[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] hvmemul_rep_movs() vs MMIO
>>> On 20.09.13 at 14:05, Tim Deegan <tim@xxxxxxx> wrote: > At 12:46 +0100 on 20 Sep (1379681171), Jan Beulich wrote: >> Tim, >> >> was it really intended for "x86/hvm: use unlocked p2m lookups in >> hvmemul_rep_movs()" to special case p2m_mmio_dm but not >> p2m_mmio_direct? > > Hmm. It certainly doesn't seem to handle that case very well now, but > I'm not sure the code before was any better. AFAICT it would have > passed mmio_direct accesses to hvmemul_do_mmio(), which would send them > to qemu. Hmm, wait - if MMIO of a passed through device, other than for its port I/O, doesn't get intercepted at all, but instead gets taken care of by there being a valid gfn->mfn translation in place, then indeed before and after your change things aren't handled well. Perhaps we should bail from there if either side is p2m_mmio_direct as well as if both sides are p2m_mmio_dm: --- a/xen/arch/x86/hvm/emulate.c +++ b/xen/arch/x86/hvm/emulate.c @@ -799,6 +799,10 @@ static int hvmemul_rep_movs( (void) get_gfn_query_unlocked(current->domain, sgpa >> PAGE_SHIFT, &sp2mt); (void) get_gfn_query_unlocked(current->domain, dgpa >> PAGE_SHIFT, &dp2mt); + if ( sp2mt == p2m_mmio_direct || dp2mt == p2m_mmio_direct || + (sp2mt == p2m_mmio_dm && dp2mt == p2m_mmio_dm) ) + return X86EMUL_UNHANDLEABLE; + if ( sp2mt == p2m_mmio_dm ) return hvmemul_do_mmio( sgpa, reps, bytes_per_rep, dgpa, IOREQ_READ, df, NULL); Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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