From mboxrd@z Thu Jan 1 00:00:00 1970 From: robin.murphy@arm.com (Robin Murphy) Date: Mon, 24 Oct 2016 12:01:50 +0100 Subject: [PATCH] iommu: arm-smmu-v2: Enable 16 bit ASID In-Reply-To: <1477112524-13023-1-git-send-email-gakula@caviumnetworks.com> References: <1477112524-13023-1-git-send-email-gakula@caviumnetworks.com> Message-ID: <565784ce-a740-315d-e4db-5fdbb5a0316e@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Geetha, On 22/10/16 06:02, Geetha sowjanya wrote: > Support up to 16 bit ASID. This patch enables > 16 bit ASID when supported. Why? "Because we can" is not a compelling rationale. I assume this is actually related to the globally-unique ASID workaround for the TLB sharing erratum, but if so that should be called out explicitly - describe the problem being fixed. > Signed-off-by: Geetha sowjanya > Acked-by: Tirumalesh Chalamarla > --- > drivers/iommu/arm-smmu.c | 6 ++++++ > 1 files changed, 6 insertions(+), 0 deletions(-) > > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > index c841eb7..9740846 100644 > --- a/drivers/iommu/arm-smmu.c > +++ b/drivers/iommu/arm-smmu.c > @@ -258,6 +258,9 @@ enum arm_smmu_s2cr_privcfg { > #define TTBCR2_SEP_SHIFT 15 > #define TTBCR2_SEP_UPSTREAM (0x7 << TTBCR2_SEP_SHIFT) > > +#define TTBCR2_AS_SHIFT 4 > +#define TTBCR2_AS_ENABLE (1 << TTBCR2_AS_SHIFT) > + The style here for single-bit fields is simply: #define TTBCR2_AS (1 << 4) > #define TTBRn_ASID_SHIFT 48 > > #define FSR_MULTI (1 << 31) > @@ -773,6 +776,9 @@ static void arm_smmu_init_context_bank(struct arm_smmu_domain *smmu_domain, > reg = pgtbl_cfg->arm_lpae_s1_cfg.tcr; > reg2 = pgtbl_cfg->arm_lpae_s1_cfg.tcr >> 32; > reg2 |= TTBCR2_SEP_UPSTREAM; > + /* Enable 16 bit ASID if 16 bit VMID is supported */ > + if (smmu->features & ARM_SMMU_FEAT_VMID16) This should be a check for AArch64 context format - VMID16 has nothing to do with it. 16-bit ASID support for stage 1 AArch64 contexts is already implied by SMMUv2 (TCR2.AS is not optional). Robin. > + reg |= TTBCR2_AS_ENABLE; > } > if (smmu->version > ARM_SMMU_V1) > writel_relaxed(reg2, cb_base + ARM_SMMU_CB_TTBCR2); >