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Tue, 18 Feb 2020 15:31:03 +0000 MIME-Version: 1.0 Date: Tue, 18 Feb 2020 15:31:02 +0000 From: Marc Zyngier To: Zenghui Yu Subject: Re: [PATCH v4 08/20] irqchip/gic-v4.1: Plumb get/set_irqchip_state SGI callbacks In-Reply-To: <75597af0d2373ac4d92d8162a1338cbb@kernel.org> References: <20200214145736.18550-1-maz@kernel.org> <20200214145736.18550-9-maz@kernel.org> <4b7f71f1-5e7f-e6af-f47d-7ed0d3a8739f@huawei.com> <75597af0d2373ac4d92d8162a1338cbb@kernel.org> Message-ID: <19a7c193f0e4b97343e822a35f0911ed@kernel.org> X-Sender: maz@kernel.org User-Agent: Roundcube Webmail/1.3.10 X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: yuzenghui@huawei.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, lorenzo.pieralisi@arm.com, jason@lakedaemon.net, rrichter@marvell.com, tglx@linutronix.de, eric.auger@redhat.com, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200218_073108_797590_B99B7C8B X-CRM114-Status: GOOD ( 28.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lorenzo Pieralisi , Jason Cooper , kvm@vger.kernel.org, Suzuki K Poulose , linux-kernel@vger.kernel.org, Eric Auger , Robert Richter , James Morse , Julien Thierry , Thomas Gleixner , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Zenghui, On 2020-02-18 09:27, Marc Zyngier wrote: > Hi Zenghui, > > On 2020-02-18 07:00, Zenghui Yu wrote: >> Hi Marc, [...] >> There might be a race on reading the 'vpe->col_idx' against a >> concurrent >> vPE schedule (col_idx will be modified in its_vpe_set_affinity)? Will >> we >> end up accessing the GICR_VSGI* registers of the old redistributor, >> while the vPE is now resident on the new one? Or is it harmful? > > Very well spotted. There is a potential problem if old and new RDs are > not part > of the same CommonLPIAff group. > >> The same question for direct_lpi_inv(), where 'vpe->col_idx' will be >> used in irq_to_cpuid(). > > Same problem indeed. We need to ensure that no VMOVP operation can > occur whilst > we use col_idx to access a redistributor. This means a vPE lock of some > sort > that will protect the affinity. > > But I think there is a slightly more general problem here, which we > failed to > see initially: the same issue exists for physical LPIs, as col_map[] > can be > updated (its_set_affinity()) in parallel with a direct invalidate. > > The good old invalidation through the ITS does guarantee that the two > operation > don't overlap, but direct invalidation breaks it. > > Let me have a think about it. So I've thought about it, wrote a patch, and I don't really like the look of it. This is pretty invasive, and we end-up serializing a lot more than we used to (the repurposing of vlpi_lock to a general "lpi mapping lock" is probably too coarse). It of course needs splitting over at least three patches, but it'd be good if you could have a look (applies on top of the whole series). Thanks, M. diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 7656b353a95f..0ed286dba827 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -144,7 +144,7 @@ struct event_lpi_map { u16 *col_map; irq_hw_number_t lpi_base; int nr_lpis; - raw_spinlock_t vlpi_lock; + raw_spinlock_t map_lock; struct its_vm *vm; struct its_vlpi_map *vlpi_maps; int nr_vlpis; @@ -240,15 +240,33 @@ 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 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) { + raw_spin_lock_irqsave(&map->vpe->vpe_lock, *flags); + cpu = map->vpe->col_idx; + } else { + struct its_device *its_dev = irq_data_get_irq_chip_data(d); + raw_spin_lock_irqsave(&its_dev->event_map.map_lock, *flags); + cpu = its_dev->event_map.col_map[its_get_event_id(d)]; + } - 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) { + raw_spin_unlock_irqrestore(&map->vpe->vpe_lock, flags); + } else { + struct its_device *its_dev = irq_data_get_irq_chip_data(d); + raw_spin_unlock_irqrestore(&its_dev->event_map.map_lock, flags); + } } static struct its_collection *valid_col(struct its_collection *col) @@ -1384,6 +1402,8 @@ static void direct_lpi_inv(struct irq_data *d) { struct its_vlpi_map *map = get_vlpi_map(d); void __iomem *rdbase; + unsigned long flags; + int cpu; u64 val; if (map) { @@ -1399,10 +1419,12 @@ 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) @@ -1471,11 +1493,11 @@ static void its_unmask_irq(struct irq_data *d) static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val, bool force) { - unsigned int cpu; const struct cpumask *cpu_mask = cpu_online_mask; struct its_device *its_dev = irq_data_get_irq_chip_data(d); struct its_collection *target_col; - u32 id = its_get_event_id(d); + unsigned int from, cpu; + unsigned long flags; /* A forwarded interrupt should use irq_set_vcpu_affinity */ if (irqd_is_forwarded_to_vcpu(d)) @@ -1496,12 +1518,16 @@ static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val, return -EINVAL; /* don't set the affinity when the target cpu is same as current one */ - if (cpu != its_dev->event_map.col_map[id]) { + from = irq_to_cpuid_lock(d, &flags); + if (cpu != from) { + u32 id = its_get_event_id(d); + target_col = &its_dev->its->collections[cpu]; its_send_movi(its_dev, target_col, id); its_dev->event_map.col_map[id] = cpu; irq_data_update_effective_affinity(d, cpumask_of(cpu)); } + irq_to_cpuid_unlock(d, flags); return IRQ_SET_MASK_OK_DONE; } @@ -1636,7 +1662,7 @@ static int its_vlpi_map(struct irq_data *d, struct its_cmd_info *info) if (!info->map) return -EINVAL; - raw_spin_lock(&its_dev->event_map.vlpi_lock); + raw_spin_lock(&its_dev->event_map.map_lock); if (!its_dev->event_map.vm) { struct its_vlpi_map *maps; @@ -1685,7 +1711,7 @@ static int its_vlpi_map(struct irq_data *d, struct its_cmd_info *info) } out: - raw_spin_unlock(&its_dev->event_map.vlpi_lock); + raw_spin_unlock(&its_dev->event_map.map_lock); return ret; } @@ -1695,7 +1721,7 @@ static int its_vlpi_get(struct irq_data *d, struct its_cmd_info *info) struct its_vlpi_map *map; int ret = 0; - raw_spin_lock(&its_dev->event_map.vlpi_lock); + raw_spin_lock(&its_dev->event_map.map_lock); map = get_vlpi_map(d); @@ -1708,7 +1734,7 @@ static int its_vlpi_get(struct irq_data *d, struct its_cmd_info *info) *info->map = *map; out: - raw_spin_unlock(&its_dev->event_map.vlpi_lock); + raw_spin_unlock(&its_dev->event_map.map_lock); return ret; } @@ -1718,7 +1744,7 @@ static int its_vlpi_unmap(struct irq_data *d) u32 event = its_get_event_id(d); int ret = 0; - raw_spin_lock(&its_dev->event_map.vlpi_lock); + raw_spin_lock(&its_dev->event_map.map_lock); if (!its_dev->event_map.vm || !irqd_is_forwarded_to_vcpu(d)) { ret = -EINVAL; @@ -1748,7 +1774,7 @@ static int its_vlpi_unmap(struct irq_data *d) } out: - raw_spin_unlock(&its_dev->event_map.vlpi_lock); + raw_spin_unlock(&its_dev->event_map.map_lock); return ret; } @@ -3193,7 +3219,7 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id, dev->event_map.col_map = col_map; dev->event_map.lpi_base = lpi_base; dev->event_map.nr_lpis = nr_lpis; - raw_spin_lock_init(&dev->event_map.vlpi_lock); + raw_spin_lock_init(&dev->event_map.map_lock); dev->device_id = dev_id; INIT_LIST_HEAD(&dev->entry); @@ -3560,6 +3586,7 @@ 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 @@ -3567,6 +3594,7 @@ static int its_vpe_set_affinity(struct irq_data *d, * into the proxy device, we need to move the doorbell * interrupt to its new location. */ + raw_spin_lock_irqsave(&vpe->vpe_lock, flags); if (vpe->col_idx == cpu) goto out; @@ -3586,6 +3614,7 @@ static int its_vpe_set_affinity(struct irq_data *d, out: irq_data_update_effective_affinity(d, cpumask_of(cpu)); + raw_spin_unlock_irqrestore(&vpe->vpe_lock, flags); return IRQ_SET_MASK_OK_DONE; } @@ -3695,11 +3724,15 @@ static void its_vpe_send_inv(struct irq_data *d) if (gic_rdists->has_direct_lpi) { void __iomem *rdbase; + unsigned long flags; + int cpu; /* Target the redistributor this VPE is currently known on */ - rdbase = per_cpu_ptr(gic_rdists->rdist, vpe->col_idx)->rd_base; + cpu = irq_to_cpuid_lock(d, &flags); + rdbase = per_cpu_ptr(gic_rdists->rdist, cpu)->rd_base; gic_write_lpir(d->parent_data->hwirq, rdbase + GICR_INVLPIR); wait_for_syncr(rdbase); + irq_to_cpuid_unlock(d, flags); } else { its_vpe_send_cmd(vpe, its_send_inv); } @@ -3735,14 +3768,18 @@ static int its_vpe_set_irqchip_state(struct irq_data *d, if (gic_rdists->has_direct_lpi) { void __iomem *rdbase; + unsigned long flags; + int cpu; - rdbase = per_cpu_ptr(gic_rdists->rdist, vpe->col_idx)->rd_base; + cpu = irq_to_cpuid_lock(d, &flags); + rdbase = per_cpu_ptr(gic_rdists->rdist, cpu)->rd_base; if (state) { gic_write_lpir(vpe->vpe_db_lpi, rdbase + GICR_SETLPIR); } else { gic_write_lpir(vpe->vpe_db_lpi, rdbase + GICR_CLRLPIR); wait_for_syncr(rdbase); } + irq_to_cpuid_unlock(d, flags); } else { if (state) its_vpe_send_cmd(vpe, its_send_int); @@ -3854,14 +3891,17 @@ static void its_vpe_4_1_deschedule(struct its_vpe *vpe, static void its_vpe_4_1_invall(struct its_vpe *vpe) { void __iomem *rdbase; + unsigned long flags; u64 val; val = GICR_INVALLR_V; val |= FIELD_PREP(GICR_INVALLR_VPEID, vpe->vpe_id); /* Target the redistributor this vPE is currently known on */ + raw_spin_lock_irqsave(&vpe->vpe_lock, flags); rdbase = per_cpu_ptr(gic_rdists->rdist, vpe->col_idx)->rd_base; gic_write_lpir(val, rdbase + GICR_INVALLR); + raw_spin_unlock_irqrestore(&vpe->vpe_lock, flags); } static int its_vpe_4_1_set_vcpu_affinity(struct irq_data *d, void *vcpu_info) @@ -3960,13 +4000,17 @@ static int its_sgi_get_irqchip_state(struct irq_data *d, enum irqchip_irq_state which, bool *val) { struct its_vpe *vpe = irq_data_get_irq_chip_data(d); - void __iomem *base = gic_data_rdist_cpu(vpe->col_idx)->rd_base + SZ_128K; + void __iomem *base; + unsigned long flags; u32 count = 1000000; /* 1s! */ u32 status; + int cpu; if (which != IRQCHIP_STATE_PENDING) return -EINVAL; + cpu = irq_to_cpuid_lock(d, &flags); + base = gic_data_rdist_cpu(cpu)->rd_base + SZ_128K; writel_relaxed(vpe->vpe_id, base + GICR_VSGIR); do { status = readl_relaxed(base + GICR_VSGIPENDR); @@ -3983,6 +4027,7 @@ static int its_sgi_get_irqchip_state(struct irq_data *d, } while(count); out: + irq_to_cpuid_unlock(d, flags); *val = !!(status & (1 << d->hwirq)); return 0; @@ -4102,6 +4147,7 @@ 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 46c167a6349f..fc43a63875a3 100644 --- a/include/linux/irqchip/arm-gic-v4.h +++ b/include/linux/irqchip/arm-gic-v4.h @@ -60,6 +60,7 @@ struct its_vpe { }; }; + 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 -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel