On Mon, Mar 14, 2022 at 02:25:42PM +0000, David Woodhouse wrote: > From: David Woodhouse <dwmw@xxxxxxxxxxxx> > > By setting none of the SAGAW bits we can indicate to a guest that DMA > translation isn't supported. Tested by booting Windows 10, as well as > Linux guests with the fix at https://git.kernel.org/torvalds/c/c40aaaac10 > > Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> > Reviewed-by: Peter Xu <peterx@xxxxxxxxxx> > Acked-by: Jason Wang <jasowang@xxxxxxxxxx> this is borderline like a feature, but ... > --- > hw/i386/intel_iommu.c | 14 ++++++++++---- > include/hw/i386/intel_iommu.h | 1 + > 2 files changed, 11 insertions(+), 4 deletions(-) > > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c > index 32471a44cb..948c653e74 100644 > --- a/hw/i386/intel_iommu.c > +++ b/hw/i386/intel_iommu.c > @@ -2214,7 +2214,7 @@ static void vtd_handle_gcmd_write(IntelIOMMUState *s) > uint32_t changed = status ^ val; > > trace_vtd_reg_write_gcmd(status, val); > - if (changed & VTD_GCMD_TE) { > + if ((changed & VTD_GCMD_TE) && s->dma_translation) { > /* Translation enable/disable */ > vtd_handle_gcmd_te(s, val & VTD_GCMD_TE); > } > @@ -3122,6 +3122,7 @@ static Property vtd_properties[] = { > DEFINE_PROP_BOOL("x-scalable-mode", IntelIOMMUState, scalable_mode, FALSE), > DEFINE_PROP_BOOL("snoop-control", IntelIOMMUState, snoop_control, false), > DEFINE_PROP_BOOL("dma-drain", IntelIOMMUState, dma_drain, true), > + DEFINE_PROP_BOOL("dma-translation", IntelIOMMUState, dma_translation, true), > DEFINE_PROP_END_OF_LIST(), > }; > > @@ -3627,12 +3628,17 @@ static void vtd_init(IntelIOMMUState *s) > s->next_frcd_reg = 0; > s->cap = VTD_CAP_FRO | VTD_CAP_NFR | VTD_CAP_ND | > VTD_CAP_MAMV | VTD_CAP_PSI | VTD_CAP_SLLPS | > - VTD_CAP_SAGAW_39bit | VTD_CAP_MGAW(s->aw_bits); > + VTD_CAP_MGAW(s->aw_bits); > if (s->dma_drain) { > s->cap |= VTD_CAP_DRAIN; > } > - if (s->aw_bits == VTD_HOST_AW_48BIT) { > - s->cap |= VTD_CAP_SAGAW_48bit; > + if (s->dma_translation) { > + if (s->aw_bits >= VTD_HOST_AW_39BIT) { > + s->cap |= VTD_CAP_SAGAW_39bit; > + } > + if (s->aw_bits >= VTD_HOST_AW_48BIT) { > + s->cap |= VTD_CAP_SAGAW_48bit; > + } > } > s->ecap = VTD_ECAP_QI | VTD_ECAP_IRO; > ... this looks like you are actually fixing aw_bits < VTD_HOST_AW_39BIT, right? So maybe this patch is ok like this since it also fixes a bug. Pls add this to commit log though. > diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h > index 3b5ac869db..d898be85ce 100644 > --- a/include/hw/i386/intel_iommu.h > +++ b/include/hw/i386/intel_iommu.h > @@ -267,6 +267,7 @@ struct IntelIOMMUState { > bool buggy_eim; /* Force buggy EIM unless eim=off */ > uint8_t aw_bits; /* Host/IOVA address width (in bits) */ > bool dma_drain; /* Whether DMA r/w draining enabled */ > + bool dma_translation; /* Whether DMA translation supported */ > > /* > * Protects IOMMU states in general. Currently it protects the > -- > 2.33.1
