linux-kernel - RE: [PATCH v6 4/7] iommu/dma: Move PCI window region reservation back into dma specific path.

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Date:   Tue, 24 Apr 2018 13:16:19 +0000
From:   Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>
To:     Joerg Roedel <joro@...tes.org>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        Linuxarm <linuxarm@...wei.com>,
        John Garry <john.garry@...wei.com>,
        "xuwei (O)" <xuwei5@...wei.com>,
        Robin Murphy <robin.murphy@....com>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "eric.auger@...hat.com" <eric.auger@...hat.com>,
        "pmorel@...ux.vnet.ibm.com" <pmorel@...ux.vnet.ibm.com>
Subject: RE: [PATCH v6 4/7] iommu/dma: Move PCI window region reservation
 back into dma specific path.

Hi Joerg,

Could you please take a look at this patch and let me know.

I have rebased this to 4.17-rc1  and added Robin's R-by.

This series[1] is now pending on this patch as without this it will break few
ARM platforms[2]. 

Please take a look and let me know.

Thanks,
Shameer

[1] https://lkml.org/lkml/2018/4/18/293
[2] https://lkml.org/lkml/2018/3/14/881


> -----Original Message-----
> From: Shameerali Kolothum Thodi
> Sent: Wednesday, April 18, 2018 12:41 PM
> To: alex.williamson@...hat.com; eric.auger@...hat.com;
> pmorel@...ux.vnet.ibm.com
> Cc: kvm@...r.kernel.org; linux-kernel@...r.kernel.org; iommu@...ts.linux-
> foundation.org; Linuxarm <linuxarm@...wei.com>; John Garry
> <john.garry@...wei.com>; xuwei (O) <xuwei5@...wei.com>; Shameerali
> Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>; Joerg Roedel
> <joro@...tes.org>
> Subject: [PATCH v6 4/7] iommu/dma: Move PCI window region reservation
> back into dma specific path.
> 
> This pretty much reverts commit 273df9635385 ("iommu/dma: Make PCI
> window reservation generic")  by moving the PCI window region
> reservation back into the dma specific path so that these regions
> doesn't get exposed via the IOMMU API interface. With this change,
> the vfio interface will report only iommu specific reserved regions
> to the user space.
> 
> Cc: Joerg Roedel <joro@...tes.org>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
> Reviewed-by: Robin Murphy <robin.murphy@....com>
> ---
>  drivers/iommu/dma-iommu.c | 54 ++++++++++++++++++++++----------------------
> ---
>  1 file changed, 25 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index f05f3cf..ddcbbdb 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -167,40 +167,16 @@ EXPORT_SYMBOL(iommu_put_dma_cookie);
>   * @list: Reserved region list from iommu_get_resv_regions()
>   *
>   * IOMMU drivers can use this to implement their .get_resv_regions callback
> - * for general non-IOMMU-specific reservations. Currently, this covers host
> - * bridge windows for PCI devices and GICv3 ITS region reservation on ACPI
> - * based ARM platforms that may require HW MSI reservation.
> + * for general non-IOMMU-specific reservations. Currently, this covers GICv3
> + * ITS region reservation on ACPI based ARM platforms that may require HW
> MSI
> + * reservation.
>   */
>  void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list)
>  {
> -	struct pci_host_bridge *bridge;
> -	struct resource_entry *window;
> -
> -	if (!is_of_node(dev->iommu_fwspec->iommu_fwnode) &&
> -		iort_iommu_msi_get_resv_regions(dev, list) < 0)
> -		return;
> -
> -	if (!dev_is_pci(dev))
> -		return;
> -
> -	bridge = pci_find_host_bridge(to_pci_dev(dev)->bus);
> -	resource_list_for_each_entry(window, &bridge->windows) {
> -		struct iommu_resv_region *region;
> -		phys_addr_t start;
> -		size_t length;
> -
> -		if (resource_type(window->res) != IORESOURCE_MEM)
> -			continue;
> 
> -		start = window->res->start - window->offset;
> -		length = window->res->end - window->res->start + 1;
> -		region = iommu_alloc_resv_region(start, length, 0,
> -				IOMMU_RESV_RESERVED);
> -		if (!region)
> -			return;
> +	if (!is_of_node(dev->iommu_fwspec->iommu_fwnode))
> +		iort_iommu_msi_get_resv_regions(dev, list);
> 
> -		list_add_tail(&region->list, list);
> -	}
>  }
>  EXPORT_SYMBOL(iommu_dma_get_resv_regions);
> 
> @@ -229,6 +205,23 @@ static int cookie_init_hw_msi_region(struct
> iommu_dma_cookie *cookie,
>  	return 0;
>  }
> 
> +static void iova_reserve_pci_windows(struct pci_dev *dev,
> +		struct iova_domain *iovad)
> +{
> +	struct pci_host_bridge *bridge = pci_find_host_bridge(dev->bus);
> +	struct resource_entry *window;
> +	unsigned long lo, hi;
> +
> +	resource_list_for_each_entry(window, &bridge->windows) {
> +		if (resource_type(window->res) != IORESOURCE_MEM)
> +			continue;
> +
> +		lo = iova_pfn(iovad, window->res->start - window->offset);
> +		hi = iova_pfn(iovad, window->res->end - window->offset);
> +		reserve_iova(iovad, lo, hi);
> +	}
> +}
> +
>  static int iova_reserve_iommu_regions(struct device *dev,
>  		struct iommu_domain *domain)
>  {
> @@ -238,6 +231,9 @@ static int iova_reserve_iommu_regions(struct device
> *dev,
>  	LIST_HEAD(resv_regions);
>  	int ret = 0;
> 
> +	if (dev_is_pci(dev))
> +		iova_reserve_pci_windows(to_pci_dev(dev), iovad);
> +
>  	iommu_get_resv_regions(dev, &resv_regions);
>  	list_for_each_entry(region, &resv_regions, list) {
>  		unsigned long lo, hi;
> --
> 2.7.4
>