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Message-ID: <CAKTKpr4rZMJVTN0DaKXhwV1WzUiU=j4X_KVRJ1z5dogLVWN+8w@mail.gmail.com>
Date: Fri, 19 Jan 2018 19:52:34 +0530
From: Ganapatrao Kulkarni <gklkml16@...il.com>
To: Marc Zyngier <marc.zyngier@....com>
Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@...ium.com>,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
Thomas Gleixner <tglx@...utronix.de>, jason@...edaemon.net,
catalin.marinas@....com, Will Deacon <will.deacon@....com>,
Jonathan Corbet <corbet@....net>, jnair@...iumnetworks.com,
Robert Richter <Robert.Richter@...ium.com>,
Jan.Glauber@...ium.com, Vadim.Lomovtsev@...ium.com
Subject: Re: [PATCH v2] irqchip/gic-v3-its: Add workaround for ThunderX2
erratum #174
On Fri, Jan 19, 2018 at 5:53 PM, Marc Zyngier <marc.zyngier@....com> wrote:
> On 18/01/18 05:28, Ganapatrao Kulkarni wrote:
>> This erratum is observed on the ThunderX2 GICv3 ITS. When a
>> MOVI command is used to change affinity of a LPI to a collection/cpu
>> on another node, the LPI is not delivered to the cpu.
>> An additional INV command is required after the MOVI to deliver
>> the LPI to the new destination.
>>
>> If we add INV after MOVI, there is a chance that we lose LPIs which
>> are raised when the affinity is changed. So for now, adding workaround fix
>> to disable inter node affinity change.
>>
>> Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@...ium.com>
>> ---
>>
>> v2: Added workaround to avoid inter node affinity change.
>>
>> v1: Initial patch
>>
>> Documentation/arm64/silicon-errata.txt | 1 +
>> arch/arm64/Kconfig | 10 ++++++++++
>> drivers/irqchip/irq-gic-v3-its.c | 21 ++++++++++++++++++++-
>> 3 files changed, 31 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
>> index fc1c884..fb27cb5 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 Core | #30115 | CAVIUM_ERRATUM_30115 |
>> | Cavium | ThunderX SMMUv2 | #27704 | N/A |
>> +| Cavium | ThunderX2 ITS | #174 | CAVIUM_ERRATUM_174 |
>> | Cavium | ThunderX2 SMMUv3| #74 | N/A |
>> | Cavium | ThunderX2 SMMUv3| #126 | N/A |
>> | | | | |
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index c9a7e9e..0dbf3bd 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -461,6 +461,16 @@ config ARM64_ERRATUM_843419
>>
>> If unsure, say Y.
>>
>> +config CAVIUM_ERRATUM_174
>> + bool "Cavium ThunderX2 erratum 174"
>> + default y
>> + help
>> + Cavium ThunderX2 dual socket systems may loose interrupts
>> + on affinity change to a cpu on other node.
>> + This workaround fix avoids inter node affinity change.
>> +
>> + If unsure, say Y.
>> +
>> config CAVIUM_ERRATUM_22375
>> bool "Cavium erratum 22375, 24313"
>> default y
>> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
>> index 06f025f..b0cb528 100644
>> --- a/drivers/irqchip/irq-gic-v3-its.c
>> +++ b/drivers/irqchip/irq-gic-v3-its.c
>> @@ -46,6 +46,7 @@
>> #define ITS_FLAGS_CMDQ_NEEDS_FLUSHING (1ULL << 0)
>> #define ITS_FLAGS_WORKAROUND_CAVIUM_22375 (1ULL << 1)
>> #define ITS_FLAGS_WORKAROUND_CAVIUM_23144 (1ULL << 2)
>> +#define ITS_FLAGS_WORKAROUND_CAVIUM_174 (1ULL << 3)
>
> Instead of inventing a new flag, please rename the existing one to
> ITS_FLAG_WORKAROUND_RESTRICT_NODE_AFFINITY (or something similar). There
> is really no need to have two flags that do the exact same thing,
#23144 is used to restrict ITS to collection mapping too,
where as 174 is only restricts cross node affinity.
Having said that, Since we are restricting affinity in #174,
i see there is no use of having ITS to other node collection mapping.
There should not be any issue if we club flag. I will post this change
in next version.
>
>>
>> #define RDIST_FLAGS_PROPBASE_NEEDS_FLUSHING (1 << 0)
>>
>> @@ -1102,7 +1103,8 @@ static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
>> return -EINVAL;
>>
>> /* lpi cannot be routed to a redistributor that is on a foreign node */
>> - if (its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144) {
>> + if (its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144 ||
>> + its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_174) {
>> if (its_dev->its->numa_node >= 0) {
>> cpu_mask = cpumask_of_node(its_dev->its->numa_node);
>> if (!cpumask_intersects(mask_val, cpu_mask))
>> @@ -2904,6 +2906,15 @@ static int its_force_quiescent(void __iomem *base)
>> }
>> }
>>
>> +static bool __maybe_unused its_enable_quirk_cavium_174(void *data)
>> +{
>> + struct its_node *its = data;
>> +
>> + its->flags |= ITS_FLAGS_WORKAROUND_CAVIUM_174;
>> +
>> + return true;
>> +}
>> +
>> static bool __maybe_unused its_enable_quirk_cavium_22375(void *data)
>> {
>> struct its_node *its = data;
>> @@ -3031,6 +3042,14 @@ static const struct gic_quirk its_quirks[] = {
>> .init = its_enable_quirk_hip07_161600802,
>> },
>> #endif
>> +#ifdef CONFIG_CAVIUM_ERRATUM_174
>> + {
>> + .desc = "ITS: Cavium ThunderX2 erratum 174",
>> + .iidr = 0x13f, /* ThunderX2 pass A1/A2/B0 */
>> + .mask = 0xffffffff,
>> + .init = its_enable_quirk_cavium_174,
>> + },
>> +#endif
>> {
>> }
>> };
>>
>
> Thanks,
>
> M.
> --
> Jazz is not dead. It just smells funny...
thanks
Ganapat
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