| From d0905c76eca8694104f41edb84f257db6e443de7 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Fri, 5 Mar 2021 16:32:34 +0000 |
| Subject: iommu/dma: Resurrect the "forcedac" option |
| |
| From: Robin Murphy <robin.murphy@arm.com> |
| |
| [ Upstream commit 3542dcb15cef66c0b9e6c3b33168eb657e0d9520 ] |
| |
| In converting intel-iommu over to the common IOMMU DMA ops, it quietly |
| lost the functionality of its "forcedac" option. Since this is a handy |
| thing both for testing and for performance optimisation on certain |
| platforms, reimplement it under the common IOMMU parameter namespace. |
| |
| For the sake of fixing the inadvertent breakage of the Intel-specific |
| parameter, remove the dmar_forcedac remnants and hook it up as an alias |
| while documenting the transition to the new common parameter. |
| |
| Fixes: c588072bba6b ("iommu/vt-d: Convert intel iommu driver to the iommu ops") |
| Signed-off-by: Robin Murphy <robin.murphy@arm.com> |
| Acked-by: Lu Baolu <baolu.lu@linux.intel.com> |
| Reviewed-by: John Garry <john.garry@huawei.com> |
| Link: https://lore.kernel.org/r/7eece8e0ea7bfbe2cd0e30789e0d46df573af9b0.1614961776.git.robin.murphy@arm.com |
| Signed-off-by: Joerg Roedel <jroedel@suse.de> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| Documentation/admin-guide/kernel-parameters.txt | 15 ++++++++------- |
| drivers/iommu/dma-iommu.c | 13 ++++++++++++- |
| drivers/iommu/intel/iommu.c | 5 ++--- |
| include/linux/dma-iommu.h | 2 ++ |
| 4 files changed, 24 insertions(+), 11 deletions(-) |
| |
| diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt |
| index a10b545c2070..b537a9608895 100644 |
| --- a/Documentation/admin-guide/kernel-parameters.txt |
| +++ b/Documentation/admin-guide/kernel-parameters.txt |
| @@ -1854,13 +1854,6 @@ |
| bypassed by not enabling DMAR with this option. In |
| this case, gfx device will use physical address for |
| DMA. |
| - forcedac [X86-64] |
| - With this option iommu will not optimize to look |
| - for io virtual address below 32-bit forcing dual |
| - address cycle on pci bus for cards supporting greater |
| - than 32-bit addressing. The default is to look |
| - for translation below 32-bit and if not available |
| - then look in the higher range. |
| strict [Default Off] |
| With this option on every unmap_single operation will |
| result in a hardware IOTLB flush operation as opposed |
| @@ -1949,6 +1942,14 @@ |
| nobypass [PPC/POWERNV] |
| Disable IOMMU bypass, using IOMMU for PCI devices. |
| |
| + iommu.forcedac= [ARM64, X86] Control IOVA allocation for PCI devices. |
| + Format: { "0" | "1" } |
| + 0 - Try to allocate a 32-bit DMA address first, before |
| + falling back to the full range if needed. |
| + 1 - Allocate directly from the full usable range, |
| + forcing Dual Address Cycle for PCI cards supporting |
| + greater than 32-bit addressing. |
| + |
| iommu.strict= [ARM64] Configure TLB invalidation behaviour |
| Format: { "0" | "1" } |
| 0 - Lazy mode. |
| diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c |
| index 07e7b2f3ba27..9d4a29796fe4 100644 |
| --- a/drivers/iommu/dma-iommu.c |
| +++ b/drivers/iommu/dma-iommu.c |
| @@ -52,6 +52,17 @@ struct iommu_dma_cookie { |
| }; |
| |
| static DEFINE_STATIC_KEY_FALSE(iommu_deferred_attach_enabled); |
| +bool iommu_dma_forcedac __read_mostly; |
| + |
| +static int __init iommu_dma_forcedac_setup(char *str) |
| +{ |
| + int ret = kstrtobool(str, &iommu_dma_forcedac); |
| + |
| + if (!ret && iommu_dma_forcedac) |
| + pr_info("Forcing DAC for PCI devices\n"); |
| + return ret; |
| +} |
| +early_param("iommu.forcedac", iommu_dma_forcedac_setup); |
| |
| void iommu_dma_free_cpu_cached_iovas(unsigned int cpu, |
| struct iommu_domain *domain) |
| @@ -456,7 +467,7 @@ static dma_addr_t iommu_dma_alloc_iova(struct iommu_domain *domain, |
| dma_limit = min(dma_limit, (u64)domain->geometry.aperture_end); |
| |
| /* Try to get PCI devices a SAC address */ |
| - if (dma_limit > DMA_BIT_MASK(32) && dev_is_pci(dev)) |
| + if (dma_limit > DMA_BIT_MASK(32) && !iommu_dma_forcedac && dev_is_pci(dev)) |
| iova = alloc_iova_fast(iovad, iova_len, |
| DMA_BIT_MASK(32) >> shift, false); |
| |
| diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c |
| index e49a79322c53..005daf50107d 100644 |
| --- a/drivers/iommu/intel/iommu.c |
| +++ b/drivers/iommu/intel/iommu.c |
| @@ -350,7 +350,6 @@ int intel_iommu_enabled = 0; |
| EXPORT_SYMBOL_GPL(intel_iommu_enabled); |
| |
| static int dmar_map_gfx = 1; |
| -static int dmar_forcedac; |
| static int intel_iommu_strict; |
| static int intel_iommu_superpage = 1; |
| static int iommu_identity_mapping; |
| @@ -441,8 +440,8 @@ static int __init intel_iommu_setup(char *str) |
| dmar_map_gfx = 0; |
| pr_info("Disable GFX device mapping\n"); |
| } else if (!strncmp(str, "forcedac", 8)) { |
| - pr_info("Forcing DAC for PCI devices\n"); |
| - dmar_forcedac = 1; |
| + pr_warn("intel_iommu=forcedac deprecated; use iommu.forcedac instead\n"); |
| + iommu_dma_forcedac = true; |
| } else if (!strncmp(str, "strict", 6)) { |
| pr_info("Disable batched IOTLB flush\n"); |
| intel_iommu_strict = 1; |
| diff --git a/include/linux/dma-iommu.h b/include/linux/dma-iommu.h |
| index 706b68d1359b..13d1f4c14d7b 100644 |
| --- a/include/linux/dma-iommu.h |
| +++ b/include/linux/dma-iommu.h |
| @@ -40,6 +40,8 @@ void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list); |
| void iommu_dma_free_cpu_cached_iovas(unsigned int cpu, |
| struct iommu_domain *domain); |
| |
| +extern bool iommu_dma_forcedac; |
| + |
| #else /* CONFIG_IOMMU_DMA */ |
| |
| struct iommu_domain; |
| -- |
| 2.30.2 |
| |