RE: [PATCH v7 2/7] irqchip/gic-v3: Enable support for SGIs to act as NMIs

From: ito-yuichi@xxxxxxxxxxx
Date: Wed Nov 18 2020 - 07:01:50 EST


Hi Sumit,

> Subject: [PATCH v7 2/7] irqchip/gic-v3: Enable support for SGIs to act as
> NMIs
>
> Add support to handle SGIs as pseudo NMIs. As SGIs or IPIs default to a
> special flow handler: handle_percpu_devid_fasteoi_ipi(), so skip NMI handler
> update in case of SGIs.
>
> Also, enable NMI support prior to gic_smp_init() as allocation of SGIs as
> IRQs/NMIs happen as part of this routine.
>
> Signed-off-by: Sumit Garg <sumit.garg@xxxxxxxxxx>
> ---
> drivers/irqchip/irq-gic-v3.c | 29 +++++++++++++++++++++--------
> 1 file changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c index
> 16fecc0..7010ae2 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -461,6 +461,7 @@ static u32 gic_get_ppi_index(struct irq_data *d)
> static int gic_irq_nmi_setup(struct irq_data *d) {
> struct irq_desc *desc = irq_to_desc(d->irq);
> + u32 idx;
>
> if (!gic_supports_nmi())
> return -EINVAL;
> @@ -478,16 +479,22 @@ static int gic_irq_nmi_setup(struct irq_data *d)
> return -EINVAL;
>
> /* desc lock should already be held */
> - if (gic_irq_in_rdist(d)) {
> - u32 idx = gic_get_ppi_index(d);
> + switch (get_intid_range(d)) {
> + case SGI_RANGE:
> + break;
> + case PPI_RANGE:
> + case EPPI_RANGE:
> + idx = gic_get_ppi_index(d);
>
> /* Setting up PPI as NMI, only switch handler for first NMI */
> if (!refcount_inc_not_zero(&ppi_nmi_refs[idx])) {
> refcount_set(&ppi_nmi_refs[idx], 1);
> desc->handle_irq =
> handle_percpu_devid_fasteoi_nmi;
> }
> - } else {
> + break;
> + default:
> desc->handle_irq = handle_fasteoi_nmi;
> + break;
> }
>
> gic_irq_set_prio(d, GICD_INT_NMI_PRI); @@ -498,6 +505,7 @@
> static int gic_irq_nmi_setup(struct irq_data *d) static void
> gic_irq_nmi_teardown(struct irq_data *d) {
> struct irq_desc *desc = irq_to_desc(d->irq);
> + u32 idx;
>
> if (WARN_ON(!gic_supports_nmi()))
> return;
> @@ -515,14 +523,20 @@ static void gic_irq_nmi_teardown(struct irq_data *d)
> return;
>
> /* desc lock should already be held */
> - if (gic_irq_in_rdist(d)) {
> - u32 idx = gic_get_ppi_index(d);
> + switch (get_intid_range(d)) {
> + case SGI_RANGE:
> + break;
> + case PPI_RANGE:
> + case EPPI_RANGE:
> + idx = gic_get_ppi_index(d);
>
> /* Tearing down NMI, only switch handler for last NMI */
> if (refcount_dec_and_test(&ppi_nmi_refs[idx]))
> desc->handle_irq = handle_percpu_devid_irq;
> - } else {
> + break;
> + default:
> desc->handle_irq = handle_fasteoi_irq;
> + break;
> }
>
> gic_irq_set_prio(d, GICD_INT_DEF_PRI); @@ -1708,6 +1722,7 @@
> static int __init gic_init_bases(void __iomem *dist_base,
>
> gic_dist_init();
> gic_cpu_init();
> + gic_enable_nmi_support();
> gic_smp_init();
> gic_cpu_pm_init();
>
> @@ -1719,8 +1734,6 @@ static int __init gic_init_bases(void __iomem
> *dist_base,
> gicv2m_init(handle, gic_data.domain);
> }
>
> - gic_enable_nmi_support();
> -
> return 0;
>
> out_free:
> --
> 2.7.4

I checked for this patch and I think that's good.
I've tested this patch with FX1000 used my other patches.
The result is as follows.

$ echo 1 > /proc/sys/kernel/panic_on_rcu_stal
$ echo HARDLOCKUP > /sys/kernel/debug/provoke-crash/DIRECT
: kernel panics and crash kernel boot
: makedumpfile saves the system state at HARDLOCKUP in vmcore.

crash utility:
#7 [fffffe0029e4fd30] lkdtm_HARDLOCKUP at fffffe0010856eec
#8 [fffffe0029e4fd40] direct_entry at fffffe0010856c94
#9 [fffffe0029e4fd90] full_proxy_write at fffffe001055ced0
#10 [fffffe0029e4fdd0] vfs_write at fffffe001047436c
#11 [fffffe0029e4fe10] ksys_write at fffffe001047466c
#12 [fffffe0029e4fe60] __arm64_sys_write at fffffe0010474718
#13 [fffffe0029e4fe70] do_el0_svc at fffffe00101590cc
#14 [fffffe0029e4fea0] el0_svc at fffffe0010147a30
#15 [fffffe0029e4feb0] el0_sync_handler at fffffe001014835c
#16 [fffffe0029e4fff0] el0_sync at fffffe0010142c14

Best regards,

Yuichi Ito