Commit b4a96ab5 authored by Sourabh Jain's avatar Sourabh Jain Committed by Madhavan Srinivasan
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powerpc/kdump: Add support for crashkernel CMA reservation 



Commit 35c18f29 ("Add a new optional ",cma" suffix to the
crashkernel= command line option") and commit ab475510 ("kdump:
implement reserve_crashkernel_cma") added CMA support for kdump
crashkernel reservation.

Extend crashkernel CMA reservation support to powerpc.

The following changes are made to enable CMA reservation on powerpc:

- Parse and obtain the CMA reservation size along with other crashkernel
  parameters
- Call reserve_crashkernel_cma() to allocate the CMA region for kdump
- Include the CMA-reserved ranges in the usable memory ranges for the
  kdump kernel to use.
- Exclude the CMA-reserved ranges from the crash kernel memory to
  prevent them from being exported through /proc/vmcore.

With the introduction of the CMA crashkernel regions,
crash_exclude_mem_range() needs to be called multiple times to exclude
both crashk_res and crashk_cma_ranges from the crash memory ranges. To
avoid repetitive logic for validating mem_ranges size and handling
reallocation when required, this functionality is moved to a new wrapper
function crash_exclude_mem_range_guarded().

To ensure proper CMA reservation, reserve_crashkernel_cma() is called
after pageblock_order is initialized.

Update kernel-parameters.txt to document CMA support for crashkernel on
powerpc architecture.

Signed-off-by: default avatarSourabh Jain <sourabhjain@linux.ibm.com>
Reviewed-by: default avatarRitesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: default avatarMadhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20251107080334.708028-1-sourabhjain@linux.ibm.com
parent 8127c4fd

Documentation/admin-guide/kernel-parameters.txt

+1 −1
Original line number Diff line number Diff line
@@ -1013,7 +1013,7 @@ 
			It will be ignored when crashkernel=X,high is not used

			or memory reserved is below 4G.

	crashkernel=size[KMG],cma

			[KNL, X86] Reserve additional crash kernel memory from

			[KNL, X86, ppc] Reserve additional crash kernel memory from

			CMA. This reservation is usable by the first system's

			userspace memory and kernel movable allocations (memory

			balloon, zswap). Pages allocated from this memory range

arch/powerpc/include/asm/kexec.h

+2 −0
Original line number Diff line number Diff line
@@ -115,9 +115,11 @@ int setup_new_fdt_ppc64(const struct kimage *image, void *fdt, struct crash_mem 
#ifdef CONFIG_CRASH_RESERVE

int __init overlaps_crashkernel(unsigned long start, unsigned long size);

extern void arch_reserve_crashkernel(void);

extern void kdump_cma_reserve(void);

#else

static inline void arch_reserve_crashkernel(void) {}

static inline int overlaps_crashkernel(unsigned long start, unsigned long size) { return 0; }

static inline void kdump_cma_reserve(void) { }

#endif



#if defined(CONFIG_CRASH_DUMP)

arch/powerpc/kernel/setup-common.c

+3 −1
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ 
#include <linux/of_irq.h>

#include <linux/hugetlb.h>

#include <linux/pgtable.h>

#include <asm/kexec.h>

#include <asm/io.h>

#include <asm/paca.h>

#include <asm/processor.h>
@@ -995,11 +996,12 @@ void __init setup_arch(char **cmdline_p) 
	initmem_init();



	/*

	 * Reserve large chunks of memory for use by CMA for fadump, KVM and

	 * Reserve large chunks of memory for use by CMA for kdump, fadump, KVM and

	 * hugetlb. These must be called after initmem_init(), so that

	 * pageblock_order is initialised.

	 */

	fadump_cma_init();

	kdump_cma_reserve();

	kvm_cma_reserve();

	gigantic_hugetlb_cma_reserve();

arch/powerpc/kexec/core.c

+9 −1
Original line number Diff line number Diff line
@@ -59,6 +59,8 @@ void machine_kexec(struct kimage *image) 


#ifdef CONFIG_CRASH_RESERVE



static unsigned long long crashk_cma_size;



static unsigned long long __init get_crash_base(unsigned long long crash_base)

{
@@ -110,7 +112,7 @@ void __init arch_reserve_crashkernel(void) 


	/* use common parsing */

	ret = parse_crashkernel(boot_command_line, total_mem_sz, &crash_size,

				&crash_base, NULL, NULL, NULL);

				&crash_base, NULL, &crashk_cma_size, NULL);



	if (ret)

		return;
@@ -130,6 +132,12 @@ void __init arch_reserve_crashkernel(void) 
	reserve_crashkernel_generic(crash_size, crash_base, 0, false);

}



void __init kdump_cma_reserve(void)

{

	if (crashk_cma_size)

		reserve_crashkernel_cma(crashk_cma_size);

}



int __init overlaps_crashkernel(unsigned long start, unsigned long size)

{

	return (start + size) > crashk_res.start && start <= crashk_res.end;

arch/powerpc/kexec/ranges.c

+32 −11
Original line number Diff line number Diff line
@@ -515,7 +515,7 @@ int get_exclude_memory_ranges(struct crash_mem **mem_ranges) 
 */

int get_usable_memory_ranges(struct crash_mem **mem_ranges)

{

	int ret;

	int ret, i;



	/*

	 * Early boot failure observed on guests when low memory (first memory
@@ -528,6 +528,13 @@ int get_usable_memory_ranges(struct crash_mem **mem_ranges) 
	if (ret)

		goto out;



	for (i = 0; i < crashk_cma_cnt; i++) {

		ret = add_mem_range(mem_ranges, crashk_cma_ranges[i].start,

				    crashk_cma_ranges[i].end - crashk_cma_ranges[i].start + 1);

		if (ret)

			goto out;

	}



	ret = add_rtas_mem_range(mem_ranges);

	if (ret)

		goto out;
@@ -546,6 +553,22 @@ int get_usable_memory_ranges(struct crash_mem **mem_ranges) 
#endif /* CONFIG_KEXEC_FILE */



#ifdef CONFIG_CRASH_DUMP

static int crash_exclude_mem_range_guarded(struct crash_mem **mem_ranges,

					   unsigned long long mstart,

					   unsigned long long mend)

{

	struct crash_mem *tmem = *mem_ranges;



	/* Reallocate memory ranges if there is no space to split ranges */

	if (tmem && (tmem->nr_ranges == tmem->max_nr_ranges)) {

		tmem = realloc_mem_ranges(mem_ranges);

		if (!tmem)

			return -ENOMEM;

	}



	return crash_exclude_mem_range(tmem, mstart, mend);

}



/**

 * get_crash_memory_ranges - Get crash memory ranges. This list includes

 *                           first/crashing kernel's memory regions that
@@ -557,7 +580,6 @@ int get_usable_memory_ranges(struct crash_mem **mem_ranges) 
int get_crash_memory_ranges(struct crash_mem **mem_ranges)

{

	phys_addr_t base, end;

	struct crash_mem *tmem;

	u64 i;

	int ret;
@@ -582,18 +604,17 @@ int get_crash_memory_ranges(struct crash_mem **mem_ranges) 
			sort_memory_ranges(*mem_ranges, true);

	}



	/* Reallocate memory ranges if there is no space to split ranges */

	tmem = *mem_ranges;

	if (tmem && (tmem->nr_ranges == tmem->max_nr_ranges)) {

		tmem = realloc_mem_ranges(mem_ranges);

		if (!tmem)

	/* Exclude crashkernel region */

	ret = crash_exclude_mem_range_guarded(mem_ranges, crashk_res.start, crashk_res.end);

	if (ret)

		goto out;

	}



	/* Exclude crashkernel region */

	ret = crash_exclude_mem_range(tmem, crashk_res.start, crashk_res.end);

	for (i = 0; i < crashk_cma_cnt; ++i) {

		ret = crash_exclude_mem_range_guarded(mem_ranges, crashk_cma_ranges[i].start,

					      crashk_cma_ranges[i].end);

		if (ret)

			goto out;

	}



	/*

	 * FIXME: For now, stay in parity with kexec-tools but if RTAS/OPAL