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    |   xen-devel
Re: [Xen-devel] [PATCH 1/5] Add MSI support to XEN 
| To: | "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>,	"Shan, Haitao" <haitao.shan@xxxxxxxxx>,	Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>,	xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx> |  
| Subject: | Re: [Xen-devel] [PATCH 1/5] Add MSI support to XEN |  
| From: | Keir Fraser <keir.fraser@xxxxxxxxxxxxx> |  
| Date: | Fri, 28 Mar 2008 09:45:27 +0000 |  
| Cc: | "Tian, Kevin" <kevin.tian@xxxxxxxxx>, "Li, Xin B" <xin.b.li@xxxxxxxxx> |  
| Delivery-date: | Fri, 28 Mar 2008 02:47:09 -0700 |  
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| Thread-topic: | [Xen-devel] [PATCH 1/5] Add MSI support to XEN |  
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On 28/3/08 09:37, "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx> wrote:
> DomainU  (PV and hvm) should have no idea of vector. Do you think it
> will matter if domain0 have such idea?
> one thing missed here is, if domainU want to access the MSI config
> spafce, pci backend should return 0xff. Then it should be secure if
> domain0 can have idea of vector.
No, it's not a security risk for dom0 kernel to know about real vectors.
It's already part of the TCB.
It's just a question of which is the cleanest design. And letting Xen get
some access to PCI config space (just a little -- not a lot -- and under
direction of dom0 kernel) will let it properly mask MSIs, which would be a
nicer and deadlock-free alternative to the 'ACK-NEW' masking method.
 -- Keir
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