On Mon, Dec 02, 2024 at 09:55:42AM -0600, Nathan Fontenot wrote:
> Update handling of SOFT RESERVE iomem resources that intersect with
> CXL region resources to remove the intersections from the SOFT RESERVE
> resources. The current approach of leaving the SOFT RESERVE
> resource as is can cause failures during hotplug replace of CXL
> devices because the resource is not available for reuse after
> teardown of the CXL device.
>
> The approach is to trim out any pieces of SOFT RESERVE resources
> that intersect CXL regions. To do this, first set aside any SOFT RESERVE
> resources that intersect with a CFMWS into a separate resource tree
> during e820__reserve_resources_late() that would have been otherwise
> added to the iomem resource tree.
>
> As CXL regions are created the cxl resource created for the new
> region is used to trim intersections from the SOFT RESERVE
> resources that were previously set aside.
>
> Once CXL device probe has completed ant remaining SOFT RESERVE resources
> remaining are added to the iomem resource tree. As each resource
> is added to the oiomem resource tree a new notifier chain is invoked
> to notify the dax driver of newly added SOFT RESERVE resources so that
> the dax driver can consume them.
...
> void __init e820__reserve_resources_late(void)
> {
> - int i;
> struct resource *res;
> + int i;
Unrelated change.
...
> - for (i = 0; i < e820_table->nr_entries; i++) {
> + for (i = 0; i < e820_table->nr_entries; i++, res++) {
> - res++;
Unrelated change.
> }
...
> +static struct notifier_block hmem_nb = {
> + .notifier_call = dax_hmem_cb
It's better to leave trailing comma as it reduces churn in the future is
anything to add here.
> +};
...
> +++ b/drivers/dax/hmem/hmem.h
> @@ -0,0 +1,11 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#ifndef _HMEM_H
> +#define _HMEM_H
This needs a few forward declarations
struct device;
struct platform_device;
struct resource;
> +typedef int (*walk_hmem_fn)(struct device *dev, int target_nid,
> + const struct resource *res);
> +int walk_hmem_resources(struct device *dev, walk_hmem_fn fn);
> +
> +extern struct platform_device *hmem_pdev;
> +
> +#endif
...
> #include <linux/compiler.h>
> #include <linux/minmax.h>
> #include <linux/types.h>
> +#include <linux/notifier.h>
I would put it before types.h to have more ordered piece.
...
> +extern void trim_soft_reserve_resources(const struct resource *res);
> +extern void merge_soft_reserve_resources(void);
> +extern int insert_soft_reserve_resource(struct resource *res);
> +extern int register_soft_reserve_notifier(struct notifier_block *nb);
> +extern int unregister_soft_reserve_notifier(struct notifier_block *nb);
Why extern?
...
> +++ b/kernel/resource.c
> @@ -30,7 +30,7 @@
> #include <linux/string.h>
> #include <linux/vmalloc.h>
> #include <asm/io.h>
> -
> +#include <linux/acpi.h>
We don't usually interleave linux and asm headers, moreover the list seems to
be sorted (ordered, please preserve the ordering).
...
> +struct resource srmem_resource = {
> + .name = "Soft Reserved mem",
> + .start = 0,
> + .end = -1,
> + .flags = IORESOURCE_MEM,
This can use DEFINE_RES_MEM_NAMED() as well.
> +};
...
> + if (sr_res->start == res->start && sr_res->end == res->end) {
Wondering if we have a helper to exact match the resource by range...
> + release_resource(sr_res);
> + free_resource(sr_res);
> + } else if (sr_res->start == res->start) {
> + WARN_ON(adjust_resource(sr_res, res->end + 1,
> + sr_res->end - res->end));
> + } else if (sr_res->end == res->end) {
> + WARN_ON(adjust_resource(sr_res, sr_res->start,
> + res->start - sr_res->start));
> + } else {
> + /*
> + * Adjust existing resource to cover the resource
> + * range prior to the range to be trimmed.
> + */
> + adjust_resource(sr_res, sr_res->start,
> + res->start - sr_res->start);
> +
> + /*
> + * Add new resource to cover the resource range for
> + * the range after the range to be trimmed.
> + */
> + new_res = alloc_resource(GFP_KERNEL);
> + if (!new_res)
> + return;
> +
> + *new_res = DEFINE_RES_NAMED(res->end + 1, sr_res->end - res->end,
> + "Soft Reserved", sr_res->flags);
> + new_res->desc = IORES_DESC_SOFT_RESERVED;
> + insert_resource(&srmem_resource, new_res);
> + }
...
> +void trim_soft_reserve_resources(const struct resource *res)
> +{
> + struct resource *sr_res;
> +
> + write_lock(&srmem_resource_lock);
> + for (sr_res = srmem_resource.child; sr_res; sr_res = sr_res->sibling) {
Can this utilise for_each_resource*()?
Ditto for the rest of open coded for each type of loops.
> + if (resource_contains(sr_res, res)) {
> + trim_soft_reserve(sr_res, res);
> + break;
> + }
> + }
> + write_unlock(&srmem_resource_lock);
> +}
...
> + cfmws_res = DEFINE_RES_MEM(cfmws->base_hpa,
> + cfmws->base_hpa + cfmws->window_size);
Can be one line.
But is this correct? The parameters are start,size, and here it seems like start,end.
...
> +static bool resource_overlaps_cfmws(struct resource *res)
> +{
> + struct srmem_arg arg = {
> + .res = res,
> + .overlaps = 0
Keep trailing comma.
> + };
> +
> + acpi_table_parse_cedt(ACPI_CEDT_TYPE_CFMWS, srmem_parse_cfmws, &arg);
> + if (arg.overlaps)
> + return true;
> +
> + return false;
return arg.overlaps;
> +}
...
> +int insert_soft_reserve_resource(struct resource *res)
> +{
> + if (resource_overlaps_cfmws(res)) {
> + pr_info("Reserving Soft Reserve %pr\n", res);
Btw, do we have pr_fmt() defined in this file?
> + return insert_resource(&srmem_resource, res);
> + }
> +
> + return insert_resource(&iomem_resource, res);
> +}
--
With Best Regards,
Andy Shevchenko
