On Tue, May 21, 2019 at 06:43:34PM +0100, Robin Murphy wrote: > On 21/05/2019 17:13, Jordan Crouse wrote: > >Allow IOMMU enabled devices specified on an opt-in list to create a > >default identity domain for a new IOMMU group and bypass the DMA > >domain created by the IOMMU core. This allows the group to be properly > >set up but otherwise skips touching the hardware until the client > >device attaches a unmanaged domain of its own. > > All the cool kids are using iommu_request_dm_for_dev() to force an identity > domain for particular devices, won't that suffice for this case too? There > is definite scope for improvement in this area, so I'd really like to keep > things as consistent as possible to make that easier in future.
I initially rejected iommu_request_dm_for_dev() since it still allowed the DMA domain to consume the context bank but now that I look at it again as long as the domain free returns the context bank to the pool it might work. Let me give it a shot and see if it does what we need. Jordan > >Signed-off-by: Jordan Crouse <jcro...@codeaurora.org> > >--- > > > > drivers/iommu/arm-smmu.c | 42 ++++++++++++++++++++++++++++++++++++++++++ > > drivers/iommu/iommu.c | 29 +++++++++++++++++++++++------ > > include/linux/iommu.h | 3 +++ > > 3 files changed, 68 insertions(+), 6 deletions(-) > > > >diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > >index 5e54cc0..a795ada 100644 > >--- a/drivers/iommu/arm-smmu.c > >+++ b/drivers/iommu/arm-smmu.c > >@@ -1235,6 +1235,35 @@ static int arm_smmu_domain_add_master(struct > >arm_smmu_domain *smmu_domain, > > return 0; > > } > >+struct arm_smmu_client_match_data { > >+ bool use_identity_domain; > >+}; > >+ > >+static const struct arm_smmu_client_match_data qcom_adreno = { > >+ .use_identity_domain = true, > >+}; > >+ > >+static const struct arm_smmu_client_match_data qcom_mdss = { > >+ .use_identity_domain = true, > >+}; > >+ > >+static const struct of_device_id arm_smmu_client_of_match[] = { > >+ { .compatible = "qcom,adreno", .data = &qcom_adreno }, > >+ { .compatible = "qcom,mdp4", .data = &qcom_mdss }, > >+ { .compatible = "qcom,mdss", .data = &qcom_mdss }, > >+ { .compatible = "qcom,sdm845-mdss", .data = &qcom_mdss }, > >+ {}, > >+}; > >+ > >+static const struct arm_smmu_client_match_data * > >+arm_smmu_client_data(struct device *dev) > >+{ > >+ const struct of_device_id *match = > >+ of_match_device(arm_smmu_client_of_match, dev); > >+ > >+ return match ? match->data : NULL; > >+} > >+ > > static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device > > *dev) > > { > > int ret; > >@@ -1552,6 +1581,7 @@ static struct iommu_group > >*arm_smmu_device_group(struct device *dev) > > { > > struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); > > struct arm_smmu_device *smmu = fwspec_smmu(fwspec); > >+ const struct arm_smmu_client_match_data *client; > > struct iommu_group *group = NULL; > > int i, idx; > >@@ -1573,6 +1603,18 @@ static struct iommu_group > >*arm_smmu_device_group(struct device *dev) > > else > > group = generic_device_group(dev); > >+ client = arm_smmu_client_data(dev); > >+ > >+ /* > >+ * If the client chooses to bypass the dma domain, create a identity > >+ * domain as a default placeholder. This will give the device a > >+ * default domain but skip DMA operations and not consume a context > >+ * bank > >+ */ > >+ if (client && client->no_dma_domain) > >+ iommu_group_set_default_domain(group, dev, > >+ IOMMU_DOMAIN_IDENTITY); > >+ > > return group; > > } > >diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > >index 67ee662..af3e1ed 100644 > >--- a/drivers/iommu/iommu.c > >+++ b/drivers/iommu/iommu.c > >@@ -1062,6 +1062,24 @@ struct iommu_group *fsl_mc_device_group(struct device > >*dev) > > return group; > > } > >+struct iommu_domain *iommu_group_set_default_domain(struct iommu_group > >*group, > >+ struct device *dev, unsigned int type) > >+{ > >+ struct iommu_domain *dom; > >+ > >+ dom = __iommu_domain_alloc(dev->bus, type); > >+ if (!dom) > >+ return NULL; > >+ > >+ /* FIXME: Error if the default domain is already set? */ > >+ group->default_domain = dom; > >+ if (!group->domain) > >+ group->domain = dom; > >+ > >+ return dom; > >+} > >+EXPORT_SYMBOL_GPL(iommu_group_set_default_domain); > >+ > > /** > > * iommu_group_get_for_dev - Find or create the IOMMU group for a device > > * @dev: target device > >@@ -1099,9 +1117,12 @@ struct iommu_group *iommu_group_get_for_dev(struct > >device *dev) > > if (!group->default_domain) { > > struct iommu_domain *dom; > >- dom = __iommu_domain_alloc(dev->bus, iommu_def_domain_type); > >+ dom = iommu_group_set_default_domain(group, dev, > >+ iommu_def_domain_type); > >+ > > if (!dom && iommu_def_domain_type != IOMMU_DOMAIN_DMA) { > >- dom = __iommu_domain_alloc(dev->bus, IOMMU_DOMAIN_DMA); > >+ dom = iommu_group_set_default_domain(group, dev, > >+ IOMMU_DOMAIN_DMA); > > if (dom) { > > dev_warn(dev, > > "failed to allocate default IOMMU > > domain of type %u; falling back to IOMMU_DOMAIN_DMA", > >@@ -1109,10 +1130,6 @@ struct iommu_group *iommu_group_get_for_dev(struct > >device *dev) > > } > > } > >- group->default_domain = dom; > >- if (!group->domain) > >- group->domain = dom; > >- > > if (dom && !iommu_dma_strict) { > > int attr = 1; > > iommu_domain_set_attr(dom, > >diff --git a/include/linux/iommu.h b/include/linux/iommu.h > >index a815cf6..4ef8bd5 100644 > >--- a/include/linux/iommu.h > >+++ b/include/linux/iommu.h > >@@ -394,6 +394,9 @@ extern int iommu_group_id(struct iommu_group *group); > > extern struct iommu_group *iommu_group_get_for_dev(struct device *dev); > > extern struct iommu_domain *iommu_group_default_domain(struct iommu_group > > *); > >+struct iommu_domain *iommu_group_set_default_domain(struct iommu_group > >*group, > >+ struct device *dev, unsigned int type); > >+ > > extern int iommu_domain_get_attr(struct iommu_domain *domain, enum > > iommu_attr, > > void *data); > > extern int iommu_domain_set_attr(struct iommu_domain *domain, enum > > iommu_attr, > > -- The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu