Messages in this thread | | | Date | Mon, 11 Jul 2016 09:19:59 +0200 | From | Joerg Roedel <> | Subject | Re: [PATCH] iommu/amd: Fix unity mapping initialization race |
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On Sun, Jul 10, 2016 at 07:40:53PM +0800, Wan Zongshun wrote: > Do you mean we need enable the V and TV bits to DTE entry after all > DTEs tables were initialized completely?
Yes, this is what my patch does and what fixes the bug that was reported on machines which have unity-mapping entries.
> I checked this function 'init_device_table_dma', and find it just set > V and TV bit, to set translation info valid and DTE bits127:1 valid.
Right, if no other bits are set this blocks all DMA from the gives device-id.
> So I just think all things it should to do are to allow DMA access, > GPA-to-SPA translation should be active, why you add function > comments below is to not allow DMA access and suppress all page > faults? > > /* > * Init the device table to not allow DMA access for devices and > * suppress all page faults > */
Yeah, that comment needs to be updated. Not all DMA is blocked and page-faults are not suppressed at all. Thanks for noticing.
Joerg
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