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Cc:     baolu.lu@linux.intel.com, Joerg Roedel <jroedel@suse.de>,
        Ran Rozenstein <ranro@mellanox.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        Maor Gottlieb <maorg@mellanox.com>
Subject: Re: Failure to recreate virtual functions
To:     Robin Murphy <robin.murphy@arm.com>,
        Vlad Buslov <vladbu@mellanox.com>
References: <vbf8sskwyiv.fsf@mellanox.com>
 <d4166595-ec4a-fc4a-3b5f-463b79c42936@linux.intel.com>
 <vbfzhkx9n32.fsf@mellanox.com>
 <838a00c4-d5bd-08db-e39c-5f00686858b5@linux.intel.com>
 <6ece232e-3fe8-4bd9-cd4b-c8d90a106a30@arm.com>
From:   Lu Baolu <baolu.lu@linux.intel.com>
Message-ID: <abba9e2b-4bd4-bca5-dd50-05ca9ad96d1f@linux.intel.com>
Date:   Wed, 31 Jul 2019 15:29:42 +0800
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Hi,

On 7/30/19 7:22 PM, Robin Murphy wrote:
> On 30/07/2019 05:28, Lu Baolu wrote:
>> Hi,
>>
>> On 7/29/19 6:05 PM, Vlad Buslov wrote:
>>> On Sat 27 Jul 2019 at 05:15, Lu Baolu<baolu.lu@linux.intel.com>  wrote:
>>>> Hi Vilad,
>>>>
>>>> On 7/27/19 12:30 AM, Vlad Buslov wrote:
>>>>> Hi Lu Baolu,
>>>>>
>>>>> Our mlx5 driver fails to recreate VFs when cmdline includes
>>>>> "intel_iommu=on iommu=pt" after recent merge of patch set "iommu/vt-d:
>>>>> Delegate DMA domain to generic iommu". I've bisected the failure to
>>>>> patch b7297783c2bb ("iommu/vt-d: Remove duplicated code for device
>>>>> hotplug"). Here is the dmesg log for following case: enable switchdev
>>>>> mode, set number of VFs to 0, then set it back to any value
>>>>>> 0.
>>>>> [  223.525282] mlx5_core 0000:81:00.0: E-Switch: E-Switch enable 
>>>>> SRIOV: nvfs(2) mode (1)
>>>>> [  223.562027] mlx5_core 0000:81:00.0: E-Switch: SRIOV enabled: 
>>>>> active vports(3)
>>>>> [  223.663766] pci 0000:81:00.2: [15b3:101a] type 00 class 0x020000
>>>>> [  223.663864] pci 0000:81:00.2: enabling Extended Tags
>>>>> [  223.665143] pci 0000:81:00.2: Adding to iommu group 52
>>>>> [  223.665215] pci 0000:81:00.2: Using iommu direct mapping
>>>>> [  223.665771] mlx5_core 0000:81:00.2: enabling device (0000 -> 0002)
>>>>> [  223.665890] mlx5_core 0000:81:00.2: firmware version: 16.26.148
>>>>> [  223.889908] mlx5_core 0000:81:00.2: Rate limit: 127 rates are 
>>>>> supported, range: 0Mbps to 97656Mbps
>>>>> [  223.896438] mlx5_core 0000:81:00.2: MLX5E: StrdRq(1) RqSz(8) 
>>>>> StrdSz(2048) RxCqeCmprss(0)
>>>>> [  223.896636] mlx5_core 0000:81:00.2: Assigned random MAC address 
>>>>> 56:1f:95:e0:51:d6
>>>>> [  224.012905] mlx5_core 0000:81:00.2 ens1f0v0: renamed from eth0
>>>>> [  224.041651] pci 0000:81:00.3: [15b3:101a] type 00 class 0x020000
>>>>> [  224.041711] pci 0000:81:00.3: enabling Extended Tags
>>>>> [  224.043660] pci 0000:81:00.3: Adding to iommu group 53
>>>>> [  224.043738] pci 0000:81:00.3: Using iommu direct mapping
>>>>> [  224.044196] mlx5_core 0000:81:00.3: enabling device (0000 -> 0002)
>>>>> [  224.044298] mlx5_core 0000:81:00.3: firmware version: 16.26.148
>>>>> [  224.268099] mlx5_core 0000:81:00.3: Rate limit: 127 rates are 
>>>>> supported, range: 0Mbps to 97656Mbps
>>>>> [  224.274983] mlx5_core 0000:81:00.3: MLX5E: StrdRq(1) RqSz(8) 
>>>>> StrdSz(2048) RxCqeCmprss(0)
>>>>> [  224.275195] mlx5_core 0000:81:00.3: Assigned random MAC address 
>>>>> a6:1e:56:0a:d9:f2
>>>>> [  224.388359] mlx5_core 0000:81:00.3 ens1f0v1: renamed from eth0
>>>>> [  236.325027] mlx5_core 0000:81:00.0: E-Switch: disable SRIOV: 
>>>>> active vports(3) mode(1)
>>>>> [  236.362766] mlx5_core 0000:81:00.0: E-Switch: E-Switch enable 
>>>>> SRIOV: nvfs(2) mode (2)
>>>>> [  237.290066] mlx5_core 0000:81:00.0: MLX5E: StrdRq(1) RqSz(8) 
>>>>> StrdSz(2048) RxCqeCmprss(0)
>>>>> [  237.350215] mlx5_core 0000:81:00.0: MLX5E: StrdRq(1) RqSz(8) 
>>>>> StrdSz(2048) RxCqeCmprss(0)
>>>>> [  237.373052] mlx5_core 0000:81:00.0 ens1f0: renamed from eth0
>>>>> [  237.390768] mlx5_core 0000:81:00.0: MLX5E: StrdRq(1) RqSz(8) 
>>>>> StrdSz(2048) RxCqeCmprss(0)
>>>>> [  237.447846] ens1f0_0: renamed from eth0
>>>>> [  237.460399] mlx5_core 0000:81:00.0: E-Switch: SRIOV enabled: 
>>>>> active vports(3)
>>>>> [  237.526880] ens1f0_1: renamed from eth1
>>>>> [  248.953873] pci 0000:81:00.2: Removing from iommu group 52
>>>>> [  248.954114] pci 0000:81:00.3: Removing from iommu group 53
>>>>> [  249.960570] mlx5_core 0000:81:00.0: E-Switch: disable SRIOV: 
>>>>> active vports(3) mode(2)
>>>>> [  250.319135] mlx5_core 0000:81:00.0: MLX5E: StrdRq(1) RqSz(8) 
>>>>> StrdSz(2048) RxCqeCmprss(0)
>>>>> [  250.559431] mlx5_core 0000:81:00.0 ens1f0: renamed from eth0
>>>>> [  258.819162] mlx5_core 0000:81:00.0: E-Switch: E-Switch enable 
>>>>> SRIOV: nvfs(2) mode (1)
>>>>> [  258.831625] mlx5_core 0000:81:00.0: E-Switch: SRIOV enabled: 
>>>>> active vports(3)
>>>>> [  258.936160] pci 0000:81:00.2: [15b3:101a] type 00 class 0x020000
>>>>> [  258.936258] pci 0000:81:00.2: enabling Extended Tags
>>>>> [  258.937438] pci 0000:81:00.2: Failed to add to iommu group 52: -16
>>>> It seems that an EBUSY error returned from iommu_group_add_device(). 
>>>> Can
>>>> you please hack some debug messages in iommu_group_add_device() so that
>>>> we can know where the EBUSY returns?
>>>>
>>>> Best regards,
>>>> Baolu
>>> The error code is returned by __iommu_attach_device().
>>>
>>
>> Thanks!
>>
>> It looks like the system has already a domain for specific pci bdf
>> device. Does this VF share the bdf with other devices? Or has been
>> previously created, and system failed to get chance to remove it?
> 
> At a glance, it looks like it might be down to 
> intel_iommu_remove_device() not calling dmar_remove_one_dev_info() like 
> the old notifier did. If the group is getting torn down and recreated, 
> but the driver still has a stale pointer to the old default domain 
> cached, which dmar_insert_one_dev_info() finds and returns, that would 
> seem to explain the observed behaviour.

Yes agreed.

Vlad,

Can you please try below change?

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index baf21001c339..abffc520fe05 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5575,6 +5575,8 @@ static void intel_iommu_remove_device(struct 
device *dev)
         if (!iommu)
                 return;

+       dmar_remove_one_dev_info(dev);
+
         iommu_group_remove_device(dev);

         iommu_device_unlink(&iommu->iommu, dev);

Best regards,
Baolu