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Tue, 21 Jan 2025 21:52:43 -0800 (PST) Received: from gpd ([2601:646:8f03:9fee:1eca:6066:421d:7396]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-72dab9c8ed3sm10013391b3a.113.2025.01.21.21.52.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Jan 2025 21:52:43 -0800 (PST) From: Fan Ni X-Google-Original-From: Fan Ni Date: Tue, 21 Jan 2025 21:52:48 -0800 To: Nathan Fontenot Cc: linux-cxl@vger.kernel.org, dan.j.williams@intel.com, alison.schofield@intel.com, linux-mm@kvack.org, gourry@gourry.net Subject: Re: [PATCH v2 1/4] kernel/resource: Introduce managed SOFT RESERVED resources Message-ID: References: <1800b17449d1c231292c85f59b226aff39a81552.1737046620.git.nathan.fontenot@amd.com> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1800b17449d1c231292c85f59b226aff39a81552.1737046620.git.nathan.fontenot@amd.com> On Thu, Jan 16, 2025 at 11:42:05AM -0600, Nathan Fontenot wrote: > Introduce the ability to manage SOFT RESERVED kernel resources prior to > these resources being placed in the iomem resource tree. This provides > the ability for drivers to update SOFT RESERVED resources that intersect > with their memory resources. > > During boot, any resources marked as IORES_DESC_SOFT_RESERVED are placed > on the soft reserve resource tree. Once boot completes all resources > are placed on the iomem resource tree. This behavior is gated by a new > kernel option CONFIG_SOFT_RESERVED_MANAGED. > > As part of this update two new interfaces are added for management of > the SOFT RESERVED resources. The release_srmem_region_adjustable() > routine allows for removing pieces of SOFT RESERVED resources. The > the merge_srmem_resources() allows drivers to merge any remaining SOFT > RESERVED resources into the iomem resource tree once updatea are complete. > > Signed-off-by: Nathan Fontenot > --- > include/linux/ioport.h | 9 +++++ > kernel/resource.c | 79 +++++++++++++++++++++++++++++++++++++++--- > lib/Kconfig | 4 +++ > 3 files changed, 87 insertions(+), 5 deletions(-) > > diff --git a/include/linux/ioport.h b/include/linux/ioport.h > index 6e9fb667a1c5..2c95cf0be45e 100644 > --- a/include/linux/ioport.h > +++ b/include/linux/ioport.h > @@ -249,6 +249,15 @@ struct resource *lookup_resource(struct resource *root, resource_size_t start); > int adjust_resource(struct resource *res, resource_size_t start, > resource_size_t size); > resource_size_t resource_alignment(struct resource *res); > + > +#ifdef CONFIG_SOFT_RESERVED_MANAGED > +void merge_srmem_resources(void); > +extern void release_srmem_region_adjustable(resource_size_t start, > + resource_size_t size); > +#else > +static inline void merge_srmem_resources(void) { } > +#endif > + > static inline resource_size_t resource_size(const struct resource *res) > { > return res->end - res->start + 1; > diff --git a/kernel/resource.c b/kernel/resource.c > index a83040fde236..9db420078a3f 100644 > --- a/kernel/resource.c > +++ b/kernel/resource.c > @@ -48,6 +48,14 @@ struct resource iomem_resource = { > }; > EXPORT_SYMBOL(iomem_resource); > > +static struct resource srmem_resource = { > + .name = "Soft Reserved mem", > + .start = 0, > + .end = -1, > + .flags = IORESOURCE_MEM, > + .desc = IORES_DESC_SOFT_RESERVED, > +}; > + > static DEFINE_RWLOCK(resource_lock); > > static struct resource *next_resource(struct resource *p, bool skip_children) > @@ -818,6 +826,19 @@ static struct resource * __insert_resource(struct resource *parent, struct resou > { > struct resource *first, *next; > > + if (IS_ENABLED(CONFIG_SOFT_RESERVED_MANAGED)) { > + /* > + * During boot SOFT RESERVED resources are placed on the srmem > + * resource tree. These resources may be updated later in boot, > + * for example see the CXL driver, prior to being merged into > + * the iomem resource tree. > + */ > + if (system_state < SYSTEM_RUNNING && > + parent == &iomem_resource && > + new->desc == IORES_DESC_SOFT_RESERVED) > + parent = &srmem_resource; > + } > + > for (;; parent = first) { > first = __request_resource(parent, new); > if (!first) > @@ -1336,11 +1357,12 @@ void __release_region(struct resource *parent, resource_size_t start, > } > EXPORT_SYMBOL(__release_region); > > -#ifdef CONFIG_MEMORY_HOTREMOVE If CONFIG_MEMORY_HOTREMOVE not defined, it seems we do not have a user for release_region_adjustable as release_mem_region_adjustable() will not exist. Fan > /** > - * release_mem_region_adjustable - release a previously reserved memory region > + * release_region_adjustable - release a previously reserved memory region > + * @parent: resource tree to release resource from > * @start: resource start address > * @size: resource region size > + * @busy_check: check for IORESOURCE_BUSY > * > * This interface is intended for memory hot-delete. The requested region > * is released from a currently busy memory resource. The requested region > @@ -1356,9 +1378,11 @@ EXPORT_SYMBOL(__release_region); > * assumes that all children remain in the lower address entry for > * simplicity. Enhance this logic when necessary. > */ > -void release_mem_region_adjustable(resource_size_t start, resource_size_t size) > +static void release_region_adjustable(struct resource *parent, > + resource_size_t start, > + resource_size_t size, > + bool busy_check) > { > - struct resource *parent = &iomem_resource; > struct resource *new_res = NULL; > bool alloc_nofail = false; > struct resource **p; > @@ -1395,7 +1419,7 @@ void release_mem_region_adjustable(resource_size_t start, resource_size_t size) > if (!(res->flags & IORESOURCE_MEM)) > break; > > - if (!(res->flags & IORESOURCE_BUSY)) { > + if (busy_check && !(res->flags & IORESOURCE_BUSY)) { > p = &res->child; > continue; > } > @@ -1445,6 +1469,51 @@ void release_mem_region_adjustable(resource_size_t start, resource_size_t size) > write_unlock(&resource_lock); > free_resource(new_res); > } > + > +#ifdef CONFIG_SOFT_RESERVED_MANAGED > +/** > + * merge_srmem_resources - merge srmem resources into the iomem resource tree > + * > + * This is intended to allow kernel drivers that manage the SOFT RESERVED > + * resources to merge any remaining resources into the iomem resource tree > + * once any updates have been made. > + */ > +void merge_srmem_resources(void) > +{ > + struct resource *res, *next; > + int rc; > + > + for (res = srmem_resource.child; res; res = next) { > + next = next_resource(res, true); > + > + write_lock(&resource_lock); > + > + if (WARN_ON(__release_resource(res, true))) { > + write_unlock(&resource_lock); > + continue; > + } > + > + if (WARN_ON(__insert_resource(&iomem_resource, res))) > + __insert_resource(&srmem_resource, res); > + > + write_unlock(&resource_lock); > + } > +} > +EXPORT_SYMBOL_GPL(merge_srmem_resources); > + > +void release_srmem_region_adjustable(resource_size_t start, > + resource_size_t size) > +{ > + release_region_adjustable(&srmem_resource, start, size, false); > +} > +EXPORT_SYMBOL(release_srmem_region_adjustable); > +#endif > + > +#ifdef CONFIG_MEMORY_HOTREMOVE > +void release_mem_region_adjustable(resource_size_t start, resource_size_t size) > +{ > + release_region_adjustable(&iomem_resource, start, size, true); > +} > #endif /* CONFIG_MEMORY_HOTREMOVE */ > > #ifdef CONFIG_MEMORY_HOTPLUG > diff --git a/lib/Kconfig b/lib/Kconfig > index b38849af6f13..4f4011334051 100644 > --- a/lib/Kconfig > +++ b/lib/Kconfig > @@ -777,3 +777,7 @@ config POLYNOMIAL > > config FIRMWARE_TABLE > bool > + > +config SOFT_RESERVED_MANAGED > + bool > + default n > -- > 2.43.0 >