+                                             boot_params.hdr.ramdisk_image,
+                                             boot_params.hdr.ramdisk_size);
                if (!new_area) {
                        xen_raw_console_write("Can't find new memory area for 
initrd needed due to E820 map conflict\n");
                        BUG();
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 3cbce3b..d3342b8 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -41,14 +41,15 @@ void __init xen_pt_check_e820(void);
 void xen_mm_pin_all(void);
 void xen_mm_unpin_all(void);
 #ifdef CONFIG_X86_64
-void __init xen_relocate_p2m(void);
+void __init xen_relocate_p2m(phys_addr_t cur_start, phys_addr_t cur_size);
 #endif
 
 bool __init xen_is_e820_reserved(phys_addr_t start, phys_addr_t size);
 unsigned long __ref xen_chk_extra_mem(unsigned long pfn);
 void __init xen_inv_extra_mem(void);
 void __init xen_remap_memory(void);
-phys_addr_t __init xen_find_free_area(phys_addr_t size);
+phys_addr_t __init xen_find_free_area(phys_addr_t size, phys_addr_t cur_start,
+                                     phys_addr_t cur_size);
 char * __init xen_memory_setup(void);
 char * xen_auto_xlated_memory_setup(void);
 void __init xen_arch_setup(void);
-- 
2.7.4


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