Re: [PATCH v9 3/3] iommu/arm-smmu-v3: Add workaround for Cavium ThunderX2 erratum #126

Geetha Akula
2017-06-23T06:21:19Z

On Thu, Jun 22, 2017 at 11:52 PM, Will Deacon <will.deacon@arm.com> wrote:
> Hi Geetha,
>
> On Thu, Jun 22, 2017 at 05:35:38PM +0530, Geetha sowjanya wrote:
>> From: Geetha Sowjanya <geethasowjanya.akula@cavium.com>
>>
>> Cavium ThunderX2 SMMU doesn't support MSI and also doesn't have unique irq
>> lines for gerror, eventq and cmdq-sync.
>>
>> New named irq "combined" is set as a errata workaround, which allows to
>> share the irq line by register single irq handler for all the interrupts.
>>
>> Signed-off-by: Geetha sowjanya <gakula@caviumnetworks.com>
>> ---
>> Documentation/arm64/silicon-errata.txt | 1 +
>> .../devicetree/bindings/iommu/arm,smmu-v3.txt | 1 +
>> drivers/acpi/arm64/iort.c | 54 +++++++----
>> drivers/iommu/arm-smmu-v3.c | 105 +++++++++++++++-----
>> 4 files changed, 116 insertions(+), 45 deletions(-)
>
> Thanks, this looks much better. Two things to change below, and I'd like to
> see Lorenzo ack the iort changes.

Thanks Will. I have resend the patch with suggested changes.

Geetha.
>
>> diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
>> index 4693a32..42422f6 100644
>> --- a/Documentation/arm64/silicon-errata.txt
>> +++ b/Documentation/arm64/silicon-errata.txt
>> @@ -63,6 +63,7 @@ stable kernels.
>> | Cavium | ThunderX Core | #27456 | CAVIUM_ERRATUM_27456 |
>> | Cavium | ThunderX SMMUv2 | #27704 | N/A |
>> | Cavium | ThunderX2 SMMUv3| #74 | N/A |
>> +| Cavium | ThunderX2 SMMUv3| #126 | N/A |
>> | | | | |
>> | Freescale/NXP | LS2080A/LS1043A | A-008585 | FSL_ERRATUM_A008585 |
>> | | | | |
>> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu-v3.txt b/Documentation/devicetree/bindings/iommu/arm,smmu-v3.txt
>> index 6ecc48c..a5a1ca4 100644
>> --- a/Documentation/devicetree/bindings/iommu/arm,smmu-v3.txt
>> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu-v3.txt
>> @@ -26,6 +26,7 @@ the PCIe specification.
>> * "priq" - PRI Queue not empty
>> * "cmdq-sync" - CMD_SYNC complete
>> * "gerror" - Global Error activated
>> + * "combined" - Handles above all 4 interrupts.
>
> Please make it clear that:
>
> * The combined interrupt is optional, and should only be provided if
> the hardware supports just a single, combined interrupt line.
>
> * If provided, then the combined interrupt will be used in preference
> to any others.
>
>> - #iommu-cells : See the generic IOMMU binding described in
>> devicetree/bindings/pci/pci-iommu.txt
>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
>> index c166f3e..43e1f13 100644
>> --- a/drivers/acpi/arm64/iort.c
>> +++ b/drivers/acpi/arm64/iort.c
>> @@ -828,6 +828,18 @@ static int __init arm_smmu_v3_count_resources(struct acpi_iort_node *node)
>> return num_res;
>> }
>>
>> +static bool arm_smmu_v3_is_combined_irq(struct acpi_iort_smmu_v3 *smmu)
>> +{
>> + /*
>> + * Cavium ThunderX2 implementation doesn't not support unique
>> + * irq line. Use single irq line for all the SMMUv3 interrupts.
>> + */
>> + if (smmu->model == ACPI_IORT_SMMU_V3_CAVIUM_CN99XX)
>> + return true;
>> +
>> + return false;
>> +}
>> +
>> static unsigned long arm_smmu_v3_resource_size(struct acpi_iort_smmu_v3 *smmu)
>> {
>> /*
>> @@ -855,26 +867,32 @@ static void __init arm_smmu_v3_init_resources(struct resource *res,
>> res[num_res].flags = IORESOURCE_MEM;
>>
>> num_res++;
>> -
>> - if (smmu->event_gsiv)
>> - acpi_iort_register_irq(smmu->event_gsiv, "eventq",
>> - ACPI_EDGE_SENSITIVE,
>> - &res[num_res++]);
>> -
>> - if (smmu->pri_gsiv)
>> - acpi_iort_register_irq(smmu->pri_gsiv, "priq",
>> - ACPI_EDGE_SENSITIVE,
>> - &res[num_res++]);
>> -
>> - if (smmu->gerr_gsiv)
>> - acpi_iort_register_irq(smmu->gerr_gsiv, "gerror",
>> - ACPI_EDGE_SENSITIVE,
>> - &res[num_res++]);
>> -
>> - if (smmu->sync_gsiv)
>> - acpi_iort_register_irq(smmu->sync_gsiv, "cmdq-sync",
>> + if (arm_smmu_v3_is_combined_irq(smmu))
>> + acpi_iort_register_irq(smmu->event_gsiv, "combined",
>> ACPI_EDGE_SENSITIVE,
>> &res[num_res++]);
>> + else {
>> +
>> + if (smmu->event_gsiv)
>> + acpi_iort_register_irq(smmu->event_gsiv, "eventq",
>> + ACPI_EDGE_SENSITIVE,
>> + &res[num_res++]);
>> +
>> + if (smmu->pri_gsiv)
>> + acpi_iort_register_irq(smmu->pri_gsiv, "priq",
>> + ACPI_EDGE_SENSITIVE,
>> + &res[num_res++]);
>> +
>> + if (smmu->gerr_gsiv)
>> + acpi_iort_register_irq(smmu->gerr_gsiv, "gerror",
>> + ACPI_EDGE_SENSITIVE,
>> + &res[num_res++]);
>> +
>> + if (smmu->sync_gsiv)
>> + acpi_iort_register_irq(smmu->sync_gsiv, "cmdq-sync",
>> + ACPI_EDGE_SENSITIVE,
>> + &res[num_res++]);
>> + }
>> }
>>
>> static bool __init arm_smmu_v3_is_coherent(struct acpi_iort_node *node)
>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>> index 2dea4a9..0f83f7d 100644
>> --- a/drivers/iommu/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm-smmu-v3.c
>> @@ -605,6 +605,7 @@ struct arm_smmu_device {
>> struct arm_smmu_priq priq;
>>
>> int gerr_irq;
>> + int combined_irq;
>>
>> unsigned long ias; /* IPA */
>> unsigned long oas; /* PA */
>> @@ -1314,6 +1315,29 @@ static irqreturn_t arm_smmu_gerror_handler(int irq, void *dev)
>> return IRQ_HANDLED;
>> }
>>
>> +static irqreturn_t arm_smmu_combined_irq_thread(int irq, void *dev)
>> +{
>> + struct arm_smmu_device *smmu = dev;
>> +
>> + arm_smmu_evtq_thread(irq, dev);
>> + if (smmu->features & ARM_SMMU_FEAT_PRI)
>> + arm_smmu_priq_thread(irq, dev);
>> +
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static irqreturn_t arm_smmu_combined_irq_handler(int irq, void *dev)
>> +{
>> + irqreturn_t ret;
>> +
>> + ret = arm_smmu_gerror_handler(irq, dev);
>> + if (ret == IRQ_NONE) {
>
> I don't think you can play that trick if the irq is an edge-triggered
> interrupt, since you could lose an interrupt that fired whilst we were
> in the handler.
>
> The easiest thing is to always run the gerror and cmdq_sync handlers, and
> then always return IRQ_WAKE_THREAD.
>
> Will