From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: [PATCH 2/2] iommu/arm-smmu: Don't allocate resources for bypass domains Date: Wed, 20 Apr 2016 14:53:33 +0100 Message-ID: <1461160413-15403-3-git-send-email-will.deacon@arm.com> References: <1461160413-15403-1-git-send-email-will.deacon@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1461160413-15403-1-git-send-email-will.deacon-5wv7dgnIgG8@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: jroedel-l3A5Bk7waGM@public.gmane.org Cc: yang.shi-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, eric.auger-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, Will Deacon , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: iommu@lists.linux-foundation.org From: Robin Murphy Until we get fully plumbed into of_iommu_configure, our default IOMMU_DOMAIN_DMA domains just bypass translation. Since we achieve that by leaving the stream table entries set to bypass instead of pointing at a translation context, the context bank we allocate for the domain is completely wasted. Context banks are typically a rather limited resource, so don't hog ones we don't need. Reported-by: Eric Auger Tested-by: Eric Auger Signed-off-by: Robin Murphy Signed-off-by: Will Deacon --- drivers/iommu/arm-smmu.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index 5158febd889d..7c39ac4b9c53 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c @@ -826,6 +826,12 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain, if (smmu_domain->smmu) goto out_unlock; + /* We're bypassing these SIDs, so don't allocate an actual context */ + if (domain->type == IOMMU_DOMAIN_DMA) { + smmu_domain->smmu = smmu; + goto out_unlock; + } + /* * Mapping the requested stage onto what we support is surprisingly * complicated, mainly because the spec allows S1+S2 SMMUs without @@ -948,7 +954,7 @@ static void arm_smmu_destroy_domain_context(struct iommu_domain *domain) void __iomem *cb_base; int irq; - if (!smmu) + if (!smmu || domain->type == IOMMU_DOMAIN_DMA) return; /* -- 2.1.4 From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Wed, 20 Apr 2016 14:53:33 +0100 Subject: [PATCH 2/2] iommu/arm-smmu: Don't allocate resources for bypass domains In-Reply-To: <1461160413-15403-1-git-send-email-will.deacon@arm.com> References: <1461160413-15403-1-git-send-email-will.deacon@arm.com> Message-ID: <1461160413-15403-3-git-send-email-will.deacon@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Robin Murphy Until we get fully plumbed into of_iommu_configure, our default IOMMU_DOMAIN_DMA domains just bypass translation. Since we achieve that by leaving the stream table entries set to bypass instead of pointing at a translation context, the context bank we allocate for the domain is completely wasted. Context banks are typically a rather limited resource, so don't hog ones we don't need. Reported-by: Eric Auger Tested-by: Eric Auger Signed-off-by: Robin Murphy Signed-off-by: Will Deacon --- drivers/iommu/arm-smmu.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index 5158febd889d..7c39ac4b9c53 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c @@ -826,6 +826,12 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain, if (smmu_domain->smmu) goto out_unlock; + /* We're bypassing these SIDs, so don't allocate an actual context */ + if (domain->type == IOMMU_DOMAIN_DMA) { + smmu_domain->smmu = smmu; + goto out_unlock; + } + /* * Mapping the requested stage onto what we support is surprisingly * complicated, mainly because the spec allows S1+S2 SMMUs without @@ -948,7 +954,7 @@ static void arm_smmu_destroy_domain_context(struct iommu_domain *domain) void __iomem *cb_base; int irq; - if (!smmu) + if (!smmu || domain->type == IOMMU_DOMAIN_DMA) return; /* -- 2.1.4