Re: [Xen-devel] [PATCH v3 2/2] ioreq-server: write protected range and forwarding

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.09.14 at 11:19, <JBeulich@xxxxxxxx> wrote:
>>>> On 10.09.14 at 07:32, <wei.ye@xxxxxxxxx> wrote:
> 
>> 
>>> -----Original Message-----
>>> From: xen-devel-bounces@xxxxxxxxxxxxx [mailto:xen-devel-
>>> bounces@xxxxxxxxxxxxx] On Behalf Of Jan Beulich
>>> Sent: Wednesday, September 3, 2014 9:17 PM
>>> To: Ye, Wei
>>> Cc: Tian, Kevin; keir@xxxxxxx; ian.campbell@xxxxxxxxxx;
>>> stefano.stabellini@xxxxxxxxxxxxx; tim@xxxxxxx; ian.jackson@xxxxxxxxxxxxx;
>>> Dugger, Donald D; xen-devel@xxxxxxxxxxxxx; Paul.Durrant@xxxxxxxxxx; Lv,
>>> Zhiyuan; Zhang, Yang Z
>>> Subject: Re: [Xen-devel] [PATCH v3 2/2] ioreq-server: write protected range
>>> and forwarding
>>> 
>>> >>> On 03.09.14 at 23:53, <wei.ye@xxxxxxxxx> wrote:
>>> > +static int hvm_change_p2m_type_ioreq_server(struct domain *d,
>>> uint16_t set,
>>> > +                                            uint64_t start, uint64_t
>>> > +end) {
>>> > +    int rc = -EINVAL;
>>> > +    uint64_t gpfn_s, gpfn_e, gpfn;
>>> > +    p2m_type_t ot, nt;
>>> > +
>>> > +    if ( set )
>>> > +    {
>>> > +        ot = p2m_ram_rw;
>>> > +        nt = p2m_mmio_write_dm;
>>> > +    }
>>> > +    else
>>> > +    {
>>> > +        ot = p2m_mmio_write_dm;
>>> > +        nt = p2m_ram_rw;
>>> > +    }
>>> > +
>>> > +    gpfn_s = start >> PAGE_SHIFT;
>>> > +    gpfn_e = end >> PAGE_SHIFT;
>>> 
>>> Considering that the first really ought to be PFN_DOWN() - is the latter 
>> really
>>> correct? I'd rather expect that to be PFN_UP()...
>>> 
>> I think the latter one is also should be PFN_DOWN. Considering a range is 
>> [0x0000, 0x1000],
>> then only the first pfn 0 should be changed. Note that the follow loop:
>> for (gpfn = gpfn_s; gpfn <= gpfn_e; gpfn++)
>> The gpfn_e is included. If PFN_UP is to calculate the gpfn_e, there's wrong 
>> p2m type change
>> to pfn 1.
> 
> But then (i.e. if the range is inclusive) it still needs to be

Of course this should read "... is not inclusive) ..."

Jan

> PFN_UP(end - 1).
> 
> Jan



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