| Message ID | 20240907081836.5801-12-alejandro.lucero-palau@amd.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | cxl: add Type2 device support | expand |
On Sat, 7 Sep 2024 09:18:27 +0100 alejandro.lucero-palau@amd.com wrote: > From: Alejandro Lucero <alucerop@amd.com> > > CXL region creation involves allocating capacity from device DPA > (device-physical-address space) and assigning it to decode a given HPA > (host-physical-address space). Before determining how much DPA to > allocate the amount of available HPA must be determined. Also, not all > HPA is create equal, some specifically targets RAM, some target PMEM, > some is prepared for device-memory flows like HDM-D and HDM-DB, and some > is host-only (HDM-H). > > Wrap all of those concerns into an API that retrieves a root decoder > (platform CXL window) that fits the specified constraints and the > capacity available for a new region. > > Based on https://lore.kernel.org/linux-cxl/168592159290.1948938.13522227102445462976.stgit@dwillia2-xfh.jf.intel.com/ > > Signed-off-by: Alejandro Lucero <alucerop@amd.com> > Co-developed-by: Dan Williams <dan.j.williams@intel.com> Trivial comment inline. J > --- > drivers/cxl/core/region.c | 141 ++++++++++++++++++++++++++++++++++++++ > drivers/cxl/cxl.h | 3 + > drivers/cxl/cxlmem.h | 3 + > include/linux/cxl/cxl.h | 8 +++ > 4 files changed, 155 insertions(+) > > diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c > index 21ad5f242875..bb227bf894c4 100644 > --- a/drivers/cxl/core/region.c > +++ b/drivers/cxl/core/region.c > @@ -703,6 +703,147 @@ static int free_hpa(struct cxl_region *cxlr) > return 0; > } > > +struct cxlrd_max_context { > + struct device *host_bridge; > + unsigned long flags; > + resource_size_t max_hpa; > + struct cxl_root_decoder *cxlrd; > +}; > + > +static int find_max_hpa(struct device *dev, void *data) > +{ > + struct cxlrd_max_context *ctx = data; > + struct cxl_switch_decoder *cxlsd; > + struct cxl_root_decoder *cxlrd; > + struct resource *res, *prev; > + struct cxl_decoder *cxld; > + resource_size_t max; > + > + if (!is_root_decoder(dev)) > + return 0; > + > + cxlrd = to_cxl_root_decoder(dev); > + cxld = &cxlrd->cxlsd.cxld; > + if ((cxld->flags & ctx->flags) != ctx->flags) { > + dev_dbg(dev, "%s, flags not matching: %08lx vs %08lx\n", > + __func__, cxld->flags, ctx->flags); > + return 0; > + } > + > + /* An accelerator can not be part of an interleaved HPA range. */ > + if (cxld->interleave_ways != 1) { > + dev_dbg(dev, "%s, interleave_ways not matching\n", __func__); > + return 0; > + } > + > + cxlsd = &cxlrd->cxlsd; Perhaps move this before the cxld = and use it there as well? > + > + guard(rwsem_read)(&cxl_region_rwsem); > + if (ctx->host_bridge != cxlsd->target[0]->dport_dev) { > + dev_dbg(dev, "%s, HOST BRIDGE DOES NOT MATCH\n", __func__); Capitals seem a bit ott. > + return 0; > + } > + > + /* > + * Walk the root decoder resource range relying on cxl_region_rwsem to > + * preclude sibling arrival/departure and find the largest free space > + * gap. > + */ > + lockdep_assert_held_read(&cxl_region_rwsem); > + max = 0; > + res = cxlrd->res->child; > + if (!res) > + max = resource_size(cxlrd->res); > + else > + max = 0; > + > + for (prev = NULL; res; prev = res, res = res->sibling) { > + struct resource *next = res->sibling; > + resource_size_t free = 0; > + > + if (!prev && res->start > cxlrd->res->start) { > + free = res->start - cxlrd->res->start; > + max = max(free, max); > + } > + if (prev && res->start > prev->end + 1) { > + free = res->start - prev->end + 1; > + max = max(free, max); > + } > + if (next && res->end + 1 < next->start) { > + free = next->start - res->end + 1; > + max = max(free, max); > + } > + if (!next && res->end + 1 < cxlrd->res->end + 1) { > + free = cxlrd->res->end + 1 - res->end + 1; > + max = max(free, max); > + } > + } > + > + dev_dbg(CXLRD_DEV(cxlrd), "%s, found %pa bytes of free space\n", > + __func__, &max); > + if (max > ctx->max_hpa) { > + if (ctx->cxlrd) > + put_device(CXLRD_DEV(ctx->cxlrd)); > + get_device(CXLRD_DEV(cxlrd)); > + ctx->cxlrd = cxlrd; > + ctx->max_hpa = max; > + dev_dbg(CXLRD_DEV(cxlrd), "%s, found %pa bytes of free space\n", > + __func__, &max); > + } > + return 0; > +}
On 9/13/24 18:52, Jonathan Cameron wrote: > On Sat, 7 Sep 2024 09:18:27 +0100 > alejandro.lucero-palau@amd.com wrote: > >> From: Alejandro Lucero <alucerop@amd.com> >> >> CXL region creation involves allocating capacity from device DPA >> (device-physical-address space) and assigning it to decode a given HPA >> (host-physical-address space). Before determining how much DPA to >> allocate the amount of available HPA must be determined. Also, not all >> HPA is create equal, some specifically targets RAM, some target PMEM, >> some is prepared for device-memory flows like HDM-D and HDM-DB, and some >> is host-only (HDM-H). >> >> Wrap all of those concerns into an API that retrieves a root decoder >> (platform CXL window) that fits the specified constraints and the >> capacity available for a new region. >> >> Based on https://lore.kernel.org/linux-cxl/168592159290.1948938.13522227102445462976.stgit@dwillia2-xfh.jf.intel.com/ >> >> Signed-off-by: Alejandro Lucero <alucerop@amd.com> >> Co-developed-by: Dan Williams <dan.j.williams@intel.com> > Trivial comment inline. > > J >> --- >> drivers/cxl/core/region.c | 141 ++++++++++++++++++++++++++++++++++++++ >> drivers/cxl/cxl.h | 3 + >> drivers/cxl/cxlmem.h | 3 + >> include/linux/cxl/cxl.h | 8 +++ >> 4 files changed, 155 insertions(+) >> >> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c >> index 21ad5f242875..bb227bf894c4 100644 >> --- a/drivers/cxl/core/region.c >> +++ b/drivers/cxl/core/region.c >> @@ -703,6 +703,147 @@ static int free_hpa(struct cxl_region *cxlr) >> return 0; >> } >> >> +struct cxlrd_max_context { >> + struct device *host_bridge; >> + unsigned long flags; >> + resource_size_t max_hpa; >> + struct cxl_root_decoder *cxlrd; >> +}; >> + >> +static int find_max_hpa(struct device *dev, void *data) >> +{ >> + struct cxlrd_max_context *ctx = data; >> + struct cxl_switch_decoder *cxlsd; >> + struct cxl_root_decoder *cxlrd; >> + struct resource *res, *prev; >> + struct cxl_decoder *cxld; >> + resource_size_t max; >> + >> + if (!is_root_decoder(dev)) >> + return 0; >> + >> + cxlrd = to_cxl_root_decoder(dev); >> + cxld = &cxlrd->cxlsd.cxld; >> + if ((cxld->flags & ctx->flags) != ctx->flags) { >> + dev_dbg(dev, "%s, flags not matching: %08lx vs %08lx\n", >> + __func__, cxld->flags, ctx->flags); >> + return 0; >> + } >> + >> + /* An accelerator can not be part of an interleaved HPA range. */ >> + if (cxld->interleave_ways != 1) { >> + dev_dbg(dev, "%s, interleave_ways not matching\n", __func__); >> + return 0; >> + } >> + >> + cxlsd = &cxlrd->cxlsd; > Perhaps move this before the > cxld = and use it there as well? > Yes, I'll do. >> + >> + guard(rwsem_read)(&cxl_region_rwsem); >> + if (ctx->host_bridge != cxlsd->target[0]->dport_dev) { >> + dev_dbg(dev, "%s, HOST BRIDGE DOES NOT MATCH\n", __func__); > Capitals seem a bit ott. I agree! Thanks >> + return 0; >> + } >> + >> + /* >> + * Walk the root decoder resource range relying on cxl_region_rwsem to >> + * preclude sibling arrival/departure and find the largest free space >> + * gap. >> + */ >> + lockdep_assert_held_read(&cxl_region_rwsem); >> + max = 0; >> + res = cxlrd->res->child; >> + if (!res) >> + max = resource_size(cxlrd->res); >> + else >> + max = 0; >> + >> + for (prev = NULL; res; prev = res, res = res->sibling) { >> + struct resource *next = res->sibling; >> + resource_size_t free = 0; >> + >> + if (!prev && res->start > cxlrd->res->start) { >> + free = res->start - cxlrd->res->start; >> + max = max(free, max); >> + } >> + if (prev && res->start > prev->end + 1) { >> + free = res->start - prev->end + 1; >> + max = max(free, max); >> + } >> + if (next && res->end + 1 < next->start) { >> + free = next->start - res->end + 1; >> + max = max(free, max); >> + } >> + if (!next && res->end + 1 < cxlrd->res->end + 1) { >> + free = cxlrd->res->end + 1 - res->end + 1; >> + max = max(free, max); >> + } >> + } >> + >> + dev_dbg(CXLRD_DEV(cxlrd), "%s, found %pa bytes of free space\n", >> + __func__, &max); >> + if (max > ctx->max_hpa) { >> + if (ctx->cxlrd) >> + put_device(CXLRD_DEV(ctx->cxlrd)); >> + get_device(CXLRD_DEV(cxlrd)); >> + ctx->cxlrd = cxlrd; >> + ctx->max_hpa = max; >> + dev_dbg(CXLRD_DEV(cxlrd), "%s, found %pa bytes of free space\n", >> + __func__, &max); >> + } >> + return 0; >> +}
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index 21ad5f242875..bb227bf894c4 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -703,6 +703,147 @@ static int free_hpa(struct cxl_region *cxlr) return 0; } +struct cxlrd_max_context { + struct device *host_bridge; + unsigned long flags; + resource_size_t max_hpa; + struct cxl_root_decoder *cxlrd; +}; + +static int find_max_hpa(struct device *dev, void *data) +{ + struct cxlrd_max_context *ctx = data; + struct cxl_switch_decoder *cxlsd; + struct cxl_root_decoder *cxlrd; + struct resource *res, *prev; + struct cxl_decoder *cxld; + resource_size_t max; + + if (!is_root_decoder(dev)) + return 0; + + cxlrd = to_cxl_root_decoder(dev); + cxld = &cxlrd->cxlsd.cxld; + if ((cxld->flags & ctx->flags) != ctx->flags) { + dev_dbg(dev, "%s, flags not matching: %08lx vs %08lx\n", + __func__, cxld->flags, ctx->flags); + return 0; + } + + /* An accelerator can not be part of an interleaved HPA range. */ + if (cxld->interleave_ways != 1) { + dev_dbg(dev, "%s, interleave_ways not matching\n", __func__); + return 0; + } + + cxlsd = &cxlrd->cxlsd; + + guard(rwsem_read)(&cxl_region_rwsem); + if (ctx->host_bridge != cxlsd->target[0]->dport_dev) { + dev_dbg(dev, "%s, HOST BRIDGE DOES NOT MATCH\n", __func__); + return 0; + } + + /* + * Walk the root decoder resource range relying on cxl_region_rwsem to + * preclude sibling arrival/departure and find the largest free space + * gap. + */ + lockdep_assert_held_read(&cxl_region_rwsem); + max = 0; + res = cxlrd->res->child; + if (!res) + max = resource_size(cxlrd->res); + else + max = 0; + + for (prev = NULL; res; prev = res, res = res->sibling) { + struct resource *next = res->sibling; + resource_size_t free = 0; + + if (!prev && res->start > cxlrd->res->start) { + free = res->start - cxlrd->res->start; + max = max(free, max); + } + if (prev && res->start > prev->end + 1) { + free = res->start - prev->end + 1; + max = max(free, max); + } + if (next && res->end + 1 < next->start) { + free = next->start - res->end + 1; + max = max(free, max); + } + if (!next && res->end + 1 < cxlrd->res->end + 1) { + free = cxlrd->res->end + 1 - res->end + 1; + max = max(free, max); + } + } + + dev_dbg(CXLRD_DEV(cxlrd), "%s, found %pa bytes of free space\n", + __func__, &max); + if (max > ctx->max_hpa) { + if (ctx->cxlrd) + put_device(CXLRD_DEV(ctx->cxlrd)); + get_device(CXLRD_DEV(cxlrd)); + ctx->cxlrd = cxlrd; + ctx->max_hpa = max; + dev_dbg(CXLRD_DEV(cxlrd), "%s, found %pa bytes of free space\n", + __func__, &max); + } + return 0; +} + +/** + * cxl_get_hpa_freespace - find a root decoder with free capacity per constraints + * @endpoint: an endpoint that is mapped by the returned decoder + * @flags: CXL_DECODER_F flags for selecting RAM vs PMEM, and HDM-H vs HDM-D[B] + * @max_avail_contig: output parameter of max contiguous bytes available in the + * returned decoder + * + * The return tuple of a 'struct cxl_root_decoder' and 'bytes available (@max)' + * is a point in time snapshot. If by the time the caller goes to use this root + * decoder's capacity the capacity is reduced then caller needs to loop and + * retry. + * + * The returned root decoder has an elevated reference count that needs to be + * put with put_device(cxlrd_dev(cxlrd)). Locking context is with + * cxl_{acquire,release}_endpoint(), that ensures removal of the root decoder + * does not race. + */ +struct cxl_root_decoder *cxl_get_hpa_freespace(struct cxl_port *endpoint, + unsigned long flags, + resource_size_t *max_avail_contig) +{ + struct cxlrd_max_context ctx = { + .host_bridge = endpoint->host_bridge, + .flags = flags, + }; + struct cxl_port *root_port; + struct cxl_root *root __free(put_cxl_root) = find_cxl_root(endpoint); + + if (!is_cxl_endpoint(endpoint)) { + dev_dbg(&endpoint->dev, "hpa requestor is not an endpoint\n"); + return ERR_PTR(-EINVAL); + } + + if (!root) { + dev_dbg(&endpoint->dev, "endpoint can not be related to a root port\n"); + return ERR_PTR(-ENXIO); + } + + root_port = &root->port; + down_read(&cxl_region_rwsem); + device_for_each_child(&root_port->dev, &ctx, find_max_hpa); + up_read(&cxl_region_rwsem); + + if (!ctx.cxlrd) + return ERR_PTR(-ENOMEM); + + *max_avail_contig = ctx.max_hpa; + return ctx.cxlrd; +} +EXPORT_SYMBOL_NS_GPL(cxl_get_hpa_freespace, CXL); + static ssize_t size_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index 07c153aa3d77..5d83e4a960ef 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -772,6 +772,9 @@ static inline void cxl_setup_parent_dport(struct device *host, struct cxl_decoder *to_cxl_decoder(struct device *dev); struct cxl_root_decoder *to_cxl_root_decoder(struct device *dev); struct cxl_switch_decoder *to_cxl_switch_decoder(struct device *dev); + +#define CXLRD_DEV(cxlrd) (&(cxlrd)->cxlsd.cxld.dev) + struct cxl_endpoint_decoder *to_cxl_endpoint_decoder(struct device *dev); bool is_root_decoder(struct device *dev); bool is_switch_decoder(struct device *dev); diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h index 37c043100300..07259840da8f 100644 --- a/drivers/cxl/cxlmem.h +++ b/drivers/cxl/cxlmem.h @@ -875,4 +875,7 @@ struct cxl_hdm { struct seq_file; struct dentry *cxl_debugfs_create_dir(const char *dir); void cxl_dpa_debug(struct seq_file *file, struct cxl_dev_state *cxlds); +struct cxl_root_decoder *cxl_get_hpa_freespace(struct cxl_port *endpoint, + unsigned long flags, + resource_size_t *max); #endif /* __CXL_MEM_H__ */ diff --git a/include/linux/cxl/cxl.h b/include/linux/cxl/cxl.h index 7e4580fb8659..60a32f60401f 100644 --- a/include/linux/cxl/cxl.h +++ b/include/linux/cxl/cxl.h @@ -7,6 +7,10 @@ #include <linux/device.h> #include <linux/pci.h> +#define CXL_DECODER_F_RAM BIT(0) +#define CXL_DECODER_F_PMEM BIT(1) +#define CXL_DECODER_F_TYPE2 BIT(2) + enum cxl_resource { CXL_ACCEL_RES_DPA, CXL_ACCEL_RES_RAM, @@ -59,4 +63,8 @@ struct cxl_memdev *devm_cxl_add_memdev(struct device *host, struct cxl_dev_state *cxlds); struct cxl_port *cxl_acquire_endpoint(struct cxl_memdev *cxlmd); void cxl_release_endpoint(struct cxl_memdev *cxlmd, struct cxl_port *endpoint); + +struct cxl_root_decoder *cxl_get_hpa_freespace(struct cxl_port *endpoint, + unsigned long flags, + resource_size_t *max); #endif