[PATCH] powerpc/kdump: Add support for crashkernel CMA reservation

[PATCH] powerpc/kdump: Add support for crashkernel CMA reservation

[Sourabh Jain]

Commit 35c18f2933c5 ("Add a new optional ",cma" suffix to the
crashkernel= command line option") and commit ab475510e042 ("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

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

Cc: Baoquan he <bhe@redhat.com>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 arch/powerpc/include/asm/kexec.h   |  7 +++++++
 arch/powerpc/kernel/setup-common.c |  4 +++-
 arch/powerpc/kexec/core.c          | 11 ++++++++++-
 arch/powerpc/kexec/ranges.c        | 16 +++++++++++++++-
 4 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index 4bbf9f699aaa..c158ffbfeadb 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -51,9 +51,16 @@
 
 #ifndef __ASSEMBLER__
 #include <asm/reg.h>
+#include <linux/crash_reserve.h>
 
 typedef void (*crash_shutdown_t)(void);
 
+#ifdef CRASHKERNEL_CMA
+void kdump_cma_reserve(void);
+#else
+static inline void kdump_cma_reserve(void) { }
+#endif
+
 #ifdef CONFIG_KEXEC_CORE
 struct kimage;
 struct pt_regs;
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 68d47c53876c..1279e8777366 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -35,6 +35,7 @@
 #include <linux/of_irq.h>
 #include <linux/hugetlb.h>
 #include <linux/pgtable.h>
+#include <linux/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();
 
diff --git a/arch/powerpc/kexec/core.c b/arch/powerpc/kexec/core.c
index d1a2d755381c..3328b1acd875 100644
--- a/arch/powerpc/kexec/core.c
+++ b/arch/powerpc/kexec/core.c
@@ -33,6 +33,9 @@ void machine_kexec_cleanup(struct kimage *image)
 {
 }
 
+
+static unsigned long long cma_size;
+
 /*
  * Do not allocate memory (or fail in any way) in machine_kexec().
  * We are past the point of no return, committed to rebooting now.
@@ -110,7 +113,7 @@ 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, &cma_size, NULL);
 
 	if (ret)
 		return;
@@ -130,6 +133,12 @@ void __init arch_reserve_crashkernel(void)
 	reserve_crashkernel_generic(crash_size, crash_base, 0, false);
 }
 
+void __init kdump_cma_reserve(void)
+{
+	if (cma_size)
+		reserve_crashkernel_cma(cma_size);
+}
+
 int __init overlaps_crashkernel(unsigned long start, unsigned long size)
 {
 	return (start + size) > crashk_res.start && start <= crashk_res.end;
diff --git a/arch/powerpc/kexec/ranges.c b/arch/powerpc/kexec/ranges.c
index 3702b0bdab14..dad58fc38251 100644
--- a/arch/powerpc/kexec/ranges.c
+++ b/arch/powerpc/kexec/ranges.c
@@ -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);
+		if (ret)
+			goto out;
+	}
+
 	ret = add_rtas_mem_range(mem_ranges);
 	if (ret)
 		goto out;
@@ -595,6 +602,13 @@ int get_crash_memory_ranges(struct crash_mem **mem_ranges)
 	if (ret)
 		goto out;
 
+	for (i = 0; i < crashk_cma_cnt; ++i) {
+		ret = crash_exclude_mem_range(tmem, 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
 	 *        regions are exported to save their context at the time of
-- 
2.51.0

Re: [PATCH] powerpc/kdump: Add support for crashkernel CMA reservation

[kernel test robot]

Hi Sourabh,

kernel test robot noticed the following build errors:

[auto build test ERROR on powerpc/next]
[also build test ERROR on powerpc/fixes linus/master v6.18-rc2 next-20251022]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sourabh-Jain/powerpc-kdump-Add-support-for-crashkernel-CMA-reservation/20251022-182711
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
patch link:    https://lore.kernel.org/r/20251022102531.657147-1-sourabhjain%40linux.ibm.com
patch subject: [PATCH] powerpc/kdump: Add support for crashkernel CMA reservation
config: powerpc-allnoconfig (https://download.01.org/0day-ci/archive/20251023/202510230817.h1gNa0VV-lkp@intel.com/config)
compiler: powerpc-linux-gcc (GCC) 15.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251023/202510230817.h1gNa0VV-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510230817.h1gNa0VV-lkp@intel.com/

All errors (new ones prefixed by >>):

   arch/powerpc/kernel/setup-common.c: In function 'setup_arch':
>> arch/powerpc/kernel/setup-common.c:1004:9: error: implicit declaration of function 'kdump_cma_reserve'; did you mean 'kvm_cma_reserve'? [-Wimplicit-function-declaration]
    1004 |         kdump_cma_reserve();
         |         ^~~~~~~~~~~~~~~~~
         |         kvm_cma_reserve


vim +1004 arch/powerpc/kernel/setup-common.c

   976	
   977		/* Print various info about the machine that has been gathered so far. */
   978		print_system_info();
   979	
   980		klp_init_thread_info(&init_task);
   981	
   982		setup_initial_init_mm(_stext, _etext, _edata, _end);
   983		/* sched_init() does the mmgrab(&init_mm) for the primary CPU */
   984		VM_WARN_ON(cpumask_test_cpu(smp_processor_id(), mm_cpumask(&init_mm)));
   985		cpumask_set_cpu(smp_processor_id(), mm_cpumask(&init_mm));
   986		inc_mm_active_cpus(&init_mm);
   987		mm_iommu_init(&init_mm);
   988	
   989		irqstack_early_init();
   990		exc_lvl_early_init();
   991		emergency_stack_init();
   992	
   993		mce_init();
   994		smp_release_cpus();
   995	
   996		initmem_init();
   997	
   998		/*
   999		 * Reserve large chunks of memory for use by CMA for kdump, fadump, KVM and
  1000		 * hugetlb. These must be called after initmem_init(), so that
  1001		 * pageblock_order is initialised.
  1002		 */
  1003		fadump_cma_init();
> 1004		kdump_cma_reserve();

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH] powerpc/kdump: Add support for crashkernel CMA reservation

[kernel test robot]

Hi Sourabh,

kernel test robot noticed the following build warnings:

[auto build test WARNING on powerpc/next]
[also build test WARNING on powerpc/fixes linus/master v6.18-rc2 next-20251022]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sourabh-Jain/powerpc-kdump-Add-support-for-crashkernel-CMA-reservation/20251022-182711
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
patch link:    https://lore.kernel.org/r/20251022102531.657147-1-sourabhjain%40linux.ibm.com
patch subject: [PATCH] powerpc/kdump: Add support for crashkernel CMA reservation
config: powerpc-randconfig-002-20251023 (https://download.01.org/0day-ci/archive/20251023/202510230923.E37rbvtF-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 754ebc6ebb9fb9fbee7aef33478c74ea74949853)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251023/202510230923.E37rbvtF-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510230923.E37rbvtF-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> arch/powerpc/kexec/core.c:37:27: warning: unused variable 'cma_size' [-Wunused-variable]
      37 | static unsigned long long cma_size;
         |                           ^~~~~~~~
   1 warning generated.

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for HOTPLUG_CPU
   Depends on [n]: SMP [=y] && (PPC_PSERIES [=n] || PPC_PMAC [=n] || PPC_POWERNV [=n] || FSL_SOC_BOOKE [=n])
   Selected by [y]:
   - PM_SLEEP_SMP [=y] && SMP [=y] && (ARCH_SUSPEND_POSSIBLE [=y] || ARCH_HIBERNATION_POSSIBLE [=y]) && PM_SLEEP [=y]


vim +/cma_size +37 arch/powerpc/kexec/core.c

    35	
    36	
  > 37	static unsigned long long cma_size;
    38	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH] powerpc/kdump: Add support for crashkernel CMA reservation

[kernel test robot]

Hi Sourabh,

kernel test robot noticed the following build errors:

[auto build test ERROR on powerpc/next]
[also build test ERROR on powerpc/fixes linus/master v6.18-rc2 next-20251022]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sourabh-Jain/powerpc-kdump-Add-support-for-crashkernel-CMA-reservation/20251022-182711
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
patch link:    https://lore.kernel.org/r/20251022102531.657147-1-sourabhjain%40linux.ibm.com
patch subject: [PATCH] powerpc/kdump: Add support for crashkernel CMA reservation
config: powerpc64-randconfig-002-20251023 (https://download.01.org/0day-ci/archive/20251023/202510230903.b7vsK8xg-lkp@intel.com/config)
compiler: powerpc64-linux-gcc (GCC) 10.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251023/202510230903.b7vsK8xg-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510230903.b7vsK8xg-lkp@intel.com/

All errors (new ones prefixed by >>):

>> arch/powerpc/kexec/core.c:136:13: error: redefinition of 'kdump_cma_reserve'
     136 | void __init kdump_cma_reserve(void)
         |             ^~~~~~~~~~~~~~~~~
   In file included from include/linux/kexec.h:38,
                    from arch/powerpc/kexec/core.c:10:
   arch/powerpc/include/asm/kexec.h:61:20: note: previous definition of 'kdump_cma_reserve' was here
      61 | static inline void kdump_cma_reserve(void) { }
         |                    ^~~~~~~~~~~~~~~~~


vim +/kdump_cma_reserve +136 arch/powerpc/kexec/core.c

   135	
 > 136	void __init kdump_cma_reserve(void)
   137	{
   138		if (cma_size)
   139			reserve_crashkernel_cma(cma_size);
   140	}
   141	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki