From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v3 2/2] iommu/arm-smmu: add support for iova_to_phys through ATS1PR Date: Tue, 30 Sep 2014 11:23:34 +0100 Message-ID: <20140930102334.GH8075@arm.com> References: <1411874849-343-1-git-send-email-mitchelh@codeaurora.org> <1411874849-343-3-git-send-email-mitchelh@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1411874849-343-3-git-send-email-mitchelh-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Mitchel Humpherys Cc: "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: iommu@lists.linux-foundation.org Hi Mitch, On Sun, Sep 28, 2014 at 04:27:29AM +0100, Mitchel Humpherys wrote: > Currently, we provide the iommu_ops.iova_to_phys service by doing a > table walk in software to translate IO virtual addresses to physical > addresses. On SMMUs that support it, it can be useful to ask the SMMU > itself to do the translation. This can be used to warm the TLBs for an > SMMU. It can also be useful for testing and hardware validation. > > Since the address translation registers are optional on SMMUv2, only > enable hardware translations when using SMMUv1 or when SMMU_IDR0.S1TS=1 > and SMMU_IDR0.ATOSNS=0, as described in the ARM SMMU v1-v2 spec. [...] > +static phys_addr_t arm_smmu_iova_to_phys_hard(struct iommu_domain *domain, > + dma_addr_t iova) > +{ > + struct arm_smmu_domain *smmu_domain = domain->priv; > + struct arm_smmu_device *smmu = smmu_domain->smmu; > + struct arm_smmu_cfg *cfg = &smmu_domain->cfg; > + struct device *dev = smmu->dev; > + void __iomem *cb_base; > + u32 tmp; > + u64 phys; > + > + cb_base = ARM_SMMU_CB_BASE(smmu) + ARM_SMMU_CB(smmu, cfg->cbndx); > + > + if (smmu->version == 1) { > + u32 reg = iova & ~0xFFF; Cosmetic comment, but hex constants are lowercase everywhere else in the file. > + writel_relaxed(reg, cb_base + ARM_SMMU_CB_ATS1PR_LO); > + } else { > + u32 reg = iova & ~0xFFF; > + writel_relaxed(reg, cb_base + ARM_SMMU_CB_ATS1PR_LO); > + reg = (iova & ~0xFFF) >> 32; > + writel_relaxed(reg, cb_base + ARM_SMMU_CB_ATS1PR_HI); > + } > + > + if (readl_poll_timeout(cb_base + ARM_SMMU_CB_ATSR, tmp, > + !(tmp & ATSR_ACTIVE), 10, ATSR_LOOP_TIMEOUT)) { > + dev_err(dev, > + "iova to phys timed out on 0x%pa. Falling back to software table walk.\n", > + &iova); > + return arm_smmu_iova_to_phys_soft(domain, iova); > + } > + > + phys = readl_relaxed(cb_base + ARM_SMMU_CB_PAR_LO); > + phys |= ((u64) readl_relaxed(cb_base + ARM_SMMU_CB_PAR_HI)) << 32; The absence of locking in this function concerns me a bit. For the software implementation, we're just reading page tables, but here we're writing ATS registers and I think we need to ensure serialisation against another iova_to_phys on the same domain. > + if (phys & CB_PAR_F) { > + dev_err(dev, "translation fault!\n"); > + dev_err(dev, "PAR = 0x%llx\n", phys); > + } > + phys = (phys & 0xFFFFFFF000ULL) | (iova & 0x00000FFF); > + > + return phys; You can return phys == 0 on failure (at least, the callers in kvm and vfio treat this as an error). Will From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Tue, 30 Sep 2014 11:23:34 +0100 Subject: [PATCH v3 2/2] iommu/arm-smmu: add support for iova_to_phys through ATS1PR In-Reply-To: <1411874849-343-3-git-send-email-mitchelh@codeaurora.org> References: <1411874849-343-1-git-send-email-mitchelh@codeaurora.org> <1411874849-343-3-git-send-email-mitchelh@codeaurora.org> Message-ID: <20140930102334.GH8075@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Mitch, On Sun, Sep 28, 2014 at 04:27:29AM +0100, Mitchel Humpherys wrote: > Currently, we provide the iommu_ops.iova_to_phys service by doing a > table walk in software to translate IO virtual addresses to physical > addresses. On SMMUs that support it, it can be useful to ask the SMMU > itself to do the translation. This can be used to warm the TLBs for an > SMMU. It can also be useful for testing and hardware validation. > > Since the address translation registers are optional on SMMUv2, only > enable hardware translations when using SMMUv1 or when SMMU_IDR0.S1TS=1 > and SMMU_IDR0.ATOSNS=0, as described in the ARM SMMU v1-v2 spec. [...] > +static phys_addr_t arm_smmu_iova_to_phys_hard(struct iommu_domain *domain, > + dma_addr_t iova) > +{ > + struct arm_smmu_domain *smmu_domain = domain->priv; > + struct arm_smmu_device *smmu = smmu_domain->smmu; > + struct arm_smmu_cfg *cfg = &smmu_domain->cfg; > + struct device *dev = smmu->dev; > + void __iomem *cb_base; > + u32 tmp; > + u64 phys; > + > + cb_base = ARM_SMMU_CB_BASE(smmu) + ARM_SMMU_CB(smmu, cfg->cbndx); > + > + if (smmu->version == 1) { > + u32 reg = iova & ~0xFFF; Cosmetic comment, but hex constants are lowercase everywhere else in the file. > + writel_relaxed(reg, cb_base + ARM_SMMU_CB_ATS1PR_LO); > + } else { > + u32 reg = iova & ~0xFFF; > + writel_relaxed(reg, cb_base + ARM_SMMU_CB_ATS1PR_LO); > + reg = (iova & ~0xFFF) >> 32; > + writel_relaxed(reg, cb_base + ARM_SMMU_CB_ATS1PR_HI); > + } > + > + if (readl_poll_timeout(cb_base + ARM_SMMU_CB_ATSR, tmp, > + !(tmp & ATSR_ACTIVE), 10, ATSR_LOOP_TIMEOUT)) { > + dev_err(dev, > + "iova to phys timed out on 0x%pa. Falling back to software table walk.\n", > + &iova); > + return arm_smmu_iova_to_phys_soft(domain, iova); > + } > + > + phys = readl_relaxed(cb_base + ARM_SMMU_CB_PAR_LO); > + phys |= ((u64) readl_relaxed(cb_base + ARM_SMMU_CB_PAR_HI)) << 32; The absence of locking in this function concerns me a bit. For the software implementation, we're just reading page tables, but here we're writing ATS registers and I think we need to ensure serialisation against another iova_to_phys on the same domain. > + if (phys & CB_PAR_F) { > + dev_err(dev, "translation fault!\n"); > + dev_err(dev, "PAR = 0x%llx\n", phys); > + } > + phys = (phys & 0xFFFFFFF000ULL) | (iova & 0x00000FFF); > + > + return phys; You can return phys == 0 on failure (at least, the callers in kvm and vfio treat this as an error). Will