[PATCH 1/2] kvm: qemu: add warning message when assign device without IOMMU

[PATCH 1/2] kvm: qemu: add warning message when assign device without IOMMU

[Han, Weidong]

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When user wants to assign device with IOMMU, but IOMMU is not
enabled, add warning messages to prompt user this situation, and
return error. Or device will be assigned but it cannot work.

Signed-off-by: Weidong Han <weidong.han@intel.com>
---
 qemu/hw/device-assignment.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/qemu/hw/device-assignment.c b/qemu/hw/device-assignment.c
index b7f9fa6..cef7c8a 100644
--- a/qemu/hw/device-assignment.c
+++ b/qemu/hw/device-assignment.c
@@ -616,6 +616,11 @@ static int assign_device(AssignedDevInfo *adev)
     r = kvm_check_extension(kvm_context, KVM_CAP_IOMMU);
     if (r && !adev->disable_iommu)
 	assigned_dev_data.flags |= KVM_DEV_ASSIGN_ENABLE_IOMMU;
+    else if (!adev->disable_iommu && r == 0) {
+	fprintf(stderr, "IOMMU is not enabled. You cannot use "
+                "it to assign device!\n");
+	return -EINVAL;
+    }
 #endif
 
     r = kvm_assign_pci_device(kvm_context, &assigned_dev_data);
-- 
1.6.0.4

[-- Attachment #2: 0001-kvm-qemu-add-warning-message-when-assign-device-wi.patch --]
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From bd6db2f1a3946a2c85b1e1389be0919b0871ce76 Mon Sep 17 00:00:00 2001
From: Weidong Han <weidong.han@intel.com>
Date: Fri, 27 Mar 2009 00:47:08 +0800
Subject: [PATCH] kvm: qemu: add warning message when assign device without IOMMU

When user wants to assign device with IOMMU, but IOMMU is not
enabled, add warning messages to prompt user this situation, and
return error. Or device will be assigned but it cannot work.

Signed-off-by: Weidong Han <weidong.han@intel.com>
---
 qemu/hw/device-assignment.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/qemu/hw/device-assignment.c b/qemu/hw/device-assignment.c
index b7f9fa6..cef7c8a 100644
--- a/qemu/hw/device-assignment.c
+++ b/qemu/hw/device-assignment.c
@@ -616,6 +616,11 @@ static int assign_device(AssignedDevInfo *adev)
     r = kvm_check_extension(kvm_context, KVM_CAP_IOMMU);
     if (r && !adev->disable_iommu)
 	assigned_dev_data.flags |= KVM_DEV_ASSIGN_ENABLE_IOMMU;
+    else if (!adev->disable_iommu && r == 0) {
+	fprintf(stderr, "IOMMU is not enabled. You cannot use "
+                "it to assign device!\n");
+	return -EINVAL;
+    }
 #endif
 
     r = kvm_assign_pci_device(kvm_context, &assigned_dev_data);
-- 
1.6.0.4

Re: [PATCH 1/2] kvm: qemu: add warning message when assign device without IOMMU

[Avi Kivity]

Han, Weidong wrote:
> When user wants to assign device with IOMMU, but IOMMU is not
> enabled, add warning messages to prompt user this situation, and
> return error. Or device will be assigned but it cannot work.
>   

If the device has does not do DMA (say a serial port) then it can be 
assigned.  Can we check the device for dma capability and allow this 
special case?


-- 
error compiling committee.c: too many arguments to function

RE: [PATCH 1/2] kvm: qemu: add warning message when assign device without IOMMU

[Han, Weidong]

Avi Kivity wrote:
> Han, Weidong wrote:
>> When user wants to assign device with IOMMU, but IOMMU is not
>> enabled, add warning messages to prompt user this situation, and
>> return error. Or device will be assigned but it cannot work.
>> 
> 
> If the device has does not do DMA (say a serial port) then it can be
> assigned.  Can we check the device for dma capability and allow this
> special case?

Do you have any hint to check it? This warning be triggered only when user wants to assign device with IOMMU. If user doesn't want to use IOMMU to assign device, he can use "-pcidevice host=xx:yy.z,dma=none". 

Regards,
Weidong