Jonathan Cameron wrote:
> On Thu, 23 Jun 2022 19:46:13 -0700
> Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
>
> > Previously the target routing specifics of switch decoders were factored
> > out of 'struct cxl_decoder' into 'struct cxl_switch_decoder'.
> >
> > This patch, 2 of 3, adds a 'struct cxl_root_decoder' as a superset of a
> > switch decoder that also track the associated CXL window platform
> > resource.
> >
> > Note that the reason the resource for a given root decoder needs to be
> > looked up after the fact (i.e. after cxl_parse_cfmws() and
> > add_cxl_resource()) is because add_cxl_resource() may have merged CXL
> > windows in order to keep them at the top of the resource tree / decode
> > hierarchy.
>
> One trivial comment below that follows from earlier patch.
>
> Otherwise, I'll look again at this when I understand what the constraints
> of CXL windows are that you are dealing with. I don't get why they might not
> be at the top of the resource tree without the merging!
>
> >
> > Co-developed-by: Ben Widawsky <bwidawsk@xxxxxxxxxx>
> > Signed-off-by: Ben Widawsky <bwidawsk@xxxxxxxxxx>
> > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> > ---
> > drivers/cxl/acpi.c | 40 ++++++++++++++++++++++++++++++++++++----
> > drivers/cxl/core/port.c | 43 +++++++++++++++++++++++++++++++++++++------
> > drivers/cxl/cxl.h | 15 +++++++++++++--
> > 3 files changed, 86 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> > index 003fa4fde357..5972f380cdf2 100644
> > --- a/drivers/cxl/acpi.c
> > +++ b/drivers/cxl/acpi.c
> > @@ -82,7 +82,7 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > int target_map[CXL_DECODER_MAX_INTERLEAVE];
> > struct cxl_cfmws_context *ctx = arg;
> > struct cxl_port *root_port = ctx->root_port;
> > - struct cxl_switch_decoder *cxlsd;
> > + struct cxl_root_decoder *cxlrd;
> > struct device *dev = ctx->dev;
> > struct acpi_cedt_cfmws *cfmws;
> > struct resource *cxl_res;
> > @@ -128,11 +128,11 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > if (rc)
> > goto err_insert;
> >
> > - cxlsd = cxl_root_decoder_alloc(root_port, ways);
> > - if (IS_ERR(cxld))
> > + cxlrd = cxl_root_decoder_alloc(root_port, ways);
> > + if (IS_ERR(cxlrd))
> > return 0;
> >
> > - cxld = &cxlsd->cxld;
> > + cxld = &cxlrd->cxlsd.cxld;
> > cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
> > cxld->target_type = CXL_DECODER_EXPANDER;
> > cxld->hpa_range = (struct range) {
> > @@ -375,6 +375,32 @@ static int add_cxl_resources(struct resource *cxl)
> > return 0;
> > }
> >
> > +static int pair_cxl_resource(struct device *dev, void *data)
> > +{
> > + struct resource *cxl_res = data;
> > + struct resource *p;
> > +
> > + if (!is_root_decoder(dev))
> > + return 0;
> > +
> > + for (p = cxl_res->child; p; p = p->sibling) {
> > + struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);
> > + struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld;
> > + struct resource res = {
> > + .start = cxld->hpa_range.start,
> > + .end = cxld->hpa_range.end,
> > + .flags = IORESOURCE_MEM,
> > + };
> > +
> > + if (resource_contains(p, &res)) {
> > + cxlrd->res = (struct resource *)p->desc;
> > + break;
> > + }
> > + }
> > +
> > + return 0;
> > +}
> > +
> > static int cxl_acpi_probe(struct platform_device *pdev)
> > {
> > int rc;
> > @@ -425,6 +451,12 @@ static int cxl_acpi_probe(struct platform_device *pdev)
> > if (rc)
> > return rc;
> >
> > + /*
> > + * Populate the root decoders with their related iomem resource,
> > + * if present
> > + */
> > + device_for_each_child(&root_port->dev, cxl_res, pair_cxl_resource);
> > +
> > /*
> > * Root level scanned with host-bridge as dports, now scan host-bridges
> > * for their role as CXL uports to their CXL-capable PCIe Root Ports.
> > diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> > index fd1cac13cd2e..abf3455c4eff 100644
> > --- a/drivers/cxl/core/port.c
> > +++ b/drivers/cxl/core/port.c
> > @@ -259,6 +259,23 @@ static void cxl_switch_decoder_release(struct device *dev)
> > kfree(cxlsd);
> > }
> >
> > +struct cxl_root_decoder *to_cxl_root_decoder(struct device *dev)
> > +{
> > + if (dev_WARN_ONCE(dev, !is_root_decoder(dev),
> > + "not a cxl_root_decoder device\n"))
> > + return NULL;
> > + return container_of(dev, struct cxl_root_decoder, cxlsd.cxld.dev);
> > +}
> > +EXPORT_SYMBOL_NS_GPL(to_cxl_root_decoder, CXL);
> > +
> > +static void cxl_root_decoder_release(struct device *dev)
> > +{
> > + struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);
> > +
> > + __cxl_decoder_release(&cxlrd->cxlsd.cxld);
> > + kfree(cxlrd);
> > +}
> > +
> > static const struct device_type cxl_decoder_endpoint_type = {
> > .name = "cxl_decoder_endpoint",
> > .release = cxl_decoder_release,
> > @@ -273,7 +290,7 @@ static const struct device_type cxl_decoder_switch_type = {
> >
> > static const struct device_type cxl_decoder_root_type = {
> > .name = "cxl_decoder_root",
> > - .release = cxl_switch_decoder_release,
> > + .release = cxl_root_decoder_release,
> > .groups = cxl_decoder_root_attribute_groups,
> > };
> >
> > @@ -1218,9 +1235,23 @@ static struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port,
> >
> > if (nr_targets) {
> > struct cxl_switch_decoder *cxlsd;
> > + struct cxl_root_decoder *cxlrd;
> > +
> > + if (is_cxl_root(port)) {
> > + alloc = kzalloc(struct_size(cxlrd, cxlsd.target,
> > + nr_targets),
> > + GFP_KERNEL);
> > + cxlrd = alloc;
> > + if (cxlrd)
> > + cxlsd = &cxlrd->cxlsd;
> > + else
> > + cxlsd = NULL;
> > + } else {
> > + alloc = kzalloc(struct_size(cxlsd, target, nr_targets),
> > + GFP_KERNEL);
> > + cxlsd = alloc;
>
> As earlier, I'd prefer you just handled errors when they happened rather than
> dancing onwards...
Yes, this gets cleaned up with moving the allocation to
cxl_root_decoder_alloc() directly.
>
> > + }
> >
> > - alloc = kzalloc(struct_size(cxlsd, target, nr_targets), GFP_KERNEL);
> > - cxlsd = alloc;
> > if (cxlsd) {
> > cxlsd->nr_targets = nr_targets;
> > seqlock_init(&cxlsd->target_lock);
> > @@ -1279,8 +1310,8 @@ static struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port,
> > * firmware description of CXL resources into a CXL standard decode
> > * topology.
> > */
> > -struct cxl_switch_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
> > - unsigned int nr_targets)
> > +struct cxl_root_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
> > + unsigned int nr_targets)
> > {
> > struct cxl_decoder *cxld;
> >
> > @@ -1290,7 +1321,7 @@ struct cxl_switch_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
> > cxld = cxl_decoder_alloc(port, nr_targets);
> > if (IS_ERR(cxld))
> > return ERR_CAST(cxld);
> > - return to_cxl_switch_decoder(&cxld->dev);
> > + return to_cxl_root_decoder(&cxld->dev);
> > }
> > EXPORT_SYMBOL_NS_GPL(cxl_root_decoder_alloc, CXL);
> >
> > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> > index 7525b55b11bb..6dd1e4c57a67 100644
> > --- a/drivers/cxl/cxl.h
> > +++ b/drivers/cxl/cxl.h
> > @@ -253,6 +253,16 @@ struct cxl_switch_decoder {
> > struct cxl_dport *target[];
> > };
> >
> > +/**
> > + * struct cxl_root_decoder - Static platform CXL address decoder
> > + * @res: host / parent resource for region allocations
> > + * @cxlsd: base cxl switch decoder
> > + */
> > +struct cxl_root_decoder {
> > + struct resource *res;
> > + struct cxl_switch_decoder cxlsd;
>
> Could be nice to those container of macros and just put the cxlsd first.
Not possible. @cxlsd needs to be the last attribute because it has a
variably sized flex-array at its end.
