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SubjectRe: [PATCH v2 3/7] iommu/vt-d: Expose ISA direct mapping region via iommu_get_resv_regions
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Hi James,

On 3/14/19 7:58 PM, James Sewart wrote:
> To support mapping ISA region via iommu_group_create_direct_mappings,
> make sure its exposed by iommu_get_resv_regions. This allows
> deduplication of reserved region mappings
>
> Signed-off-by: James Sewart <jamessewart@arista.com>
> ---
> drivers/iommu/intel-iommu.c | 42 +++++++++++++++++++++++++++++--------
> 1 file changed, 33 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 8e0a4e2ff77f..2e00e8708f06 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -337,6 +337,8 @@ static LIST_HEAD(dmar_rmrr_units);
> #define for_each_rmrr_units(rmrr) \
> list_for_each_entry(rmrr, &dmar_rmrr_units, list)
>
> +static struct iommu_resv_region *isa_resv_region;
> +
> /* bitmap for indexing intel_iommus */
> static int g_num_of_iommus;
>
> @@ -2780,26 +2782,34 @@ static inline int iommu_prepare_rmrr_dev(struct dmar_rmrr_unit *rmrr,
> rmrr->end_address);
> }
>
> +static inline struct iommu_resv_region *iommu_get_isa_resv_region(void)
> +{
> + if (!isa_resv_region)
> + isa_resv_region = iommu_alloc_resv_region(0,
> + 16*1024*1024,
> + 0, IOMMU_RESV_DIRECT);
> +
> + return isa_resv_region;
> +}
> +
> #ifdef CONFIG_INTEL_IOMMU_FLOPPY_WA
> -static inline void iommu_prepare_isa(void)
> +static inline void iommu_prepare_isa(struct pci_dev *pdev)
> {
> - struct pci_dev *pdev;
> int ret;
> + struct iommu_resv_region *reg = iommu_get_isa_resv_region();
>
> - pdev = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, NULL);
> - if (!pdev)
> + if (!reg)
> return;
>
> pr_info("Prepare 0-16MiB unity mapping for LPC\n");
> - ret = iommu_prepare_identity_map(&pdev->dev, 0, 16*1024*1024 - 1);
> + ret = iommu_prepare_identity_map(&pdev->dev, reg->start,
> + reg->start + reg->length - 1);
>
> if (ret)
> pr_err("Failed to create 0-16MiB identity map - floppy might not work\n");
> -
> - pci_dev_put(pdev);
> }
> #else
> -static inline void iommu_prepare_isa(void)
> +static inline void iommu_prepare_isa(struct pci_dev *pdev)
> {
> return;
> }
> @@ -3289,6 +3299,7 @@ static int __init init_dmars(void)
> struct dmar_rmrr_unit *rmrr;
> bool copied_tables = false;
> struct device *dev;
> + struct pci_dev *pdev;
> struct intel_iommu *iommu;
> int i, ret;
>
> @@ -3469,7 +3480,11 @@ static int __init init_dmars(void)
> }
> }
>
> - iommu_prepare_isa();
> + pdev = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, NULL);
> + if (pdev) {
> + iommu_prepare_isa(pdev);
> + pci_dev_put(pdev);
> + }
>
> domains_done:
>
> @@ -5266,6 +5281,7 @@ static void intel_iommu_get_resv_regions(struct device *device,
> struct iommu_resv_region *reg;
> struct dmar_rmrr_unit *rmrr;
> struct device *i_dev;
> + struct pci_dev *pdev;
> int i;
>
> rcu_read_lock();
> @@ -5280,6 +5296,14 @@ static void intel_iommu_get_resv_regions(struct device *device,
> }
> rcu_read_unlock();
>
> + if (dev_is_pci(device)) {
> + pdev = to_pci_dev(device);
> + if ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA) {
> + reg = iommu_get_isa_resv_region();
> + list_add_tail(&reg->list, head);
> + }
> + }
> +

Just wondering why not just

+#ifdef CONFIG_INTEL_IOMMU_FLOPPY_WA
+ if (dev_is_pci(device)) {
+ pdev = to_pci_dev(device);
+ if ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA) {
+ reg = iommu_alloc_resv_region(0,
+ 16*1024*1024,
+ 0, IOMMU_RESV_DIRECT);
+ if (reg)
+ list_add_tail(&reg->list, head);
+ }
+ }
+#endif

and, remove all other related code?

Best regards,
Lu Baolu

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