[PATCH v7 1/1] iommu: enhance IOMMU dma mode build options

[Zhen Lei <thunder.leizhen@huawei.com>]

First, add build option IOMMU_DEFAULT_{LAZY|STRICT}, so that we have the
opportunity to set {lazy|strict} mode as default at build time. Then put
the three config options in an choice, make people can only choose one of
the three at a time.

The default IOMMU dma modes on each ARCHs have no change.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
---
 arch/ia64/kernel/pci-dma.c                |  2 +-
 arch/powerpc/platforms/powernv/pci-ioda.c |  3 ++-
 arch/s390/pci/pci_dma.c                   |  2 +-
 arch/x86/kernel/pci-dma.c                 |  7 ++---
 drivers/iommu/Kconfig                     | 44 ++++++++++++++++++++++++++-----
 drivers/iommu/amd_iommu_init.c            |  3 ++-
 drivers/iommu/intel-iommu.c               |  2 +-
 drivers/iommu/iommu.c                     |  3 ++-
 8 files changed, 48 insertions(+), 18 deletions(-)

diff --git a/arch/ia64/kernel/pci-dma.c b/arch/ia64/kernel/pci-dma.c
index fe988c49f01ce6a..655511dbf3c3b34 100644
--- a/arch/ia64/kernel/pci-dma.c
+++ b/arch/ia64/kernel/pci-dma.c
@@ -22,7 +22,7 @@
 int force_iommu __read_mostly;
 #endif

-int iommu_pass_through;
+int iommu_pass_through = IS_ENABLED(CONFIG_IOMMU_DEFAULT_PASSTHROUGH);

 static int __init pci_iommu_init(void)
 {
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 3ead4c237ed0ec9..383e082a9bb985c 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -85,7 +85,8 @@ void pe_level_printk(const struct pnv_ioda_pe *pe, const char *level,
 	va_end(args);
 }

-static bool pnv_iommu_bypass_disabled __read_mostly;
+static bool pnv_iommu_bypass_disabled __read_mostly =
+			!IS_ENABLED(CONFIG_IOMMU_DEFAULT_PASSTHROUGH);
 static bool pci_reset_phbs __read_mostly;

 static int __init iommu_setup(char *str)
diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
index 9e52d1527f71495..784ad1e0acecfb1 100644
--- a/arch/s390/pci/pci_dma.c
+++ b/arch/s390/pci/pci_dma.c
@@ -17,7 +17,7 @@

 static struct kmem_cache *dma_region_table_cache;
 static struct kmem_cache *dma_page_table_cache;
-static int s390_iommu_strict;
+static int s390_iommu_strict = IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);

 static int zpci_refresh_global(struct zpci_dev *zdev)
 {
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index d460998ae828514..fb2bab42a0a3173 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -43,11 +43,8 @@
  * It is also possible to disable by default in kernel config, and enable with
  * iommu=nopt at boot time.
  */
-#ifdef CONFIG_IOMMU_DEFAULT_PASSTHROUGH
-int iommu_pass_through __read_mostly = 1;
-#else
-int iommu_pass_through __read_mostly;
-#endif
+int iommu_pass_through __read_mostly =
+			IS_ENABLED(CONFIG_IOMMU_DEFAULT_PASSTHROUGH);

 extern struct iommu_table_entry __iommu_table[], __iommu_table_end[];

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 6f07f3b21816c64..8a1f1793cde76b4 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -74,17 +74,47 @@ config IOMMU_DEBUGFS
 	  debug/iommu directory, and then populate a subdirectory with
 	  entries as required.

-config IOMMU_DEFAULT_PASSTHROUGH
-	bool "IOMMU passthrough by default"
+choice
+	prompt "IOMMU default DMA mode"
 	depends on IOMMU_API
-        help
-	  Enable passthrough by default, removing the need to pass in
-	  iommu.passthrough=on or iommu=pt through command line. If this
-	  is enabled, you can still disable with iommu.passthrough=off
-	  or iommu=nopt depending on the architecture.
+	default IOMMU_DEFAULT_PASSTHROUGH if (PPC_POWERNV && PCI)
+	default IOMMU_DEFAULT_LAZY if (AMD_IOMMU || INTEL_IOMMU || S390_IOMMU)
+	default IOMMU_DEFAULT_STRICT
+	help
+	  This option allows IOMMU DMA mode to be chose at build time, to
+	  override the default DMA mode of each ARCHs, removing the need to
+	  pass in kernel parameters through command line. You can still use
+	  ARCHs specific boot options to override this option again.
+
+config IOMMU_DEFAULT_PASSTHROUGH
+	bool "passthrough"
+	help
+	  In this mode, the DMA access through IOMMU without any addresses
+	  translation. That means, the wrong or illegal DMA access can not
+	  be caught, no error information will be reported.

 	  If unsure, say N here.

+config IOMMU_DEFAULT_LAZY
+	bool "lazy"
+	help
+	  Support lazy mode, where for every IOMMU DMA unmap operation, the
+	  flush operation of IOTLB and the free operation of IOVA are deferred.
+	  They are only guaranteed to be done before the related IOVA will be
+	  reused.
+
+config IOMMU_DEFAULT_STRICT
+	bool "strict"
+	help
+	  For every IOMMU DMA unmap operation, the flush operation of IOTLB and
+	  the free operation of IOVA are guaranteed to be done in the unmap
+	  function.
+
+	  This mode is safer than the two above, but it maybe slower in some
+	  high performace scenarios.
+
+endchoice
+
 config OF_IOMMU
        def_bool y
        depends on OF && IOMMU_API
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index ff40ba758cf365e..16c02b08adb4cb2 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -166,7 +166,8 @@ struct ivmd_header {
 					   to handle */
 LIST_HEAD(amd_iommu_unity_map);		/* a list of required unity mappings
 					   we find in ACPI */
-bool amd_iommu_unmap_flush;		/* if true, flush on every unmap */
+bool amd_iommu_unmap_flush = IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);
+					/* if true, flush on every unmap */

 LIST_HEAD(amd_iommu_list);		/* list of all AMD IOMMUs in the
 					   system */
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 28cb713d728ceef..0c3cc716210f35a 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -362,7 +362,7 @@ static int domain_detach_iommu(struct dmar_domain *domain,

 static int dmar_map_gfx = 1;
 static int dmar_forcedac;
-static int intel_iommu_strict;
+static int intel_iommu_strict = IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);
 static int intel_iommu_superpage = 1;
 static int intel_iommu_sm;
 static int iommu_identity_mapping;
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 109de67d5d727c2..0ec5952ac60e2a3 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -43,7 +43,8 @@
 #else
 static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA;
 #endif
-static bool iommu_dma_strict __read_mostly = true;
+static bool iommu_dma_strict __read_mostly =
+			IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);

 struct iommu_group {
 	struct kobject kobj;
--
1.8.3