Re: [XEN][PATCH v11 12/20] xen/smmu: Add remove_device callback for smmu_iommu ops

[Stefano Stabellini]

On Mon, 4 Sep 2023, Michal Orzel wrote:
> On 01/09/2023 06:59, Vikram Garhwal wrote:
> > Add remove_device callback for removing the device entry from smmu-master 
> > using
> > following steps:
> > 1. Find if SMMU master exists for the device node.
> > 2. Check if device is currently in use.
> Just like in v10: you are not checking it. I asked you to add a check 
> following Julien suggestion
> but you did not reply to it. Even if you do not want to add this extra layer 
> of protection, you
> should mention that you rely on a check in iommu_remove_dt_device() instead. 
> You can wait for Stefano
> to give his opinion (and possibly ack this patch as is).

Yes I would have appreciated a reply on the list. I'll ack it as is.

Acked-by: Stefano Stabellini 

Re: [XEN][PATCH v11 12/20] xen/smmu: Add remove_device callback for smmu_iommu ops

[Vikram Garhwal]

Hi Michal, 
On Mon, Sep 04, 2023 at 12:38:01PM +0200, Michal Orzel wrote:
> 
> 
> On 01/09/2023 06:59, Vikram Garhwal wrote:
> > Add remove_device callback for removing the device entry from smmu-master 
> > using
> > following steps:
> > 1. Find if SMMU master exists for the device node.
> > 2. Check if device is currently in use.
> Just like in v10: you are not checking it. I asked you to add a check 
> following Julien suggestion
> but you did not reply to it. Even if you do not want to add this extra layer 
> of protection, you
> should mention that you rely on a check in iommu_remove_dt_device() instead. 
> You can wait for Stefano
> to give his opinion (and possibly ack this patch as is).
> 
Caller checks it already so that was the reason for not adding here. IIUC, 
Stefano
was okay with v10 patch so that's why i didn't make changes.

> ~Michal

Re: [XEN][PATCH v11 12/20] xen/smmu: Add remove_device callback for smmu_iommu ops

[Michal Orzel]

On 01/09/2023 06:59, Vikram Garhwal wrote:
> Add remove_device callback for removing the device entry from smmu-master 
> using
> following steps:
> 1. Find if SMMU master exists for the device node.
> 2. Check if device is currently in use.
Just like in v10: you are not checking it. I asked you to add a check following 
Julien suggestion
but you did not reply to it. Even if you do not want to add this extra layer of 
protection, you
should mention that you rely on a check in iommu_remove_dt_device() instead. 
You can wait for Stefano
to give his opinion (and possibly ack this patch as is).

~Michal

[XEN][PATCH v11 12/20] xen/smmu: Add remove_device callback for smmu_iommu ops

[Vikram Garhwal]

Add remove_device callback for removing the device entry from smmu-master using
following steps:
1. Find if SMMU master exists for the device node.
2. Check if device is currently in use.
3. Remove the SMMU master.

Signed-off-by: Vikram Garhwal 

---
 Changes from v9:
Remove iommu_dt_device_is_assigned_locked().
Add comment regarding caller holding the locks to protect concurrent access.
 Changes from v7:
Added comments on arm_smmu_dt_remove_device_generic().
---
---
 xen/drivers/passthrough/arm/smmu.c | 60 ++
 1 file changed, 60 insertions(+)

diff --git a/xen/drivers/passthrough/arm/smmu.c 
b/xen/drivers/passthrough/arm/smmu.c
index c37fa9af13..71799064f8 100644
--- a/xen/drivers/passthrough/arm/smmu.c
+++ b/xen/drivers/passthrough/arm/smmu.c
@@ -815,6 +815,19 @@ static int insert_smmu_master(struct arm_smmu_device *smmu,
return 0;
 }
 
+static int remove_smmu_master(struct arm_smmu_device *smmu,
+ struct arm_smmu_master *master)
+{
+   if (!smmu->masters.rb_node) {
+   ASSERT_UNREACHABLE();
+   return -ENOENT;
+   }
+
+   rb_erase(>node, >masters);
+
+   return 0;
+}
+
 static int arm_smmu_dt_add_device_legacy(struct arm_smmu_device *smmu,
 struct device *dev,
 struct iommu_fwspec *fwspec)
@@ -852,6 +865,32 @@ static int arm_smmu_dt_add_device_legacy(struct 
arm_smmu_device *smmu,
return insert_smmu_master(smmu, master);
 }
 
+static int arm_smmu_dt_remove_device_legacy(struct arm_smmu_device *smmu,
+struct device *dev)
+{
+   struct arm_smmu_master *master;
+   struct device_node *dev_node = dev_get_dev_node(dev);
+   int ret;
+
+   master = find_smmu_master(smmu, dev_node);
+   if (master == NULL) {
+   dev_err(dev,
+   "No registrations found for master device %s\n",
+   dev_node->name);
+   return -EINVAL;
+   }
+
+   ret = remove_smmu_master(smmu, master);
+   if (ret)
+   return ret;
+
+   /* Protected by dt_host_lock and dtdevs_lock as caller holds these 
locks. */
+   dev_node->is_protected = false;
+
+   kfree(master);
+   return 0;
+}
+
 static int register_smmu_master(struct arm_smmu_device *smmu,
struct device *dev,
struct of_phandle_args *masterspec)
@@ -875,6 +914,26 @@ static int register_smmu_master(struct arm_smmu_device 
*smmu,
 fwspec);
 }
 
+/*
+ * The driver which supports generic IOMMU DT bindings must have this
+ * callback implemented.
+ */
+static int arm_smmu_dt_remove_device_generic(u8 devfn, struct device *dev)
+{
+   struct arm_smmu_device *smmu;
+   struct iommu_fwspec *fwspec;
+
+   fwspec = dev_iommu_fwspec_get(dev);
+   if (fwspec == NULL)
+   return -ENXIO;
+
+   smmu = find_smmu(fwspec->iommu_dev);
+   if (smmu == NULL)
+   return -ENXIO;
+
+   return arm_smmu_dt_remove_device_legacy(smmu, dev);
+}
+
 static int arm_smmu_dt_add_device_generic(u8 devfn, struct device *dev)
 {
struct arm_smmu_device *smmu;
@@ -2859,6 +2918,7 @@ static const struct iommu_ops arm_smmu_iommu_ops = {
 .init = arm_smmu_iommu_domain_init,
 .hwdom_init = arch_iommu_hwdom_init,
 .add_device = arm_smmu_dt_add_device_generic,
+.remove_device = arm_smmu_dt_remove_device_generic,
 .teardown = arm_smmu_iommu_domain_teardown,
 .iotlb_flush = arm_smmu_iotlb_flush,
 .assign_device = arm_smmu_assign_dev,
-- 
2.17.1