Messages in this thread | | | Date | Mon, 14 Nov 2022 16:24:06 -0800 | From | Dan Williams <> | Subject | RE: [PATCH v3 4/9] cxl/mem: Skip intermediate port enumeration of restricted endpoints (RCDs) |
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Robert Richter wrote: > When an endpoint is found, all ports in beetween the endpoint and the > CXL host bridge need to be created. In the RCH case there are no ports > in between a host bridge and the endpoint. Skip the enumeration of > intermediate ports. > > The port enumeration does not only create all ports, it also > initializes the endpoint chain by adding the endpoint to every > downstream port up to the root bridge. This must be done also in RCD > mode, but is much more simple as the endpoint only needs to be added > to the host bridge's dport. > > Note: For endpoint removal the cxl_detach_ep() is not needed as it is > released in cxl_port_release(). > > Signed-off-by: Robert Richter <rrichter@amd.com> > --- > drivers/cxl/core/port.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c > index d10c3580719b..e21a9c3fe4da 100644 > --- a/drivers/cxl/core/port.c > +++ b/drivers/cxl/core/port.c > @@ -1366,8 +1366,24 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd) > { > struct device *dev = &cxlmd->dev; > struct device *iter; > + struct cxl_dport *dport; > + struct cxl_port *port; > int rc; > > + /* > + * Skip intermediate port enumeration in the RCH case, there > + * are no ports in between a host bridge and an endpoint. Only > + * initialize the EP chain. > + */ > + if (is_cxl_restricted(cxlmd)) { > + port = cxl_mem_find_port(cxlmd, &dport); > + if (!port) > + return -ENXIO; > + rc = cxl_add_ep(dport, &cxlmd->dev);
On second look, this seems problematic. While yes it will be deleted when the root CXL port dies, it will not be deleted if the cxl_pci driver is reloaded. I will code up a unit test to double check.
I note that cxl_add_ep() for the VH case is skipped for the root CXL port, so I do not suspect it is needed here either. Did you add it for a specific reason?
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