diff mbox series

[v4,5/5] iommu/arm-smmu-v3: add bootup option "arm_iommu"

Message ID 1533558424-16748-6-git-send-email-thunder.leizhen@huawei.com
State New
Headers show
Series add non-strict mode support for arm-smmu-v3 | expand

Commit Message

Zhen Lei Aug. 6, 2018, 12:27 p.m. UTC 
Add a bootup option to make the system manager can choose which mode to
be used. The default mode is strict.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>

---
 Documentation/admin-guide/kernel-parameters.txt |  9 +++++++++
 drivers/iommu/arm-smmu-v3.c                     | 17 ++++++++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

--
1.8.3

Comments

Robin Murphy Aug. 9, 2018, 11:08 a.m. UTC | #1 
On 06/08/18 13:27, Zhen Lei wrote:
> Add a bootup option to make the system manager can choose which mode to

> be used. The default mode is strict.

> 

> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>

> ---

>   Documentation/admin-guide/kernel-parameters.txt |  9 +++++++++

>   drivers/iommu/arm-smmu-v3.c                     | 17 ++++++++++++++++-

>   2 files changed, 25 insertions(+), 1 deletion(-)

> 

> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt

> index 533ff5c..426e989 100644

> --- a/Documentation/admin-guide/kernel-parameters.txt

> +++ b/Documentation/admin-guide/kernel-parameters.txt

> @@ -1720,6 +1720,15 @@

>   		nobypass	[PPC/POWERNV]

>   			Disable IOMMU bypass, using IOMMU for PCI devices.

> 

> +	arm_iommu=	[ARM64]

> +		non-strict	[Default Off]


Again, I'd much rather have "iommu.non_strict= { "0" | "1" }" in line 
with the passthrough option.

Robin.

> +			Put off TLBs invalidation and release memory first.

> +			It's good for scatter-gather performance but lacks full

> +			isolation, an untrusted device can access the reused

> +			memory because the TLBs may still valid. Please take

> +			full consideration before choosing this mode.

> +			Note that, VFIO will always use strict mode.

> +

>   	iommu.passthrough=

>   			[ARM64] Configure DMA to bypass the IOMMU by default.

>   			Format: { "0" | "1" }

> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c

> index 904bc1e..9a30892 100644

> --- a/drivers/iommu/arm-smmu-v3.c

> +++ b/drivers/iommu/arm-smmu-v3.c

> @@ -631,6 +631,21 @@ struct arm_smmu_option_prop {

>   	{ 0, NULL},

>   };

> 

> +static u32 smmu_non_strict __read_mostly;

> +

> +static int __init arm_smmu_setup(char *str)

> +{

> +	if (!strncmp(str, "non-strict", 10)) {

> +		smmu_non_strict = 1;

> +		pr_warn("WARNING: iommu non-strict mode is chosen.\n"

> +			"It's good for scatter-gather performance but lacks full isolation\n");

> +		add_taint(TAINT_WARN, LOCKDEP_STILL_OK);

> +	}

> +

> +	return 0;

> +}

> +early_param("arm_iommu", arm_smmu_setup);

> +

>   static inline void __iomem *arm_smmu_page1_fixup(unsigned long offset,

>   						 struct arm_smmu_device *smmu)

>   {

> @@ -1622,7 +1637,7 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain)

>   	if (smmu->features & ARM_SMMU_FEAT_COHERENCY)

>   		pgtbl_cfg.quirks = IO_PGTABLE_QUIRK_NO_DMA;

> 

> -	if (domain->type == IOMMU_DOMAIN_DMA) {

> +	if ((domain->type == IOMMU_DOMAIN_DMA) && smmu_non_strict) {

>   		domain->non_strict = 1;

>   		pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;

>   	}

> --

> 1.8.3

> 

>
Zhen Lei Aug. 13, 2018, 7:50 a.m. UTC | #2 
On 2018/8/9 19:08, Robin Murphy wrote:
> On 06/08/18 13:27, Zhen Lei wrote:

>> Add a bootup option to make the system manager can choose which mode to

>> be used. The default mode is strict.

>>

>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>

>> ---

>>   Documentation/admin-guide/kernel-parameters.txt |  9 +++++++++

>>   drivers/iommu/arm-smmu-v3.c                     | 17 ++++++++++++++++-

>>   2 files changed, 25 insertions(+), 1 deletion(-)

>>

>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt

>> index 533ff5c..426e989 100644

>> --- a/Documentation/admin-guide/kernel-parameters.txt

>> +++ b/Documentation/admin-guide/kernel-parameters.txt

>> @@ -1720,6 +1720,15 @@

>>           nobypass    [PPC/POWERNV]

>>               Disable IOMMU bypass, using IOMMU for PCI devices.

>>

>> +    arm_iommu=    [ARM64]

>> +        non-strict    [Default Off]

> 

> Again, I'd much rather have "iommu.non_strict= { "0" | "1" }" in line with the passthrough option.


OK，I will change it in the next version.

> 

> Robin.

> 

>> +            Put off TLBs invalidation and release memory first.

>> +            It's good for scatter-gather performance but lacks full

>> +            isolation, an untrusted device can access the reused

>> +            memory because the TLBs may still valid. Please take

>> +            full consideration before choosing this mode.

>> +            Note that, VFIO will always use strict mode.

>> +

>>       iommu.passthrough=

>>               [ARM64] Configure DMA to bypass the IOMMU by default.

>>               Format: { "0" | "1" }

>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c

>> index 904bc1e..9a30892 100644

>> --- a/drivers/iommu/arm-smmu-v3.c

>> +++ b/drivers/iommu/arm-smmu-v3.c

>> @@ -631,6 +631,21 @@ struct arm_smmu_option_prop {

>>       { 0, NULL},

>>   };

>>

>> +static u32 smmu_non_strict __read_mostly;

>> +

>> +static int __init arm_smmu_setup(char *str)

>> +{

>> +    if (!strncmp(str, "non-strict", 10)) {

>> +        smmu_non_strict = 1;

>> +        pr_warn("WARNING: iommu non-strict mode is chosen.\n"

>> +            "It's good for scatter-gather performance but lacks full isolation\n");

>> +        add_taint(TAINT_WARN, LOCKDEP_STILL_OK);

>> +    }

>> +

>> +    return 0;

>> +}

>> +early_param("arm_iommu", arm_smmu_setup);

>> +

>>   static inline void __iomem *arm_smmu_page1_fixup(unsigned long offset,

>>                            struct arm_smmu_device *smmu)

>>   {

>> @@ -1622,7 +1637,7 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain)

>>       if (smmu->features & ARM_SMMU_FEAT_COHERENCY)

>>           pgtbl_cfg.quirks = IO_PGTABLE_QUIRK_NO_DMA;

>>

>> -    if (domain->type == IOMMU_DOMAIN_DMA) {

>> +    if ((domain->type == IOMMU_DOMAIN_DMA) && smmu_non_strict) {

>>           domain->non_strict = 1;

>>           pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;

>>       }

>> -- 

>> 1.8.3

>>

>>

> 

> .

> 


-- 
Thanks!
BestRegards
diff mbox series

Patch

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 533ff5c..426e989 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1720,6 +1720,15 @@ 
 		nobypass	[PPC/POWERNV]
 			Disable IOMMU bypass, using IOMMU for PCI devices.

+	arm_iommu=	[ARM64]
+		non-strict	[Default Off]
+			Put off TLBs invalidation and release memory first.
+			It's good for scatter-gather performance but lacks full
+			isolation, an untrusted device can access the reused
+			memory because the TLBs may still valid. Please take
+			full consideration before choosing this mode.
+			Note that, VFIO will always use strict mode.
+
 	iommu.passthrough=
 			[ARM64] Configure DMA to bypass the IOMMU by default.
 			Format: { "0" | "1" }
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 904bc1e..9a30892 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -631,6 +631,21 @@  struct arm_smmu_option_prop {
 	{ 0, NULL},
 };

+static u32 smmu_non_strict __read_mostly;
+
+static int __init arm_smmu_setup(char *str)
+{
+	if (!strncmp(str, "non-strict", 10)) {
+		smmu_non_strict = 1;
+		pr_warn("WARNING: iommu non-strict mode is chosen.\n"
+			"It's good for scatter-gather performance but lacks full isolation\n");
+		add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
+	}
+
+	return 0;
+}
+early_param("arm_iommu", arm_smmu_setup);
+
 static inline void __iomem *arm_smmu_page1_fixup(unsigned long offset,
 						 struct arm_smmu_device *smmu)
 {
@@ -1622,7 +1637,7 @@  static int arm_smmu_domain_finalise(struct iommu_domain *domain)
 	if (smmu->features & ARM_SMMU_FEAT_COHERENCY)
 		pgtbl_cfg.quirks = IO_PGTABLE_QUIRK_NO_DMA;

-	if (domain->type == IOMMU_DOMAIN_DMA) {
+	if ((domain->type == IOMMU_DOMAIN_DMA) && smmu_non_strict) {
 		domain->non_strict = 1;
 		pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;
 	}