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

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Date:	Fri, 9 Jan 2015 12:51:35 +0000
From:	David Vrabel <david.vrabel@...rix.com>
To:	Jan Beulich <JBeulich@...e.com>, Juergen Gross <JGross@...e.com>
CC:	xen-devel <xen-devel@...ts.xenproject.org>,
	<boris.ostrovsky@...cle.com>, <david.vrabel@...rix.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [Xen-devel] [PATCH 3/3] xen: use correct type for physical addresses

On 09/01/15 09:57, Jan Beulich wrote:
>>>> On 08.01.15 at 18:01, <JGross@...e.com> wrote:
>> --- a/arch/x86/xen/setup.c
>> +++ b/arch/x86/xen/setup.c
>> @@ -140,7 +140,7 @@ static void __init xen_del_extra_mem(u64 start, u64 size)
>>  unsigned long __ref xen_chk_extra_mem(unsigned long pfn)
>>  {
>>  	int i;
>> -	unsigned long addr = PFN_PHYS(pfn);
>> +	u64 addr = PFN_PHYS(pfn);
> 
> Isn't phys_addr_t the type to use here?

Agreed.

>> @@ -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))

David
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