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

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Date:	Tue, 24 Feb 2015 07:34:23 +0100
From:	Juergen Gross <jgross@...e.com>
To:	David Vrabel <dvrabel@...tab.net>, linux-kernel@...r.kernel.org,
	xen-devel@...ts.xensource.com, konrad.wilk@...cle.com,
	david.vrabel@...rix.com, boris.ostrovsky@...cle.com
Subject: Re: [Xen-devel] [PATCH 08/13] xen: add service function to copy physical
 memory areas

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@...rix.com>
>
> David
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