From: Jane Chu <[email protected]> Date: Mon, 5 Jun 2017 16:48:31 -0600
> Linux SPARC64 limits NR_CPUS to 4064 because init_cpu_send_mondo_info() > only allocates a single page for NR_CPUS mondo entries. Thus we cannot > use all 4096 CPUs on some SPARC platforms. > > To fix, allocate (2^order) pages where order is set according to the size > of cpu_list for possible cpus. Since cpu_list_pa and cpu_mondo_block_pa > are not used in asm code, there are no imm13 offsets from the base PA > that will break because they can only reach one page. > > Orabug: 25505750 > > Signed-off-by: Jane Chu <[email protected]> > > Reviewed-by: Bob Picco <[email protected]> > Reviewed-by: Atish Patra <[email protected]> > --- > arch/sparc/Kconfig | 4 ++-- > arch/sparc/kernel/irq_64.c | 16 ++++++++++++---- > 2 files changed, 14 insertions(+), 6 deletions(-) > > diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig > index 58243b0..4399be7 100644 > --- a/arch/sparc/Kconfig > +++ b/arch/sparc/Kconfig > @@ -192,9 +192,9 @@ config NR_CPUS > int "Maximum number of CPUs" > depends on SMP > range 2 32 if SPARC32 > - range 2 1024 if SPARC64 > + range 2 4096 if SPARC64 > default 32 if SPARC32 > - default 64 if SPARC64 > + default 4096 if SPARC64 > > source kernel/Kconfig.hz > > diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c > index 4d0248a..cc8f6c3 100644 > --- a/arch/sparc/kernel/irq_64.c > +++ b/arch/sparc/kernel/irq_64.c > @@ -1034,17 +1034,25 @@ static void __init init_cpu_send_mondo_info(struct > trap_per_cpu *tb) > { > #ifdef CONFIG_SMP > unsigned long page; > + void *mondo; > > - BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > (PAGE_SIZE - 64)); > + BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > PAGE_SIZE); > + > + /* Make sure mondo block is 64byte aligned */ > + mondo = kzalloc(64, GFP_KERNEL); > + if (!mondo) { > + prom_printf("SUN4V: Error, cannot allocate mondo block.\n"); > + prom_halt(); > + } > + tb->cpu_mondo_block_pa = __pa(mondo); Hmmm, you said that this has to be 64 byte aligned right? We might have to do something in order to insure that, as kmalloc() only guarantees ARCH_KMALLOC_MINALIGN which I think is 8 on sparc. I suppose this would work: mondo = kzalloc(64 + 63, GFP_KERNEL); and then 64-byte align that pointer.
