[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [v2][PATCH 1/1] xen:vtd: missing RMRR mapping while share EPT
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx] > Sent: Thursday, July 24, 2014 2:32 AM > > >>> On 24.07.14 at 11:11, <andrew.cooper3@xxxxxxxxxx> wrote: > > On 24/07/14 10:03, Chen, Tiejun wrote: > >> On 2014/7/24 16:57, Andrew Cooper wrote: > >>> On 24/07/14 09:50, Tiejun Chen wrote: > >>>> --- a/xen/drivers/passthrough/vtd/iommu.c > >>>> +++ b/xen/drivers/passthrough/vtd/iommu.c > >>>> @@ -41,6 +41,7 @@ > >>>> #include "extern.h" > >>>> #include "vtd.h" > >>>> #include "../ats.h" > >>>> +#include "../../../arch/x86/mm/mm-locks.h" > >>> > >>> <asm/mm/mm-locks.h> > >> > >> iommu.c:38:29: fatal error: asm/mm/mm-locks.h: No such file or directory > >> #include <asm/mm/mm-locks.h> > >> ^ > >> compilation terminated. > >> > >> Tiejun > > > > Hmm - my mistake. The lack of easy access to this header file goes to > > emphasise that it is private to arch/x86/mm, and there are indeed no > > current users outside of that part of the tree. > > > > Would it not be better have some public p2m_set_identity() function in > > p2m.c ? > > Actually I think this should be using set_mmio_p2m_entry(), which in > turn points out another problem: What is happening with the GFN > that gets replaced here? How will the guest know this is not RAM? I > pointed out on an earlier occasion that passing through devices with > associated RMRR is problematic/dangerous - this is another proof. > Perhaps this should be disallowed, at least when sharing page tables. > yes, that's a problem. we need some way (possibly a new hypercall) to tell user space reserving a list of GFN holes in guest e820. I'm not sure the sequence of current e820 construction and device pass-through. A simpler policy may be always reserve those holes even when no device is assigned. Thanks Kevin _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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