Subject: [PATCHv10 2/3] powerpc/kernel: Extend arrays' size to make room for a hole in cpu_possible_mask

From: Pingfan Liu <[email-masked]>
Date: Wed, 27 Dec 2023 10:41:26 +0800

From: Pingfan Liu <[email-masked]>

This patch aims to mark all the arrays which size is decided by
nr_cpu_ids or num_possible_cpus().  Later if a hole is allowed in
cpu_possible_mask, the corresponding array should extend to hold the
last bit number in cpu_possible_mask.

Signed-off-by: Pingfan Liu <[email-masked]>
Cc: Michael Ellerman <[email-masked]>
Cc: Nicholas Piggin <[email-masked]>
Cc: Christophe Leroy <[email-masked]>
Cc: Mahesh Salgaonkar <[email-masked]>
Cc: Wen Xiong <[email-masked]>
Cc: Baoquan He <[email-masked]>
Cc: Ming Lei <[email-masked]>
Cc: Sourabh Jain <[email-masked]>
Cc: Hari Bathini <[email-masked]>
Cc: [email-masked]
To: [email-masked]
---
 arch/powerpc/include/asm/paca.h    | 2 ++
 arch/powerpc/kernel/paca.c         | 8 ++++----
 arch/powerpc/kernel/setup-common.c | 2 +-
 arch/powerpc/kernel/smp.c          | 3 ++-
 4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index e667d455ecb4..a577d98dd0d8 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -299,5 +299,7 @@ static inline void free_unused_pacas(void) { }
 
 #endif /* CONFIG_PPC64 */
 
+extern int paca_last_cpu_num;
+
 #endif /* __KERNEL__ */
 #endif /* _ASM_POWERPC_PACA_H */
diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c
index 760f371cf096..840c74dd17d6 100644
--- a/arch/powerpc/kernel/paca.c
+++ b/arch/powerpc/kernel/paca.c
@@ -236,15 +236,15 @@ void setup_paca(struct paca_struct *new_paca)
 
 }
 
-static int __initdata paca_nr_cpu_ids;
+int __initdata paca_last_cpu_num;
 static int __initdata paca_ptrs_size;
 static int __initdata paca_struct_size;
 
 void __init allocate_paca_ptrs(void)
 {
-	paca_nr_cpu_ids = nr_cpu_ids;
+	paca_last_cpu_num = nr_cpu_ids;
 
-	paca_ptrs_size = sizeof(struct paca_struct *) * nr_cpu_ids;
+	paca_ptrs_size = sizeof(struct paca_struct *) * paca_last_cpu_num;
 	paca_ptrs = memblock_alloc_raw(paca_ptrs_size, SMP_CACHE_BYTES);
 	if (!paca_ptrs)
 		panic("Failed to allocate %d bytes for paca pointers\n",
@@ -258,7 +258,7 @@ void __init allocate_paca(int cpu)
 	u64 limit;
 	struct paca_struct *paca;
 
-	BUG_ON(cpu >= paca_nr_cpu_ids);
+	BUG_ON(cpu >= paca_last_cpu_num);
 
 #ifdef CONFIG_PPC_BOOK3S_64
 	/*
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 2f1026fba00d..f9f5f313abf0 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -453,7 +453,7 @@ void __init smp_setup_cpu_maps(void)
 
 	DBG("smp_setup_cpu_maps()\n");
 
-	cpu_to_phys_id = memblock_alloc(nr_cpu_ids * sizeof(u32),
+	cpu_to_phys_id = memblock_alloc(paca_last_cpu_num * sizeof(u32),
 					__alignof__(u32));
 	if (!cpu_to_phys_id)
 		panic("%s: Failed to allocate %zu bytes align=0x%zx\n",
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 5826f5108a12..6fefe22fd118 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1140,7 +1140,8 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 	}
 
 	if (cpu_to_chip_id(boot_cpuid) != -1) {
-		int idx = DIV_ROUND_UP(num_possible_cpus(), threads_per_core);
+		int idx = DIV_ROUND_UP(cpumask_last(cpu_possible_mask),
+				threads_per_core);
 
 		/*
 		 * All threads of a core will all belong to the same core,
-- 
2.31.1