RE: [PATCH 2/3 v2] iommu/fsl: Enable default DMA window for PCIedevices
From: Bhushan Bharat-R65777
Date: Wed Oct 16 2013 - 12:50:16 EST
> -----Original Message-----
> From: Sethi Varun-B16395
> Sent: Wednesday, October 16, 2013 4:53 PM
> To: joro@xxxxxxxxxx; iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx; linuxppc-
> dev@xxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Yoder Stuart-B08248; Wood
> Scott-B07421; alex.williamson@xxxxxxxxxx; 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@xxxxxxxxxxxxx>
> ---
> 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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