On Sat, Feb 17, 2018 at 12:26:19PM +0100, Jan Kiszka wrote: > From: Jan Kiszka <jan.kis...@siemens.com> > > Xen is doing this [1] and currently triggers an abort. > > [1] > http://xenbits.xenproject.org/gitweb/?p=xen.git;a=blob;f=xen/drivers/passthrough/vtd/iommu.c;h=daaed0abbdd06b6ba3d948ea103aadf02651e83c;hb=refs/heads/master#l1108 > > Reported-by: Luis Lloret <luis_llo...@mentor.com> > Signed-off-by: Jan Kiszka <jan.kis...@siemens.com> > --- > hw/i386/intel_iommu.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c > index 2e841cde27..b61d0da270 100644 > --- a/hw/i386/intel_iommu.c > +++ b/hw/i386/intel_iommu.c > @@ -2129,7 +2129,12 @@ static void vtd_mem_write(void *opaque, hwaddr addr, > > /* Fault Event Address Register, 32-bit */ > case DMAR_FEADDR_REG: > - assert(size == 4); > + /* > + * While the register is 32-bit only, some guests (Xen...) write to > it > + * with 64-bit. Ignore the upper part, that's likely what the > hardware > + * does as well (plus the upper part is not used by our model > anyway). > + */ > + assert(size >= 4); > vtd_set_long(s, addr, val); > break;
(Sorry for the late response due to Chinese Spring Festival) I agree with the problem there, but do we still better provide a conditional vtd_set_quad()? Since from the spec 10.4.13 the upper 32 bits may still be used when x2apic (Extended Interrupt Mode) is enabled? Thanks, -- Peter Xu
