Peter, Besides the gPA->hPA mapping, pt mode enabling requires some sanity check on s->pt_supported. See comments inline.
> -----Original Message----- > From: Qemu-devel [mailto:qemu-devel-bounces+yi.l.liu=intel....@nongnu.org] On > Behalf Of Peter Xu > Sent: Monday, April 17, 2017 7:32 PM > To: qemu-devel@nongnu.org > Cc: Lan, Tianyu <tianyu....@intel.com>; Michael S . Tsirkin <m...@redhat.com>; > Jason Wang <jasow...@redhat.com>; pet...@redhat.com; Marcel Apfelbaum > <mar...@redhat.com>; David Gibson <da...@gibson.dropbear.id.au> > Subject: [Qemu-devel] [PATCH v2 7/7] intel_iommu: support passthrough (PT) > > Signed-off-by: Peter Xu <pet...@redhat.com> > --- > hw/i386/intel_iommu.c | 109 > +++++++++++++++++++++++++++++++++-------- > hw/i386/intel_iommu_internal.h | 1 + > hw/i386/trace-events | 1 + > hw/i386/x86-iommu.c | 1 + > include/hw/i386/x86-iommu.h | 1 + > 5 files changed, 93 insertions(+), 20 deletions(-) > > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c index > 05ae631..deb2007 100644 > --- a/hw/i386/intel_iommu.c > +++ b/hw/i386/intel_iommu.c > @@ -872,7 +872,7 @@ static int vtd_dev_to_context_entry(IntelIOMMUState *s, > uint8_t bus_num, > } else { > switch (vtd_ce_get_type(ce)) { > case VTD_CONTEXT_TT_MULTI_LEVEL: > - /* fall through */ > + case VTD_CONTEXT_TT_PASS_THROUGH: Passthru type is a reserved type if ecap.PT=0, so add a check here. If s->pt_supported is false, report this translation type as unsupported and report an invalid context programming to guest. > case VTD_CONTEXT_TT_DEV_IOTLB: > break; > default: > @@ -883,6 +883,73 @@ static int vtd_dev_to_context_entry(IntelIOMMUState *s, > uint8_t bus_num, > return 0; > } > > +/* Fetch translation type for specific device. Returns <0 if error > + * happens, otherwise return the shifted type to check against > + * VTD_CONTEXT_TT_*. */ > +static int vtd_dev_get_trans_type(VTDAddressSpace *as) { > + IntelIOMMUState *s; > + VTDContextEntry ce; > + int ret; > + > + s = as->iommu_state; > + > + ret = vtd_dev_to_context_entry(s, pci_bus_num(as->bus), > + as->devfn, &ce); > + if (ret) { > + return ret; > + } > + > + return vtd_ce_get_type(&ce); > +} > + > +static bool vtd_dev_pt_enabled(VTDAddressSpace *as) { > + int ret; > + > + assert(as); > + > + ret = vtd_dev_get_trans_type(as); > + if (ret < 0) { > + /* > + * Possibly failed to parse the context entry for some reason > + * (e.g., during init, or any guest configuration errors on > + * context entries). We should assume PT not enabled for > + * safety. > + */ > + return false; > + } > + > + return ret == VTD_CONTEXT_TT_PASS_THROUGH; } > + > +static void vtd_switch_address_space(VTDAddressSpace *as) { > + bool use_iommu; > + > + assert(as); > + > + use_iommu = as->iommu_state->dmar_enabled; > + if (use_iommu) { if s->pt_supported is false, no need to check the context.TT, even context.TT=pt, then it should be an invalid context programming. Regards, Yi L
