linux-kernel - Re: [Xen-devel] [PATCH 3/3] xen: use correct type for physical addresses

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Message-ID: <54AFEF78.8050603@citrix.com>
Date:	Fri, 9 Jan 2015 15:10:48 +0000
From:	David Vrabel <david.vrabel@...rix.com>
To:	Jan Beulich <JBeulich@...e.com>,
	David Vrabel <david.vrabel@...rix.com>,
	Juergen Gross <JGross@...e.com>
CC:	xen-devel <xen-devel@...ts.xenproject.org>,
	<boris.ostrovsky@...cle.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [Xen-devel] [PATCH 3/3] xen: use correct type for physical addresses

On 09/01/15 12:56, Jan Beulich wrote:
>>>> On 09.01.15 at 13:51, <david.vrabel@...rix.com> wrote:
>> On 09/01/15 09:57, Jan Beulich wrote:
>>>>>> On 08.01.15 at 18:01, <JGross@...e.com> wrote:
>>>> @@ -284,7 +286,7 @@ static void __init xen_update_mem_tables(unsigned long pfn, unsigned long mfn)
>>>>  	}
>>>>  
>>>>  	/* Update kernel mapping, but not for highmem. */
>>>> -	if ((pfn << PAGE_SHIFT) >= __pa(high_memory))
>>>> +	if (PFN_PHYS(pfn) >= (u64)(__pa(high_memory)))
>>>
>>> I don't think you really need the cast on the right side - __pa()
>>> should be returning a value of suitable type (and unsigned long
>>> would be sufficient for anything up to and including high_memory).
>>
>> I'd prefer:
>>
>>     if (pfn >= PFN_DOWN(__pa(high_memory))
> 
> Even better indeed. Just one more point: Strictly speaking
> __pa(high_memory) is invalid, as __pa() is defined for low
> memory only. Hence perhaps PFN_UP(__pa(high_memory - 1))?

Yes.

David
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