On Tue, 8 Feb 2022 at 15:08, Eric Auger <eric.au...@redhat.com> wrote: > > Representing the CRB cmd/response buffer as a standard > RAM region causes some trouble when the device is used > with VFIO. Indeed VFIO attempts to DMA_MAP this region > as usual RAM but this latter does not have a valid page > size alignment causing such an error report: > "vfio_listener_region_add received unaligned region". > To allow VFIO to detect that failing dma mapping > this region is not an issue, let's use a ram_device > memory region type instead.
This seems like VFIO's problem to me. There's nothing that guarantees alignment for memory regions at all, whether they're RAM, IO or anything else. > + s->crb_cmd_buf = qemu_memalign(qemu_real_host_page_size, > + HOST_PAGE_ALIGN(CRB_CTRL_CMD_SIZE)); > + > memory_region_init_io(&s->mmio, OBJECT(s), &tpm_crb_memory_ops, s, > "tpm-crb-mmio", sizeof(s->regs)); > - memory_region_init_ram(&s->cmdmem, OBJECT(s), > - "tpm-crb-cmd", CRB_CTRL_CMD_SIZE, errp); > + memory_region_init_ram_device_ptr(&s->cmdmem, OBJECT(s), "tpm-crb-cmd", > + CRB_CTRL_CMD_SIZE, s->crb_cmd_buf); > + vmstate_register_ram(&s->cmdmem, dev); > > memory_region_add_subregion(get_system_memory(), > TPM_CRB_ADDR_BASE, &s->mmio); > @@ -309,12 +315,25 @@ static void tpm_crb_realize(DeviceState *dev, Error > **errp) > qemu_register_reset(tpm_crb_reset, dev); > } As QEMU code goes, this seems much worse than what it replaces. To have a memory region backed by RAM and migrated in the usual way, memory_region_init_ram() is the right thing. thanks -- PMM
