[Patch V5 11/16] xen: check for initrd conflicting with e820 map

From: Juergen Gross
Date: Fri Jul 10 2015 - 09:05:03 EST


Check whether the initrd is placed at a location which is conflicting
with the target E820 map. If this is the case relocate it to a new
area unused up to now and compliant to the E820 map.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
arch/x86/xen/setup.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 3fca9c1..0d7f881 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -632,6 +632,36 @@ phys_addr_t __init xen_find_free_area(phys_addr_t size)
}

/*
+ * Like memcpy, but with physical addresses for dest and src.
+ */
+static void __init xen_phys_memcpy(phys_addr_t dest, phys_addr_t src,
+ phys_addr_t n)
+{
+ phys_addr_t dest_off, src_off, dest_len, src_len, len;
+ void *from, *to;
+
+ while (n) {
+ dest_off = dest & ~PAGE_MASK;
+ src_off = src & ~PAGE_MASK;
+ dest_len = n;
+ if (dest_len > (NR_FIX_BTMAPS << PAGE_SHIFT) - dest_off)
+ dest_len = (NR_FIX_BTMAPS << PAGE_SHIFT) - dest_off;
+ src_len = n;
+ if (src_len > (NR_FIX_BTMAPS << PAGE_SHIFT) - src_off)
+ src_len = (NR_FIX_BTMAPS << PAGE_SHIFT) - src_off;
+ len = min(dest_len, src_len);
+ to = early_memremap(dest - dest_off, dest_len + dest_off);
+ from = early_memremap(src - src_off, src_len + src_off);
+ memcpy(to, from, len);
+ early_memunmap(to, dest_len + dest_off);
+ early_memunmap(from, src_len + src_off);
+ n -= len;
+ dest += len;
+ src += len;
+ }
+}
+
+/*
* Reserve Xen mfn_list.
* See comment above "struct start_info" in <xen/interface/xen.h>
* We tried to make the the memblock_reserve more selective so
@@ -810,6 +840,27 @@ char * __init xen_memory_setup(void)

xen_reserve_xen_mfnlist();

+ /* Check for a conflict of the initrd with the target E820 map. */
+ if (xen_is_e820_reserved(boot_params.hdr.ramdisk_image,
+ boot_params.hdr.ramdisk_size)) {
+ phys_addr_t new_area, start, size;
+
+ new_area = xen_find_free_area(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();
+ }
+
+ start = boot_params.hdr.ramdisk_image;
+ size = boot_params.hdr.ramdisk_size;
+ xen_phys_memcpy(new_area, start, size);
+ pr_info("initrd moved from [mem %#010llx-%#010llx] to [mem %#010llx-%#010llx]\n",
+ start, start + size, new_area, new_area + size);
+ memblock_free(start, size);
+ boot_params.hdr.ramdisk_image = new_area;
+ boot_params.ext_ramdisk_image = new_area >> 32;
+ }
+
/*
* Set identity map on non-RAM pages and prepare remapping the
* underlying RAM.
--
2.1.4

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