[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC PATCH 0/3] AMD IOMMU: Share p2m table with iommu
At 14:33 +0100 on 23 May (1306161213), Zhang, Yang Z wrote: > Another question? Does this change ok? How to covert the p2m_type > whose value great than 7 to flags, like the type p2m_ram_shared which > equal to 13? The mask is 7F, not 7. Tim. > diff -r 51d89366c859 -r 78145a98915c xen/arch/x86/mm/p2m.c > --- a/xen/arch/x86/mm/p2m.c Mon Apr 18 15:12:04 2011 +0100 > +++ b/xen/arch/x86/mm/p2m.c Mon Apr 18 17:24:21 2011 +0100 > @@ -80,7 +80,12 @@ > { > unsigned long flags; > #ifdef __x86_64__ > - flags = (unsigned long)(t & 0x3fff) << 9; > + /* > + * AMD IOMMU: When we share p2m table with iommu, bit 9 - bit 11 will be > + * used for iommu hardware to encode next io page level. Bit 59 - bit 62 > + * are used for iommu flags, We could not use these bits to store p2m > types. > + */ > + flags = (unsigned long)(t & 0x7f) << 12; > > best regards > yang > > > > -----Original Message----- > > From: Tim Deegan [mailto:Tim.Deegan@xxxxxxxxxx] > > Sent: Monday, May 23, 2011 6:58 PM > > To: Kay, Allen M > > Cc: Zhang, Yang Z; Wei Wang; xen-devel@xxxxxxxxxxxxxxxxxxx > > Subject: Re: [Xen-devel] [RFC PATCH 0/3] AMD IOMMU: Share p2m table with > > iommu > > > > Hi, > > > > At 01:51 +0100 on 21 May (1305942710), Kay, Allen M wrote: > > > The common code that caused problem is the following. > > > > > > typedef enum { > > > - p2m_invalid = 0, /* Nothing mapped here */ > > > - p2m_ram_rw = 1, /* Normal read/write guest RAM */ > > > + p2m_ram_rw = 0, /* Normal read/write guest RAM */ > > > + p2m_invalid = 1, /* Nothing mapped here */ > > > > > > With the above change, guest with device direct assignment fails to > > > boot. QEMU VGA displays some weird color patterns. > > > > Unfortunately this change seems to be necessary for AMD IOMMU to share > > pagetables with the p2m. I'd rather we didn't have it, because it means > > empty ptes look like RAM mappings of frame 0. :( > > > > Wei, is there any way we can reorganise the AMD IOMMU pagetables so we > > can store the p2m type somewhere that's not required to be zero? If not, > > I'm > > inclined to revert the p2m-sharing for AMD IOMMUs, since at the very least > > we'd like to be able to handle types other than ram_rw (e.g. ram_ro). > > > > In the meantime, Allen, does the attached patch make things any better for > > you? > > > > Cheers, > > > > Tim. > > > > -- > > Tim Deegan <Tim.Deegan@xxxxxxxxxx> > > Principal Software Engineer, Xen Platform Team Citrix Systems UK Ltd. > > (Company #02937203, SL9 0BG) -- Tim Deegan <Tim.Deegan@xxxxxxxxxx> Principal Software Engineer, Xen Platform Team Citrix Systems UK Ltd. (Company #02937203, SL9 0BG) _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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