linux-kernel - Re: [PATCH] iommu/amd: Fix IOMMU page flush when detach all devices from a domain

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Date:   Wed, 16 Jan 2019 14:40:59 +0000
From:   "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>
To:     "joro@...tes.org" <joro@...tes.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        "Singh, Brijesh" <brijesh.singh@....com>
Subject: Re: [PATCH] iommu/amd: Fix IOMMU page flush when detach all devices
 from a domain

Joerg,

On 1/16/19 8:26 PM, joro@...tes.org wrote:
> How about the attached diff? If
> I understand the problem correctly, it should fix the problem more
> reliably.
> 
> Thanks,
> 
> 	Joerg
> 
> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> index 87ba23a75b38..dc1e2a8a19d7 100644
> --- a/drivers/iommu/amd_iommu.c
> +++ b/drivers/iommu/amd_iommu.c
> @@ -1991,25 +1991,36 @@ static void do_attach(struct iommu_dev_data *dev_data,
>   
>   static void do_detach(struct iommu_dev_data *dev_data)
>   {
> +	struct protection_domain *domain = dev_data->domain;
>   	struct amd_iommu *iommu;
>   	u16 alias;
>   
>   	iommu = amd_iommu_rlookup_table[dev_data->devid];
>   	alias = dev_data->alias;
>   
> -	/* decrease reference counters */
> -	dev_data->domain->dev_iommu[iommu->index] -= 1;
> -	dev_data->domain->dev_cnt                 -= 1;
> -
>   	/* Update data structures */
>   	dev_data->domain = NULL;
>   	list_del(&dev_data->list);
> -	clear_dte_entry(dev_data->devid);
> -	if (alias != dev_data->devid)
> -		clear_dte_entry(alias);
>   
> +	clear_dte_entry(dev_data->devid);
>   	/* Flush the DTE entry */
>   	device_flush_dte(dev_data);
> +
> +	if (alias != dev_data->devid) {
> +		clear_dte_entry(alias);
> +		/* Flush the Alias DTE entry */
> +		device_flush_dte(alias);
> +	}
> +

Actually, device_flush_dte(alias) should be needed regardless of this patch.
Are you planning to add this?

Regards,
Suravee