From: Julien Grall <julien.grall@linaro.org>
To: Ian Campbell <Ian.Campbell@citrix.com>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: julien.grall@citrix.com, xen-devel@lists.xensource.com
Subject: Re: [RFC PATCH 1/2] xen: introduce arch_iommu_grant_(un)map_page
Date: Wed, 16 Jul 2014 19:19:46 +0100 [thread overview]
Message-ID: <53C6C242.8030007@linaro.org> (raw)
In-Reply-To: <1405526198.1087.45.camel@kazak.uk.xensource.com>
Hi Ian,
On 16/07/14 16:56, Ian Campbell wrote:
> On Tue, 2014-07-08 at 16:53 +0100, Stefano Stabellini wrote:
>> +int arch_iommu_grant_map_page(struct domain *d, unsigned long frame,
>> + unsigned flags)
>> +{
>> + p2m_type_t t;
>> +
>> + /* Grant mappings can be used for DMA requests. The dev_bus_addr returned by
>> + * the hypercall is the MFN (not the IPA). For device protected by
>> + * an IOMMU, Xen needs to add a 1:1 mapping in the domain p2m to
>> + * allow DMA request to work.
>> + * This is only valid when the domain is directed mapped.
>> + */
>> + BUG_ON(!is_domain_direct_mapped(d));
>
> What stops a non-1:1 guest from trying to map a grant reference and
> ending up here?
The function is protected by gnttab_need_iommu_mapping which check if
the domain use direct mapping for the memory.
Regards,
--
Julien Grall
next prev parent reply other threads:[~2014-07-16 18:19 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-08 15:52 [RFC PATCH 0/2] map grant refs at pfn = mfn Stefano Stabellini
2014-07-08 15:53 ` [RFC PATCH 1/2] xen: introduce arch_iommu_grant_(un)map_page Stefano Stabellini
2014-07-08 16:46 ` Julien Grall
2014-07-16 15:56 ` Ian Campbell
2014-07-16 18:19 ` Julien Grall [this message]
2014-07-23 11:27 ` Jan Beulich
2014-07-08 15:53 ` [RFC PATCH 2/2] xen/arm: introduce XENFEAT_grant_map_11 Stefano Stabellini
2014-07-16 15:59 ` Ian Campbell
2014-07-22 14:36 ` Stefano Stabellini
2014-07-23 11:17 ` Jan Beulich
2014-07-23 13:31 ` Stefano Stabellini
2014-07-23 14:15 ` Jan Beulich
2014-07-23 11:21 ` [RFC PATCH 0/2] map grant refs at pfn = mfn Jan Beulich
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