[PATCH v12 0/5] Enhance IOMMU default DMA mode build options

[PATCH v12 0/5] Enhance IOMMU default DMA mode build options

[John Garry]

This is a reboot of Zhen Lei's series from a couple of years ago, which
never made it across the line.

I still think that it has some value, so taking up the mantle.

Motivation:
Allow lazy mode be default mode for DMA domains for all ARCHs, and not
only those who hardcode it (to be lazy). For ARM64, currently we must use
a kernel command line parameter to use lazy mode, which is less than
ideal.

I have now included the print for strict/lazy mode, which I originally
sent in:
https://lore.kernel.org/linux-iommu/72eb3de9-1d1c-ae46-c5a9-95f26525d435@huawei.com/

There was some concern there about drivers and their custom prints
conflicting with the print in that patch, but I think that it
should be ok.

Difference to v11:
- Rebase to next-20210610
- Drop strict mode globals in Intel and AMD drivers
- Include patch to print strict vs lazy mode
- Include patch to remove argument from iommu_set_dma_strict()

Differences to v10:
- Rebase to v5.13-rc4
- Correct comment and typo in Kconfig (Randy)
- Make Kconfig choice depend on relevant architectures

Differences to v9:
https://lore.kernel.org/linux-iommu/20190613084240.16768-1-thunder.leizhen@huawei.com/#t
- Rebase to v5.13-rc2
- Remove CONFIG_IOMMU_DEFAULT_PASSTHROUGH from choice:
  Since we can dynamically change default domain of group, lazy or strict and
  passthrough are not mutually exclusive
- Drop ia64 patch, which I don't think was ever required
- Drop "x86/dma: use IS_ENABLED() to simplify the code", which is no
  longer required
- Drop s390/pci patch, as this arch does not use CONFIG_IOMMU_API or even
  already honour CONFIG_IOMMU_DEFAULT_PASSTHROUGH
  https://lore.kernel.org/linux-iommu/20190613084240.16768-4-thunder.leizhen@huawei.com/
- Drop powernv/iommu patch, as I no longer think that it is relevant
  https://lore.kernel.org/linux-iommu/20190613084240.16768-5-thunder.leizhen@huawei.com/
- Some tidying

John Garry (2):
  iommu: Print strict or lazy mode at init time
  iommu: Remove mode argument from iommu_set_dma_strict()

Zhen Lei (3):
  iommu: Enhance IOMMU default DMA mode build options
  iommu/vt-d: Add support for IOMMU default DMA mode build options
  iommu/amd: Add support for IOMMU default DMA mode build options

 drivers/iommu/Kconfig               | 39 +++++++++++++++++++++++++++++
 drivers/iommu/amd/amd_iommu_types.h |  6 -----
 drivers/iommu/amd/init.c            |  3 +--
 drivers/iommu/amd/iommu.c           |  6 -----
 drivers/iommu/intel/iommu.c         | 15 +++++------
 drivers/iommu/iommu.c               | 13 +++++++---
 include/linux/iommu.h               |  2 +-
 7 files changed, 56 insertions(+), 28 deletions(-)

-- 
2.26.2

[PATCH v12 0/5] Enhance IOMMU default DMA mode build options

[John Garry]

This is a reboot of Zhen Lei's series from a couple of years ago, which
never made it across the line.

I still think that it has some value, so taking up the mantle.

Motivation:
Allow lazy mode be default mode for DMA domains for all ARCHs, and not
only those who hardcode it (to be lazy). For ARM64, currently we must use
a kernel command line parameter to use lazy mode, which is less than
ideal.

I have now included the print for strict/lazy mode, which I originally
sent in:
https://lore.kernel.org/linux-iommu/72eb3de9-1d1c-ae46-c5a9-95f26525d435@huawei.com/

There was some concern there about drivers and their custom prints
conflicting with the print in that patch, but I think that it
should be ok.

Difference to v11:
- Rebase to next-20210610
- Drop strict mode globals in Intel and AMD drivers
- Include patch to print strict vs lazy mode
- Include patch to remove argument from iommu_set_dma_strict()

Differences to v10:
- Rebase to v5.13-rc4
- Correct comment and typo in Kconfig (Randy)
- Make Kconfig choice depend on relevant architectures

Differences to v9:
https://lore.kernel.org/linux-iommu/20190613084240.16768-1-thunder.leizhen@huawei.com/#t
- Rebase to v5.13-rc2
- Remove CONFIG_IOMMU_DEFAULT_PASSTHROUGH from choice:
  Since we can dynamically change default domain of group, lazy or strict and
  passthrough are not mutually exclusive
- Drop ia64 patch, which I don't think was ever required
- Drop "x86/dma: use IS_ENABLED() to simplify the code", which is no
  longer required
- Drop s390/pci patch, as this arch does not use CONFIG_IOMMU_API or even
  already honour CONFIG_IOMMU_DEFAULT_PASSTHROUGH
  https://lore.kernel.org/linux-iommu/20190613084240.16768-4-thunder.leizhen@huawei.com/
- Drop powernv/iommu patch, as I no longer think that it is relevant
  https://lore.kernel.org/linux-iommu/20190613084240.16768-5-thunder.leizhen@huawei.com/
- Some tidying

John Garry (2):
  iommu: Print strict or lazy mode at init time
  iommu: Remove mode argument from iommu_set_dma_strict()

Zhen Lei (3):
  iommu: Enhance IOMMU default DMA mode build options
  iommu/vt-d: Add support for IOMMU default DMA mode build options
  iommu/amd: Add support for IOMMU default DMA mode build options

 drivers/iommu/Kconfig               | 39 +++++++++++++++++++++++++++++
 drivers/iommu/amd/amd_iommu_types.h |  6 -----
 drivers/iommu/amd/init.c            |  3 +--
 drivers/iommu/amd/iommu.c           |  6 -----
 drivers/iommu/intel/iommu.c         | 15 +++++------
 drivers/iommu/iommu.c               | 13 +++++++---
 include/linux/iommu.h               |  2 +-
 7 files changed, 56 insertions(+), 28 deletions(-)

-- 
2.26.2

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[PATCH v12 1/5] iommu: Print strict or lazy mode at init time

[John Garry]

As well as the default domain type, it's useful to know whether strict
or lazy for DMA domains, so add this info in a separate print.

The (stict/lazy) mode may be also set via iommu.strict earlyparm, but
this will be processed prior to iommu_subsys_init(), so that print will be
accurate for drivers which don't set the mode via custom means.

For the drivers which do set the mode via custom means - the AMD and Intel
drivers - they still maintain prints to notify the change in policy.

Signed-off-by: John Garry <john.garry@huawei.com>
---
 drivers/iommu/iommu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 5419c4b9f27a..cf58949cc2f3 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -138,6 +138,11 @@ static int __init iommu_subsys_init(void)
 		(iommu_cmd_line & IOMMU_CMD_LINE_DMA_API) ?
 			"(set via kernel command line)" : "");
 
+	pr_info("DMA domain TLB invalidation policy: %s mode %s\n",
+		iommu_dma_strict ? "strict" : "lazy",
+		(iommu_cmd_line & IOMMU_CMD_LINE_STRICT) ?
+			"(set via kernel command line)" : "");
+
 	return 0;
 }
 subsys_initcall(iommu_subsys_init);
-- 
2.26.2

[PATCH v12 1/5] iommu: Print strict or lazy mode at init time

[John Garry]

As well as the default domain type, it's useful to know whether strict
or lazy for DMA domains, so add this info in a separate print.

The (stict/lazy) mode may be also set via iommu.strict earlyparm, but
this will be processed prior to iommu_subsys_init(), so that print will be
accurate for drivers which don't set the mode via custom means.

For the drivers which do set the mode via custom means - the AMD and Intel
drivers - they still maintain prints to notify the change in policy.

Signed-off-by: John Garry <john.garry@huawei.com>
---
 drivers/iommu/iommu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 5419c4b9f27a..cf58949cc2f3 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -138,6 +138,11 @@ static int __init iommu_subsys_init(void)
 		(iommu_cmd_line & IOMMU_CMD_LINE_DMA_API) ?
 			"(set via kernel command line)" : "");
 
+	pr_info("DMA domain TLB invalidation policy: %s mode %s\n",
+		iommu_dma_strict ? "strict" : "lazy",
+		(iommu_cmd_line & IOMMU_CMD_LINE_STRICT) ?
+			"(set via kernel command line)" : "");
+
 	return 0;
 }
 subsys_initcall(iommu_subsys_init);
-- 
2.26.2

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Re: [PATCH v12 1/5] iommu: Print strict or lazy mode at init time

[Robin Murphy]

On 2021-06-11 13:20, John Garry wrote:
> As well as the default domain type, it's useful to know whether strict
> or lazy for DMA domains, so add this info in a separate print.
> 
> The (stict/lazy) mode may be also set via iommu.strict earlyparm, but
> this will be processed prior to iommu_subsys_init(), so that print will be
> accurate for drivers which don't set the mode via custom means.
> 
> For the drivers which do set the mode via custom means - the AMD and Intel
> drivers - they still maintain prints to notify the change in policy.

Note that you then start removing said prints later in the series, but 
if we repurpose then as deprecation warnings instead as Baolu suggests 
then I reckon it all works out OK. Assuming that,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
>   drivers/iommu/iommu.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 5419c4b9f27a..cf58949cc2f3 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -138,6 +138,11 @@ static int __init iommu_subsys_init(void)
>   		(iommu_cmd_line & IOMMU_CMD_LINE_DMA_API) ?
>   			"(set via kernel command line)" : "");
>   
> +	pr_info("DMA domain TLB invalidation policy: %s mode %s\n",
> +		iommu_dma_strict ? "strict" : "lazy",
> +		(iommu_cmd_line & IOMMU_CMD_LINE_STRICT) ?
> +			"(set via kernel command line)" : "");
> +
>   	return 0;
>   }
>   subsys_initcall(iommu_subsys_init);
> 

Re: [PATCH v12 1/5] iommu: Print strict or lazy mode at init time

[Robin Murphy]

On 2021-06-11 13:20, John Garry wrote:
> As well as the default domain type, it's useful to know whether strict
> or lazy for DMA domains, so add this info in a separate print.
> 
> The (stict/lazy) mode may be also set via iommu.strict earlyparm, but
> this will be processed prior to iommu_subsys_init(), so that print will be
> accurate for drivers which don't set the mode via custom means.
> 
> For the drivers which do set the mode via custom means - the AMD and Intel
> drivers - they still maintain prints to notify the change in policy.

Note that you then start removing said prints later in the series, but 
if we repurpose then as deprecation warnings instead as Baolu suggests 
then I reckon it all works out OK. Assuming that,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
>   drivers/iommu/iommu.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 5419c4b9f27a..cf58949cc2f3 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -138,6 +138,11 @@ static int __init iommu_subsys_init(void)
>   		(iommu_cmd_line & IOMMU_CMD_LINE_DMA_API) ?
>   			"(set via kernel command line)" : "");
>   
> +	pr_info("DMA domain TLB invalidation policy: %s mode %s\n",
> +		iommu_dma_strict ? "strict" : "lazy",
> +		(iommu_cmd_line & IOMMU_CMD_LINE_STRICT) ?
> +			"(set via kernel command line)" : "");
> +
>   	return 0;
>   }
>   subsys_initcall(iommu_subsys_init);
> 
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[PATCH v12 2/5] iommu: Enhance IOMMU default DMA mode build options

[John Garry]

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

First, add build options IOMMU_DEFAULT_{LAZY|STRICT}, so that we have the
opportunity to set {lazy|strict} mode as default at build time. Then put
the two config options in an choice, as they are mutually exclusive.

[jpg: Make choice between strict and lazy only (and not passthrough)]
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
---
 drivers/iommu/Kconfig | 38 ++++++++++++++++++++++++++++++++++++++
 drivers/iommu/iommu.c |  3 ++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 1f111b399bca..2a71347611d4 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -90,6 +90,44 @@ config IOMMU_DEFAULT_PASSTHROUGH
 
 	  If unsure, say N here.
 
+choice
+	prompt "IOMMU default DMA mode"
+	depends on IOMMU_DMA
+
+	default IOMMU_DEFAULT_STRICT
+	help
+	  This option allows an IOMMU DMA mode to be chosen at build time, to
+	  override the default DMA mode of each ARCH, removing the need to
+	  pass in kernel parameters through command line. It is still possible
+	  to provide ARCH-specific or common boot options to override this
+	  option.
+
+	  If unsure, keep the default.
+
+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.
+
+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.
+
+	  The isolation provided in this mode is not as secure as STRICT mode,
+	  such that a vulnerable time window may be created between the DMA
+	  unmap and the mapping finally being torn down in the IOMMU, where the
+	  device can still access the system memory. However this mode may
+	  provide better performance in high throughput scenarios, and is still
+	  considerably more secure than passthrough mode or no IOMMU.
+
+endchoice
+
 config OF_IOMMU
 	def_bool y
 	depends on OF && IOMMU_API
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index cf58949cc2f3..ccbd5d4c1a50 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -29,7 +29,8 @@ static struct kset *iommu_group_kset;
 static DEFINE_IDA(iommu_group_ida);
 
 static unsigned int iommu_def_domain_type __read_mostly;
-static bool iommu_dma_strict __read_mostly = true;
+static bool iommu_dma_strict __read_mostly =
+			IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);
 static u32 iommu_cmd_line __read_mostly;
 
 struct iommu_group {
-- 
2.26.2

[PATCH v12 2/5] iommu: Enhance IOMMU default DMA mode build options

[John Garry]

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

First, add build options IOMMU_DEFAULT_{LAZY|STRICT}, so that we have the
opportunity to set {lazy|strict} mode as default at build time. Then put
the two config options in an choice, as they are mutually exclusive.

[jpg: Make choice between strict and lazy only (and not passthrough)]
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
---
 drivers/iommu/Kconfig | 38 ++++++++++++++++++++++++++++++++++++++
 drivers/iommu/iommu.c |  3 ++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 1f111b399bca..2a71347611d4 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -90,6 +90,44 @@ config IOMMU_DEFAULT_PASSTHROUGH
 
 	  If unsure, say N here.
 
+choice
+	prompt "IOMMU default DMA mode"
+	depends on IOMMU_DMA
+
+	default IOMMU_DEFAULT_STRICT
+	help
+	  This option allows an IOMMU DMA mode to be chosen at build time, to
+	  override the default DMA mode of each ARCH, removing the need to
+	  pass in kernel parameters through command line. It is still possible
+	  to provide ARCH-specific or common boot options to override this
+	  option.
+
+	  If unsure, keep the default.
+
+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.
+
+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.
+
+	  The isolation provided in this mode is not as secure as STRICT mode,
+	  such that a vulnerable time window may be created between the DMA
+	  unmap and the mapping finally being torn down in the IOMMU, where the
+	  device can still access the system memory. However this mode may
+	  provide better performance in high throughput scenarios, and is still
+	  considerably more secure than passthrough mode or no IOMMU.
+
+endchoice
+
 config OF_IOMMU
 	def_bool y
 	depends on OF && IOMMU_API
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index cf58949cc2f3..ccbd5d4c1a50 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -29,7 +29,8 @@ static struct kset *iommu_group_kset;
 static DEFINE_IDA(iommu_group_ida);
 
 static unsigned int iommu_def_domain_type __read_mostly;
-static bool iommu_dma_strict __read_mostly = true;
+static bool iommu_dma_strict __read_mostly =
+			IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);
 static u32 iommu_cmd_line __read_mostly;
 
 struct iommu_group {
-- 
2.26.2

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Re: [PATCH v12 2/5] iommu: Enhance IOMMU default DMA mode build options

[Lu Baolu]

On 2021/6/11 20:20, John Garry wrote:
> +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.
> +
> +	  The isolation provided in this mode is not as secure as STRICT mode,
> +	  such that a vulnerable time window may be created between the DMA
> +	  unmap and the mapping finally being torn down in the IOMMU, where the
> +	  device can still access the system memory. However this mode may

" ... and the mappings cached in the IOMMU IOTLB or device TLB finally
being invalidated, where the device probably can still access the memory
which has already been unmapped by the device driver."

Best regards,
baolu

Re: [PATCH v12 2/5] iommu: Enhance IOMMU default DMA mode build options

[Lu Baolu]

On 2021/6/11 20:20, John Garry wrote:
> +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.
> +
> +	  The isolation provided in this mode is not as secure as STRICT mode,
> +	  such that a vulnerable time window may be created between the DMA
> +	  unmap and the mapping finally being torn down in the IOMMU, where the
> +	  device can still access the system memory. However this mode may

" ... and the mappings cached in the IOMMU IOTLB or device TLB finally
being invalidated, where the device probably can still access the memory
which has already been unmapped by the device driver."

Best regards,
baolu
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Re: [PATCH v12 2/5] iommu: Enhance IOMMU default DMA mode build options

[John Garry]

On 12/06/2021 02:21, Lu Baolu wrote:
> On 2021/6/11 20:20, John Garry wrote:
>> +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.
>> +
>> +      The isolation provided in this mode is not as secure as STRICT 
>> mode,
>> +      such that a vulnerable time window may be created between the DMA
>> +      unmap and the mapping finally being torn down in the IOMMU, 
>> where the
>> +      device can still access the system memory. However this mode may
> 
> " ... and the mappings cached in the IOMMU IOTLB or device TLB finally
> being invalidated, where the device probably can still access the memory
> which has already been unmapped by the device driver."

ok, I can try to incorporate some of this wording.

As for this:

On 12/06/2021 03:12, Lu Baolu wrote:
 > On 2021/6/11 20:20, John Garry wrote:
 >> +choice
 >> +    prompt "IOMMU default DMA mode"
 >
 > This is not explicit.
 >
 > How about
 >
 > "IOMMU DMA default cache invalidation policy"
 >
 > ?
 >

OK, but I'd rather use IOTLB, as that better matches the relevant 
iommu.c API name (iommu_ops.flush_iotlb_all).

Thanks,
john

Re: [PATCH v12 2/5] iommu: Enhance IOMMU default DMA mode build options

[John Garry]

On 12/06/2021 02:21, Lu Baolu wrote:
> On 2021/6/11 20:20, John Garry wrote:
>> +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.
>> +
>> +      The isolation provided in this mode is not as secure as STRICT 
>> mode,
>> +      such that a vulnerable time window may be created between the DMA
>> +      unmap and the mapping finally being torn down in the IOMMU, 
>> where the
>> +      device can still access the system memory. However this mode may
> 
> " ... and the mappings cached in the IOMMU IOTLB or device TLB finally
> being invalidated, where the device probably can still access the memory
> which has already been unmapped by the device driver."

ok, I can try to incorporate some of this wording.

As for this:

On 12/06/2021 03:12, Lu Baolu wrote:
 > On 2021/6/11 20:20, John Garry wrote:
 >> +choice
 >> +    prompt "IOMMU default DMA mode"
 >
 > This is not explicit.
 >
 > How about
 >
 > "IOMMU DMA default cache invalidation policy"
 >
 > ?
 >

OK, but I'd rather use IOTLB, as that better matches the relevant 
iommu.c API name (iommu_ops.flush_iotlb_all).

Thanks,
john
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Re: [PATCH v12 2/5] iommu: Enhance IOMMU default DMA mode build options

[Lu Baolu]

On 2021/6/11 20:20, John Garry wrote:
> +choice
> +	prompt "IOMMU default DMA mode"

This is not explicit.

How about

"IOMMU DMA default cache invalidation policy"

?

Best regards,
baolu

> +	depends on IOMMU_DMA
> +
> +	default IOMMU_DEFAULT_STRICT
> +	help
> +	  This option allows an IOMMU DMA mode to be chosen at build time, to
> +	  override the default DMA mode of each ARCH, removing the need to
> +	  pass in kernel parameters through command line. It is still possible
> +	  to provide ARCH-specific or common boot options to override this
> +	  option.
> +
> +	  If unsure, keep the default.

Re: [PATCH v12 2/5] iommu: Enhance IOMMU default DMA mode build options

[Lu Baolu]

On 2021/6/11 20:20, John Garry wrote:
> +choice
> +	prompt "IOMMU default DMA mode"

This is not explicit.

How about

"IOMMU DMA default cache invalidation policy"

?

Best regards,
baolu

> +	depends on IOMMU_DMA
> +
> +	default IOMMU_DEFAULT_STRICT
> +	help
> +	  This option allows an IOMMU DMA mode to be chosen at build time, to
> +	  override the default DMA mode of each ARCH, removing the need to
> +	  pass in kernel parameters through command line. It is still possible
> +	  to provide ARCH-specific or common boot options to override this
> +	  option.
> +
> +	  If unsure, keep the default.
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Re: [PATCH v12 2/5] iommu: Enhance IOMMU default DMA mode build options

[Robin Murphy]

On 2021-06-11 13:20, John Garry wrote:
> From: Zhen Lei <thunder.leizhen@huawei.com>
> 
> First, add build options IOMMU_DEFAULT_{LAZY|STRICT}, so that we have the
> opportunity to set {lazy|strict} mode as default at build time. Then put
> the two config options in an choice, as they are mutually exclusive.
> 
> [jpg: Make choice between strict and lazy only (and not passthrough)]
> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
>   drivers/iommu/Kconfig | 38 ++++++++++++++++++++++++++++++++++++++
>   drivers/iommu/iommu.c |  3 ++-
>   2 files changed, 40 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 1f111b399bca..2a71347611d4 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -90,6 +90,44 @@ config IOMMU_DEFAULT_PASSTHROUGH
>   
>   	  If unsure, say N here.
>   
> +choice
> +	prompt "IOMMU default DMA mode"
> +	depends on IOMMU_DMA
> +
> +	default IOMMU_DEFAULT_STRICT
> +	help
> +	  This option allows an IOMMU DMA mode to be chosen at build time, to
> +	  override the default DMA mode of each ARCH, removing the need to
> +	  pass in kernel parameters through command line. It is still possible
> +	  to provide ARCH-specific or common boot options to override this
> +	  option.
> +
> +	  If unsure, keep the default.
> +
> +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.
> +
> +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.
> +
> +	  The isolation provided in this mode is not as secure as STRICT mode,
> +	  such that a vulnerable time window may be created between the DMA
> +	  unmap and the mapping finally being torn down in the IOMMU, where the
> +	  device can still access the system memory. However this mode may
> +	  provide better performance in high throughput scenarios, and is still
> +	  considerably more secure than passthrough mode or no IOMMU.
> +
> +endchoice
> +
>   config OF_IOMMU
>   	def_bool y
>   	depends on OF && IOMMU_API
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index cf58949cc2f3..ccbd5d4c1a50 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -29,7 +29,8 @@ static struct kset *iommu_group_kset;
>   static DEFINE_IDA(iommu_group_ida);
>   
>   static unsigned int iommu_def_domain_type __read_mostly;
> -static bool iommu_dma_strict __read_mostly = true;
> +static bool iommu_dma_strict __read_mostly =
> +			IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);

Nit: I reckon this is a fine place to wield the 100-character 
relaxation, but it's not my call in the end.

With the wording tweaks already mentioned,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

>   static u32 iommu_cmd_line __read_mostly;
>   
>   struct iommu_group {
> 

Re: [PATCH v12 2/5] iommu: Enhance IOMMU default DMA mode build options

[Robin Murphy]

On 2021-06-11 13:20, John Garry wrote:
> From: Zhen Lei <thunder.leizhen@huawei.com>
> 
> First, add build options IOMMU_DEFAULT_{LAZY|STRICT}, so that we have the
> opportunity to set {lazy|strict} mode as default at build time. Then put
> the two config options in an choice, as they are mutually exclusive.
> 
> [jpg: Make choice between strict and lazy only (and not passthrough)]
> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
>   drivers/iommu/Kconfig | 38 ++++++++++++++++++++++++++++++++++++++
>   drivers/iommu/iommu.c |  3 ++-
>   2 files changed, 40 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 1f111b399bca..2a71347611d4 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -90,6 +90,44 @@ config IOMMU_DEFAULT_PASSTHROUGH
>   
>   	  If unsure, say N here.
>   
> +choice
> +	prompt "IOMMU default DMA mode"
> +	depends on IOMMU_DMA
> +
> +	default IOMMU_DEFAULT_STRICT
> +	help
> +	  This option allows an IOMMU DMA mode to be chosen at build time, to
> +	  override the default DMA mode of each ARCH, removing the need to
> +	  pass in kernel parameters through command line. It is still possible
> +	  to provide ARCH-specific or common boot options to override this
> +	  option.
> +
> +	  If unsure, keep the default.
> +
> +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.
> +
> +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.
> +
> +	  The isolation provided in this mode is not as secure as STRICT mode,
> +	  such that a vulnerable time window may be created between the DMA
> +	  unmap and the mapping finally being torn down in the IOMMU, where the
> +	  device can still access the system memory. However this mode may
> +	  provide better performance in high throughput scenarios, and is still
> +	  considerably more secure than passthrough mode or no IOMMU.
> +
> +endchoice
> +
>   config OF_IOMMU
>   	def_bool y
>   	depends on OF && IOMMU_API
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index cf58949cc2f3..ccbd5d4c1a50 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -29,7 +29,8 @@ static struct kset *iommu_group_kset;
>   static DEFINE_IDA(iommu_group_ida);
>   
>   static unsigned int iommu_def_domain_type __read_mostly;
> -static bool iommu_dma_strict __read_mostly = true;
> +static bool iommu_dma_strict __read_mostly =
> +			IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);

Nit: I reckon this is a fine place to wield the 100-character 
relaxation, but it's not my call in the end.

With the wording tweaks already mentioned,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

>   static u32 iommu_cmd_line __read_mostly;
>   
>   struct iommu_group {
> 
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[PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options

[John Garry]

From: Zhen Lei <thunder.leizhen@huawei.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@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.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

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

[John Garry]

From: Zhen Lei <thunder.leizhen@huawei.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@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.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

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

[Lu Baolu]

On 2021/6/11 20:20, John Garry wrote:
> 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

If two default values are different. Which one will be overridden?

Best regards,
baolu

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

[Lu Baolu]

On 2021/6/11 20:20, John Garry wrote:
> 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

If two default values are different. Which one will be overridden?

Best regards,
baolu
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Re: [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options

[John Garry]

On 12/06/2021 03:14, Lu Baolu wrote:
> On 2021/6/11 20:20, John Garry wrote:
>> 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
> 
> If two default values are different. Which one will be overridden?

If I understand your question correctly, I think you are asking if both 
are set:
CONFIG_IOMMU_DEFAULT_LAZY=y
CONFIG_IOMMU_DEFAULT_STRICT=y

If this happens, then make defconfig complains about both being set, and 
selects the 2nd, whatever that is.

If neither are set, then IOMMU_DEFAULT_LAZY is set if INTEL_IOMMU is 
set, otherwise IOMMU_DEFAULT_STRICT.

Thanks,
John

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

[John Garry]

On 12/06/2021 03:14, Lu Baolu wrote:
> On 2021/6/11 20:20, John Garry wrote:
>> 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
> 
> If two default values are different. Which one will be overridden?

If I understand your question correctly, I think you are asking if both 
are set:
CONFIG_IOMMU_DEFAULT_LAZY=y
CONFIG_IOMMU_DEFAULT_STRICT=y

If this happens, then make defconfig complains about both being set, and 
selects the 2nd, whatever that is.

If neither are set, then IOMMU_DEFAULT_LAZY is set if INTEL_IOMMU is 
set, otherwise IOMMU_DEFAULT_STRICT.

Thanks,
John
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Re: [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options

[Lu Baolu]

Hi John,

On 6/14/21 4:03 PM, John Garry wrote:
> On 12/06/2021 03:14, Lu Baolu wrote:
>> On 2021/6/11 20:20, John Garry wrote:
>>> 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
>>
>> If two default values are different. Which one will be overridden?
> 
> If I understand your question correctly, I think you are asking if both 
> are set:
> CONFIG_IOMMU_DEFAULT_LAZY=y
> CONFIG_IOMMU_DEFAULT_STRICT=y
> 
> If this happens, then make defconfig complains about both being set, and 
> selects the 2nd, whatever that is.

On x86, Intel or AMD, this will be

	prompt "IOMMU default DMA mode"
	  depends on IOMMU_DMA
	  default IOMMU_DEFAULT_LAZY
	  default IOMMU_DEFAULT_STRICT

which will be default, LAZY or STRICT? Will it cause complains?

> 
> If neither are set, then IOMMU_DEFAULT_LAZY is set if INTEL_IOMMU is 
> set, otherwise IOMMU_DEFAULT_STRICT.
> 
> Thanks,
> John

Best regards,
baolu

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

[Lu Baolu]

Hi John,

On 6/14/21 4:03 PM, John Garry wrote:
> On 12/06/2021 03:14, Lu Baolu wrote:
>> On 2021/6/11 20:20, John Garry wrote:
>>> 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
>>
>> If two default values are different. Which one will be overridden?
> 
> If I understand your question correctly, I think you are asking if both 
> are set:
> CONFIG_IOMMU_DEFAULT_LAZY=y
> CONFIG_IOMMU_DEFAULT_STRICT=y
> 
> If this happens, then make defconfig complains about both being set, and 
> selects the 2nd, whatever that is.

On x86, Intel or AMD, this will be

	prompt "IOMMU default DMA mode"
	  depends on IOMMU_DMA
	  default IOMMU_DEFAULT_LAZY
	  default IOMMU_DEFAULT_STRICT

which will be default, LAZY or STRICT? Will it cause complains?

> 
> If neither are set, then IOMMU_DEFAULT_LAZY is set if INTEL_IOMMU is 
> set, otherwise IOMMU_DEFAULT_STRICT.
> 
> Thanks,
> John

Best regards,
baolu
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Re: [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options

[Robin Murphy]

On 2021-06-15 08:26, Lu Baolu wrote:
> Hi John,
> 
> On 6/14/21 4:03 PM, John Garry wrote:
>> On 12/06/2021 03:14, Lu Baolu wrote:
>>> On 2021/6/11 20:20, John Garry wrote:
>>>> 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
>>>
>>> If two default values are different. Which one will be overridden?
>>
>> If I understand your question correctly, I think you are asking if 
>> both are set:
>> CONFIG_IOMMU_DEFAULT_LAZY=y
>> CONFIG_IOMMU_DEFAULT_STRICT=y
>>
>> If this happens, then make defconfig complains about both being set, 
>> and selects the 2nd, whatever that is.
> 
> On x86, Intel or AMD, this will be
> 
>      prompt "IOMMU default DMA mode"
>        depends on IOMMU_DMA
>        default IOMMU_DEFAULT_LAZY
>        default IOMMU_DEFAULT_STRICT
> 
> which will be default, LAZY or STRICT? Will it cause complains?

See Documentation/kbuild/kconfig-language.rst:

   A config option can have any number of default values. If multiple
   default values are visible, only the first defined one is active.


Robin.

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

[Robin Murphy]

On 2021-06-15 08:26, Lu Baolu wrote:
> Hi John,
> 
> On 6/14/21 4:03 PM, John Garry wrote:
>> On 12/06/2021 03:14, Lu Baolu wrote:
>>> On 2021/6/11 20:20, John Garry wrote:
>>>> 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
>>>
>>> If two default values are different. Which one will be overridden?
>>
>> If I understand your question correctly, I think you are asking if 
>> both are set:
>> CONFIG_IOMMU_DEFAULT_LAZY=y
>> CONFIG_IOMMU_DEFAULT_STRICT=y
>>
>> If this happens, then make defconfig complains about both being set, 
>> and selects the 2nd, whatever that is.
> 
> On x86, Intel or AMD, this will be
> 
>      prompt "IOMMU default DMA mode"
>        depends on IOMMU_DMA
>        default IOMMU_DEFAULT_LAZY
>        default IOMMU_DEFAULT_STRICT
> 
> which will be default, LAZY or STRICT? Will it cause complains?

See Documentation/kbuild/kconfig-language.rst:

   A config option can have any number of default values. If multiple
   default values are visible, only the first defined one is active.


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

[Lu Baolu]

On 2021/6/15 16:25, Robin Murphy wrote:
> On 2021-06-15 08:26, Lu Baolu wrote:
>> Hi John,
>>
>> On 6/14/21 4:03 PM, John Garry wrote:
>>> On 12/06/2021 03:14, Lu Baolu wrote:
>>>> On 2021/6/11 20:20, John Garry wrote:
>>>>> 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
>>>>
>>>> If two default values are different. Which one will be overridden?
>>>
>>> If I understand your question correctly, I think you are asking if 
>>> both are set:
>>> CONFIG_IOMMU_DEFAULT_LAZY=y
>>> CONFIG_IOMMU_DEFAULT_STRICT=y
>>>
>>> If this happens, then make defconfig complains about both being set, 
>>> and selects the 2nd, whatever that is.
>>
>> On x86, Intel or AMD, this will be
>>
>>      prompt "IOMMU default DMA mode"
>>        depends on IOMMU_DMA
>>        default IOMMU_DEFAULT_LAZY
>>        default IOMMU_DEFAULT_STRICT
>>
>> which will be default, LAZY or STRICT? Will it cause complains?
> 
> See Documentation/kbuild/kconfig-language.rst:
> 
>    A config option can have any number of default values. If multiple
>    default values are visible, only the first defined one is active.

Get it. Thank you, Robin.

Best regards,
baolu

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

[Lu Baolu]

On 2021/6/15 16:25, Robin Murphy wrote:
> On 2021-06-15 08:26, Lu Baolu wrote:
>> Hi John,
>>
>> On 6/14/21 4:03 PM, John Garry wrote:
>>> On 12/06/2021 03:14, Lu Baolu wrote:
>>>> On 2021/6/11 20:20, John Garry wrote:
>>>>> 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
>>>>
>>>> If two default values are different. Which one will be overridden?
>>>
>>> If I understand your question correctly, I think you are asking if 
>>> both are set:
>>> CONFIG_IOMMU_DEFAULT_LAZY=y
>>> CONFIG_IOMMU_DEFAULT_STRICT=y
>>>
>>> If this happens, then make defconfig complains about both being set, 
>>> and selects the 2nd, whatever that is.
>>
>> On x86, Intel or AMD, this will be
>>
>>      prompt "IOMMU default DMA mode"
>>        depends on IOMMU_DMA
>>        default IOMMU_DEFAULT_LAZY
>>        default IOMMU_DEFAULT_STRICT
>>
>> which will be default, LAZY or STRICT? Will it cause complains?
> 
> See Documentation/kbuild/kconfig-language.rst:
> 
>    A config option can have any number of default values. If multiple
>    default values are visible, only the first defined one is active.

Get it. Thank you, Robin.

Best regards,
baolu
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Re: [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options

[Lu Baolu]

On 2021/6/11 20:20, John Garry wrote:
> @@ -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);

I would like to deprecate this command line and ask users to use
iommu.strict instead.

--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -436,7 +436,7 @@ 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");
+                       pr_warn("intel_iommu=strict deprecated; use 
iommu.strict instead\n");
                         intel_iommu_strict = 1;

Also update Documentation/admin-guide/kernel-parameters.txt accordingly.

Best regards,
baolu

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

[Lu Baolu]

On 2021/6/11 20:20, John Garry wrote:
> @@ -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);

I would like to deprecate this command line and ask users to use
iommu.strict instead.

--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -436,7 +436,7 @@ 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");
+                       pr_warn("intel_iommu=strict deprecated; use 
iommu.strict instead\n");
                         intel_iommu_strict = 1;

Also update Documentation/admin-guide/kernel-parameters.txt accordingly.

Best regards,
baolu
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Re: [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options

[John Garry]

On 12/06/2021 03:22, Lu Baolu wrote:
> On 2021/6/11 20:20, John Garry wrote:
>> @@ -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);
> 
> I would like to deprecate this command line and ask users to use
> iommu.strict instead.

ok, but then I should probably make the AMD driver also officially 
support this.

> 
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -436,7 +436,7 @@ 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");
> +                       pr_warn("intel_iommu=strict deprecated; use 
> iommu.strict instead\n");
>                          intel_iommu_strict = 1;
> 
> Also update Documentation/admin-guide/kernel-parameters.txt accordingly.

Thanks,
John

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

[John Garry]

On 12/06/2021 03:22, Lu Baolu wrote:
> On 2021/6/11 20:20, John Garry wrote:
>> @@ -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);
> 
> I would like to deprecate this command line and ask users to use
> iommu.strict instead.

ok, but then I should probably make the AMD driver also officially 
support this.

> 
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -436,7 +436,7 @@ 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");
> +                       pr_warn("intel_iommu=strict deprecated; use 
> iommu.strict instead\n");
>                          intel_iommu_strict = 1;
> 
> Also update Documentation/admin-guide/kernel-parameters.txt accordingly.

Thanks,
John
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Re: [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options

[Robin Murphy]

On 2021-06-14 08:53, John Garry wrote:
> On 12/06/2021 03:22, Lu Baolu wrote:
>> On 2021/6/11 20:20, John Garry wrote:
>>> @@ -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);
>>
>> I would like to deprecate this command line and ask users to use
>> iommu.strict instead.
> 
> ok, but then I should probably make the AMD driver also officially 
> support this.

Oops, I should have documented that "iommu.strict" already applies to 
x86 as well. The interaction with the driver-specific parameters is a 
bit weird and unintuitive, but it was done knowingly. Let me quickly 
spin a kernel-parameters.txt fix for that...

Cheers,
Robin.

>>
>> --- a/drivers/iommu/intel/iommu.c
>> +++ b/drivers/iommu/intel/iommu.c
>> @@ -436,7 +436,7 @@ 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");
>> +                       pr_warn("intel_iommu=strict deprecated; use 
>> iommu.strict instead\n");
>>                          intel_iommu_strict = 1;
>>
>> Also update Documentation/admin-guide/kernel-parameters.txt accordingly.
> 
> Thanks,
> John

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

[Robin Murphy]

On 2021-06-14 08:53, John Garry wrote:
> On 12/06/2021 03:22, Lu Baolu wrote:
>> On 2021/6/11 20:20, John Garry wrote:
>>> @@ -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);
>>
>> I would like to deprecate this command line and ask users to use
>> iommu.strict instead.
> 
> ok, but then I should probably make the AMD driver also officially 
> support this.

Oops, I should have documented that "iommu.strict" already applies to 
x86 as well. The interaction with the driver-specific parameters is a 
bit weird and unintuitive, but it was done knowingly. Let me quickly 
spin a kernel-parameters.txt fix for that...

Cheers,
Robin.

>>
>> --- a/drivers/iommu/intel/iommu.c
>> +++ b/drivers/iommu/intel/iommu.c
>> @@ -436,7 +436,7 @@ 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");
>> +                       pr_warn("intel_iommu=strict deprecated; use 
>> iommu.strict instead\n");
>>                          intel_iommu_strict = 1;
>>
>> Also update Documentation/admin-guide/kernel-parameters.txt accordingly.
> 
> Thanks,
> John
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Re: [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options

[John Garry]

On 14/06/2021 15:11, Robin Murphy wrote:
> On 2021-06-14 08:53, John Garry wrote:
>> On 12/06/2021 03:22, Lu Baolu wrote:
>>> On 2021/6/11 20:20, John Garry wrote:
>>>> @@ -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);
>>> I would like to deprecate this command line and ask users to use
>>> iommu.strict instead.
>> ok, but then I should probably make the AMD driver also officially
>> support this.
> Oops, I should have documented that "iommu.strict" already applies to
> x86 as well. The interaction with the driver-specific parameters is a
> bit weird and unintuitive, but it was done knowingly. Let me quickly
> spin a kernel-parameters.txt fix for that...

So I already had a pending patch here for the same to be included in 
this series:
https://github.com/hisilicon/kernel-dev/commit/2375a2d888d78de9eb7d91d6f2c5891395300a96

If you want to do it, then ok. I might have to reorder the series though...

Thanks,
John

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

[John Garry]

On 14/06/2021 15:11, Robin Murphy wrote:
> On 2021-06-14 08:53, John Garry wrote:
>> On 12/06/2021 03:22, Lu Baolu wrote:
>>> On 2021/6/11 20:20, John Garry wrote:
>>>> @@ -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);
>>> I would like to deprecate this command line and ask users to use
>>> iommu.strict instead.
>> ok, but then I should probably make the AMD driver also officially
>> support this.
> Oops, I should have documented that "iommu.strict" already applies to
> x86 as well. The interaction with the driver-specific parameters is a
> bit weird and unintuitive, but it was done knowingly. Let me quickly
> spin a kernel-parameters.txt fix for that...

So I already had a pending patch here for the same to be included in 
this series:
https://github.com/hisilicon/kernel-dev/commit/2375a2d888d78de9eb7d91d6f2c5891395300a96

If you want to do it, then ok. I might have to reorder the series though...

Thanks,
John


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

[Robin Murphy]

On 2021-06-14 15:19, John Garry wrote:
> On 14/06/2021 15:11, Robin Murphy wrote:
>> On 2021-06-14 08:53, John Garry wrote:
>>> On 12/06/2021 03:22, Lu Baolu wrote:
>>>> On 2021/6/11 20:20, John Garry wrote:
>>>>> @@ -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);
>>>> I would like to deprecate this command line and ask users to use
>>>> iommu.strict instead.
>>> ok, but then I should probably make the AMD driver also officially
>>> support this.
>> Oops, I should have documented that "iommu.strict" already applies to
>> x86 as well. The interaction with the driver-specific parameters is a
>> bit weird and unintuitive, but it was done knowingly. Let me quickly
>> spin a kernel-parameters.txt fix for that...
> 
> So I already had a pending patch here for the same to be included in 
> this series:
> https://github.com/hisilicon/kernel-dev/commit/2375a2d888d78de9eb7d91d6f2c5891395300a96 
> 
> 
> If you want to do it, then ok. I might have to reorder the series though...

Yeah, sorry for the complication. Your subsequent deprecation of the x86 
parameters doesn't need to conflict, but we should probably also update 
that the default value now depends on the kernel config, which will :(

Thanks,
Robin.

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

[Robin Murphy]

On 2021-06-14 15:19, John Garry wrote:
> On 14/06/2021 15:11, Robin Murphy wrote:
>> On 2021-06-14 08:53, John Garry wrote:
>>> On 12/06/2021 03:22, Lu Baolu wrote:
>>>> On 2021/6/11 20:20, John Garry wrote:
>>>>> @@ -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);
>>>> I would like to deprecate this command line and ask users to use
>>>> iommu.strict instead.
>>> ok, but then I should probably make the AMD driver also officially
>>> support this.
>> Oops, I should have documented that "iommu.strict" already applies to
>> x86 as well. The interaction with the driver-specific parameters is a
>> bit weird and unintuitive, but it was done knowingly. Let me quickly
>> spin a kernel-parameters.txt fix for that...
> 
> So I already had a pending patch here for the same to be included in 
> this series:
> https://github.com/hisilicon/kernel-dev/commit/2375a2d888d78de9eb7d91d6f2c5891395300a96 
> 
> 
> If you want to do it, then ok. I might have to reorder the series though...

Yeah, sorry for the complication. Your subsequent deprecation of the x86 
parameters doesn't need to conflict, but we should probably also update 
that the default value now depends on the kernel config, which will :(

Thanks,
Robin.
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[PATCH v12 4/5] iommu/amd: Add support for IOMMU default DMA mode build options

[John Garry]

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

Make IOMMU_DEFAULT_LAZY default for when AMD_IOMMU config is set, which
matches current behaviour.

For "fullflush" param, just call iommu_set_dma_strict(true) directly.
Since this is called from __setup(), it should occur prior to
iommu_subsys_init(). As such, since we get a strict vs lazy mode print
there, drop the prints in amd_iommu_init_dma_ops().

Also drop global flag amd_iommu_unmap_flush, as it has no purpose
any longer.

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

[jpg: Rebase for relocated file an drop amd_iommu_unmap_flush]
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
---
 drivers/iommu/Kconfig               | 2 +-
 drivers/iommu/amd/amd_iommu_types.h | 6 ------
 drivers/iommu/amd/init.c            | 3 +--
 drivers/iommu/amd/iommu.c           | 6 ------
 4 files changed, 2 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 4467353f981b..8c1e0f2bba0d 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -94,7 +94,7 @@ choice
 	prompt "IOMMU default DMA mode"
 	depends on IOMMU_DMA
 
-	default IOMMU_DEFAULT_LAZY if INTEL_IOMMU
+	default IOMMU_DEFAULT_LAZY if (AMD_IOMMU || 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/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index 94c1a7a9876d..8dbe61e2b3c1 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -779,12 +779,6 @@ extern u16 amd_iommu_last_bdf;
 /* allocation bitmap for domain ids */
 extern unsigned long *amd_iommu_pd_alloc_bitmap;
 
-/*
- * If true, the addresses will be flushed on unmap time, not when
- * they are reused
- */
-extern bool amd_iommu_unmap_flush;
-
 /* Smallest max PASID supported by any IOMMU in the system */
 extern u32 amd_iommu_max_pasid;
 
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 46280e6e1535..0e6ae6d68f14 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -161,7 +161,6 @@ u16 amd_iommu_last_bdf;			/* largest PCI device id we have
 					   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 */
 
 LIST_HEAD(amd_iommu_list);		/* list of all AMD IOMMUs in the
 					   system */
@@ -3099,7 +3098,7 @@ static int __init parse_amd_iommu_options(char *str)
 {
 	for (; *str; ++str) {
 		if (strncmp(str, "fullflush", 9) == 0)
-			amd_iommu_unmap_flush = true;
+			iommu_set_dma_strict(true);
 		if (strncmp(str, "force_enable", 12) == 0)
 			amd_iommu_force_enable = true;
 		if (strncmp(str, "off", 3) == 0)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index b1fbf2c83df5..32b541ee2e11 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1775,12 +1775,6 @@ void amd_iommu_domain_update(struct protection_domain *domain)
 static void __init amd_iommu_init_dma_ops(void)
 {
 	swiotlb = (iommu_default_passthrough() || sme_me_mask) ? 1 : 0;
-
-	if (amd_iommu_unmap_flush)
-		pr_info("IO/TLB flush on unmap enabled\n");
-	else
-		pr_info("Lazy IO/TLB flushing enabled\n");
-	iommu_set_dma_strict(amd_iommu_unmap_flush);
 }
 
 int __init amd_iommu_init_api(void)
-- 
2.26.2

[PATCH v12 4/5] iommu/amd: Add support for IOMMU default DMA mode build options

[John Garry]

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

Make IOMMU_DEFAULT_LAZY default for when AMD_IOMMU config is set, which
matches current behaviour.

For "fullflush" param, just call iommu_set_dma_strict(true) directly.
Since this is called from __setup(), it should occur prior to
iommu_subsys_init(). As such, since we get a strict vs lazy mode print
there, drop the prints in amd_iommu_init_dma_ops().

Also drop global flag amd_iommu_unmap_flush, as it has no purpose
any longer.

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

[jpg: Rebase for relocated file an drop amd_iommu_unmap_flush]
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
---
 drivers/iommu/Kconfig               | 2 +-
 drivers/iommu/amd/amd_iommu_types.h | 6 ------
 drivers/iommu/amd/init.c            | 3 +--
 drivers/iommu/amd/iommu.c           | 6 ------
 4 files changed, 2 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 4467353f981b..8c1e0f2bba0d 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -94,7 +94,7 @@ choice
 	prompt "IOMMU default DMA mode"
 	depends on IOMMU_DMA
 
-	default IOMMU_DEFAULT_LAZY if INTEL_IOMMU
+	default IOMMU_DEFAULT_LAZY if (AMD_IOMMU || 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/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index 94c1a7a9876d..8dbe61e2b3c1 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -779,12 +779,6 @@ extern u16 amd_iommu_last_bdf;
 /* allocation bitmap for domain ids */
 extern unsigned long *amd_iommu_pd_alloc_bitmap;
 
-/*
- * If true, the addresses will be flushed on unmap time, not when
- * they are reused
- */
-extern bool amd_iommu_unmap_flush;
-
 /* Smallest max PASID supported by any IOMMU in the system */
 extern u32 amd_iommu_max_pasid;
 
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 46280e6e1535..0e6ae6d68f14 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -161,7 +161,6 @@ u16 amd_iommu_last_bdf;			/* largest PCI device id we have
 					   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 */
 
 LIST_HEAD(amd_iommu_list);		/* list of all AMD IOMMUs in the
 					   system */
@@ -3099,7 +3098,7 @@ static int __init parse_amd_iommu_options(char *str)
 {
 	for (; *str; ++str) {
 		if (strncmp(str, "fullflush", 9) == 0)
-			amd_iommu_unmap_flush = true;
+			iommu_set_dma_strict(true);
 		if (strncmp(str, "force_enable", 12) == 0)
 			amd_iommu_force_enable = true;
 		if (strncmp(str, "off", 3) == 0)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index b1fbf2c83df5..32b541ee2e11 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1775,12 +1775,6 @@ void amd_iommu_domain_update(struct protection_domain *domain)
 static void __init amd_iommu_init_dma_ops(void)
 {
 	swiotlb = (iommu_default_passthrough() || sme_me_mask) ? 1 : 0;
-
-	if (amd_iommu_unmap_flush)
-		pr_info("IO/TLB flush on unmap enabled\n");
-	else
-		pr_info("Lazy IO/TLB flushing enabled\n");
-	iommu_set_dma_strict(amd_iommu_unmap_flush);
 }
 
 int __init amd_iommu_init_api(void)
-- 
2.26.2

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[PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[John Garry]

We only ever now set strict mode enabled in iommu_set_dma_strict(), so
just remove the argument.

Signed-off-by: John Garry <john.garry@huawei.com>
---
 drivers/iommu/amd/init.c    | 2 +-
 drivers/iommu/intel/iommu.c | 6 +++---
 drivers/iommu/iommu.c       | 5 ++---
 include/linux/iommu.h       | 2 +-
 4 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 0e6ae6d68f14..27e9677ec303 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3098,7 +3098,7 @@ static int __init parse_amd_iommu_options(char *str)
 {
 	for (; *str; ++str) {
 		if (strncmp(str, "fullflush", 9) == 0)
-			iommu_set_dma_strict(true);
+			iommu_set_dma_strict();
 		if (strncmp(str, "force_enable", 12) == 0)
 			amd_iommu_force_enable = true;
 		if (strncmp(str, "off", 3) == 0)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 6763e516362c..e77b8b6e7838 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -452,7 +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)) {
-			iommu_set_dma_strict(true);
+			iommu_set_dma_strict();
 		} else if (!strncmp(str, "sp_off", 6)) {
 			pr_info("Disable supported super page\n");
 			intel_iommu_superpage = 0;
@@ -4392,7 +4392,7 @@ int __init intel_iommu_init(void)
 		 */
 		if (cap_caching_mode(iommu->cap)) {
 			pr_warn("IOMMU batching disallowed due to virtualization\n");
-			iommu_set_dma_strict(true);
+			iommu_set_dma_strict();
 		}
 		iommu_device_sysfs_add(&iommu->iommu, NULL,
 				       intel_iommu_groups,
@@ -5663,7 +5663,7 @@ 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");
-		iommu_set_dma_strict(true);
+		iommu_set_dma_strict();
 	}
 }
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, quirk_calpella_no_shadow_gtt);
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index ccbd5d4c1a50..146cb71c7441 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
 }
 early_param("iommu.strict", iommu_dma_setup);
 
-void iommu_set_dma_strict(bool strict)
+void iommu_set_dma_strict(void)
 {
-	if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
-		iommu_dma_strict = strict;
+		iommu_dma_strict = true;
 }
 
 bool iommu_get_dma_strict(struct iommu_domain *domain)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 32d448050bf7..754f67d6dd90 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -476,7 +476,7 @@ int iommu_enable_nesting(struct iommu_domain *domain);
 int iommu_set_pgtable_quirks(struct iommu_domain *domain,
 		unsigned long quirks);
 
-void iommu_set_dma_strict(bool val);
+void iommu_set_dma_strict(void);
 bool iommu_get_dma_strict(struct iommu_domain *domain);
 
 extern int report_iommu_fault(struct iommu_domain *domain, struct device *dev,
-- 
2.26.2

[PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[John Garry]

We only ever now set strict mode enabled in iommu_set_dma_strict(), so
just remove the argument.

Signed-off-by: John Garry <john.garry@huawei.com>
---
 drivers/iommu/amd/init.c    | 2 +-
 drivers/iommu/intel/iommu.c | 6 +++---
 drivers/iommu/iommu.c       | 5 ++---
 include/linux/iommu.h       | 2 +-
 4 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 0e6ae6d68f14..27e9677ec303 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3098,7 +3098,7 @@ static int __init parse_amd_iommu_options(char *str)
 {
 	for (; *str; ++str) {
 		if (strncmp(str, "fullflush", 9) == 0)
-			iommu_set_dma_strict(true);
+			iommu_set_dma_strict();
 		if (strncmp(str, "force_enable", 12) == 0)
 			amd_iommu_force_enable = true;
 		if (strncmp(str, "off", 3) == 0)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 6763e516362c..e77b8b6e7838 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -452,7 +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)) {
-			iommu_set_dma_strict(true);
+			iommu_set_dma_strict();
 		} else if (!strncmp(str, "sp_off", 6)) {
 			pr_info("Disable supported super page\n");
 			intel_iommu_superpage = 0;
@@ -4392,7 +4392,7 @@ int __init intel_iommu_init(void)
 		 */
 		if (cap_caching_mode(iommu->cap)) {
 			pr_warn("IOMMU batching disallowed due to virtualization\n");
-			iommu_set_dma_strict(true);
+			iommu_set_dma_strict();
 		}
 		iommu_device_sysfs_add(&iommu->iommu, NULL,
 				       intel_iommu_groups,
@@ -5663,7 +5663,7 @@ 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");
-		iommu_set_dma_strict(true);
+		iommu_set_dma_strict();
 	}
 }
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, quirk_calpella_no_shadow_gtt);
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index ccbd5d4c1a50..146cb71c7441 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
 }
 early_param("iommu.strict", iommu_dma_setup);
 
-void iommu_set_dma_strict(bool strict)
+void iommu_set_dma_strict(void)
 {
-	if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
-		iommu_dma_strict = strict;
+		iommu_dma_strict = true;
 }
 
 bool iommu_get_dma_strict(struct iommu_domain *domain)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 32d448050bf7..754f67d6dd90 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -476,7 +476,7 @@ int iommu_enable_nesting(struct iommu_domain *domain);
 int iommu_set_pgtable_quirks(struct iommu_domain *domain,
 		unsigned long quirks);
 
-void iommu_set_dma_strict(bool val);
+void iommu_set_dma_strict(void);
 bool iommu_get_dma_strict(struct iommu_domain *domain);
 
 extern int report_iommu_fault(struct iommu_domain *domain, struct device *dev,
-- 
2.26.2

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Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[Lu Baolu]

On 2021/6/11 20:20, John Garry wrote:
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index ccbd5d4c1a50..146cb71c7441 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
>   }
>   early_param("iommu.strict", iommu_dma_setup);
>   
> -void iommu_set_dma_strict(bool strict)
> +void iommu_set_dma_strict(void)
>   {
> -	if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
> -		iommu_dma_strict = strict;
> +		iommu_dma_strict = true;
>   }

Will this change break the functionality of iommu.strict?

Best regards,
baolu

Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[Lu Baolu]

On 2021/6/11 20:20, John Garry wrote:
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index ccbd5d4c1a50..146cb71c7441 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
>   }
>   early_param("iommu.strict", iommu_dma_setup);
>   
> -void iommu_set_dma_strict(bool strict)
> +void iommu_set_dma_strict(void)
>   {
> -	if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
> -		iommu_dma_strict = strict;
> +		iommu_dma_strict = true;
>   }

Will this change break the functionality of iommu.strict?

Best regards,
baolu
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Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[John Garry]

On 12/06/2021 03:23, Lu Baolu wrote:
> On 2021/6/11 20:20, John Garry wrote:
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index ccbd5d4c1a50..146cb71c7441 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
>>   }
>>   early_param("iommu.strict", iommu_dma_setup);
>> -void iommu_set_dma_strict(bool strict)
>> +void iommu_set_dma_strict(void)
>>   {
>> -    if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
>> -        iommu_dma_strict = strict;
>> +        iommu_dma_strict = true;
>>   }
> 
> Will this change break the functionality of iommu.strict?
> 

No, iommu_dma_strict is written directly in iommu_dma_setup() for 
iommu.strict cmdline processing.

Here I'm just saying that anyone that who uses iommu_set_dma_strict(bool 
strict) always passes true, so I just remove that argument and simplify 
that function.

Thanks,
John

Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[John Garry]

On 12/06/2021 03:23, Lu Baolu wrote:
> On 2021/6/11 20:20, John Garry wrote:
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index ccbd5d4c1a50..146cb71c7441 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
>>   }
>>   early_param("iommu.strict", iommu_dma_setup);
>> -void iommu_set_dma_strict(bool strict)
>> +void iommu_set_dma_strict(void)
>>   {
>> -    if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
>> -        iommu_dma_strict = strict;
>> +        iommu_dma_strict = true;
>>   }
> 
> Will this change break the functionality of iommu.strict?
> 

No, iommu_dma_strict is written directly in iommu_dma_setup() for 
iommu.strict cmdline processing.

Here I'm just saying that anyone that who uses iommu_set_dma_strict(bool 
strict) always passes true, so I just remove that argument and simplify 
that function.

Thanks,
John

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Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[Robin Murphy]

On 2021-06-11 13:20, John Garry wrote:
> We only ever now set strict mode enabled in iommu_set_dma_strict(), so
> just remove the argument.
> 
> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
>   drivers/iommu/amd/init.c    | 2 +-
>   drivers/iommu/intel/iommu.c | 6 +++---
>   drivers/iommu/iommu.c       | 5 ++---
>   include/linux/iommu.h       | 2 +-
>   4 files changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
> index 0e6ae6d68f14..27e9677ec303 100644
> --- a/drivers/iommu/amd/init.c
> +++ b/drivers/iommu/amd/init.c
> @@ -3098,7 +3098,7 @@ static int __init parse_amd_iommu_options(char *str)
>   {
>   	for (; *str; ++str) {
>   		if (strncmp(str, "fullflush", 9) == 0)
> -			iommu_set_dma_strict(true);
> +			iommu_set_dma_strict();
>   		if (strncmp(str, "force_enable", 12) == 0)
>   			amd_iommu_force_enable = true;
>   		if (strncmp(str, "off", 3) == 0)
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 6763e516362c..e77b8b6e7838 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -452,7 +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)) {
> -			iommu_set_dma_strict(true);
> +			iommu_set_dma_strict();
>   		} else if (!strncmp(str, "sp_off", 6)) {
>   			pr_info("Disable supported super page\n");
>   			intel_iommu_superpage = 0;
> @@ -4392,7 +4392,7 @@ int __init intel_iommu_init(void)
>   		 */
>   		if (cap_caching_mode(iommu->cap)) {
>   			pr_warn("IOMMU batching disallowed due to virtualization\n");
> -			iommu_set_dma_strict(true);
> +			iommu_set_dma_strict();
>   		}
>   		iommu_device_sysfs_add(&iommu->iommu, NULL,
>   				       intel_iommu_groups,
> @@ -5663,7 +5663,7 @@ 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");
> -		iommu_set_dma_strict(true);
> +		iommu_set_dma_strict();
>   	}
>   }
>   DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, quirk_calpella_no_shadow_gtt);
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index ccbd5d4c1a50..146cb71c7441 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
>   }
>   early_param("iommu.strict", iommu_dma_setup);
>   
> -void iommu_set_dma_strict(bool strict)
> +void iommu_set_dma_strict(void)
>   {
> -	if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))

We shouldn't need to keep IOMMU_CMD_LINE_STRICT at all now, since it was 
only to prevent a driver's "default lazy" setting passed in here from 
downgrading an explicitly-set strict mode.

With that cleaned up too,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

Thanks,
Robin.

> -		iommu_dma_strict = strict;
> +		iommu_dma_strict = true;
>   }
>   
>   bool iommu_get_dma_strict(struct iommu_domain *domain)
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 32d448050bf7..754f67d6dd90 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -476,7 +476,7 @@ int iommu_enable_nesting(struct iommu_domain *domain);
>   int iommu_set_pgtable_quirks(struct iommu_domain *domain,
>   		unsigned long quirks);
>   
> -void iommu_set_dma_strict(bool val);
> +void iommu_set_dma_strict(void);
>   bool iommu_get_dma_strict(struct iommu_domain *domain);
>   
>   extern int report_iommu_fault(struct iommu_domain *domain, struct device *dev,
> 

Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[Robin Murphy]

On 2021-06-11 13:20, John Garry wrote:
> We only ever now set strict mode enabled in iommu_set_dma_strict(), so
> just remove the argument.
> 
> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
>   drivers/iommu/amd/init.c    | 2 +-
>   drivers/iommu/intel/iommu.c | 6 +++---
>   drivers/iommu/iommu.c       | 5 ++---
>   include/linux/iommu.h       | 2 +-
>   4 files changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
> index 0e6ae6d68f14..27e9677ec303 100644
> --- a/drivers/iommu/amd/init.c
> +++ b/drivers/iommu/amd/init.c
> @@ -3098,7 +3098,7 @@ static int __init parse_amd_iommu_options(char *str)
>   {
>   	for (; *str; ++str) {
>   		if (strncmp(str, "fullflush", 9) == 0)
> -			iommu_set_dma_strict(true);
> +			iommu_set_dma_strict();
>   		if (strncmp(str, "force_enable", 12) == 0)
>   			amd_iommu_force_enable = true;
>   		if (strncmp(str, "off", 3) == 0)
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 6763e516362c..e77b8b6e7838 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -452,7 +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)) {
> -			iommu_set_dma_strict(true);
> +			iommu_set_dma_strict();
>   		} else if (!strncmp(str, "sp_off", 6)) {
>   			pr_info("Disable supported super page\n");
>   			intel_iommu_superpage = 0;
> @@ -4392,7 +4392,7 @@ int __init intel_iommu_init(void)
>   		 */
>   		if (cap_caching_mode(iommu->cap)) {
>   			pr_warn("IOMMU batching disallowed due to virtualization\n");
> -			iommu_set_dma_strict(true);
> +			iommu_set_dma_strict();
>   		}
>   		iommu_device_sysfs_add(&iommu->iommu, NULL,
>   				       intel_iommu_groups,
> @@ -5663,7 +5663,7 @@ 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");
> -		iommu_set_dma_strict(true);
> +		iommu_set_dma_strict();
>   	}
>   }
>   DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, quirk_calpella_no_shadow_gtt);
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index ccbd5d4c1a50..146cb71c7441 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
>   }
>   early_param("iommu.strict", iommu_dma_setup);
>   
> -void iommu_set_dma_strict(bool strict)
> +void iommu_set_dma_strict(void)
>   {
> -	if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))

We shouldn't need to keep IOMMU_CMD_LINE_STRICT at all now, since it was 
only to prevent a driver's "default lazy" setting passed in here from 
downgrading an explicitly-set strict mode.

With that cleaned up too,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

Thanks,
Robin.

> -		iommu_dma_strict = strict;
> +		iommu_dma_strict = true;
>   }
>   
>   bool iommu_get_dma_strict(struct iommu_domain *domain)
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 32d448050bf7..754f67d6dd90 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -476,7 +476,7 @@ int iommu_enable_nesting(struct iommu_domain *domain);
>   int iommu_set_pgtable_quirks(struct iommu_domain *domain,
>   		unsigned long quirks);
>   
> -void iommu_set_dma_strict(bool val);
> +void iommu_set_dma_strict(void);
>   bool iommu_get_dma_strict(struct iommu_domain *domain);
>   
>   extern int report_iommu_fault(struct iommu_domain *domain, struct device *dev,
> 
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[John Garry]

On 14/06/2021 17:25, Robin Murphy wrote:
> On 2021-06-11 13:20, John Garry wrote:
>> We only ever now set strict mode enabled in iommu_set_dma_strict(), so
>> just remove the argument.
>>
>> Signed-off-by: John Garry <john.garry@huawei.com>
>> ---
>>   drivers/iommu/amd/init.c    | 2 +-
>>   drivers/iommu/intel/iommu.c | 6 +++---
>>   drivers/iommu/iommu.c       | 5 ++---
>>   include/linux/iommu.h       | 2 +-
>>   4 files changed, 7 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
>> index 0e6ae6d68f14..27e9677ec303 100644
>> --- a/drivers/iommu/amd/init.c
>> +++ b/drivers/iommu/amd/init.c
>> @@ -3098,7 +3098,7 @@ static int __init parse_amd_iommu_options(char 
>> *str)
>>   {
>>       for (; *str; ++str) {
>>           if (strncmp(str, "fullflush", 9) == 0)
>> -            iommu_set_dma_strict(true);
>> +            iommu_set_dma_strict();
>>           if (strncmp(str, "force_enable", 12) == 0)
>>               amd_iommu_force_enable = true;
>>           if (strncmp(str, "off", 3) == 0)
>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>> index 6763e516362c..e77b8b6e7838 100644
>> --- a/drivers/iommu/intel/iommu.c
>> +++ b/drivers/iommu/intel/iommu.c
>> @@ -452,7 +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)) {
>> -            iommu_set_dma_strict(true);
>> +            iommu_set_dma_strict();
>>           } else if (!strncmp(str, "sp_off", 6)) {
>>               pr_info("Disable supported super page\n");
>>               intel_iommu_superpage = 0;
>> @@ -4392,7 +4392,7 @@ int __init intel_iommu_init(void)
>>            */
>>           if (cap_caching_mode(iommu->cap)) {
>>               pr_warn("IOMMU batching disallowed due to 
>> virtualization\n");
>> -            iommu_set_dma_strict(true);
>> +            iommu_set_dma_strict();
>>           }
>>           iommu_device_sysfs_add(&iommu->iommu, NULL,
>>                          intel_iommu_groups,
>> @@ -5663,7 +5663,7 @@ 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");
>> -        iommu_set_dma_strict(true);
>> +        iommu_set_dma_strict();
>>       }
>>   }
>>   DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, 
>> quirk_calpella_no_shadow_gtt);
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index ccbd5d4c1a50..146cb71c7441 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
>>   }
>>   early_param("iommu.strict", iommu_dma_setup);
>> -void iommu_set_dma_strict(bool strict)
>> +void iommu_set_dma_strict(void)
>>   {
>> -    if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
> 
> We shouldn't need to keep IOMMU_CMD_LINE_STRICT at all now, since it was 
> only to prevent a driver's "default lazy" setting passed in here from 
> downgrading an explicitly-set strict mode.
> 
> With that cleaned up too,
> 

Patch 1/5 mentions whether the invalidation policy comes from the 
cmdline - similar to the default domain type print - so I was going to 
keep that.

And then maybe we should also set it from the deprecated x86 
driver-specific params.

But if you think that there is not much value in this additional info, 
then I can just drop it.

Cheers,
John

Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[John Garry]

On 14/06/2021 17:25, Robin Murphy wrote:
> On 2021-06-11 13:20, John Garry wrote:
>> We only ever now set strict mode enabled in iommu_set_dma_strict(), so
>> just remove the argument.
>>
>> Signed-off-by: John Garry <john.garry@huawei.com>
>> ---
>>   drivers/iommu/amd/init.c    | 2 +-
>>   drivers/iommu/intel/iommu.c | 6 +++---
>>   drivers/iommu/iommu.c       | 5 ++---
>>   include/linux/iommu.h       | 2 +-
>>   4 files changed, 7 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
>> index 0e6ae6d68f14..27e9677ec303 100644
>> --- a/drivers/iommu/amd/init.c
>> +++ b/drivers/iommu/amd/init.c
>> @@ -3098,7 +3098,7 @@ static int __init parse_amd_iommu_options(char 
>> *str)
>>   {
>>       for (; *str; ++str) {
>>           if (strncmp(str, "fullflush", 9) == 0)
>> -            iommu_set_dma_strict(true);
>> +            iommu_set_dma_strict();
>>           if (strncmp(str, "force_enable", 12) == 0)
>>               amd_iommu_force_enable = true;
>>           if (strncmp(str, "off", 3) == 0)
>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>> index 6763e516362c..e77b8b6e7838 100644
>> --- a/drivers/iommu/intel/iommu.c
>> +++ b/drivers/iommu/intel/iommu.c
>> @@ -452,7 +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)) {
>> -            iommu_set_dma_strict(true);
>> +            iommu_set_dma_strict();
>>           } else if (!strncmp(str, "sp_off", 6)) {
>>               pr_info("Disable supported super page\n");
>>               intel_iommu_superpage = 0;
>> @@ -4392,7 +4392,7 @@ int __init intel_iommu_init(void)
>>            */
>>           if (cap_caching_mode(iommu->cap)) {
>>               pr_warn("IOMMU batching disallowed due to 
>> virtualization\n");
>> -            iommu_set_dma_strict(true);
>> +            iommu_set_dma_strict();
>>           }
>>           iommu_device_sysfs_add(&iommu->iommu, NULL,
>>                          intel_iommu_groups,
>> @@ -5663,7 +5663,7 @@ 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");
>> -        iommu_set_dma_strict(true);
>> +        iommu_set_dma_strict();
>>       }
>>   }
>>   DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, 
>> quirk_calpella_no_shadow_gtt);
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index ccbd5d4c1a50..146cb71c7441 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
>>   }
>>   early_param("iommu.strict", iommu_dma_setup);
>> -void iommu_set_dma_strict(bool strict)
>> +void iommu_set_dma_strict(void)
>>   {
>> -    if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
> 
> We shouldn't need to keep IOMMU_CMD_LINE_STRICT at all now, since it was 
> only to prevent a driver's "default lazy" setting passed in here from 
> downgrading an explicitly-set strict mode.
> 
> With that cleaned up too,
> 

Patch 1/5 mentions whether the invalidation policy comes from the 
cmdline - similar to the default domain type print - so I was going to 
keep that.

And then maybe we should also set it from the deprecated x86 
driver-specific params.

But if you think that there is not much value in this additional info, 
then I can just drop it.

Cheers,
John
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[Robin Murphy]

On 2021-06-14 18:03, John Garry wrote:
> On 14/06/2021 17:25, Robin Murphy wrote:
>> On 2021-06-11 13:20, John Garry wrote:
>>> We only ever now set strict mode enabled in iommu_set_dma_strict(), so
>>> just remove the argument.
>>>
>>> Signed-off-by: John Garry <john.garry@huawei.com>
>>> ---
>>>   drivers/iommu/amd/init.c    | 2 +-
>>>   drivers/iommu/intel/iommu.c | 6 +++---
>>>   drivers/iommu/iommu.c       | 5 ++---
>>>   include/linux/iommu.h       | 2 +-
>>>   4 files changed, 7 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
>>> index 0e6ae6d68f14..27e9677ec303 100644
>>> --- a/drivers/iommu/amd/init.c
>>> +++ b/drivers/iommu/amd/init.c
>>> @@ -3098,7 +3098,7 @@ static int __init parse_amd_iommu_options(char 
>>> *str)
>>>   {
>>>       for (; *str; ++str) {
>>>           if (strncmp(str, "fullflush", 9) == 0)
>>> -            iommu_set_dma_strict(true);
>>> +            iommu_set_dma_strict();
>>>           if (strncmp(str, "force_enable", 12) == 0)
>>>               amd_iommu_force_enable = true;
>>>           if (strncmp(str, "off", 3) == 0)
>>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>>> index 6763e516362c..e77b8b6e7838 100644
>>> --- a/drivers/iommu/intel/iommu.c
>>> +++ b/drivers/iommu/intel/iommu.c
>>> @@ -452,7 +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)) {
>>> -            iommu_set_dma_strict(true);
>>> +            iommu_set_dma_strict();
>>>           } else if (!strncmp(str, "sp_off", 6)) {
>>>               pr_info("Disable supported super page\n");
>>>               intel_iommu_superpage = 0;
>>> @@ -4392,7 +4392,7 @@ int __init intel_iommu_init(void)
>>>            */
>>>           if (cap_caching_mode(iommu->cap)) {
>>>               pr_warn("IOMMU batching disallowed due to 
>>> virtualization\n");
>>> -            iommu_set_dma_strict(true);
>>> +            iommu_set_dma_strict();
>>>           }
>>>           iommu_device_sysfs_add(&iommu->iommu, NULL,
>>>                          intel_iommu_groups,
>>> @@ -5663,7 +5663,7 @@ 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");
>>> -        iommu_set_dma_strict(true);
>>> +        iommu_set_dma_strict();
>>>       }
>>>   }
>>>   DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, 
>>> quirk_calpella_no_shadow_gtt);
>>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>>> index ccbd5d4c1a50..146cb71c7441 100644
>>> --- a/drivers/iommu/iommu.c
>>> +++ b/drivers/iommu/iommu.c
>>> @@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
>>>   }
>>>   early_param("iommu.strict", iommu_dma_setup);
>>> -void iommu_set_dma_strict(bool strict)
>>> +void iommu_set_dma_strict(void)
>>>   {
>>> -    if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
>>
>> We shouldn't need to keep IOMMU_CMD_LINE_STRICT at all now, since it 
>> was only to prevent a driver's "default lazy" setting passed in here 
>> from downgrading an explicitly-set strict mode.
>>
>> With that cleaned up too,
>>
> 
> Patch 1/5 mentions whether the invalidation policy comes from the 
> cmdline - similar to the default domain type print - so I was going to 
> keep that.

Oh, silly me, I'd forgotten that already and was just looking at my 
local tree... Let's keep it for consistency with how we report the 
domain type then.

> And then maybe we should also set it from the deprecated x86 
> driver-specific params.

I don't think it's worth exporting more low-level guts to allow that to 
happen - tying in to iommu_set_dma_strict() would be too late, as 
before. I think the separate pr_warn()s which announce the relevant 
parameter is deprecated (but has still taken effect) should be enough.

Cheers,
Robin.

Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[Robin Murphy]

On 2021-06-14 18:03, John Garry wrote:
> On 14/06/2021 17:25, Robin Murphy wrote:
>> On 2021-06-11 13:20, John Garry wrote:
>>> We only ever now set strict mode enabled in iommu_set_dma_strict(), so
>>> just remove the argument.
>>>
>>> Signed-off-by: John Garry <john.garry@huawei.com>
>>> ---
>>>   drivers/iommu/amd/init.c    | 2 +-
>>>   drivers/iommu/intel/iommu.c | 6 +++---
>>>   drivers/iommu/iommu.c       | 5 ++---
>>>   include/linux/iommu.h       | 2 +-
>>>   4 files changed, 7 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
>>> index 0e6ae6d68f14..27e9677ec303 100644
>>> --- a/drivers/iommu/amd/init.c
>>> +++ b/drivers/iommu/amd/init.c
>>> @@ -3098,7 +3098,7 @@ static int __init parse_amd_iommu_options(char 
>>> *str)
>>>   {
>>>       for (; *str; ++str) {
>>>           if (strncmp(str, "fullflush", 9) == 0)
>>> -            iommu_set_dma_strict(true);
>>> +            iommu_set_dma_strict();
>>>           if (strncmp(str, "force_enable", 12) == 0)
>>>               amd_iommu_force_enable = true;
>>>           if (strncmp(str, "off", 3) == 0)
>>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>>> index 6763e516362c..e77b8b6e7838 100644
>>> --- a/drivers/iommu/intel/iommu.c
>>> +++ b/drivers/iommu/intel/iommu.c
>>> @@ -452,7 +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)) {
>>> -            iommu_set_dma_strict(true);
>>> +            iommu_set_dma_strict();
>>>           } else if (!strncmp(str, "sp_off", 6)) {
>>>               pr_info("Disable supported super page\n");
>>>               intel_iommu_superpage = 0;
>>> @@ -4392,7 +4392,7 @@ int __init intel_iommu_init(void)
>>>            */
>>>           if (cap_caching_mode(iommu->cap)) {
>>>               pr_warn("IOMMU batching disallowed due to 
>>> virtualization\n");
>>> -            iommu_set_dma_strict(true);
>>> +            iommu_set_dma_strict();
>>>           }
>>>           iommu_device_sysfs_add(&iommu->iommu, NULL,
>>>                          intel_iommu_groups,
>>> @@ -5663,7 +5663,7 @@ 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");
>>> -        iommu_set_dma_strict(true);
>>> +        iommu_set_dma_strict();
>>>       }
>>>   }
>>>   DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, 
>>> quirk_calpella_no_shadow_gtt);
>>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>>> index ccbd5d4c1a50..146cb71c7441 100644
>>> --- a/drivers/iommu/iommu.c
>>> +++ b/drivers/iommu/iommu.c
>>> @@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
>>>   }
>>>   early_param("iommu.strict", iommu_dma_setup);
>>> -void iommu_set_dma_strict(bool strict)
>>> +void iommu_set_dma_strict(void)
>>>   {
>>> -    if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
>>
>> We shouldn't need to keep IOMMU_CMD_LINE_STRICT at all now, since it 
>> was only to prevent a driver's "default lazy" setting passed in here 
>> from downgrading an explicitly-set strict mode.
>>
>> With that cleaned up too,
>>
> 
> Patch 1/5 mentions whether the invalidation policy comes from the 
> cmdline - similar to the default domain type print - so I was going to 
> keep that.

Oh, silly me, I'd forgotten that already and was just looking at my 
local tree... Let's keep it for consistency with how we report the 
domain type then.

> And then maybe we should also set it from the deprecated x86 
> driver-specific params.

I don't think it's worth exporting more low-level guts to allow that to 
happen - tying in to iommu_set_dma_strict() would be too late, as 
before. I think the separate pr_warn()s which announce the relevant 
parameter is deprecated (but has still taken effect) should be enough.

Cheers,
Robin.
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Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[John Garry]

On 14/06/2021 18:19, Robin Murphy wrote:
>>> We shouldn't need to keep IOMMU_CMD_LINE_STRICT at all now, since it 
>>> was only to prevent a driver's "default lazy" setting passed in here 
>>> from downgrading an explicitly-set strict mode.
>>>
>>> With that cleaned up too,
>>>
>>
>> Patch 1/5 mentions whether the invalidation policy comes from the 
>> cmdline - similar to the default domain type print - so I was going to 
>> keep that.
> 
> Oh, silly me, I'd forgotten that already and was just looking at my 
> local tree... Let's keep it for consistency with how we report the 
> domain type then.
> 
>> And then maybe we should also set it from the deprecated x86 
>> driver-specific params.
> 
> I don't think it's worth exporting more low-level guts to allow that to 
> happen - tying in to iommu_set_dma_strict() would be too late, as 
> before. I think the separate pr_warn()s which announce the relevant 
> parameter is deprecated (but has still taken effect) should be enough.
> 

Fine, I suppose someone using a deprecated interface can't complain 
about imperfect prints.

And I'll pick up your RB tag (unless you mention otherwise).

Thanks,
John

Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma_strict()

[John Garry]

On 14/06/2021 18:19, Robin Murphy wrote:
>>> We shouldn't need to keep IOMMU_CMD_LINE_STRICT at all now, since it 
>>> was only to prevent a driver's "default lazy" setting passed in here 
>>> from downgrading an explicitly-set strict mode.
>>>
>>> With that cleaned up too,
>>>
>>
>> Patch 1/5 mentions whether the invalidation policy comes from the 
>> cmdline - similar to the default domain type print - so I was going to 
>> keep that.
> 
> Oh, silly me, I'd forgotten that already and was just looking at my 
> local tree... Let's keep it for consistency with how we report the 
> domain type then.
> 
>> And then maybe we should also set it from the deprecated x86 
>> driver-specific params.
> 
> I don't think it's worth exporting more low-level guts to allow that to 
> happen - tying in to iommu_set_dma_strict() would be too late, as 
> before. I think the separate pr_warn()s which announce the relevant 
> parameter is deprecated (but has still taken effect) should be enough.
> 

Fine, I suppose someone using a deprecated interface can't complain 
about imperfect prints.

And I'll pick up your RB tag (unless you mention otherwise).

Thanks,
John


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