linux-kernel - [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options

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Date:   Fri, 11 Jun 2021 20:20:41 +0800
From:   John Garry <john.garry@...wei.com>
To:     <joro@...tes.org>, <will@...nel.org>, <dwmw2@...radead.org>,
        <baolu.lu@...ux.intel.com>, <robin.murphy@....com>
CC:     <linux-kernel@...r.kernel.org>, <iommu@...ts.linux-foundation.org>,
        <linuxarm@...wei.com>, <thunder.leizhen@...wei.com>,
        <chenxiang66@...ilicon.com>, John Garry <john.garry@...wei.com>
Subject: [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options

From: Zhen Lei <thunder.leizhen@...wei.com>

Make IOMMU_DEFAULT_LAZY default for when INTEL_IOMMU config is set,
as is current behaviour.

Also delete global flag intel_iommu_strict:
- In intel_iommu_setup(), call iommu_set_dma_strict(true) directly. The
  accompanying print is removed, as it replicates the print in
  iommu_subsys_init(), and, since called from __setup(), should before
  iommu_subsys_init() (so desired ordering).

- For cap_caching_mode() set in intel_iommu_setup(), call
  iommu_set_dma_strict(true) directly, and reword the accompanying print
  and add the missing '\n'.

- For Ironlake GPU, again call iommu_set_dma_strict(true) directly and
  keep the accompanying print.

Note that we should not conflict with iommu.strict param conflicting when
we set strict mode, as that param is not for x86.

[jpg: Remove intel_iommu_strict]
Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
Signed-off-by: John Garry <john.garry@...wei.com>
---
 drivers/iommu/Kconfig       |  1 +
 drivers/iommu/intel/iommu.c | 15 ++++++---------
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 2a71347611d4..4467353f981b 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -94,6 +94,7 @@ choice
 	prompt "IOMMU default DMA mode"
 	depends on IOMMU_DMA
 
+	default IOMMU_DEFAULT_LAZY if INTEL_IOMMU
 	default IOMMU_DEFAULT_STRICT
 	help
 	  This option allows an IOMMU DMA mode to be chosen at build time, to
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index be35284a2016..6763e516362c 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -360,7 +360,6 @@ int intel_iommu_enabled = 0;
 EXPORT_SYMBOL_GPL(intel_iommu_enabled);
 
 static int dmar_map_gfx = 1;
-static int intel_iommu_strict;
 static int intel_iommu_superpage = 1;
 static int iommu_identity_mapping;
 static int iommu_skip_te_disable;
@@ -453,8 +452,7 @@ static int __init intel_iommu_setup(char *str)
 			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;
+			iommu_set_dma_strict(true);
 		} else if (!strncmp(str, "sp_off", 6)) {
 			pr_info("Disable supported super page\n");
 			intel_iommu_superpage = 0;
@@ -4392,9 +4390,9 @@ int __init intel_iommu_init(void)
 		 * is likely to be much lower than the overhead of synchronizing
 		 * the virtual and physical IOMMU page-tables.
 		 */
-		if (!intel_iommu_strict && cap_caching_mode(iommu->cap)) {
-			pr_warn("IOMMU batching is disabled due to virtualization");
-			intel_iommu_strict = 1;
+		if (cap_caching_mode(iommu->cap)) {
+			pr_warn("IOMMU batching disallowed due to virtualization\n");
+			iommu_set_dma_strict(true);
 		}
 		iommu_device_sysfs_add(&iommu->iommu, NULL,
 				       intel_iommu_groups,
@@ -4403,7 +4401,6 @@ int __init intel_iommu_init(void)
 	}
 	up_read(&dmar_global_lock);
 
-	iommu_set_dma_strict(intel_iommu_strict);
 	bus_set_iommu(&pci_bus_type, &intel_iommu_ops);
 	if (si_domain && !hw_pass_through)
 		register_memory_notifier(&intel_iommu_memory_nb);
@@ -5666,8 +5663,8 @@ static void quirk_calpella_no_shadow_gtt(struct pci_dev *dev)
 	} else if (dmar_map_gfx) {
 		/* we have to ensure the gfx device is idle before we flush */
 		pci_info(dev, "Disabling batched IOTLB flush on Ironlake\n");
-		intel_iommu_strict = 1;
-       }
+		iommu_set_dma_strict(true);
+	}
 }
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, quirk_calpella_no_shadow_gtt);
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0044, quirk_calpella_no_shadow_gtt);
-- 
2.26.2