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Re: [Qemu-devel] [PATCH V3 05/10] intel_iommu: support device iotlb desc


From: Jason Wang
Subject: Re: [Qemu-devel] [PATCH V3 05/10] intel_iommu: support device iotlb descriptor
Date: Tue, 8 Nov 2016 14:54:19 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0



On 2016年11月08日 07:35, Peter Xu wrote:
On Mon, Nov 07, 2016 at 03:09:50PM +0800, Jason Wang wrote:

[...]

+static bool vtd_process_device_iotlb_desc(IntelIOMMUState *s,
+                                          VTDInvDesc *inv_desc)
+{
+    VTDAddressSpace *vtd_dev_as;
+    IOMMUTLBEntry entry;
Since "entry" is allocated on the stack...

[...]

+    entry.target_as = &vtd_dev_as->as;
+    entry.addr_mask = sz - 1;
+    entry.iova = addr;
+    memory_region_notify_iommu(entry.target_as->root, entry);
... here we need to assign entry.perm explicitly to IOMMU_NONE, right?

Also I think it'll be nice that we set all the fields even not used,
to avoid rubbish from the stack passed down to notifier handlers.

[...]

This is better, if no other comments on the series I will post a patch on top to fix this.


+static bool x86_iommu_device_iotlb_prop_get(Object *o, Error **errp)
+{
+    X86IOMMUState *s = X86_IOMMU_DEVICE(o);
+    return s->dt_supported;
+}
+
+static void x86_iommu_device_iotlb_prop_set(Object *o, bool value, Error 
**errp)
+{
+    X86IOMMUState *s = X86_IOMMU_DEVICE(o);
+    s->dt_supported = value;
+}
+
  static void x86_iommu_instance_init(Object *o)
  {
      X86IOMMUState *s = X86_IOMMU_DEVICE(o);
@@ -114,6 +126,11 @@ static void x86_iommu_instance_init(Object *o)
      s->intr_supported = false;
      object_property_add_bool(o, "intremap", x86_iommu_intremap_prop_get,
                               x86_iommu_intremap_prop_set, NULL);
+    s->dt_supported = false;
+    object_property_add_bool(o, "device-iotlb",
+                             x86_iommu_device_iotlb_prop_get,
+                             x86_iommu_device_iotlb_prop_set,
+                             NULL);
Again, a nit-pick here is to use Property for "device-iotlb":

     static Property vtd_properties[] = {
         DEFINE_PROP_UINT32("device-iotlb", X86IOMMUState, dt_supported, false),
         DEFINE_PROP_END_OF_LIST(),
     };

However not worth a repost.

Thanks,

-- peterx


We may want to share this with AMD IOMMU. (Looking at AMD IOMMU codes, its device-iotlb support is buggy).

Thanks



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