responses below...
On 12/11/2024 5:31 AM, Andy Shevchenko wrote:
> 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.
I can remove these unrelated changes.
>
>
>> }
>
> ...
>
>> +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;
The next version of the patch removes this newly created .h file but good point
for any new headers created.
>
>> +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.
will do.
>
> ...
>
>> +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?
You're correct, extern isn't needed. I used it to follow what is done for other
declarations in the file only.
>
> ...
>
>> +++ 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).
>
Good point, I'll correct this.
> ...
>
>> +struct resource srmem_resource = {
>> + .name = "Soft Reserved mem",
>> + .start = 0,
>> + .end = -1,
>> + .flags = IORESOURCE_MEM,
>
> This can use DEFINE_RES_MEM_NAMED() as well.
Yes. I went with this format since it is what is used for the other two
struct resource definitions currently in the file.
>
>> +};
>
> ...
>
>> + if (sr_res->start == res->start && sr_res->end == res->end) {
>
> Wondering if we have a helper to exact match the resource by range...
I don't remember seeing one but will investigate.
>
>> + 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.
This one could use for_each_resource(). There is one loop that cannot since it
moves struct resources from one list to another.
>
>> + 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.
Good catch. I'll fix this.
>
> ...
>
>> +static bool resource_overlaps_cfmws(struct resource *res)
>> +{
>> + struct srmem_arg arg = {
>> + .res = res,
>
>> + .overlaps = 0
> Keep trailing comma.
will do.
>
>> + };
>> +
>> + 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?
Yes, there is a pr_fmt for kernel/resource.c
Thanks for the review.
-Nathan
>
>> + return insert_resource(&srmem_resource, res);
>> + }
>> +
>> + return insert_resource(&iomem_resource, res);
>> +}
>
