Re: [Xen-devel] [PATCH 08/13] xen: add service function to copy physical memory areas

From: Juergen Gross
Date: Tue Feb 24 2015 - 01:34:55 EST


On 02/19/2015 06:35 PM, David Vrabel wrote:
On 18/02/2015 06:52, Juergen Gross wrote:
In case a pre-allocated memory area is to be moved in order to avoid
a conflict with the target E820 map we need a way to copy data between
physical addresses.

Add a function doing this via early_memremap().
[...]
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -766,6 +766,35 @@ phys_addr_t __init xen_find_free_area(phys_addr_t
size)
}

/*
+ * Like memcpy, but with physical addresses for dest and src.
+ */
+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_iounmap(to, dest_len + dest_off);
+ early_iounmap(from, src_len + src_off);

early_memunmap surely?

Hmm, yes, sure. I'll update the patch and send another one for
correcting the code where I took the usage from (relocate_initrd).

Juergen


Otherwise,

Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>

David
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