powerpc/64s: Allocate LPPACAs individually

We no longer allocate lppacas in an array, so this patch removes the
1kB static alignment for the structure, and enforces the PAPR
alignment requirements at allocation time. We can not reduce the 1kB
allocation size however, due to existing KVM hypervisors.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 30 insertions, 59 deletions

diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c
index eef4891c9af6..6cddb9bdc151 100644
--- a/arch/powerpc/kernel/paca.c
+++ b/arch/powerpc/kernel/paca.c
@@ -23,82 +23,50 @@
 #ifdef CONFIG_PPC_PSERIES
 
 /*
- * The structure which the hypervisor knows about - this structure
- * should not cross a page boundary.  The vpa_init/register_vpa call
- * is now known to fail if the lppaca structure crosses a page
- * boundary.  The lppaca is also used on POWER5 pSeries boxes.
- * The lppaca is 640 bytes long, and cannot readily
- * change since the hypervisor knows its layout, so a 1kB alignment
- * will suffice to ensure that it doesn't cross a page boundary.
+ * See asm/lppaca.h for more detail.
+ *
+ * lppaca structures must must be 1kB in size, L1 cache line aligned,
+ * and not cross 4kB boundary. A 1kB size and 1kB alignment will satisfy
+ * these requirements.
  */
-struct lppaca lppaca[] = {
-	[0 ... (NR_LPPACAS-1)] = {
+static inline void init_lppaca(struct lppaca *lppaca)
+{
+	BUILD_BUG_ON(sizeof(struct lppaca) != 640);
+
+	*lppaca = (struct lppaca) {
 		.desc = cpu_to_be32(0xd397d781),	/* "LpPa" */
-		.size = cpu_to_be16(sizeof(struct lppaca)),
+		.size = cpu_to_be16(0x400),
 		.fpregs_in_use = 1,
 		.slb_count = cpu_to_be16(64),
 		.vmxregs_in_use = 0,
-		.page_ins = 0,
-	},
+		.page_ins = 0, };
 };
 
-static struct lppaca *extra_lppacas;
-static long __initdata lppaca_size;
-
-static void __init allocate_lppacas(int nr_cpus, unsigned long limit)
-{
-	if (early_cpu_has_feature(CPU_FTR_HVMODE))
-		return;
-
-	if (nr_cpus <= NR_LPPACAS)
-		return;
-
-	lppaca_size = PAGE_ALIGN(sizeof(struct lppaca) *
-				 (nr_cpus - NR_LPPACAS));
-	extra_lppacas = __va(memblock_alloc_base(lppaca_size,
-						 PAGE_SIZE, limit));
-}
-
-static struct lppaca * __init new_lppaca(int cpu)
+static struct lppaca * __init new_lppaca(int cpu, unsigned long limit)
 {
 	struct lppaca *lp;
+	size_t size = 0x400;
+
+	BUILD_BUG_ON(size < sizeof(struct lppaca));
 
 	if (early_cpu_has_feature(CPU_FTR_HVMODE))
 		return NULL;
 
-	if (cpu < NR_LPPACAS)
-		return &lppaca[cpu];
-
-	lp = extra_lppacas + (cpu - NR_LPPACAS);
-	*lp = lppaca[0];
+	lp = __va(memblock_alloc_base(size, 0x400, limit));
+	init_lppaca(lp);
 
 	return lp;
 }
 
-static void __init free_lppacas(void)
+static void __init free_lppaca(struct lppaca *lp)
 {
-	long new_size = 0, nr;
+	size_t size = 0x400;
 
 	if (early_cpu_has_feature(CPU_FTR_HVMODE))
 		return;
 
-	if (!lppaca_size)
-		return;
-	nr = num_possible_cpus() - NR_LPPACAS;
-	if (nr > 0)
-		new_size = PAGE_ALIGN(nr * sizeof(struct lppaca));
-	if (new_size >= lppaca_size)
-		return;
-
-	memblock_free(__pa(extra_lppacas) + new_size, lppaca_size - new_size);
-	lppaca_size = new_size;
+	memblock_free(__pa(lp), size);
 }
-
-#else
-
-static inline void allocate_lppacas(int nr_cpus, unsigned long limit) { }
-static inline void free_lppacas(void) { }
-
 #endif /* CONFIG_PPC_BOOK3S */
 
 #ifdef CONFIG_PPC_BOOK3S_64
@@ -167,7 +135,7 @@ EXPORT_SYMBOL(paca_ptrs);
 void __init initialise_paca(struct paca_struct *new_paca, int cpu)
 {
 #ifdef CONFIG_PPC_PSERIES
-	new_paca->lppaca_ptr = new_lppaca(cpu);
+	new_paca->lppaca_ptr = NULL;
 #endif
 #ifdef CONFIG_PPC_BOOK3E
 	new_paca->kernel_pgd = swapper_pg_dir;
@@ -254,13 +222,15 @@ void __init allocate_pacas(void)
 	printk(KERN_DEBUG "Allocated %lu bytes for %u pacas\n",
 			size, nr_cpu_ids);
 
-	allocate_lppacas(nr_cpu_ids, limit);
-
 	allocate_slb_shadows(nr_cpu_ids, limit);
 
 	/* Can't use for_each_*_cpu, as they aren't functional yet */
-	for (cpu = 0; cpu < nr_cpu_ids; cpu++)
+	for (cpu = 0; cpu < nr_cpu_ids; cpu++) {
 		initialise_paca(paca_ptrs[cpu], cpu);
+#ifdef CONFIG_PPC_PSERIES
+		paca_ptrs[cpu]->lppaca_ptr = new_lppaca(cpu, limit);
+#endif
+	}
 }
 
 void __init free_unused_pacas(void)
@@ -272,6 +242,9 @@ void __init free_unused_pacas(void)
 	for (cpu = 0; cpu < paca_nr_cpu_ids; cpu++) {
 		if (!cpu_possible(cpu)) {
 			unsigned long pa = __pa(paca_ptrs[cpu]);
+#ifdef CONFIG_PPC_PSERIES
+			free_lppaca(paca_ptrs[cpu]->lppaca_ptr);
+#endif
 			memblock_free(pa, sizeof(struct paca_struct));
 			paca_ptrs[cpu] = NULL;
 			size += sizeof(struct paca_struct);
@@ -288,8 +261,6 @@ void __init free_unused_pacas(void)
 	if (size)
 		printk(KERN_DEBUG "Freed %lu bytes for unused pacas\n", size);
 
-	free_lppacas();
-
 	paca_nr_cpu_ids = nr_cpu_ids;
 	paca_ptrs_size = new_ptrs_size;
 }