x86: implement crashkernel cma reservation

Implement the crashkernel CMA reservation for x86:
- enable parsing of the cma suffix by parse_crashkernel()
- reserve memory with reserve_crashkernel_cma()
- add the CMA-reserved ranges to the e820 map for the crash kernel
- exclude the CMA-reserved ranges from vmcore

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Jiri Bohac <[email protected]>
Cc: Baoquan He <[email protected]>
Cc: Dave Young <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Donald Dutile <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Philipp Rudo <[email protected]>
Cc: Pingfan Liu <[email protected]>
Cc: Tao Liu <[email protected]>
Cc: Vivek Goyal <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: jiribohac

arch/x86/kernel/crash.c

@@ -163,10 +163,10 @@ static struct crash_mem *fill_up_crash_elf_data(void)
 		return NULL;
 
 	/*
-	 * Exclusion of crash region and/or crashk_low_res may cause
-	 * another range split. So add extra two slots here.
+	 * Exclusion of crash region, crashk_low_res and/or crashk_cma_ranges
+	 * may cause range splits. So add extra slots here.
 	 */
-	nr_ranges += 2;
+	nr_ranges += 2 + crashk_cma_cnt;
 	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
 	if (!cmem)
 		return NULL;
@@ -184,6 +184,7 @@ static struct crash_mem *fill_up_crash_elf_data(void)
 static int elf_header_exclude_ranges(struct crash_mem *cmem)
 {
 	int ret = 0;
+	int i;
 
 	/* Exclude the low 1M because it is always reserved */
 	ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
@@ -198,8 +199,17 @@ static int elf_header_exclude_ranges(struct crash_mem *cmem)
 	if (crashk_low_res.end)
 		ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
 					      crashk_low_res.end);
+	if (ret)
+		return ret;
 
-	return ret;
+	for (i = 0; i < crashk_cma_cnt; ++i) {
+		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
+					      crashk_cma_ranges[i].end);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
 }
 
 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
@@ -374,6 +384,14 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
 		add_e820_entry(params, &ei);
 	}
 
+	for (i = 0; i < crashk_cma_cnt; ++i) {
+		ei.addr = crashk_cma_ranges[i].start;
+		ei.size = crashk_cma_ranges[i].end -
+			  crashk_cma_ranges[i].start + 1;
+		ei.type = E820_TYPE_RAM;
+		add_e820_entry(params, &ei);
+	}
+
 out:
 	vfree(cmem);
 	return ret;

arch/x86/kernel/setup.c

@@ -599,7 +599,7 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 
 static void __init arch_reserve_crashkernel(void)
 {
-	unsigned long long crash_base, crash_size, low_size = 0;
+	unsigned long long crash_base, crash_size, low_size = 0, cma_size = 0;
 	bool high = false;
 	int ret;
 
@@ -608,7 +608,7 @@ static void __init arch_reserve_crashkernel(void)
 
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
 				&crash_size, &crash_base,
-				&low_size, NULL, &high);
+				&low_size, &cma_size, &high);
 	if (ret)
 		return;
 
@@ -618,6 +618,7 @@ static void __init arch_reserve_crashkernel(void)
 	}
 
 	reserve_crashkernel_generic(crash_size, crash_base, low_size, high);
+	reserve_crashkernel_cma(cma_size);
 }
 
 static struct resource standard_io_resources[] = {