[PATCH 2/3 v2] iommu/fsl: Enable default DMA window for PCIe devices

Bhushan Bharat-R65777 R65777 at freescale.com
Thu Oct 17 03:50:02 EST 2013



> -----Original Message-----
> From: Sethi Varun-B16395
> Sent: Wednesday, October 16, 2013 4:53 PM
> To: joro at 8bytes.org; iommu at lists.linux-foundation.org; linuxppc-
> dev at lists.ozlabs.org; linux-kernel at vger.kernel.org; Yoder Stuart-B08248; Wood
> Scott-B07421; alex.williamson at redhat.com; Bhushan Bharat-R65777
> Cc: Sethi Varun-B16395
> Subject: [PATCH 2/3 v2] iommu/fsl: Enable default DMA window for PCIe devices
> 
> Once the PCIe device assigned to a guest VM (via VFIO) gets detached from the
> iommu domain (when guest terminates), its PAMU table entry is disabled. So, this
> would prevent the device from being used once it's assigned back to the host.
> 
> This patch allows for creation of a default DMA window corresponding to the
> device and subsequently enabling the PAMU table entry. Before we enable the
> entry, we ensure that the device's bus master capability is disabled (device
> quiesced).
> 
> Signed-off-by: Varun Sethi <Varun.Sethi at freescale.com>
> ---
>  drivers/iommu/fsl_pamu.c        |   43 ++++++++++++++++++++++++++++--------
>  drivers/iommu/fsl_pamu.h        |    1 +
>  drivers/iommu/fsl_pamu_domain.c |   46 ++++++++++++++++++++++++++++++++++++---
>  3 files changed, 78 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/iommu/fsl_pamu.c b/drivers/iommu/fsl_pamu.c index
> cba0498..fb4a031 100644
> --- a/drivers/iommu/fsl_pamu.c
> +++ b/drivers/iommu/fsl_pamu.c
> @@ -225,6 +225,21 @@ static struct paace *pamu_get_spaace(struct paace *paace,
> u32 wnum)
>  	return spaace;
>  }
> 
> +/*
> + * Defaul PPAACE settings for an LIODN.
> + */
> +static void setup_default_ppaace(struct paace *ppaace) {
> +	pamu_init_ppaace(ppaace);
> +	/* window size is 2^(WSE+1) bytes */
> +	set_bf(ppaace->addr_bitfields, PPAACE_AF_WSE, 35);
> +	ppaace->wbah = 0;
> +	set_bf(ppaace->addr_bitfields, PPAACE_AF_WBAL, 0);
> +	set_bf(ppaace->impl_attr, PAACE_IA_ATM,
> +		PAACE_ATM_NO_XLATE);
> +	set_bf(ppaace->addr_bitfields, PAACE_AF_AP,
> +		PAACE_AP_PERMS_ALL);
> +}
>  /**
>   * pamu_get_fspi_and_allocate() - Allocates fspi index and reserves subwindows
>   *                                required for primary PAACE in the secondary
> @@ -253,6 +268,24 @@ static unsigned long pamu_get_fspi_and_allocate(u32
> subwin_cnt)
>  	return (spaace_addr - (unsigned long)spaact) / (sizeof(struct paace));  }
> 
> +/* Reset the PAACE entry to the default state */ void
> +enable_default_dma_window(int liodn) {
> +	struct paace *ppaace;
> +
> +	ppaace = pamu_get_ppaace(liodn);
> +	if (!ppaace) {
> +		pr_debug("Invalid liodn entry\n");
> +		return;
> +	}
> +
> +	memset(ppaace, 0, sizeof(struct paace));
> +
> +	setup_default_ppaace(ppaace);
> +	mb();
> +	pamu_enable_liodn(liodn);
> +}
> +
>  /* Release the subwindows reserved for a particular LIODN */  void
> pamu_free_subwins(int liodn)  { @@ -752,15 +785,7 @@ static void __init
> setup_liodns(void)
>  				continue;
>  			}
>  			ppaace = pamu_get_ppaace(liodn);
> -			pamu_init_ppaace(ppaace);
> -			/* window size is 2^(WSE+1) bytes */
> -			set_bf(ppaace->addr_bitfields, PPAACE_AF_WSE, 35);
> -			ppaace->wbah = 0;
> -			set_bf(ppaace->addr_bitfields, PPAACE_AF_WBAL, 0);
> -			set_bf(ppaace->impl_attr, PAACE_IA_ATM,
> -				PAACE_ATM_NO_XLATE);
> -			set_bf(ppaace->addr_bitfields, PAACE_AF_AP,
> -				PAACE_AP_PERMS_ALL);
> +			setup_default_ppaace(ppaace);
>  			if (of_device_is_compatible(node, "fsl,qman-portal"))
>  				setup_qbman_paace(ppaace, QMAN_PORTAL_PAACE);
>  			if (of_device_is_compatible(node, "fsl,qman")) diff --git
> a/drivers/iommu/fsl_pamu.h b/drivers/iommu/fsl_pamu.h index 8fc1a12..0edcbbbb
> 100644
> --- a/drivers/iommu/fsl_pamu.h
> +++ b/drivers/iommu/fsl_pamu.h
> @@ -406,5 +406,6 @@ void get_ome_index(u32 *omi_index, struct device *dev);  int
> pamu_update_paace_stash(int liodn, u32 subwin, u32 value);  int
> pamu_disable_spaace(int liodn, u32 subwin);
>  u32 pamu_get_max_subwin_cnt(void);
> +void enable_default_dma_window(int liodn);
> 
>  #endif  /* __FSL_PAMU_H */
> diff --git a/drivers/iommu/fsl_pamu_domain.c b/drivers/iommu/fsl_pamu_domain.c
> index 966ae70..dd6cafc 100644
> --- a/drivers/iommu/fsl_pamu_domain.c
> +++ b/drivers/iommu/fsl_pamu_domain.c
> @@ -340,17 +340,57 @@ static inline struct device_domain_info
> *find_domain(struct device *dev)
>  	return dev->archdata.iommu_domain;
>  }
> 
> +/* Disable device DMA capability and enable default DMA window */
> +static void disable_device_dma(struct device_domain_info *info,
> +				int enable_dma_window)
> +{
> +#ifdef CONFIG_PCI
> +	if (info->dev->bus == &pci_bus_type) {
> +		struct pci_dev *pdev = NULL;
> +		pdev = to_pci_dev(info->dev);
> +		if (pci_is_enabled(pdev))
> +			pci_disable_device(pdev);
> +	}
> +#endif
> +
> +	if (enable_dma_window)
> +		enable_default_dma_window(info->liodn);
> +}
> +
> +static int check_for_shared_liodn(struct device_domain_info *info) {
> +	struct device_domain_info *tmp;
> +
> +	/*
> +	 * Sanity check, to ensure that this is not a
> +	 * shared LIODN. In case of a PCIe controller
> +	 * it's possible that all PCIe devices share
> +	 * the same LIODN.
> +	 */
> +	list_for_each_entry(tmp, &info->domain->devices, link) {
> +		if (info->liodn == tmp->liodn)
> +			return 1;
> +	}
> +
> +	return 0;
> +}
> +
>  static void remove_device_ref(struct device_domain_info *info, u32 win_cnt)  {
>  	unsigned long flags;
> +	int enable_dma_window = 0;
> 
>  	list_del(&info->link);
>  	spin_lock_irqsave(&iommu_lock, flags);
> -	if (win_cnt > 1)
> -		pamu_free_subwins(info->liodn);
> -	pamu_disable_liodn(info->liodn);
> +	if (!check_for_shared_liodn(info)) {

One query; Do we really need to check for this?

Otherwise this patch series looks good to me.

Thanks
-Bharat

> +		if (win_cnt > 1)
> +			pamu_free_subwins(info->liodn);
> +		pamu_disable_liodn(info->liodn);
> +		enable_dma_window = 1;
> +	}
>  	spin_unlock_irqrestore(&iommu_lock, flags);
>  	spin_lock_irqsave(&device_domain_lock, flags);
> +	disable_device_dma(info, enable_dma_window);
>  	info->dev->archdata.iommu_domain = NULL;
>  	kmem_cache_free(iommu_devinfo_cache, info);
>  	spin_unlock_irqrestore(&device_domain_lock, flags);
> --
> 1.7.9.5




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