Messages in this thread Patch in this message | | | Subject | Re: [PATCH v5 03/23] irqchip/gic-v4.1: Ensure mutual exclusion between vPE affinity change and RD access | From | Zenghui Yu <> | Date | Thu, 12 Mar 2020 14:56:56 +0800 |
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On 2020/3/5 4:33, Marc Zyngier wrote: > Before GICv4.1, all operations would be serialized with the affinity > changes by virtue of using the same ITS command queue. With v4.1, things > change, as invalidations (and a number of other operations) are issued > using the redistributor MMIO frame. > > We must thus make sure that these redistributor accesses cannot race > against aginst the affinity change, or we may end-up talking to the ^^^^^^ > wrong redistributor. > > To ensure this, we expand the irq_to_cpuid() helper to take a spinlock > when the LPI is mapped to a vLPI (a new per-VPE lock) on each operation > that requires mutual exclusion. > > Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Thanks
> --- > drivers/irqchip/irq-gic-v3-its.c | 56 +++++++++++++++++++++++++----- > include/linux/irqchip/arm-gic-v4.h | 5 +++ > 2 files changed, 53 insertions(+), 8 deletions(-) > > diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c > index da883a691028..1af713990123 100644 > --- a/drivers/irqchip/irq-gic-v3-its.c > +++ b/drivers/irqchip/irq-gic-v3-its.c > @@ -239,15 +239,41 @@ static struct its_vlpi_map *get_vlpi_map(struct irq_data *d) > return NULL; > } > > -static int irq_to_cpuid(struct irq_data *d) > +static int vpe_to_cpuid_lock(struct its_vpe *vpe, unsigned long *flags) > +{ > + raw_spin_lock_irqsave(&vpe->vpe_lock, *flags); > + return vpe->col_idx; > +} > + > +static void vpe_to_cpuid_unlock(struct its_vpe *vpe, unsigned long flags) > +{ > + raw_spin_unlock_irqrestore(&vpe->vpe_lock, flags); > +} > + > +static int irq_to_cpuid_lock(struct irq_data *d, unsigned long *flags) > { > - struct its_device *its_dev = irq_data_get_irq_chip_data(d); > struct its_vlpi_map *map = get_vlpi_map(d); > + int cpu; > > - if (map) > - return map->vpe->col_idx; > + if (map) { > + cpu = vpe_to_cpuid_lock(map->vpe, flags); > + } else { > + /* Physical LPIs are already locked via the irq_desc lock */ > + struct its_device *its_dev = irq_data_get_irq_chip_data(d); > + cpu = its_dev->event_map.col_map[its_get_event_id(d)]; > + /* Keep GCC quiet... */ > + *flags = 0; > + } > > - return its_dev->event_map.col_map[its_get_event_id(d)]; > + return cpu; > +} > + > +static void irq_to_cpuid_unlock(struct irq_data *d, unsigned long flags) > +{ > + struct its_vlpi_map *map = get_vlpi_map(d); > + > + if (map) > + vpe_to_cpuid_unlock(map->vpe, flags); > } > > static struct its_collection *valid_col(struct its_collection *col) > @@ -1329,7 +1355,9 @@ static void direct_lpi_inv(struct irq_data *d) > { > struct its_vlpi_map *map = get_vlpi_map(d); > void __iomem *rdbase; > + unsigned long flags; > u64 val; > + int cpu; > > if (map) { > struct its_device *its_dev = irq_data_get_irq_chip_data(d); > @@ -1344,10 +1372,12 @@ static void direct_lpi_inv(struct irq_data *d) > } > > /* Target the redistributor this LPI is currently routed to */ > - rdbase = per_cpu_ptr(gic_rdists->rdist, irq_to_cpuid(d))->rd_base; > + cpu = irq_to_cpuid_lock(d, &flags); > + rdbase = per_cpu_ptr(gic_rdists->rdist, cpu)->rd_base; > gic_write_lpir(val, rdbase + GICR_INVLPIR); > > wait_for_syncr(rdbase); > + irq_to_cpuid_unlock(d, flags); > } > > static void lpi_update_config(struct irq_data *d, u8 clr, u8 set) > @@ -3486,17 +3516,25 @@ static int its_vpe_set_affinity(struct irq_data *d, > { > struct its_vpe *vpe = irq_data_get_irq_chip_data(d); > int from, cpu = cpumask_first(mask_val); > + unsigned long flags; > > /* > * Changing affinity is mega expensive, so let's be as lazy as > * we can and only do it if we really have to. Also, if mapped > * into the proxy device, we need to move the doorbell > * interrupt to its new location. > + * > + * Another thing is that changing the affinity of a vPE affects > + * *other interrupts* such as all the vLPIs that are routed to > + * this vPE. This means that the irq_desc lock is not enough to > + * protect us, and that we must ensure nobody samples vpe->col_idx > + * during the update, hence the lock below which must also be > + * taken on any vLPI handling path that evaluates vpe->col_idx. > */ > - if (vpe->col_idx == cpu) > + from = vpe_to_cpuid_lock(vpe, &flags); > + if (from == cpu) > goto out; > > - from = vpe->col_idx; > vpe->col_idx = cpu; > > /* > @@ -3512,6 +3550,7 @@ static int its_vpe_set_affinity(struct irq_data *d, > > out: > irq_data_update_effective_affinity(d, cpumask_of(cpu)); > + vpe_to_cpuid_unlock(vpe, flags); > > return IRQ_SET_MASK_OK_DONE; > } > @@ -3855,6 +3894,7 @@ static int its_vpe_init(struct its_vpe *vpe) > return -ENOMEM; > } > > + raw_spin_lock_init(&vpe->vpe_lock); > vpe->vpe_id = vpe_id; > vpe->vpt_page = vpt_page; > if (gic_rdists->has_rvpeid) > diff --git a/include/linux/irqchip/arm-gic-v4.h b/include/linux/irqchip/arm-gic-v4.h > index d9c34968467a..439963f4c66a 100644 > --- a/include/linux/irqchip/arm-gic-v4.h > +++ b/include/linux/irqchip/arm-gic-v4.h > @@ -53,6 +53,11 @@ struct its_vpe { > }; > }; > > + /* > + * Ensures mutual exclusion between affinity setting of the > + * vPE and vLPI operations using vpe->col_idx. > + */ > + raw_spinlock_t vpe_lock; > /* > * This collection ID is used to indirect the target > * redistributor for this VPE. The ID itself isn't involved in >
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