Messages in this thread | | | Subject | Re: [PATCH 2/2] irqchip/gic-v3-its: Move ITS' ->pend_page allocation into an early CPU up callback | From | Marc Zyngier <> | Date | Mon, 6 Aug 2018 09:15:32 +0100 |
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Hi Sebastian,
On 18/07/18 16:42, Sebastian Andrzej Siewior wrote: > The AP-GIC-starting callback allocates memory for the ->pend_page while > the CPU is started during boot-up. This callback is invoked on the > target CPU with disabled interrupts. > This does not work on -RT because memory allocations are not possible > with disabled interrupts. > Move the memory allocation to an earlier hotplug step which is invoked > with enabled interrupts on the boot CPU. > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- > drivers/irqchip/irq-gic-v3-its.c | 60 ++++++++++++++++++++++---------- > 1 file changed, 41 insertions(+), 19 deletions(-) > > diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c > index a616043d25ee..acc3d44c356d 100644 > --- a/drivers/irqchip/irq-gic-v3-its.c > +++ b/drivers/irqchip/irq-gic-v3-its.c > @@ -171,6 +171,7 @@ static DEFINE_RAW_SPINLOCK(vmovp_lock); > static DEFINE_IDA(its_vpeid_ida); > > #define gic_data_rdist() (raw_cpu_ptr(gic_rdists->rdist)) > +#define gic_data_rdist_cpu(cpu) (per_cpu_ptr(gic_rdists->rdist, cpu)) > #define gic_data_rdist_rd_base() (gic_data_rdist()->rd_base) > #define gic_data_rdist_vlpi_base() (gic_data_rdist_rd_base() + SZ_128K) > > @@ -1853,15 +1854,17 @@ static int its_alloc_collections(struct its_node *its) > return 0; > } > > -static struct page *its_allocate_pending_table(gfp_t gfp_flags) > +static struct page *its_allocate_pending_table(unsigned int cpu) > { > struct page *pend_page; > + unsigned int order; > /* > * The pending pages have to be at least 64kB aligned, > * hence the 'max(LPI_PENDBASE_SZ, SZ_64K)' below. > */ > - pend_page = alloc_pages(gfp_flags | __GFP_ZERO, > - get_order(max_t(u32, LPI_PENDBASE_SZ, SZ_64K))); > + order = get_order(max_t(u32, LPI_PENDBASE_SZ, SZ_64K)); > + pend_page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL | __GFP_ZERO, > + order); > if (!pend_page) > return NULL; > > @@ -1877,6 +1880,28 @@ static void its_free_pending_table(struct page *pt) > get_order(max_t(u32, LPI_PENDBASE_SZ, SZ_64K))); > } > > +static int its_alloc_pend_page(unsigned int cpu) > +{ > + struct page *pend_page; > + phys_addr_t paddr; > + > + pend_page = gic_data_rdist_cpu(cpu)->pend_page; > + if (pend_page) > + return 0; > + > + pend_page = its_allocate_pending_table(cpu); > + if (!pend_page) { > + pr_err("Failed to allocate PENDBASE for CPU%d\n", > + smp_processor_id()); > + return -ENOMEM; > + } > + > + paddr = page_to_phys(pend_page); > + pr_info("CPU%d: using LPI pending table @%pa\n", cpu, &paddr); > + gic_data_rdist_cpu(cpu)->pend_page = pend_page; > + return 0; > +} > + > static void its_cpu_init_lpis(void) > { > void __iomem *rbase = gic_data_rdist_rd_base(); > @@ -1885,21 +1910,8 @@ static void its_cpu_init_lpis(void) > > /* If we didn't allocate the pending table yet, do it now */ > pend_page = gic_data_rdist()->pend_page; > - if (!pend_page) { > - phys_addr_t paddr; > - > - pend_page = its_allocate_pending_table(GFP_NOWAIT); > - if (!pend_page) { > - pr_err("Failed to allocate PENDBASE for CPU%d\n", > - smp_processor_id()); > - return; > - } > - > - paddr = page_to_phys(pend_page); > - pr_info("CPU%d: using LPI pending table @%pa\n", > - smp_processor_id(), &paddr); > - gic_data_rdist()->pend_page = pend_page; > - } > + if (WARN_ON(!pend_page)) > + return; > > /* set PROPBASE */ > val = (page_to_phys(gic_rdists->prop_page) | > @@ -2732,7 +2744,7 @@ static int its_vpe_init(struct its_vpe *vpe) > return vpe_id; > > /* Allocate VPT */ > - vpt_page = its_allocate_pending_table(GFP_KERNEL); > + vpt_page = its_allocate_pending_table(raw_smp_processor_id()); > if (!vpt_page) { > its_vpe_id_free(vpe_id); > return -ENOMEM; > @@ -3706,6 +3718,16 @@ int __init its_init(struct fwnode_handle *handle, struct rdists *rdists, > if (err) > return err; > > + err = cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "irqchip/arm/gicv3:prepare", > + its_alloc_pend_page, NULL); > + if (err < 0) { > + pr_warn("ITS: Can't register CPU-hoplug callback.\n"); > + return err; > + } > + err = its_alloc_pend_page(smp_processor_id()); > + if (err < 0) > + return err; > + > list_for_each_entry(its, &its_nodes, entry) > has_v4 |= its->is_v4; > >
I must say I'm not overly keen on the extra hotplug notifier, and I'd rather allocate all the memory upfront on the boot CPU.
I've implemented this as part of a series that is required for kexec/kdump support[1] (and specifically this[2] patch). Could you please have a look and let me know if that works for you? I otherwise plan to post it for review once the 4.19 merge window has closed.
Thanks,
M.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=irq/gicv3-kdump [2] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=irq/gicv3-kdump&id=effe377d415900af10e206173d60dc6cc3f0662c -- Jazz is not dead. It just smells funny...
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