On 12.06.2024 04:43, Chen, Jiqian wrote: > On 2024/6/10 23:58, Jan Beulich wrote: >> On 07.06.2024 10:11, Jiqian Chen wrote: >>> If run Xen with PVH dom0 and hvm domU, hvm will map a pirq for >>> a passthrough device by using gsi, see qemu code >>> xen_pt_realize->xc_physdev_map_pirq and libxl code >>> pci_add_dm_done->xc_physdev_map_pirq. Then xc_physdev_map_pirq >>> will call into Xen, but in hvm_physdev_op, PHYSDEVOP_map_pirq >>> is not allowed because currd is PVH dom0 and PVH has no >>> X86_EMU_USE_PIRQ flag, it will fail at has_pirq check. >>> >>> So, allow PHYSDEVOP_map_pirq when dom0 is PVH and also allow >>> PHYSDEVOP_unmap_pirq for the failed path to unmap pirq. And >>> add a new check to prevent self map when subject domain has no >>> PIRQ flag. >>> >>> Signed-off-by: Huang Rui <ray.hu...@amd.com> >>> Signed-off-by: Jiqian Chen <jiqian.c...@amd.com> >>> Reviewed-by: Stefano Stabellini <sstabell...@kernel.org> >> >> What's imo missing in the description is a clarification / justification of >> why it is going to be a good idea (or at least an acceptable one) to expose >> the concept of PIRQs to PVH. If I'm not mistaken that concept so far has >> been entirely a PV one. > I didn't want to expose the concept of PIRQs to PVH. > I did this patch is for HVM that use PIRQs, what I said in commit message is > HVM will map a pirq for gsi, not PVH. > For the original code, it checks " !has_pirq(currd)", but currd is PVH dom0, > so it failed. So I need to allow PHYSDEVOP_map_pirq > even currd has no PIRQs, but the subject domain has.
But that's not what you're enforcing in do_physdev_op(). There you only prevent self-mapping. If I'm not mistaken all you need to do is drop the "d == current->domain" checks from those conditionals. Further see also https://lists.xen.org/archives/html/xen-devel/2024-06/msg00540.html. Jan
