Re: [PATCH v2 19/25] arm64: Add workaround for Cavium Thunder erratum 30115

Marc Zyngier
2017-06-06T15:18:15Z

On 06/06/17 13:48, Christoffer Dall wrote:
> On Thu, Jun 01, 2017 at 11:21:11AM +0100, Marc Zyngier wrote:
>> From: David Daney <david.daney@cavium.com>
>>
>> Some Cavium Thunder CPUs suffer a problem where a KVM guest may
>> inadvertently cause the host kernel to quit receiving interrupts.
>>
>> Use the Group-0/1 trapping in order to deal with it.
>>
>> [maz]: Adapted patch to the Group-0/1 trapping, reworked commit log
>>
>> Reviewed-by: Eric Auger <eric.auger@redhat.com>
>> Signed-off-by: David Daney <david.daney@cavium.com>
>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>> ---
>> Documentation/arm64/silicon-errata.txt | 1 +
>> arch/arm64/Kconfig | 11 +++++++++++
>> arch/arm64/include/asm/cpucaps.h | 3 ++-
>> arch/arm64/kernel/cpu_errata.c | 21 +++++++++++++++++++++
>> virt/kvm/arm/vgic/vgic-v3.c | 7 +++++++
>> 5 files changed, 42 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
>> index 10f2dddbf449..f5f93dca54b7 100644
>> --- a/Documentation/arm64/silicon-errata.txt
>> +++ b/Documentation/arm64/silicon-errata.txt
>> @@ -62,6 +62,7 @@ stable kernels.
>> | Cavium | ThunderX GICv3 | #23154 | CAVIUM_ERRATUM_23154 |
>> | Cavium | ThunderX Core | #27456 | CAVIUM_ERRATUM_27456 |
>> | Cavium | ThunderX SMMUv2 | #27704 | N/A |
>> +| Cavium | ThunderX Core | #30115 | CAVIUM_ERRATUM_30115 |
>> | | | | |
>> | Freescale/NXP | LS2080A/LS1043A | A-008585 | FSL_ERRATUM_A008585 |
>> | | | | |
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index 3dcd7ec69bca..0950b21e4d17 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -480,6 +480,17 @@ config CAVIUM_ERRATUM_27456
>>
>> If unsure, say Y.
>>
>> +config CAVIUM_ERRATUM_30115
>> + bool "Cavium erratum 30115: Guest may disable interrupts in host"
>> + default y
>> + help
>> + On ThunderX T88 pass 1.x through 2.2, T81 pass 1.0 through
>> + 1.2, and T83 Pass 1.0, KVM guest execution may disable
>> + interrupts in host. Trapping GICv3 group-1 accesses sidesteps
>> + the issue.
>> +
>> + If unsure, say Y.
>> +
>> config QCOM_FALKOR_ERRATUM_1003
>> bool "Falkor E1003: Incorrect translation due to ASID change"
>> default y
>> diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
>> index b3aab8a17868..8d2272c6822c 100644
>> --- a/arch/arm64/include/asm/cpucaps.h
>> +++ b/arch/arm64/include/asm/cpucaps.h
>> @@ -38,7 +38,8 @@
>> #define ARM64_WORKAROUND_REPEAT_TLBI 17
>> #define ARM64_WORKAROUND_QCOM_FALKOR_E1003 18
>> #define ARM64_WORKAROUND_858921 19
>> +#define ARM64_WORKAROUND_CAVIUM_30115 20
>>
>> -#define ARM64_NCAPS 20
>> +#define ARM64_NCAPS 21
>>
>> #endif /* __ASM_CPUCAPS_H */
>> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
>> index 2ed2a7657711..0e27f86ee709 100644
>> --- a/arch/arm64/kernel/cpu_errata.c
>> +++ b/arch/arm64/kernel/cpu_errata.c
>> @@ -133,6 +133,27 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
>> MIDR_RANGE(MIDR_THUNDERX_81XX, 0x00, 0x00),
>> },
>> #endif
>> +#ifdef CONFIG_CAVIUM_ERRATUM_30115
>> + {
>> + /* Cavium ThunderX, T88 pass 1.x - 2.2 */
>> + .desc = "Cavium erratum 30115",
>> + .capability = ARM64_WORKAROUND_CAVIUM_30115,
>> + MIDR_RANGE(MIDR_THUNDERX, 0x00,
>> + (1 << MIDR_VARIANT_SHIFT) | 2),
>> + },
>> + {
>> + /* Cavium ThunderX, T81 pass 1.0 - 1.2 */
>> + .desc = "Cavium erratum 30115",
>> + .capability = ARM64_WORKAROUND_CAVIUM_30115,
>> + MIDR_RANGE(MIDR_THUNDERX_81XX, 0x00, 0x02),
>> + },
>> + {
>> + /* Cavium ThunderX, T83 pass 1.0 */
>> + .desc = "Cavium erratum 30115",
>> + .capability = ARM64_WORKAROUND_CAVIUM_30115,
>> + MIDR_RANGE(MIDR_THUNDERX_83XX, 0x00, 0x00),
>> + },
>> +#endif
>> {
>> .desc = "Mismatched cache line size",
>> .capability = ARM64_MISMATCHED_CACHE_LINE_SIZE,
>> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
>> index 1486ce25edcb..062be1fe95b5 100644
>> --- a/virt/kvm/arm/vgic/vgic-v3.c
>> +++ b/virt/kvm/arm/vgic/vgic-v3.c
>> @@ -482,6 +482,13 @@ int vgic_v3_probe(const struct gic_kvm_info *info)
>> if (kvm_vgic_global_state.vcpu_base == 0)
>> kvm_info("disabling GICv2 emulation\n");
>>
>> +#ifdef CONFIG_ARM64
>> + if (cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_30115)) {
>> + group0_trap = true;
>> + group1_trap = true;
>
> Why does the config help text say that trapping group 1 accesses is
> enough, yet we trap both group 0 and group 1 ?

Ah, I missed the help text when adapting the original patch. My bad.
I'll fix that.

Thanks,

M.
--
Jazz is not dead. It just smells funny...