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Message-ID: <f83faa69-0a5e-40ad-a627-5ce78e8703fe@quicinc.com>
Date: Mon, 11 Mar 2024 16:29:49 -0700
From: Oreoluwa Babatunde <quic_obabatun@...cinc.com>
To: Rob Herring <robh@...nel.org>
CC: <catalin.marinas@....com>, <will@...nel.org>, <frowand.list@...il.com>,
<vgupta@...nel.org>, <arnd@...db.de>, <olof@...om.net>,
<soc@...nel.org>, <guoren@...nel.org>, <monstr@...str.eu>,
<palmer@...belt.com>, <aou@...s.berkeley.edu>, <dinguyen@...nel.org>,
<chenhuacai@...nel.org>, <tsbogend@...ha.franken.de>,
<jonas@...thpole.se>, <stefan.kristiansson@...nalahti.fi>,
<shorne@...il.com>, <mpe@...erman.id.au>, <ysato@...rs.sourceforge.jp>,
<dalias@...c.org>, <glaubitz@...sik.fu-berlin.de>, <richard@....at>,
<anton.ivanov@...bridgegreys.com>, <johannes@...solutions.net>,
<chris@...kel.net>, <jcmvbkbc@...il.com>,
<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
<devicetree@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
<kernel@...cinc.com>
Subject: Re: [PATCH v4 1/4] of: reserved_mem: Restruture how the reserved
memory regions are processed
On 3/11/2024 10:13 AM, Rob Herring wrote:
> On Fri, Mar 08, 2024 at 11:12:01AM -0800, Oreoluwa Babatunde wrote:
>> The current implementation processes the reserved memory regions in two
>> stages which are done with two separate functions within the
>> early_init_fdt_scan_reserved_mem() function.
>>
>> Within the two stages of processing, the reserved memory regions are
>> broken up into two groups which are processed differently:
>> i) Statically-placed reserved memory regions
>> i.e. regions defined with a static start address and size using the
>> "reg" property in the DT.
>> ii) Dynamically-placed reserved memory regions.
>> i.e. regions defined by specifying a range of addresses where they can
>> be placed in memory using the "alloc_ranges" and "size" properties
>> in the DT.
>>
>> Stage 1: fdt_scan_reserved_mem()
>> This stage of the reserved memory processing is used to scan through the
>> reserved memory nodes defined in the devicetree and do the following on
>> each of the nodes:
>>
>> 1) If the node represents a statically-placed reserved memory region,
>> i.e. it is defined using the "reg" property:
>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>> - Add the information for the reserved region to the reserved_mem array.
>> eg: fdt_reserved_mem_save_node(node, name, base, size);
>>
>> 2) If the node represents a dynamically-placed reserved memory region,
>> i.e. it is defined using "alloc-ranges" and "size" properties:
>> - Add the information for the region to the reserved_mem array with
>> the starting address and size set to 0.
>> eg: fdt_reserved_mem_save_node(node, name, 0, 0);
>>
>> Stage 2: fdt_init_reserved_mem()
>> This stage of the reserved memory processing is used to iterate through
>> the reserved_mem array which was populated in stage 1 and do the
>> following on each of the entries:
>>
>> 1) If the entry represents a statically-placed reserved memory region:
>> - Call the region specific init function.
>> 2) If the entry represents a dynamically-placed reserved memory region:
>> - Call __reserved_mem_alloc_size() which is used to allocate memory
>> for the region using memblock_phys_alloc_range(), and call
>> memblock_mark_nomap() on the allocated region if the region is
>> specified as a no-map region.
>> - Call the region specific init function.
>>
>> On architectures such as arm64, the dynamic allocation of the
>> reserved_mem array needs to be done after the page tables have been
>> setup because memblock allocated memory is not writable until then. This
>> means that the reserved_mem array will not be available to store any
>> reserved memory information until after the page tables have been setup.
>>
>> It is possible to call memblock_reserve() and memblock_mark_nomap() on
>> the statically-placed reserved memory regions and not need to save them
>> to the reserved_mem array until later. This is because all the
>> information we need is present in the devicetree.
>> Dynamically-placed reserved memory regions on the other hand get assigned
>> a start address only at runtime, and since memblock_reserve() and
>> memblock_mark_nomap() need to be called before the memory mappings are
>> created, the allocation needs to happen before the page tables are setup.
>>
>> To make it easier to handle dynamically-placed reserved memory regions
>> before the page tables are setup, this patch makes changes to the steps
>> above to process the reserved memory regions in the following ways:
>>
>> Step 1: fdt_scan_reserved_mem()
>> This stage of the reserved memory processing is used to scan through the
>> reserved memory nodes defined in the devicetree and do the following on
>> each of the nodes:
>>
>> 1) If the node represents a statically-placed reserved memory region,
>> i.e. it is defined using the "reg" property:
>> - Call memblock_reserve() or memblock_mark_nomap() as needed.
>>
>> 2) If the node represents a dynamically-placed reserved memory region,
>> i.e. it is defined using "alloc-ranges" and "size" properties:
>> - Call __reserved_mem_alloc_size() which will:
>> i) Allocate memory for the reserved memory region.
>> ii) Call memblock_mark_nomap() as needed.
>> Note: There is no need to explicitly call memblock_reserve() here
>> because it is already called by memblock when the memory for the
>> region is being allocated.
>> iii) Save the information for the region in the reserved_mem array.
>>
>> Step 2: fdt_init_reserved_mem()
>> This stage of the reserved memory processing is used to:
>>
>> 1) Add the information for the statically-placed reserved memory into
>> the reserved_mem array.
>>
>> 2) Iterate through all the entries in the array and call the region
>> specific init function for each of them.
>>
>> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@...cinc.com>
>> ---
>> drivers/of/fdt.c | 84 ++++++++++++++++++++++++++++++---
>> drivers/of/of_private.h | 2 +-
>> drivers/of/of_reserved_mem.c | 54 +++++++++------------
>> include/linux/of_fdt.h | 1 +
>> include/linux/of_reserved_mem.h | 9 ++++
>> 5 files changed, 111 insertions(+), 39 deletions(-)
>>
>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>> index bf502ba8da95..fe6c75c5a8c0 100644
>> --- a/drivers/of/fdt.c
>> +++ b/drivers/of/fdt.c
>> @@ -504,7 +504,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
>> phys_addr_t base, size;
>> int len;
>> const __be32 *prop;
>> - int first = 1;
>> bool nomap;
>>
>> prop = of_get_flat_dt_prop(node, "reg", &len);
>> @@ -532,10 +531,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
>> uname, &base, (unsigned long)(size / SZ_1M));
>>
>> len -= t_len;
>> - if (first) {
>> - fdt_reserved_mem_save_node(node, uname, base, size);
>> - first = 0;
>> - }
>> }
>> return 0;
>> }
>> @@ -563,12 +558,70 @@ static int __init __reserved_mem_check_root(unsigned long node)
>> return 0;
>> }
>>
>> +/**
>> + * fdt_scan_reserved_mem_reg_nodes() - Store info for the "reg" defined
>> + * reserved memory regions.
>> + *
>> + * This function is used to scan through the DT and store the
>> + * information for the reserved memory regions that are defined using
>> + * the "reg" property. The region node number, name, base address, and
>> + * size are all stored in the reserved_mem array by calling the
>> + * fdt_reserved_mem_save_node() function.
>> + */
>> +void __init fdt_scan_reserved_mem_reg_nodes(void)
>> +
>> +{
>> + int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
>> + const void *fdt = initial_boot_params;
>> + phys_addr_t base, size;
>> + const __be32 *prop;
>> + int node, child;
>> + int len;
>> +
>> + node = fdt_path_offset(fdt, "/reserved-memory");
>> + if (node < 0) {
>> + pr_err("Reserved memory: Did not find reserved-memory node\n");
> No reserved regions is perfectly valid.
ack
>> + return;
>> + }
>> +
>> + if (__reserved_mem_check_root(node)) {
>> + pr_err("Reserved memory: unsupported node format, ignoring\n");
>> + return;
>> + }
>> +
>> + fdt_for_each_subnode(child, fdt, node) {
>> + const char *uname;
>> +
>> + prop = of_get_flat_dt_prop(child, "reg", &len);
>> + if (!prop)
>> + continue;
>> +
>> + if (!of_fdt_device_is_available(fdt, child))
>> + continue;
>> +
>> + uname = fdt_get_name(fdt, child, NULL);
>> + if (len && len % t_len != 0) {
>> + pr_err("Reserved memory: invalid reg property in '%s', skipping node.\n",
>> + uname);
>> + continue;
>> + }
>> +
>> + base = dt_mem_next_cell(dt_root_addr_cells, &prop);
>> + size = dt_mem_next_cell(dt_root_size_cells, &prop);
>> +
>> + if (size)
>> + fdt_reserved_mem_save_node(child, uname, base, size);
>> + }
>> +}
>> +
>> /*
>> * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
>> */
>> static int __init fdt_scan_reserved_mem(void)
>> {
>> int node, child;
>> + int dynamic_nodes_cnt = 0;
>> + int dynamic_nodes[MAX_RESERVED_REGIONS];
>> const void *fdt = initial_boot_params;
>>
>> node = fdt_path_offset(fdt, "/reserved-memory");
>> @@ -590,8 +643,25 @@ static int __init fdt_scan_reserved_mem(void)
>> uname = fdt_get_name(fdt, child, NULL);
>>
>> err = __reserved_mem_reserve_reg(child, uname);
>> - if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL))
>> - fdt_reserved_mem_save_node(child, uname, 0, 0);
>> +
>> + /*
>> + * Delay allocation of the dynamically-placed regions
>> + * until after all other statically-placed regions have
>> + * been reserved or marked as nomap
>> + */
>> + if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL)) {
>> + dynamic_nodes[dynamic_nodes_cnt] = child;
>> + dynamic_nodes_cnt++;
> Can't you just call __reserved_mem_alloc_size() here instead of looping
> twice?
The reason for looping twice here is in the comment right above the
if-statement; "Delay allocation of the dynamically-placed regions until
after all other statically-placed regions have been reserved or marked
as nomap".
If we call "__reserved_mem_alloc_size()" at this point then there is a
possibility of allocating memory from one of the statically-placed
reserved memory regions since not all of them have been marked as
reserved or nomap yet.
>> + }
>> + }
>> +
>> + for (int i = 0; i < dynamic_nodes_cnt; i++) {
>> + const char *uname;
>> +
>> + child = dynamic_nodes[i];
>> + uname = fdt_get_name(fdt, child, NULL);
>> +
>> + __reserved_mem_alloc_size(child, uname);
>> }
>> return 0;
>> }
>> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
>> index f38397c7b582..542e37a37a24 100644
>> --- a/drivers/of/of_private.h
>> +++ b/drivers/of/of_private.h
>> @@ -36,6 +36,7 @@ struct alias_prop {
>> #endif
>>
>> #define OF_ROOT_NODE_SIZE_CELLS_DEFAULT 1
>> +#define MAX_RESERVED_REGIONS 64
>>
>> extern struct mutex of_mutex;
>> extern raw_spinlock_t devtree_lock;
>> @@ -175,7 +176,6 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
>> }
>> #endif
>>
>> -void fdt_init_reserved_mem(void);
> I don't see why this is moved.
True, there is no need for this anymore.
Will revert it in the next revision.
>> [...]
>>
>> @@ -328,30 +325,25 @@ void __init fdt_init_reserved_mem(void)
>> if (prop)
>> rmem->phandle = of_read_number(prop, len/4);
>>
>> - if (rmem->size == 0)
>> - err = __reserved_mem_alloc_size(node, rmem->name,
>> - &rmem->base, &rmem->size);
>> - if (err == 0) {
>> - err = __reserved_mem_init_node(rmem);
>> - if (err != 0 && err != -ENOENT) {
>> - pr_info("node %s compatible matching fail\n",
>> - rmem->name);
>> - if (nomap)
>> - memblock_clear_nomap(rmem->base, rmem->size);
>> - else
>> - memblock_phys_free(rmem->base,
>> - rmem->size);
>> - } else {
>> - phys_addr_t end = rmem->base + rmem->size - 1;
>> - bool reusable =
>> - (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
>> -
>> - pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
>> - &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
>> - nomap ? "nomap" : "map",
>> - reusable ? "reusable" : "non-reusable",
>> - rmem->name ? rmem->name : "unknown");
>> - }
>> + err = __reserved_mem_init_node(rmem);
>> + if (err != 0 && err != -ENOENT) {
>> + pr_info("node %s compatible matching fail\n",
>> + rmem->name);
> Can be 1 line now.
ack.
>> + if (nomap)
>> + memblock_clear_nomap(rmem->base, rmem->size);
>> + else
>> + memblock_phys_free(rmem->base,
>> + rmem->size);
> Can be 1 line now.
ack.
>> + } else {
>> + phys_addr_t end = rmem->base + rmem->size - 1;
>> + bool reusable =
>> + (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
>> +
>> + pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
>> + &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
>> + nomap ? "nomap" : "map",
>> + reusable ? "reusable" : "non-reusable",
>> + rmem->name ? rmem->name : "unknown");
>> }
>> }
>> }
>> diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
>> index d69ad5bb1eb1..7b2a5d93d719 100644
>> --- a/include/linux/of_fdt.h
>> +++ b/include/linux/of_fdt.h
>> @@ -73,6 +73,7 @@ extern int early_init_dt_scan_root(void);
>> extern bool early_init_dt_scan(void *params);
>> extern bool early_init_dt_verify(void *params);
>> extern void early_init_dt_scan_nodes(void);
>> +extern void fdt_scan_reserved_mem_reg_nodes(void);
> This is internal to drivers/of/, so it goes in of_private.h
ack.
>>
>> extern const char *of_flat_dt_get_machine_name(void);
>> extern const void *of_flat_dt_match_machine(const void *default_match,
>> diff --git a/include/linux/of_reserved_mem.h b/include/linux/of_reserved_mem.h
>> index 4de2a24cadc9..2a3178920bae 100644
>> --- a/include/linux/of_reserved_mem.h
>> +++ b/include/linux/of_reserved_mem.h
>> @@ -32,12 +32,14 @@ typedef int (*reservedmem_of_init_fn)(struct reserved_mem *rmem);
>> #define RESERVEDMEM_OF_DECLARE(name, compat, init) \
>> _OF_DECLARE(reservedmem, name, compat, init, reservedmem_of_init_fn)
>>
>> +void fdt_init_reserved_mem(void);
>> int of_reserved_mem_device_init_by_idx(struct device *dev,
>> struct device_node *np, int idx);
>> int of_reserved_mem_device_init_by_name(struct device *dev,
>> struct device_node *np,
>> const char *name);
>> void of_reserved_mem_device_release(struct device *dev);
>> +int __reserved_mem_alloc_size(unsigned long node, const char *uname);
> This is internal to drivers/of/, so it goes in of_private.h
ack.
>
> But really, I think fdt_scan_reserved_mem() should move to
> of_reserved_mem.c first. Then everything you add to fdt.c goes there
> too.
ack.
Regards,
Oreoluwa
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