Re: [PATCH v3 5/9] xen/vpci: add handlers to map the BARs

From: Julien Grall <julien.grall@arm.com>
To: Jan Beulich <JBeulich@suse.com>, Roger Pau Monne <roger.pau@citrix.com>
Cc: StefanoStabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Punit Agrawal <punit.agrawal@arm.com>,
	IanJackson <ian.jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>,
	xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com
Subject: Re: [PATCH v3 5/9] xen/vpci: add handlers to map the BARs
Date: Mon, 22 May 2017 12:38:55 +0100	[thread overview]
Message-ID: <716fab85-6a13-d42c-bb44-c6b4ff96ae35@arm.com> (raw)
In-Reply-To: <591F29B4020000780015B5AE@prv-mh.provo.novell.com>

Hi,

On 19/05/17 16:21, Jan Beulich wrote:
>>>> On 27.04.17 at 16:35, <roger.pau@citrix.com> wrote:
>> +                VPCI_BAR_MEM64_LO,
>> +                VPCI_BAR_MEM64_HI,
>> +            } type;
>> +            /* Hardware address. */
>> +            paddr_t paddr;
>> +            /* Guest address where the BAR should be mapped. */
>> +            paddr_t gaddr;
>> +            /* Current guest address where the BAR is mapped. */
>> +            paddr_t mapped_addr;
>
> Why do you need to track both "should be" and "is" addresses? Also
> I think all three would more naturally be frame numbers.
>
>> +            size_t size;
>
> Is this enough for e.g. ARM32 (remember this is a common
> header)?

ARM 32 support up to 40 bits address space. So theoretically it would to 
would be possible to have BAR bigger than 4GB.

Also, I have seen quite few use of GENMASK(63...) which is not going to 
work on arm32.

Cheers,

-- 
Julien Grall

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