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> Reviewed-by: Peter Xu <pet...@redhat.com> Reviewed-by: Michael S. Tsirkin <m...@redhat.com> Signed-off-by: Michael S. Tsirkin <m...@redhat.com> --- hw/i386/intel_iommu.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c index 2e841cd..fb31de9 100644 --- a/hw/i386/intel_iommu.c +++ b/hw/i386/intel_iommu.c @@ -2129,8 +2129,15 @@ static void vtd_mem_write(void *opaque, hwaddr addr, /* Fault Event Address Register, 32-bit */ case DMAR_FEADDR_REG: - assert(size == 4); - vtd_set_long(s, addr, val); + if (size == 4) { + vtd_set_long(s, addr, val); + } else { + /* + * While the register is 32-bit only, some guests (Xen...) write to + * it with 64-bit. + */ + vtd_set_quad(s, addr, val); + } break; /* Fault Event Upper Address Register, 32-bit */ -- MST
