From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Lin Ming <mlin@ss.pku.edu.cn>,
"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [Xen-devel] [PATCH] xen/apic: implement io apic read with hypercall
Date: Fri, 20 Apr 2012 14:20:17 +0100 [thread overview]
Message-ID: <4F916291.2020105@citrix.com> (raw)
In-Reply-To: <1334927566.28331.80.camel@zakaz.uk.xensource.com>
On 20/04/12 14:12, Ian Campbell wrote:
> On Fri, 2012-04-20 at 13:53 +0100, Andrew Cooper wrote:
>>> Under what circumstances can these hypercalls fail? Would a BUG_ON be
>>> appropriate/
>> -EFAULT, -EPERM, anything xsm_apic() could return (which looks only to
>> be -EPERM).
> So either the guest has called a hypercall which it is not permitted to
> or it has called it with invalid parameters of one sort or another. Both
> of these would be a code bug in the guest and therefore asserting that
> no failure occurred is reasonable?
>
> What could the caller do with the error other than log it and collapse?
>
>> The call into Xen itself will return 0 as a value if an
>> invalid physbase is passed in the hypercall.
>> So a BUG_ON() is not safe/sensible for domU.
> I think you have successfully argued that it is ;-)
>
> Ian.
>
So I have. -EMoreCoffee
Yes - I meant to say that BUG_ON() was ok for domU.
--
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com
next prev parent reply other threads:[~2012-04-20 13:20 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-20 9:25 [PATCH] xen/apic: implement io apic read with hypercall Lin Ming
2012-04-20 9:58 ` [Xen-devel] " Andrew Cooper
2012-04-20 11:13 ` Lin Ming
2012-04-20 12:38 ` Ian Campbell
2012-04-20 12:52 ` Jan Beulich
2012-04-20 12:53 ` Andrew Cooper
2012-04-20 13:12 ` Ian Campbell
2012-04-20 13:20 ` Andrew Cooper [this message]
2012-04-20 14:50 ` Lin Ming
2012-04-20 14:59 ` [Xen-devel] " Jan Beulich
2012-04-20 15:06 ` Ian Campbell
2012-04-20 15:39 ` Lin Ming
2012-04-20 16:43 ` Konrad Rzeszutek Wilk
2012-04-20 16:41 ` Konrad Rzeszutek Wilk
2012-04-23 8:42 ` Lin Ming
2012-04-23 15:11 ` Konrad Rzeszutek Wilk
2012-04-24 14:43 ` Lin Ming
2012-04-24 16:23 ` Konrad Rzeszutek Wilk
2012-04-25 10:06 ` Lin Ming
2012-04-26 15:33 ` Konrad Rzeszutek Wilk
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