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

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Message-ID: <54E61ECE.4060609@cantab.net>
Date:	Thu, 19 Feb 2015 17:35:10 +0000
From:	David Vrabel <dvrabel@...tab.net>
To:	Juergen Gross <jgross@...e.com>, 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 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?

Otherwise,

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

David
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