linux-kernel - Re: [PATCH v5 4/7] iommu/vt-d: Handle RMRR with PCI bridge device scopes

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Message-ID: <3f33a110-97a1-bd28-cacd-1df40a3922b0@linux.intel.com>
Date:   Wed, 29 May 2019 10:12:52 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Eric Auger <eric.auger@...hat.com>, eric.auger.pro@...il.com,
        joro@...tes.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, dwmw2@...radead.org,
        robin.murphy@....com
Cc:     baolu.lu@...ux.intel.com, alex.williamson@...hat.com,
        shameerali.kolothum.thodi@...wei.com, jean-philippe.brucker@....com
Subject: Re: [PATCH v5 4/7] iommu/vt-d: Handle RMRR with PCI bridge device
 scopes

Hi,

On 5/28/19 7:50 PM, Eric Auger wrote:
> When reading the vtd specification and especially the
> Reserved Memory Region Reporting Structure chapter,
> it is not obvious a device scope element cannot be a
> PCI-PCI bridge, in which case all downstream ports are
> likely to access the reserved memory region. Let's handle
> this case in device_has_rmrr.


This looks good to me.

Reviewed-by: Lu Baolu <baolu.lu@...ux.intel.com>

Best regards,
Baolu

> 
> Fixes: ea2447f700ca ("intel-iommu: Prevent devices with RMRRs from being placed into SI Domain")
> 
> Signed-off-by: Eric Auger <eric.auger@...hat.com>
> 
> ---
> 
> v1 -> v2:
> - is_downstream_to_pci_bridge helper introduced in a separate patch
> ---
>   drivers/iommu/intel-iommu.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 879f11c82b05..35508687f178 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -2910,7 +2910,8 @@ static bool device_has_rmrr(struct device *dev)
>   		 */
>   		for_each_active_dev_scope(rmrr->devices,
>   					  rmrr->devices_cnt, i, tmp)
> -			if (tmp == dev) {
> +			if (tmp == dev ||
> +			    is_downstream_to_pci_bridge(dev, tmp)) {
>   				rcu_read_unlock();
>   				return true;
>   			}
>