From: Marc Zyngier <maz@kernel.org>
To: Zenghui Yu <yuzenghui@huawei.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Jason Cooper <jason@lakedaemon.net>,
kvm@vger.kernel.org, Suzuki K Poulose <suzuki.poulose@arm.com>,
linux-kernel@vger.kernel.org, Eric Auger <eric.auger@redhat.com>,
Robert Richter <rrichter@marvell.com>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 08/20] irqchip/gic-v4.1: Plumb get/set_irqchip_state SGI callbacks
Date: Tue, 18 Feb 2020 09:27:44 +0000 [thread overview]
Message-ID: <75597af0d2373ac4d92d8162a1338cbb@kernel.org> (raw)
In-Reply-To: <4b7f71f1-5e7f-e6af-f47d-7ed0d3a8739f@huawei.com>
Hi Zenghui,
On 2020-02-18 07:00, Zenghui Yu wrote:
> Hi Marc,
>
> On 2020/2/14 22:57, Marc Zyngier wrote:
>> To implement the get/set_irqchip_state callbacks (limited to the
>> PENDING state), we have to use a particular set of hacks:
>>
>> - Reading the pending state is done by using a pair of new
>> redistributor
>> registers (GICR_VSGIR, GICR_VSGIPENDR), which allow the 16
>> interrupts
>> state to be retrieved.
>> - Setting the pending state is done by generating it as we'd otherwise
>> do
>> for a guest (writing to GITS_SGIR)
>> - Clearing the pending state is done by emiting a VSGI command with
>> the
>> "clear" bit set.
>>
>> Signed-off-by: Marc Zyngier <maz@kernel.org>
>> ---
>> drivers/irqchip/irq-gic-v3-its.c | 56
>> ++++++++++++++++++++++++++++++
>> include/linux/irqchip/arm-gic-v3.h | 14 ++++++++
>> 2 files changed, 70 insertions(+)
>>
>> diff --git a/drivers/irqchip/irq-gic-v3-its.c
>> b/drivers/irqchip/irq-gic-v3-its.c
>> index 1e448d9a16ea..a9753435c4ff 100644
>> --- a/drivers/irqchip/irq-gic-v3-its.c
>> +++ b/drivers/irqchip/irq-gic-v3-its.c
>> @@ -3915,11 +3915,67 @@ static int its_sgi_set_affinity(struct
>> irq_data *d,
>> return -EINVAL;
>> }
>> +static int its_sgi_set_irqchip_state(struct irq_data *d,
>> + enum irqchip_irq_state which,
>> + bool state)
>> +{
>> + if (which != IRQCHIP_STATE_PENDING)
>> + return -EINVAL;
>> +
>> + if (state) {
>> + struct its_vpe *vpe = irq_data_get_irq_chip_data(d);
>> + struct its_node *its = find_4_1_its();
>> + u64 val;
>> +
>> + val = FIELD_PREP(GITS_SGIR_VPEID, vpe->vpe_id);
>> + val |= FIELD_PREP(GITS_SGIR_VINTID, d->hwirq);
>> + writeq_relaxed(val, its->sgir_base + GITS_SGIR - SZ_128K);
>> + } else {
>> + its_configure_sgi(d, true);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +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;
>
> 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.
>
>> + u32 count = 1000000; /* 1s! */
>> + u32 status;
>> +
>> + if (which != IRQCHIP_STATE_PENDING)
>> + return -EINVAL;
>> +
>> + writel_relaxed(vpe->vpe_id, base + GICR_VSGIR);
>> + do {
>> + status = readl_relaxed(base + GICR_VSGIPENDR);
>> + if (!(status & GICR_VSGIPENDR_BUSY))
>> + goto out;
>> +
>> + count--;
>> + if (!count) {
>> + pr_err_ratelimited("Unable to get SGI status\n");
>> + goto out;
>> + }
>> + cpu_relax();
>> + udelay(1);
>> + } while(count);
>> +
>> +out:
>> + *val = !!(status & (1 << d->hwirq));
>> +
>> + return 0;
>> +}
>> +
>> static struct irq_chip its_sgi_irq_chip = {
>> .name = "GICv4.1-sgi",
>> .irq_mask = its_sgi_mask_irq,
>> .irq_unmask = its_sgi_unmask_irq,
>> .irq_set_affinity = its_sgi_set_affinity,
>> + .irq_set_irqchip_state = its_sgi_set_irqchip_state,
>> + .irq_get_irqchip_state = its_sgi_get_irqchip_state,
>> };
>> static int its_sgi_irq_domain_alloc(struct irq_domain *domain,
>> diff --git a/include/linux/irqchip/arm-gic-v3.h
>> b/include/linux/irqchip/arm-gic-v3.h
>> index a89578884263..64da945486ac 100644
>> --- a/include/linux/irqchip/arm-gic-v3.h
>> +++ b/include/linux/irqchip/arm-gic-v3.h
>> @@ -345,6 +345,15 @@
>> #define GICR_VPENDBASER_4_1_VGRP1EN (1ULL << 58)
>> #define GICR_VPENDBASER_4_1_VPEID GENMASK_ULL(15, 0)
>> +#define GICR_VSGIR 0x0080
>> +
>> +#define GICR_VSGIR_VPEID GENMASK(15, 0)
>> +
>> +#define GICR_VSGIPENDR 0x0088
>> +
>> +#define GICR_VSGIPENDR_BUSY (1U << 31)
>> +#define GICR_VSGIPENDR_PENDING GENMASK(15, 0)
>> +
>> /*
>> * ITS registers, offsets from ITS_base
>> */
>> @@ -368,6 +377,11 @@
>> #define GITS_TRANSLATER 0x10040
>> +#define GITS_SGIR 0x20020
>> +
>> +#define GITS_SGIR_VPEID GENMASK_ULL(47, 32)
>> +#define GITS_SGIR_VINTID GENMASK_ULL(7, 0)
>
> The spec says vINTID field is [3:0] of the GITS_SGIR.
Indeed, well spotted again!
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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next prev parent reply other threads:[~2020-02-18 9:27 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 14:57 [PATCH v4 00/20] irqchip/gic-v4: GICv4.1 architecture support Marc Zyngier
2020-02-14 14:57 ` [PATCH v4 01/20] irqchip/gic-v4.1: Skip absent CPUs while iterating over redistributors Marc Zyngier
2020-02-17 9:11 ` Zenghui Yu
2020-02-14 14:57 ` [PATCH v4 02/20] irqchip/gic-v3: Use SGIs without active state if offered Marc Zyngier
2020-02-17 9:18 ` Zenghui Yu
2020-02-14 14:57 ` [PATCH v4 03/20] irqchip/gic-v4.1: Advertise support v4.1 to KVM Marc Zyngier
2020-02-17 9:09 ` Zenghui Yu
2020-02-14 14:57 ` [PATCH v4 04/20] irqchip/gic-v4.1: Map the ITS SGIR register page Marc Zyngier
2020-02-20 3:17 ` Zenghui Yu
2020-02-14 14:57 ` [PATCH v4 05/20] irqchip/gic-v4.1: Plumb skeletal VSGI irqchip Marc Zyngier
2020-02-20 3:21 ` Zenghui Yu
2020-02-14 14:57 ` [PATCH v4 06/20] irqchip/gic-v4.1: Add initial SGI configuration Marc Zyngier
2020-02-18 7:25 ` Zenghui Yu
2020-02-18 9:46 ` Marc Zyngier
2020-02-20 3:25 ` Zenghui Yu
2020-02-14 14:57 ` [PATCH v4 07/20] irqchip/gic-v4.1: Plumb mask/unmask SGI callbacks Marc Zyngier
2020-02-20 3:32 ` Zenghui Yu
2020-02-14 14:57 ` [PATCH v4 08/20] irqchip/gic-v4.1: Plumb get/set_irqchip_state " Marc Zyngier
2020-02-18 7:00 ` Zenghui Yu
2020-02-18 9:27 ` Marc Zyngier [this message]
2020-02-18 15:31 ` Marc Zyngier
2020-02-19 11:50 ` Zenghui Yu
2020-02-19 15:18 ` Zenghui Yu
2020-02-20 3:11 ` Zenghui Yu
2020-02-28 19:37 ` Marc Zyngier
2020-03-01 19:00 ` Marc Zyngier
2020-03-02 8:18 ` Zenghui Yu
2020-03-02 12:09 ` Marc Zyngier
2020-02-14 14:57 ` [PATCH v4 09/20] irqchip/gic-v4.1: Plumb set_vcpu_affinity " Marc Zyngier
2020-02-20 3:37 ` Zenghui Yu
2020-02-28 19:00 ` Marc Zyngier
2020-02-14 14:57 ` [PATCH v4 10/20] irqchip/gic-v4.1: Move doorbell management to the GICv4 abstraction layer Marc Zyngier
2020-02-14 14:57 ` [PATCH v4 11/20] irqchip/gic-v4.1: Add VSGI allocation/teardown Marc Zyngier
2020-02-14 14:57 ` [PATCH v4 12/20] irqchip/gic-v4.1: Add VSGI property setup Marc Zyngier
2020-02-14 14:57 ` [PATCH v4 13/20] irqchip/gic-v4.1: Eagerly vmap vPEs Marc Zyngier
2020-02-14 14:57 ` [PATCH v4 14/20] KVM: arm64: GICv4.1: Let doorbells be auto-enabled Marc Zyngier
2020-02-14 14:57 ` [PATCH v4 15/20] KVM: arm64: GICv4.1: Add direct injection capability to SGI registers Marc Zyngier
2020-02-18 8:46 ` Zenghui Yu
2020-02-18 9:41 ` Marc Zyngier
2020-02-14 14:57 ` [PATCH v4 16/20] KVM: arm64: GICv4.1: Allow SGIs to switch between HW and SW interrupts Marc Zyngier
2020-02-20 3:55 ` Zenghui Yu
2020-02-28 19:16 ` Marc Zyngier
2020-03-02 2:40 ` Zenghui Yu
2020-02-14 14:57 ` [PATCH v4 17/20] KVM: arm64: GICv4.1: Plumb SGI implementation selection in the distributor Marc Zyngier
2020-02-14 14:57 ` [PATCH v4 18/20] KVM: arm64: GICv4.1: Reload VLPI configuration on distributor enable/disable Marc Zyngier
2020-02-14 14:57 ` [PATCH v4 19/20] KVM: arm64: GICv4.1: Allow non-trapping WFI when using HW SGIs Marc Zyngier
2020-02-14 14:57 ` [PATCH v4 20/20] KVM: arm64: GICv4.1: Expose HW-based SGIs in debugfs Marc Zyngier
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