[PATCH 1/1] iommu/vt-d: Check identity map for hot-added devices

[PATCH 1/1] iommu/vt-d: Check identity map for hot-added devices

[Lu Baolu]

The Intel IOMMU driver will put devices into a static identity
mapped domain during boot if the kernel parameter "iommu=pt" is
used. That means the IOMMU hardware will translate a DMA address
into the same memory address.

Unfortunately, hot-added devices are not subject to this. That
results in some devices not working properly after hot added. A
quick way to reproduce this issue is to boot a system with

    iommu=pt

and, remove then readd the pci device with

    echo 1 > /sys/bus/pci/devices/[pci_source_id]/remove
    echo 1 > /sys/bus/pci/rescan

You will find the identity mapped domain was replaced with a
normal domain.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: stable@vger.kernel.org
Reported-by: Jis Ben <jisben@google.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: James Dong <xmdong@google.com>
---
 drivers/iommu/intel-iommu.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index af23cfc2a05e..4f77657a9c25 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4564,16 +4564,19 @@ static int device_notifier(struct notifier_block *nb,
 	if (iommu_dummy(dev))
 		return 0;
 
-	if (action != BUS_NOTIFY_REMOVED_DEVICE)
-		return 0;
-
-	domain = find_domain(dev);
-	if (!domain)
-		return 0;
+	if (action == BUS_NOTIFY_REMOVED_DEVICE) {
+		domain = find_domain(dev);
+		if (!domain)
+			return 0;
 
-	dmar_remove_one_dev_info(dev);
-	if (!domain_type_is_vm_or_si(domain) && list_empty(&domain->devices))
-		domain_exit(domain);
+		dmar_remove_one_dev_info(dev);
+		if (!domain_type_is_vm_or_si(domain) &&
+		    list_empty(&domain->devices))
+			domain_exit(domain);
+	} else if (action == BUS_NOTIFY_ADD_DEVICE) {
+		if (iommu_should_identity_map(dev, 1))
+			domain_add_dev_info(si_domain, dev);
+	}
 
 	return 0;
 }
-- 
2.17.1

Re: [PATCH 1/1] iommu/vt-d: Check identity map for hot-added devices

[Joerg Roedel]

On Mon, Feb 25, 2019 at 10:46:36AM +0800, Lu Baolu wrote:
>  drivers/iommu/intel-iommu.c | 21 ++++++++++++---------
>  1 file changed, 12 insertions(+), 9 deletions(-)

Added a Fixes: tag and applied the patch, thanks.

Re: [PATCH 1/1] iommu/vt-d: Check identity map for hot-added devices

[Joerg Roedel]

Hi Sasha,

Thanks for the heads-up!

On Tue, Feb 26, 2019 at 09:24:00PM +0000, Sasha Levin wrote:
> Hi,
> 
> [This is an automated email]
> 
> This commit has been processed because it contains a -stable tag.
> The stable tag indicates that it's relevant for the following trees: all
> 
> The bot has tested the following trees: v4.20.12, v4.19.25, v4.14.103, v4.9.160, v4.4.176, v3.18.136.
> 

Lu Baolu, can you please check for which stable trees this commit is
relevant and provide the backports of the patch (with dependencies if
necessary) to the relevant stable trees?

Thanks,

	Joerg

Re: [PATCH 1/1] iommu/vt-d: Check identity map for hot-added devices

[Lu Baolu]

Hi Joerg,

On 2/28/19 5:49 PM, Joerg Roedel wrote:
> Hi Sasha,
> 
> Thanks for the heads-up!
> 
> On Tue, Feb 26, 2019 at 09:24:00PM +0000, Sasha Levin wrote:
>> Hi,
>>
>> [This is an automated email]
>>
>> This commit has been processed because it contains a -stable tag.
>> The stable tag indicates that it's relevant for the following trees: all
>>
>> The bot has tested the following trees: v4.20.12, v4.19.25, v4.14.103, v4.9.160, v4.4.176, v3.18.136.
>>
> 
> Lu Baolu, can you please check for which stable trees this commit is
> relevant and provide the backports of the patch (with dependencies if
> necessary) to the relevant stable trees?
> 

Sure. Actually, I am doing this.

Best regards,
Lu Baolu