On Fri, 12 Aug 2022 09:03:02 -0700 Dan Williams <dan.j.willi...@intel.com> wrote:
> Jonathan Cameron wrote: > > On Thu, 11 Aug 2022 18:08:57 +0100 > > Jonathan Cameron via <qemu-devel@nongnu.org> wrote: > > > > > On Tue, 9 Aug 2022 17:08:25 +0100 > > > Jonathan Cameron <jonathan.came...@huawei.com> wrote: > > > > > > > On Tue, 9 Aug 2022 21:07:06 +0800 > > > > Bobo WL <lmw.b...@gmail.com> wrote: > > > > > > > > > Hi Jonathan > > > > > > > > > > Thanks for your reply! > > > > > > > > > > On Mon, Aug 8, 2022 at 8:37 PM Jonathan Cameron > > > > > <jonathan.came...@huawei.com> wrote: > > > > > > > > > > > > Probably not related to your problem, but there is a disconnect in > > > > > > QEMU / > > > > > > kernel assumptionsaround the presence of an HDM decoder when a HB > > > > > > only > > > > > > has a single root port. Spec allows it to be provided or not as an > > > > > > implementation choice. > > > > > > Kernel assumes it isn't provide. Qemu assumes it is. > > > > > > > > > > > > The temporary solution is to throw in a second root port on the HB > > > > > > and not > > > > > > connect anything to it. Longer term I may special case this so > > > > > > that the particular > > > > > > decoder defaults to pass through settings in QEMU if there is only > > > > > > one root port. > > > > > > > > > > > > > > > > You are right! After adding an extra HB in qemu, I can create a x1 > > > > > region successfully. > > > > > But have some errors in Nvdimm: > > > > > > > > > > [ 74.925838] Unknown online node for memory at 0x10000000000, > > > > > assuming node 0 > > > > > [ 74.925846] Unknown target node for memory at 0x10000000000, > > > > > assuming node 0 > > > > > [ 74.927470] nd_region region0: nmem0: is disabled, failing probe > > > > > > > > > > > > > Ah. I've seen this one, but not chased it down yet. Was on my todo > > > > list to chase > > > > down. Once I reach this state I can verify the HDM Decode is correct > > > > which is what > > > > I've been using to test (Which wasn't true until earlier this week). > > > > I'm currently testing via devmem, more for historical reasons than > > > > because it makes > > > > that much sense anymore. > > > > > > *embarassed cough*. We haven't fully hooked the LSA up in qemu yet. > > > I'd forgotten that was still on the todo list. I don't think it will > > > be particularly hard to do and will take a look in next few days. > > > > > > Very very indirectly this error is causing a driver probe fail that means > > > that > > > we hit a code path that has a rather odd looking check on NDD_LABELING. > > > Should not have gotten near that path though - hence the problem is > > > actually > > > when we call cxl_pmem_get_config_data() and it returns an error because > > > we haven't fully connected up the command in QEMU. > > > > So a least one bug in QEMU. We were not supporting variable length payloads > > on mailbox > > inputs (but were on outputs). That hasn't mattered until we get to LSA > > writes. > > We just need to relax condition on the supplied length. > > > > diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c > > index c352a935c4..fdda9529fe 100644 > > --- a/hw/cxl/cxl-mailbox-utils.c > > +++ b/hw/cxl/cxl-mailbox-utils.c > > @@ -510,7 +510,7 @@ void cxl_process_mailbox(CXLDeviceState *cxl_dstate) > > cxl_cmd = &cxl_cmd_set[set][cmd]; > > h = cxl_cmd->handler; > > if (h) { > > - if (len == cxl_cmd->in) { > > + if (len == cxl_cmd->in || !cxl_cmd->in) { > > cxl_cmd->payload = cxl_dstate->mbox_reg_state + > > A_CXL_DEV_CMD_PAYLOAD; > > ret = (*h)(cxl_cmd, cxl_dstate, &len); > > > > > > This lets the nvdimm/region probe fine, but I'm getting some issues with > > namespace capacity so I'll look at what is causing that next. > > Unfortunately I'm not that familiar with the driver/nvdimm side of things > > so it's take a while to figure out what kicks off what! > > The whirlwind tour is that 'struct nd_region' instances that represent a > persitent memory address range are composed of one more mappings of > 'struct nvdimm' objects. The nvdimm object is driven by the dimm driver > in drivers/nvdimm/dimm.c. That driver is mainly charged with unlocking > the dimm (if locked) and interrogating the label area to look for > namespace labels. > > The label command calls are routed to the '->ndctl()' callback that was > registered when the CXL nvdimm_bus_descriptor was created. That callback > handles both 'bus' scope calls, currently none for CXL, and per nvdimm > calls. cxl_pmem_nvdimm_ctl() translates those generic LIBNVDIMM commands > to CXL commands. > > The 'struct nvdimm' objects that the CXL side registers have the > NDD_LABELING flag set which means that namespaces need to be explicitly > created / provisioned from region capacity. Otherwise, if > drivers/nvdimm/dimm.c does not find a namespace-label-index block then > the region reverts to label-less mode and a default namespace equal to > the size of the region is instantiated. > > If you are seeing small mismatches in namespace capacity then it may > just be the fact that by default 'ndctl create-namespace' results in an > 'fsdax' mode namespace which just means that it is a block device where > 1.5% of the capacity is reserved for 'struct page' metadata. You should > be able to see namespace capacity == region capacity by doing "ndctl > create-namespace -m raw", and disable DAX operation. Currently ndctl create-namespace crashes qemu ;) Which isn't ideal! > > Hope that helps. Got me looking at the right code. Thanks! Jonathan