powerpc: consider CPU count while calculating crashkernel value

The next patch in the series adds more CPUs to the capture kernel,
which increases the memory requirement for the capture kernel.
Experiments show that powerpc needs 1 MB of additional memory for every
CPU added.

Therefore, while calculating the crashkernel size, make sure to include
an additional 1 MB for every CPU configured in the capture kernel.

The changes are implemented in such a way that if the user changes the
nr_cpus value in the kdump configuration, the script will adapt
accordingly.

If other architectures decide to enable more CPUs in the kdump kernel,
then defining the _pcpu_area variable in
kdump_get_arch_recommend_crashkernel()/kdump-lib.sh function will be
sufficient for this solution.

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>

Author: sourabhjains

kdump-lib.sh

@@ -1000,10 +1000,13 @@ _crashkernel_add()
 # get default crashkernel
 # $1 dump mode, if not specified, dump_mode will be judged by is_fadump_capable
 # $2 kernel-release, if not specified, got by _get_kdump_kernel_version
+# $3: number of CPUs configured for kdump kernel (nr_cpus)
 # shellcheck disable=SC2120 # kdumpctl will call this func with an argument
 kdump_get_arch_recommend_crashkernel()
 {
 	local _arch _ck_cmdline _dump_mode
+	local _nr_cpus=$3
+	local _pcpu_area=0
 	local _delta=0
 
 	if [[ -z $1 ]]; then
@@ -1047,6 +1050,9 @@ kdump_get_arch_recommend_crashkernel()
 			has_mlx5 && ((_delta += 150))
 		fi
 	elif [[ $_arch == "ppc64le" ]]; then
+		# 1MB per CPU
+		_pcpu_area=1
+		_delta=$(( _delta + _pcpu_area * _nr_cpus ))
 		if [[ $_dump_mode == "fadump" ]]; then
 			_ck_cmdline="4G-16G:768M,16G-64G:1G,64G-128G:2G,128G-1T:4G,1T-2T:6G,2T-4T:12G,4T-8T:20G,8T-16T:36G,16T-32T:64G,32T-64T:128G,64T-:180G"
 		else
@@ -1059,16 +1065,18 @@ kdump_get_arch_recommend_crashkernel()
 
 # return recommended size based on current system RAM size
 # $1: kernel version, if not set, will defaults to $(uname -r)
+# $2: number of CPUs configured for kdump kernel (nr_cpus)
 kdump_get_arch_recommend_size()
 {
 	local _ck_cmdline _sys_mem
+	local _nr_cpus=$2
 
 	if ! [[ -r "/proc/iomem" ]]; then
 		echo "Error, can not access /proc/iomem."
 		return 1
 	fi
 	_sys_mem=$(get_system_size)
-	_ck_cmdline=$(kdump_get_arch_recommend_crashkernel)
+	_ck_cmdline=$(kdump_get_arch_recommend_crashkernel "" "" "$_nr_cpus")
 	_ck_cmdline=${_ck_cmdline//-:/-102400T:}
 	get_recommend_size "$_sys_mem" "$_ck_cmdline"
 }

kdumpctl

@@ -12,6 +12,7 @@ DEFAULT_INITRD_BAK=""
 INITRD_CHECKSUM_LOCATION=""
 KDUMP_INITRD=""
 TARGET_INITRD=""
+NR_CPUS=""
 #kdump shall be the default dump mode
 DEFAULT_DUMP_MODE="kdump"
 VMCORE_CREATION_STATUS="/var/lib/kdump/vmcore-creation.status"
@@ -147,6 +148,20 @@ determine_dump_mode()
 	ddebug "DEFAULT_DUMP_MODE=$DEFAULT_DUMP_MODE"
 }
 
+find_nr_cpus()
+{
+	local _cmdline_append
+
+	# shellcheck disable=SC2153
+	if is_fadump_capable; then
+		_cmdline_append="$FADUMP_COMMANDLINE_APPEND"
+	else
+		_cmdline_append="$KDUMP_COMMANDLINE_APPEND"
+	fi
+	NR_CPUS=$(echo "$_cmdline_append" | sed -n 's/.*nr_cpus=\([0-9]\+\).*/\1/p')
+	ddebug "Configured nr_cpus=$NR_CPUS"
+}
+
 rebuild_fadump_initrd()
 {
 	if ! $MKFADUMPRD "$DEFAULT_INITRD_BAK" "$TARGET_INITRD" --kver "$KDUMP_KERNELVER"; then
@@ -1360,7 +1375,7 @@ do_estimate()
 	esac
 
 	kdump_mods="$(lsinitrd "$TARGET_INITRD" -f /usr/lib/dracut/hostonly-kernel-modules.txt | tr '\n' ' ')"
-	baseline=$(kdump_get_arch_recommend_size)
+	baseline=$(kdump_get_arch_recommend_size "" "$NR_CPUS")
 	if [[ ${baseline: -1} == "M" ]]; then
 		baseline=${baseline%M}
 	elif [[ ${baseline: -1} == "G" ]]; then
@@ -1456,7 +1471,7 @@ get_default_crashkernel()
 {
 	local _dump_mode=$1
 
-	kdump_get_arch_recommend_crashkernel "$_dump_mode"
+	kdump_get_arch_recommend_crashkernel "$_dump_mode" "" "$NR_CPUS"
 }
 
 # Read kernel cmdline parameter for a specific kernel
@@ -1651,7 +1666,7 @@ reset_crashkernel()
 	#    to repeat it.
 	if is_ostree; then
 		_old_ck=$(rpm-ostree kargs | sed -n -E 's/.*(^|\s)crashkernel=(\S*).*/\2/p')
-		_new_ck=$(kdump_get_arch_recommend_crashkernel kdump)
+		_new_ck=$(kdump_get_arch_recommend_crashkernel kdump "" "$NR_CPUS")
 		if _update_kernel_cmdline "" crashkernel "$_old_ck" "$_new_ck"; then
 			[[ $_reboot == yes ]] && systemctl reboot
 		fi
@@ -1675,7 +1690,7 @@ reset_crashkernel()
 		_has_changed=""
 		if [[ $(uname -m) == ppc64le ]]; then
 			if [[ -n $_opt_fadump ]]; then
-				_new_ck=$(kdump_get_arch_recommend_crashkernel "$_dump_mode")
+				_new_ck=$(kdump_get_arch_recommend_crashkernel "$_dump_mode" "" "$NR_CPUS")
 				_old_fadump=$(get_grub_kernel_boot_parameter "$_kernel" fadump)
 				_new_fadump="$_opt_fadump"
 				[[ $_new_fadump == off ]] && _new_fadump=""
@@ -1688,10 +1703,10 @@ reset_crashkernel()
 				fi
 			else
 				_dump_mode="$(get_dump_mode_by_kernel "$_kernel")"
-				_new_ck=$(kdump_get_arch_recommend_crashkernel "$_dump_mode")
+				_new_ck=$(kdump_get_arch_recommend_crashkernel "$_dump_mode" "" "$NR_CPUS")
 			fi
 		else
-			_new_ck=$(kdump_get_arch_recommend_crashkernel kdump)
+			_new_ck=$(kdump_get_arch_recommend_crashkernel kdump "" "$NR_CPUS")
 		fi
 
 		_old_ck=$(get_grub_kernel_boot_parameter "$_kernel" crashkernel)
@@ -1730,7 +1745,7 @@ _update_crashkernel()
 	_old_ck=$(get_grub_kernel_boot_parameter "$_kernel" crashkernel)
 	_kver=$(parse_kver_from_path "$_kernel")
 	# The second argument is for the case of aarch64, where installing a 64k variant on a 4k kernel, or vice versa
-	_new_ck=$(kdump_get_arch_recommend_crashkernel "$_dump_mode" "$_kver")
+	_new_ck=$(kdump_get_arch_recommend_crashkernel "$_dump_mode" "$_kver" "$NR_CPUS")
 	if _update_kernel_cmdline "$_kernel" crashkernel "$_old_ck" "$_new_ck"; then
 		_msg="For kernel=$_kernel, crashkernel=$_new_ck now. Please reboot the system for the change to take effect."
 		_msg+=" Note if you don't want kdump-utils to manage the crashkernel kernel parameter, please set auto_reset_crashkernel=no in /etc/kdump.conf."
@@ -1981,6 +1996,7 @@ main()
 {
 	# Determine if the dump mode is kdump or fadump
 	determine_dump_mode
+	find_nr_cpus
 
 	case "$1" in
 	start)