Re: [PATCH v3 1/4] iommu: Introduce device_iommu_capable()

2022-04-06 Thread Robin Murphy 

On 2022-04-06 06:28, Christoph Hellwig wrote:

On Tue, Apr 05, 2022 at 11:41:01AM +0100, Robin Murphy wrote:

iommu_capable() only really works for systems where all IOMMU instances
are completely homogeneous, and all devices are IOMMU-mapped. Implement
the new variant which can give an accurate answer for whichever device
the caller is actually interested in.

Signed-off-by: Robin Murphy 
---

v3: New patch; now that the dev_iommu_ops() work has landed we can go
 straight to a proper implementation. Also s/dev/device/ to match
 the precedent of device_iommu_mapped() for the public API.


I'm a little worrited about a method with a parameter than can be
NULL.


FWIW, the intent is that that's only temporary.


Also usnic, vmd, and vdpa really want to use your new
device_iommu_capable as they check based on a device.  Just VFIO
is special as usual..


Indeed, I have those patches in my stack already, I'm just waiting for 
this to land before I think about posting them. Once the DMA ownership 
series lands in parallel, VFIO can also get converted and 
iommu_capable() goes away entirely. At that point I have a patch for the 
Arm SMMU drivers to start actually using the new device argument, but 
Jason's new proposal now puts a twist on that...


On reflection, there's no real need for the internal method to change in 
lock-step with the external interface. I've no objection to holding off 
on adding that new parameter until it's reliably useful, and indeed now 
that I'm looking at it outside the context of the entire cleanup 
mission, that does sound like the right thing to do anyway :)


(also it turns out I need to respin this patch regardless since I 
generated it from the wrong point in my branch, where iommu_present() 
was already gone from the context in iommu.h...)


Cheers,
Robin.
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Re: [PATCH v3 1/4] iommu: Introduce device_iommu_capable()

2022-04-05 Thread Christoph Hellwig 
On Tue, Apr 05, 2022 at 11:41:01AM +0100, Robin Murphy wrote:
> iommu_capable() only really works for systems where all IOMMU instances
> are completely homogeneous, and all devices are IOMMU-mapped. Implement
> the new variant which can give an accurate answer for whichever device
> the caller is actually interested in.
> 
> Signed-off-by: Robin Murphy 
> ---
> 
> v3: New patch; now that the dev_iommu_ops() work has landed we can go
> straight to a proper implementation. Also s/dev/device/ to match
> the precedent of device_iommu_mapped() for the public API.

I'm a little worrited about a method with a parameter than can be
NULL.

Also usnic, vmd, and vdpa really want to use your new
device_iommu_capable as they check based on a device.  Just VFIO
is special as usual..
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[PATCH v3 1/4] iommu: Introduce device_iommu_capable()

2022-04-05 Thread Robin Murphy 
iommu_capable() only really works for systems where all IOMMU instances
are completely homogeneous, and all devices are IOMMU-mapped. Implement
the new variant which can give an accurate answer for whichever device
the caller is actually interested in.

Signed-off-by: Robin Murphy 
---

v3: New patch; now that the dev_iommu_ops() work has landed we can go
straight to a proper implementation. Also s/dev/device/ to match
the precedent of device_iommu_mapped() for the public API.

 drivers/iommu/amd/iommu.c   |  2 +-
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  2 +-
 drivers/iommu/arm/arm-smmu/arm-smmu.c   |  2 +-
 drivers/iommu/arm/arm-smmu/qcom_iommu.c |  2 +-
 drivers/iommu/fsl_pamu_domain.c |  2 +-
 drivers/iommu/intel/iommu.c |  2 +-
 drivers/iommu/iommu.c   | 25 -
 drivers/iommu/s390-iommu.c  |  2 +-
 include/linux/iommu.h   |  8 ++-
 9 files changed, 38 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 1160a13c80ab..e412a50dce59 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2132,7 +2132,7 @@ static phys_addr_t amd_iommu_iova_to_phys(struct 
iommu_domain *dom,
return ops->iova_to_phys(ops, iova);
 }
 
-static bool amd_iommu_capable(enum iommu_cap cap)
+static bool amd_iommu_capable(struct device *dev, enum iommu_cap cap)
 {
switch (cap) {
case IOMMU_CAP_CACHE_COHERENCY:
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c 
b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 73b7b1b17b77..b221525c31b9 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -1981,7 +1981,7 @@ static const struct iommu_flush_ops arm_smmu_flush_ops = {
 };
 
 /* IOMMU API */
-static bool arm_smmu_capable(enum iommu_cap cap)
+static bool arm_smmu_capable(struct device *dev, enum iommu_cap cap)
 {
switch (cap) {
case IOMMU_CAP_CACHE_COHERENCY:
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c 
b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index f0bec4a35df5..34cab56b9c6d 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -1313,7 +1313,7 @@ static phys_addr_t arm_smmu_iova_to_phys(struct 
iommu_domain *domain,
return ops->iova_to_phys(ops, iova);
 }
 
-static bool arm_smmu_capable(enum iommu_cap cap)
+static bool arm_smmu_capable(struct device *dev, enum iommu_cap cap)
 {
switch (cap) {
case IOMMU_CAP_CACHE_COHERENCY:
diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c 
b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
index 80af00f468b4..028649203d33 100644
--- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
+++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
@@ -493,7 +493,7 @@ static phys_addr_t qcom_iommu_iova_to_phys(struct 
iommu_domain *domain,
return ret;
 }
 
-static bool qcom_iommu_capable(enum iommu_cap cap)
+static bool qcom_iommu_capable(struct device *dev, enum iommu_cap cap)
 {
switch (cap) {
case IOMMU_CAP_CACHE_COHERENCY:
diff --git a/drivers/iommu/fsl_pamu_domain.c b/drivers/iommu/fsl_pamu_domain.c
index 7274f86b2bc4..ddf5ab28615c 100644
--- a/drivers/iommu/fsl_pamu_domain.c
+++ b/drivers/iommu/fsl_pamu_domain.c
@@ -177,7 +177,7 @@ static phys_addr_t fsl_pamu_iova_to_phys(struct 
iommu_domain *domain,
return iova;
 }
 
-static bool fsl_pamu_capable(enum iommu_cap cap)
+static bool fsl_pamu_capable(struct device *dev, enum iommu_cap cap)
 {
return cap == IOMMU_CAP_CACHE_COHERENCY;
 }
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 2491ddfd..255304eb3b1f 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4544,7 +4544,7 @@ static phys_addr_t intel_iommu_iova_to_phys(struct 
iommu_domain *domain,
return phys;
 }
 
-static bool intel_iommu_capable(enum iommu_cap cap)
+static bool intel_iommu_capable(struct device *dev, enum iommu_cap cap)
 {
if (cap == IOMMU_CAP_CACHE_COHERENCY)
return domain_update_iommu_snooping(NULL);
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index efad7c1675e0..469574e84e6a 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1889,12 +1889,35 @@ static int iommu_bus_init(struct bus_type *bus)
return err;
 }
 
+/**
+ * device_iommu_capable() - check for a general IOMMU capability
+ * @dev: device to which the capability would be relevant, if available
+ * @cap: IOMMU capability
+ *
+ * Return: true if an IOMMU is present and supports the given capability
+ * for the given device, otherwise false.
+ */
+bool device_iommu_capable(struct device *dev, enum iommu_cap cap)
+{
+   const struct iommu_ops *ops;
+
+   if (!dev->iommu || !dev->iommu->iommu_dev)
+   return false;
+
+   ops = dev_iommu_ops(dev);
+   if (!ops->capable)
+