Re: [PATCH v6 1/1] iommu: enhance IOMMU dma mode build options
From: John Garry
Date: Wed May 08 2019 - 05:43:55 EST
On 18/04/2019 14:57, Zhen Lei wrote:
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@xxxxxxxxxx>
---
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 dma mode"
/s/dma/DMA/
And how about add "default", as in "Default IOMMU DMA mode" or "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
again, capitalize acronyms, i.e. /s/dma/DMA/ (more of these above and below)
+ 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
I think that it may need to be indented, along with the other choices
+ bool "passthrough"
+ help
+ In this mode, the dma access through IOMMU without any addresses
+ transformation. That means, the wrong or illegal dma access can not
transformation, or translation?
+ 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 slow in some high
slow, or slower? And passthough is not safe, so anything is implicitly
safer.
+ 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_callback_data {
const struct iommu_ops *ops;
--
1.8.3
.