| Message ID | 20220128002707.391076-9-ben.widawsky@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | CXL Region driver | expand |
On Thu, 27 Jan 2022 16:27:01 -0800 Ben Widawsky <ben.widawsky@intel.com> wrote: > Host bridge root port verification determines if the device ordering in > an interleave set can be programmed through the host bridges and > switches. > > The algorithm implemented here is based on the CXL Type 3 Memory Device > Software Guide, chapter 2.13.15. The current version of the guide does > not yet support x3 interleave configurations, and so that's not > supported here either. > > Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> > +static struct cxl_dport *get_rp(struct cxl_memdev *ep) > +{ > + struct cxl_port *port, *parent_port = port = ep->port; > + struct cxl_dport *dport; > + > + while (!is_cxl_root(port)) { > + parent_port = to_cxl_port(port->dev.parent); > + if (parent_port->depth == 1) > + list_for_each_entry(dport, &parent_port->dports, list) > + if (dport->dport == port->uport->parent->parent) > + return dport; > + port = parent_port; > + } > + > + BUG(); I know you mentioned you were reworking this patch set anyway, but I thought I'd give some quick debugging related feedback. When running against a single switch in qemu (patches out once things are actually working), I hit this BUG() printing dev_name for the port->uport->parent->parent gives pci0000:0c but the matches are sort against 0000:0c:00.0 etc So looks like one too many levels of parent in this case at least. The other bug I haven't chased down yet is that if we happen to have downstream ports of the switch with duplicate ids (far too easy to do in QEMU as port_num is an optional parameter for switch DS ports) it's detected and the probe fails - but then it tries again and we get an infinite loop of new ports being created and failing to probe... I'll get back this one once I have it working with a valid switch config. Jonathan > + return NULL; > +}
On 22-02-14 16:20:37, Jonathan Cameron wrote: > On Thu, 27 Jan 2022 16:27:01 -0800 > Ben Widawsky <ben.widawsky@intel.com> wrote: > > > Host bridge root port verification determines if the device ordering in > > an interleave set can be programmed through the host bridges and > > switches. > > > > The algorithm implemented here is based on the CXL Type 3 Memory Device > > Software Guide, chapter 2.13.15. The current version of the guide does > > not yet support x3 interleave configurations, and so that's not > > supported here either. > > > > Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> > > > > +static struct cxl_dport *get_rp(struct cxl_memdev *ep) > > +{ > > + struct cxl_port *port, *parent_port = port = ep->port; > > + struct cxl_dport *dport; > > + > > + while (!is_cxl_root(port)) { > > + parent_port = to_cxl_port(port->dev.parent); > > + if (parent_port->depth == 1) > > + list_for_each_entry(dport, &parent_port->dports, list) > > + if (dport->dport == port->uport->parent->parent) > > + return dport; > > + port = parent_port; > > + } > > + > > + BUG(); > > I know you mentioned you were reworking this patch set anyway, but > I thought I'd give some quick debugging related feedback. > > When running against a single switch in qemu (patches out once > things are actually working), I hit this BUG() > printing dev_name for the port->uport->parent->parent gives > pci0000:0c but the matches are sort against > 0000:0c:00.0 etc > > So looks like one too many levels of parent in this case at least. Hmm. This definitely looks dubious now that I see it again. Let me try to figure out how to rework it. I think it would be good to ask Dan as well. Much of the topology relationship works from bottom up, but top down is less easy. Previously I had used pci-isms to do this but Dan has been working on keeping the two domains isolated, which I agree is a good idea. > > The other bug I haven't chased down yet is that if we happen > to have downstream ports of the switch with duplicate ids > (far too easy to do in QEMU as port_num is an optional > parameter for switch DS ports) it's detected and the probe fails > - but then it tries again and we get an infinite loop of new > ports being created and failing to probe... Is this allowed by spec? We shouldn't infinite loop, but I can't imagine the driver could do anything saner than fail to probe for such a case. > I'll get back this one once I have it working with > a valid switch config. Thanks. > > Jonathan > > > + return NULL; > > +}
On Mon, 14 Feb 2022 09:51:55 -0800 Ben Widawsky <ben.widawsky@intel.com> wrote: > On 22-02-14 16:20:37, Jonathan Cameron wrote: > > On Thu, 27 Jan 2022 16:27:01 -0800 > > Ben Widawsky <ben.widawsky@intel.com> wrote: > > > > > Host bridge root port verification determines if the device ordering in > > > an interleave set can be programmed through the host bridges and > > > switches. > > > > > > The algorithm implemented here is based on the CXL Type 3 Memory Device > > > Software Guide, chapter 2.13.15. The current version of the guide does > > > not yet support x3 interleave configurations, and so that's not > > > supported here either. > > > > > > Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> > > > > > > > +static struct cxl_dport *get_rp(struct cxl_memdev *ep) > > > +{ > > > + struct cxl_port *port, *parent_port = port = ep->port; > > > + struct cxl_dport *dport; > > > + > > > + while (!is_cxl_root(port)) { > > > + parent_port = to_cxl_port(port->dev.parent); > > > + if (parent_port->depth == 1) > > > + list_for_each_entry(dport, &parent_port->dports, list) > > > + if (dport->dport == port->uport->parent->parent) > > > + return dport; > > > + port = parent_port; > > > + } > > > + > > > + BUG(); > > > > I know you mentioned you were reworking this patch set anyway, but > > I thought I'd give some quick debugging related feedback. > > > > When running against a single switch in qemu (patches out once > > things are actually working), I hit this BUG() > > printing dev_name for the port->uport->parent->parent gives > > pci0000:0c but the matches are sort against > > 0000:0c:00.0 etc > > > > So looks like one too many levels of parent in this case at least. > > Hmm. This definitely looks dubious now that I see it again. Let me try to figure > out how to rework it. I think it would be good to ask Dan as well. Much of the > topology relationship works from bottom up, but top down is less easy. > Previously I had used pci-isms to do this but Dan has been working on keeping > the two domains isolated, which I agree is a good idea. > > > > > The other bug I haven't chased down yet is that if we happen > > to have downstream ports of the switch with duplicate ids > > (far too easy to do in QEMU as port_num is an optional > > parameter for switch DS ports) it's detected and the probe fails > > - but then it tries again and we get an infinite loop of new > > ports being created and failing to probe... > > Is this allowed by spec? We shouldn't infinite loop, but I can't imagine the > driver could do anything saner than fail to probe for such a case. It would be a hardware bug, however I suspect any failure to probe will cause it rather that this specific case. I'll inject another failure when I get back to this properly. Jonathan > > > I'll get back this one once I have it working with > > a valid switch config. > > Thanks. > > > > > Jonathan > > > > > + return NULL; > > > +}
On Thu, 27 Jan 2022 16:27:01 -0800 Ben Widawsky <ben.widawsky@intel.com> wrote: > Host bridge root port verification determines if the device ordering in > an interleave set can be programmed through the host bridges and > switches. > > The algorithm implemented here is based on the CXL Type 3 Memory Device > Software Guide, chapter 2.13.15. The current version of the guide does > not yet support x3 interleave configurations, and so that's not > supported here either. > > Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> > --- > .clang-format | 1 + > drivers/cxl/core/port.c | 1 + > drivers/cxl/cxl.h | 2 + > drivers/cxl/region.c | 127 +++++++++++++++++++++++++++++++++++++++- > 4 files changed, 130 insertions(+), 1 deletion(-) > > diff --git a/.clang-format b/.clang-format > index 1221d53be90b..5e20206f905e 100644 > --- a/.clang-format > +++ b/.clang-format > @@ -171,6 +171,7 @@ ForEachMacros: > - 'for_each_cpu_wrap' > - 'for_each_cxl_decoder_target' > - 'for_each_cxl_endpoint' > + - 'for_each_cxl_endpoint_hb' > - 'for_each_dapm_widgets' > - 'for_each_dev_addr' > - 'for_each_dev_scope' > diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c > index 0847e6ce19ef..1d81c5f56a3e 100644 > --- a/drivers/cxl/core/port.c > +++ b/drivers/cxl/core/port.c > @@ -706,6 +706,7 @@ struct cxl_dport *devm_cxl_add_dport(struct cxl_port *port, > return ERR_PTR(-ENOMEM); > > INIT_LIST_HEAD(&dport->list); > + INIT_LIST_HEAD(&dport->verify_link); > dport->dport = dport_dev; > dport->port_id = port_id; > dport->component_reg_phys = component_reg_phys; > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h > index a291999431c7..ed984465b59c 100644 > --- a/drivers/cxl/cxl.h > +++ b/drivers/cxl/cxl.h > @@ -350,6 +350,7 @@ struct cxl_port { > * @component_reg_phys: downstream port component registers > * @port: reference to cxl_port that contains this downstream port > * @list: node for a cxl_port's list of cxl_dport instances > + * @verify_link: node used for hb root port verification > */ > struct cxl_dport { > struct device *dport; > @@ -357,6 +358,7 @@ struct cxl_dport { > resource_size_t component_reg_phys; > struct cxl_port *port; > struct list_head list; > + struct list_head verify_link; > }; > > /** > diff --git a/drivers/cxl/region.c b/drivers/cxl/region.c > index 562c8720da56..d2f6c990c8a8 100644 > --- a/drivers/cxl/region.c > +++ b/drivers/cxl/region.c > @@ -4,6 +4,7 @@ > #include <linux/genalloc.h> > #include <linux/device.h> > #include <linux/module.h> > +#include <linux/sort.h> > #include <linux/pci.h> > #include "cxlmem.h" > #include "region.h" > @@ -36,6 +37,12 @@ > for (idx = 0, ep = (region)->config.targets[idx]; \ > idx < region_ways(region); ep = (region)->config.targets[++idx]) > > +#define for_each_cxl_endpoint_hb(ep, region, hb, idx) \ > + for (idx = 0, (ep) = (region)->config.targets[idx]; \ > + idx < region_ways(region); \ > + idx++, (ep) = (region)->config.targets[idx]) \ > + if (get_hostbridge(ep) == (hb)) > + > #define for_each_cxl_decoder_target(dport, decoder, idx) \ > for (idx = 0, dport = (decoder)->target[idx]; \ > idx < (decoder)->nr_targets - 1; \ > @@ -299,6 +306,59 @@ static bool region_xhb_config_valid(const struct cxl_region *cxlr, > return true; > } > > +static struct cxl_dport *get_rp(struct cxl_memdev *ep) > +{ > + struct cxl_port *port, *parent_port = port = ep->port; > + struct cxl_dport *dport; > + > + while (!is_cxl_root(port)) { > + parent_port = to_cxl_port(port->dev.parent); > + if (parent_port->depth == 1) > + list_for_each_entry(dport, &parent_port->dports, list) > + if (dport->dport == port->uport->parent->parent) > + return dport; > + port = parent_port; > + } > + > + BUG(); > + return NULL; > +} > + > +static int get_num_root_ports(const struct cxl_region *cxlr) > +{ > + struct cxl_memdev *endpoint; > + struct cxl_dport *dport, *tmp; > + int num_root_ports = 0; > + LIST_HEAD(root_ports); > + int idx; > + > + for_each_cxl_endpoint(endpoint, cxlr, idx) { > + struct cxl_dport *root_port = get_rp(endpoint); > + > + if (list_empty(&root_port->verify_link)) { > + list_add_tail(&root_port->verify_link, &root_ports); > + num_root_ports++; > + } > + } > + > + list_for_each_entry_safe(dport, tmp, &root_ports, verify_link) > + list_del_init(&dport->verify_link); > + > + return num_root_ports; > +} > + > +static bool has_switch(const struct cxl_region *cxlr) > +{ > + struct cxl_memdev *ep; > + int i; > + > + for_each_cxl_endpoint(ep, cxlr, i) > + if (ep->port->depth > 2) > + return true; > + > + return false; > +} > + > /** > * region_hb_rp_config_valid() - determine root port ordering is correct > * @cxlr: Region to validate > @@ -312,7 +372,72 @@ static bool region_xhb_config_valid(const struct cxl_region *cxlr, > static bool region_hb_rp_config_valid(const struct cxl_region *cxlr, > const struct cxl_decoder *rootd) > { > - /* TODO: */ > + const int num_root_ports = get_num_root_ports(cxlr); > + struct cxl_port *hbs[CXL_DECODER_MAX_INTERLEAVE]; > + int hb_count, i; > + > + hb_count = get_unique_hostbridges(cxlr, hbs); > + > + /* TODO: Switch support */ > + if (has_switch(cxlr)) > + return false; > + > + /* > + * Are all devices in this region on the same CXL Host Bridge > + * Root Port? > + */ > + if (num_root_ports == 1 && !has_switch(cxlr)) > + return true; > + > + for (i = 0; i < hb_count; i++) { > + int idx, position_mask; > + struct cxl_dport *rp; > + struct cxl_port *hb; > + > + /* Get next CXL Host Bridge this region spans */ > + hb = hbs[i]; > + > + /* > + * Calculate the position mask: NumRootPorts = 2^PositionMask > + * for this region. > + * > + * XXX: pos_mask is actually (1 << PositionMask) - 1 > + */ > + position_mask = (1 << (ilog2(num_root_ports))) - 1; Needs to account for the root ports potentially being spread over multiple host bridges. For now I'm assuming some symmetry to move my own testing forwards but that's not strictly required if we want to be really flexible. So I've been using position_mask = (1 << (ilog2(num_root_ports/hb_count)) - 1; > + > + /* > + * Calculate the PortGrouping for each device on this CXL Host > + * Bridge Root Port: > + * PortGrouping = RegionLabel.Position & PositionMask > + * > + * The following nest iterators effectively iterate over each > + * root port in the region. > + * for_each_unique_rootport(rp, cxlr) > + */ > + list_for_each_entry(rp, &hb->dports, list) { > + struct cxl_memdev *ep; > + int port_grouping = -1; > + > + for_each_cxl_endpoint_hb(ep, cxlr, hb, idx) { > + if (get_rp(ep) != rp) > + continue; > + > + if (port_grouping == -1) > + port_grouping = idx & position_mask; > + > + /* > + * Do all devices in the region connected to this CXL > + * Host Bridge Root Port have the same PortGrouping? > + */ > + if ((idx & position_mask) != port_grouping) { > + dev_dbg(&cxlr->dev, > + "One or more devices are not connected to the correct Host Bridge Root Port\n"); > + return false; > + } > + } > + } > + } > + > return true; > } >
On Thu, Jan 27, 2022 at 4:27 PM Ben Widawsky <ben.widawsky@intel.com> wrote: > > Host bridge root port verification determines if the device ordering in > an interleave set can be programmed through the host bridges and > switches. > > The algorithm implemented here is based on the CXL Type 3 Memory Device > Software Guide, chapter 2.13.15. The current version of the guide does > not yet support x3 interleave configurations, and so that's not > supported here either. Given x3 is in a released ECN lets go ahead and include it because it may have a material effect on the design, but more importantly the ABI. > > Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> > --- > .clang-format | 1 + > drivers/cxl/core/port.c | 1 + > drivers/cxl/cxl.h | 2 + > drivers/cxl/region.c | 127 +++++++++++++++++++++++++++++++++++++++- > 4 files changed, 130 insertions(+), 1 deletion(-) > > diff --git a/.clang-format b/.clang-format > index 1221d53be90b..5e20206f905e 100644 > --- a/.clang-format > +++ b/.clang-format > @@ -171,6 +171,7 @@ ForEachMacros: > - 'for_each_cpu_wrap' > - 'for_each_cxl_decoder_target' > - 'for_each_cxl_endpoint' > + - 'for_each_cxl_endpoint_hb' > - 'for_each_dapm_widgets' > - 'for_each_dev_addr' > - 'for_each_dev_scope' > diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c > index 0847e6ce19ef..1d81c5f56a3e 100644 > --- a/drivers/cxl/core/port.c > +++ b/drivers/cxl/core/port.c > @@ -706,6 +706,7 @@ struct cxl_dport *devm_cxl_add_dport(struct cxl_port *port, > return ERR_PTR(-ENOMEM); > > INIT_LIST_HEAD(&dport->list); > + INIT_LIST_HEAD(&dport->verify_link); > dport->dport = dport_dev; > dport->port_id = port_id; > dport->component_reg_phys = component_reg_phys; > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h > index a291999431c7..ed984465b59c 100644 > --- a/drivers/cxl/cxl.h > +++ b/drivers/cxl/cxl.h > @@ -350,6 +350,7 @@ struct cxl_port { > * @component_reg_phys: downstream port component registers > * @port: reference to cxl_port that contains this downstream port > * @list: node for a cxl_port's list of cxl_dport instances > + * @verify_link: node used for hb root port verification > */ > struct cxl_dport { > struct device *dport; > @@ -357,6 +358,7 @@ struct cxl_dport { > resource_size_t component_reg_phys; > struct cxl_port *port; > struct list_head list; > + struct list_head verify_link; Is this list also protected by the port device_lock? > }; > > /** > diff --git a/drivers/cxl/region.c b/drivers/cxl/region.c > index 562c8720da56..d2f6c990c8a8 100644 > --- a/drivers/cxl/region.c > +++ b/drivers/cxl/region.c > @@ -4,6 +4,7 @@ > #include <linux/genalloc.h> > #include <linux/device.h> > #include <linux/module.h> > +#include <linux/sort.h> > #include <linux/pci.h> > #include "cxlmem.h" > #include "region.h" > @@ -36,6 +37,12 @@ > for (idx = 0, ep = (region)->config.targets[idx]; \ > idx < region_ways(region); ep = (region)->config.targets[++idx]) > > +#define for_each_cxl_endpoint_hb(ep, region, hb, idx) \ > + for (idx = 0, (ep) = (region)->config.targets[idx]; \ > + idx < region_ways(region); \ > + idx++, (ep) = (region)->config.targets[idx]) \ > + if (get_hostbridge(ep) == (hb)) > + > #define for_each_cxl_decoder_target(dport, decoder, idx) \ > for (idx = 0, dport = (decoder)->target[idx]; \ > idx < (decoder)->nr_targets - 1; \ > @@ -299,6 +306,59 @@ static bool region_xhb_config_valid(const struct cxl_region *cxlr, > return true; > } > > +static struct cxl_dport *get_rp(struct cxl_memdev *ep) > +{ > + struct cxl_port *port, *parent_port = port = ep->port; > + struct cxl_dport *dport; > + > + while (!is_cxl_root(port)) { > + parent_port = to_cxl_port(port->dev.parent); > + if (parent_port->depth == 1) > + list_for_each_entry(dport, &parent_port->dports, list) Locking? > + if (dport->dport == port->uport->parent->parent) This assumes no switches. Effectively it is identical to what devm_cxl_enumerate_ports(), which does support switches, is doing. To reduce maintenance burden it could follow the same pattern of: for (iter = dev; iter; iter = grandparent(iter)) ... if (dev_is_cxl_root_child(&port->dev)) ... > + return dport; > + port = parent_port; > + } > + > + BUG(); more kernel crashing... why? > + return NULL; > +} > + > +static int get_num_root_ports(const struct cxl_region *cxlr) > +{ > + struct cxl_memdev *endpoint; > + struct cxl_dport *dport, *tmp; > + int num_root_ports = 0; > + LIST_HEAD(root_ports); > + int idx; > + > + for_each_cxl_endpoint(endpoint, cxlr, idx) { > + struct cxl_dport *root_port = get_rp(endpoint); > + > + if (list_empty(&root_port->verify_link)) { > + list_add_tail(&root_port->verify_link, &root_ports); Doesn't this run into problems when there are multiple regions per root port? > + num_root_ports++; > + } > + } > + > + list_for_each_entry_safe(dport, tmp, &root_ports, verify_link) > + list_del_init(&dport->verify_link); > + > + return num_root_ports; > +} > + > +static bool has_switch(const struct cxl_region *cxlr) > +{ > + struct cxl_memdev *ep; > + int i; > + > + for_each_cxl_endpoint(ep, cxlr, i) > + if (ep->port->depth > 2) > + return true; > + > + return false; > +} > + > /** > * region_hb_rp_config_valid() - determine root port ordering is correct > * @cxlr: Region to validate > @@ -312,7 +372,72 @@ static bool region_xhb_config_valid(const struct cxl_region *cxlr, > static bool region_hb_rp_config_valid(const struct cxl_region *cxlr, > const struct cxl_decoder *rootd) > { > - /* TODO: */ > + const int num_root_ports = get_num_root_ports(cxlr); > + struct cxl_port *hbs[CXL_DECODER_MAX_INTERLEAVE]; In terms of stack usage, doesn't the caller also have one of these on the stack when this is called? > + int hb_count, i; > + > + hb_count = get_unique_hostbridges(cxlr, hbs); > + > + /* TODO: Switch support */ > + if (has_switch(cxlr)) > + return false; > + > + /* > + * Are all devices in this region on the same CXL Host Bridge > + * Root Port? > + */ > + if (num_root_ports == 1 && !has_switch(cxlr)) > + return true; How can this happen without any intervening switch? > + > + for (i = 0; i < hb_count; i++) { > + int idx, position_mask; > + struct cxl_dport *rp; > + struct cxl_port *hb; > + > + /* Get next CXL Host Bridge this region spans */ > + hb = hbs[i]; > + > + /* > + * Calculate the position mask: NumRootPorts = 2^PositionMask > + * for this region. > + * > + * XXX: pos_mask is actually (1 << PositionMask) - 1 > + */ > + position_mask = (1 << (ilog2(num_root_ports))) - 1; Isn't "1 << ilog2(num_root_ports)" just "num_root_ports"? > + > + /* > + * Calculate the PortGrouping for each device on this CXL Host > + * Bridge Root Port: > + * PortGrouping = RegionLabel.Position & PositionMask Still confused what a port grouping is and what it means for the algorithm especially since RegionLabels are not relevant to this part of the algorithm. This assumes someone is familiar with "guide" terminology? > + * > + * The following nest iterators effectively iterate over each > + * root port in the region. > + * for_each_unique_rootport(rp, cxlr) > + */ > + list_for_each_entry(rp, &hb->dports, list) { > + struct cxl_memdev *ep; > + int port_grouping = -1; > + > + for_each_cxl_endpoint_hb(ep, cxlr, hb, idx) { > + if (get_rp(ep) != rp) > + continue; > + > + if (port_grouping == -1) > + port_grouping = idx & position_mask; > + > + /* > + * Do all devices in the region connected to this CXL > + * Host Bridge Root Port have the same PortGrouping? > + */ > + if ((idx & position_mask) != port_grouping) { > + dev_dbg(&cxlr->dev, > + "One or more devices are not connected to the correct Host Bridge Root Port\n"); > + return false; > + } > + } > + } > + } > + > return true; > } > > -- > 2.35.0 >
diff --git a/.clang-format b/.clang-format index 1221d53be90b..5e20206f905e 100644 --- a/.clang-format +++ b/.clang-format @@ -171,6 +171,7 @@ ForEachMacros: - 'for_each_cpu_wrap' - 'for_each_cxl_decoder_target' - 'for_each_cxl_endpoint' + - 'for_each_cxl_endpoint_hb' - 'for_each_dapm_widgets' - 'for_each_dev_addr' - 'for_each_dev_scope' diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index 0847e6ce19ef..1d81c5f56a3e 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -706,6 +706,7 @@ struct cxl_dport *devm_cxl_add_dport(struct cxl_port *port, return ERR_PTR(-ENOMEM); INIT_LIST_HEAD(&dport->list); + INIT_LIST_HEAD(&dport->verify_link); dport->dport = dport_dev; dport->port_id = port_id; dport->component_reg_phys = component_reg_phys; diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index a291999431c7..ed984465b59c 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -350,6 +350,7 @@ struct cxl_port { * @component_reg_phys: downstream port component registers * @port: reference to cxl_port that contains this downstream port * @list: node for a cxl_port's list of cxl_dport instances + * @verify_link: node used for hb root port verification */ struct cxl_dport { struct device *dport; @@ -357,6 +358,7 @@ struct cxl_dport { resource_size_t component_reg_phys; struct cxl_port *port; struct list_head list; + struct list_head verify_link; }; /** diff --git a/drivers/cxl/region.c b/drivers/cxl/region.c index 562c8720da56..d2f6c990c8a8 100644 --- a/drivers/cxl/region.c +++ b/drivers/cxl/region.c @@ -4,6 +4,7 @@ #include <linux/genalloc.h> #include <linux/device.h> #include <linux/module.h> +#include <linux/sort.h> #include <linux/pci.h> #include "cxlmem.h" #include "region.h" @@ -36,6 +37,12 @@ for (idx = 0, ep = (region)->config.targets[idx]; \ idx < region_ways(region); ep = (region)->config.targets[++idx]) +#define for_each_cxl_endpoint_hb(ep, region, hb, idx) \ + for (idx = 0, (ep) = (region)->config.targets[idx]; \ + idx < region_ways(region); \ + idx++, (ep) = (region)->config.targets[idx]) \ + if (get_hostbridge(ep) == (hb)) + #define for_each_cxl_decoder_target(dport, decoder, idx) \ for (idx = 0, dport = (decoder)->target[idx]; \ idx < (decoder)->nr_targets - 1; \ @@ -299,6 +306,59 @@ static bool region_xhb_config_valid(const struct cxl_region *cxlr, return true; } +static struct cxl_dport *get_rp(struct cxl_memdev *ep) +{ + struct cxl_port *port, *parent_port = port = ep->port; + struct cxl_dport *dport; + + while (!is_cxl_root(port)) { + parent_port = to_cxl_port(port->dev.parent); + if (parent_port->depth == 1) + list_for_each_entry(dport, &parent_port->dports, list) + if (dport->dport == port->uport->parent->parent) + return dport; + port = parent_port; + } + + BUG(); + return NULL; +} + +static int get_num_root_ports(const struct cxl_region *cxlr) +{ + struct cxl_memdev *endpoint; + struct cxl_dport *dport, *tmp; + int num_root_ports = 0; + LIST_HEAD(root_ports); + int idx; + + for_each_cxl_endpoint(endpoint, cxlr, idx) { + struct cxl_dport *root_port = get_rp(endpoint); + + if (list_empty(&root_port->verify_link)) { + list_add_tail(&root_port->verify_link, &root_ports); + num_root_ports++; + } + } + + list_for_each_entry_safe(dport, tmp, &root_ports, verify_link) + list_del_init(&dport->verify_link); + + return num_root_ports; +} + +static bool has_switch(const struct cxl_region *cxlr) +{ + struct cxl_memdev *ep; + int i; + + for_each_cxl_endpoint(ep, cxlr, i) + if (ep->port->depth > 2) + return true; + + return false; +} + /** * region_hb_rp_config_valid() - determine root port ordering is correct * @cxlr: Region to validate @@ -312,7 +372,72 @@ static bool region_xhb_config_valid(const struct cxl_region *cxlr, static bool region_hb_rp_config_valid(const struct cxl_region *cxlr, const struct cxl_decoder *rootd) { - /* TODO: */ + const int num_root_ports = get_num_root_ports(cxlr); + struct cxl_port *hbs[CXL_DECODER_MAX_INTERLEAVE]; + int hb_count, i; + + hb_count = get_unique_hostbridges(cxlr, hbs); + + /* TODO: Switch support */ + if (has_switch(cxlr)) + return false; + + /* + * Are all devices in this region on the same CXL Host Bridge + * Root Port? + */ + if (num_root_ports == 1 && !has_switch(cxlr)) + return true; + + for (i = 0; i < hb_count; i++) { + int idx, position_mask; + struct cxl_dport *rp; + struct cxl_port *hb; + + /* Get next CXL Host Bridge this region spans */ + hb = hbs[i]; + + /* + * Calculate the position mask: NumRootPorts = 2^PositionMask + * for this region. + * + * XXX: pos_mask is actually (1 << PositionMask) - 1 + */ + position_mask = (1 << (ilog2(num_root_ports))) - 1; + + /* + * Calculate the PortGrouping for each device on this CXL Host + * Bridge Root Port: + * PortGrouping = RegionLabel.Position & PositionMask + * + * The following nest iterators effectively iterate over each + * root port in the region. + * for_each_unique_rootport(rp, cxlr) + */ + list_for_each_entry(rp, &hb->dports, list) { + struct cxl_memdev *ep; + int port_grouping = -1; + + for_each_cxl_endpoint_hb(ep, cxlr, hb, idx) { + if (get_rp(ep) != rp) + continue; + + if (port_grouping == -1) + port_grouping = idx & position_mask; + + /* + * Do all devices in the region connected to this CXL + * Host Bridge Root Port have the same PortGrouping? + */ + if ((idx & position_mask) != port_grouping) { + dev_dbg(&cxlr->dev, + "One or more devices are not connected to the correct Host Bridge Root Port\n"); + return false; + } + } + } + } + return true; }
Host bridge root port verification determines if the device ordering in an interleave set can be programmed through the host bridges and switches. The algorithm implemented here is based on the CXL Type 3 Memory Device Software Guide, chapter 2.13.15. The current version of the guide does not yet support x3 interleave configurations, and so that's not supported here either. Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> --- .clang-format | 1 + drivers/cxl/core/port.c | 1 + drivers/cxl/cxl.h | 2 + drivers/cxl/region.c | 127 +++++++++++++++++++++++++++++++++++++++- 4 files changed, 130 insertions(+), 1 deletion(-)