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From: | Jason Wang |
Subject: | Re: [Qemu-devel] [PATCH v6 1/3] IOMMU: add option to enable VTD_CAP_CM to vIOMMU capility exposoed to guest |
Date: | Fri, 11 Nov 2016 10:32:42 +0800 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 |
On 2016年11月10日 06:00, Michael S. Tsirkin wrote:
On Wed, Nov 09, 2016 at 03:28:02PM +0800, Jason Wang wrote:> > >On 2016年11月08日 19:04, Aviv B.D wrote:> >From: "Aviv Ben-David"<address@hidden> > > > >This capability asks the guest to invalidate cache before each map operation. > >We can use this invalidation to trap map operations in the hypervisor.> >Hi: > >Like I've asked twice in the past, I want to know why don't you cache >translation faults as what spec required (especially this is a guest visible >behavior)? > >Btw, please cc me on posting future versions. > >ThanksCaching isn't guest visible.
Seems not, if one fault mapping were cached by IOTLB. Guest can notice this behavior.
Spec just says you*can* cache, not that you must.
Yes, but what did in this patch is "don't". What I suggest is just a "can", since anyway the IOTLB entries were limited and could be replaced by other.
Thanks
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