[PATCH 3/4] powerpc/kdump: consider high crashkernel memory if enabled

[Sourabh Jain <sourabhjain@linux.ibm.com>]

The next patch adds high crashkernel reservation support on powerpc, so
kdump setup is updated to handle high crashkernel while loading the kdump
kernel.

With high crashkernel reservation, the crashkernel is split into two
regions: low crashkernel and high crashkernel. To ensure kdump loads
properly with the split reservation, the following changes are made:

 - Load the kdump image in high memory if enabled
 - Include both low and high crashkernel regions in usable memory
   ranges for the kdump kernel
 - Exclude both low and high crashkernel regions from crashkernel memory
  to prevent them from being exported through /proc/vmcore

Cc: Baoquan he <bhe@redhat.com>
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/kexec/elf_64.c       | 10 +++++++---
 arch/powerpc/kexec/file_load_64.c |  5 +++--
 arch/powerpc/kexec/ranges.c       | 24 +++++++++++++++++++++---
 3 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
index 5d6d616404cf..ab84ff6d3685 100644
--- a/arch/powerpc/kexec/elf_64.c
+++ b/arch/powerpc/kexec/elf_64.c
@@ -52,9 +52,13 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 	if (IS_ENABLED(CONFIG_CRASH_DUMP) && image->type == KEXEC_TYPE_CRASH) {
 		/* min & max buffer values for kdump case */
 		kbuf.buf_min = pbuf.buf_min = crashk_res.start;
-		kbuf.buf_max = pbuf.buf_max =
-				((crashk_res.end < ppc64_rma_size) ?
-				 crashk_res.end : (ppc64_rma_size - 1));
+
+		if (crashk_low_res.end)
+			kbuf.buf_max = pbuf.buf_max = crashk_res.end;
+		else
+			kbuf.buf_max = pbuf.buf_max =
+					((crashk_res.end < ppc64_rma_size) ?
+					crashk_res.end : (ppc64_rma_size - 1));
 	}
 
 	ret = kexec_elf_load(image, &ehdr, &elf_info, &kbuf, &kernel_load_addr);
diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
index e7ef8b2a2554..d45f5748e75c 100644
--- a/arch/powerpc/kexec/file_load_64.c
+++ b/arch/powerpc/kexec/file_load_64.c
@@ -746,6 +746,7 @@ int setup_new_fdt_ppc64(const struct kimage *image, void *fdt, struct crash_mem
 	int i, nr_ranges, ret;
 
 #ifdef CONFIG_CRASH_DUMP
+	uint64_t crashk_start;
 	/*
 	 * Restrict memory usage for kdump kernel by setting up
 	 * usable memory ranges and memory reserve map.
@@ -765,8 +766,8 @@ int setup_new_fdt_ppc64(const struct kimage *image, void *fdt, struct crash_mem
 		 * Ensure we don't touch crashed kernel's memory except the
 		 * first 64K of RAM, which will be backed up.
 		 */
-		ret = fdt_add_mem_rsv(fdt, BACKUP_SRC_END + 1,
-				      crashk_res.start - BACKUP_SRC_SIZE);
+		crashk_start = crashk_low_res.end ? crashk_low_res.start : crashk_res.start;
+		ret = fdt_add_mem_rsv(fdt, BACKUP_SRC_END + 1, crashk_start - BACKUP_SRC_SIZE);
 		if (ret) {
 			pr_err("Error reserving crash memory: %s\n",
 			       fdt_strerror(ret));
diff --git a/arch/powerpc/kexec/ranges.c b/arch/powerpc/kexec/ranges.c
index c61aa96f0942..53e52e1f07c8 100644
--- a/arch/powerpc/kexec/ranges.c
+++ b/arch/powerpc/kexec/ranges.c
@@ -524,9 +524,20 @@ int get_usable_memory_ranges(struct crash_mem **mem_ranges)
 	 * Also, crashed kernel's memory must be added to reserve map to
 	 * avoid kdump kernel from using it.
 	 */
-	ret = add_mem_range(mem_ranges, 0, crashk_res.end + 1);
-	if (ret)
-		goto out;
+	if (crashk_low_res.end) {
+		ret = add_mem_range(mem_ranges, 0, crashk_low_res.end + 1);
+		if (ret)
+			goto out;
+
+		ret = add_mem_range(mem_ranges, crashk_res.start,
+				    crashk_res.end - crashk_res.start + 1);
+		if (ret)
+			goto out;
+	} else {
+		ret = add_mem_range(mem_ranges, 0, crashk_res.end + 1);
+		if (ret)
+			goto out;
+	}
 
 	for (i = 0; i < crashk_cma_cnt; i++) {
 		ret = add_mem_range(mem_ranges, crashk_cma_ranges[i].start,
@@ -610,6 +621,13 @@ int get_crash_memory_ranges(struct crash_mem **mem_ranges)
 	if (ret)
 		goto out;
 
+	if (crashk_low_res.end) {
+		ret = crash_exclude_mem_range_guarded(mem_ranges, crashk_low_res.start,
+						      crashk_low_res.end);
+		if (ret)
+			goto out;
+	}
+
 	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);
-- 
2.51.0