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SubjectRe: [PATH v5 3/3] iommu/vt-d: debugfs: Support dumping a specified page table
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On 10/13/23 9:58 PM, Jingqi Liu wrote:
> The original debugfs only dumps all page tables without pasid. With
> pasid supported, the page table with pasid also needs to be dumped.
>
> This patch supports dumping a specified page table in legacy mode or
> scalable mode with or without a specified pasid.
>
> For legacy mode, according to bus number and DEVFN, traverse the root
> table and context table to get the pointer of page table in the
> context table entry, then dump the specified page table.
>
> For scalable mode, according to bus number, DEVFN and pasid, traverse
> the root table, context table, pasid directory and pasid table to get
> the pointer of page table in the pasid table entry, then dump the
> specified page table..
>
> Examples are as follows:
> 1) Dump the page table of device "0000:00:1f.0" that only supports
> legacy mode.
> $ sudo cat
> /sys/kernel/debug/iommu/intel/0000:00:1f.0/domain_translation_struct
>
> 2) Dump the page table of device "0000:00:0a.0" with PASID "1" that
> supports scalable mode.
> $ sudo cat
> /sys/kernel/debug/iommu/intel/0000:00:0a.0/1/domain_translation_struct
>
> Suggested-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Jingqi Liu <Jingqi.liu@intel.com>
> ---
> drivers/iommu/intel/debugfs.c | 154 ++++++++++++++++++++++++++--------
> 1 file changed, 120 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/iommu/intel/debugfs.c b/drivers/iommu/intel/debugfs.c
> index 8a18a7be5215..239136727ac4 100644
> --- a/drivers/iommu/intel/debugfs.c
> +++ b/drivers/iommu/intel/debugfs.c
> @@ -347,58 +347,141 @@ static void pgtable_walk_level(struct seq_file *m, struct dma_pte *pde,
> }
> }
>
> -static int __show_device_domain_translation(struct device *dev, void *data)
> +static int domain_translation_struct_show(struct seq_file *m,
> + struct device_domain_info *info,
> + ioasid_t pasid)
> {
> - struct dmar_domain *domain;
> - struct seq_file *m = data;
> - u64 path[6] = { 0 };
> -
> - domain = to_dmar_domain(iommu_get_domain_for_dev(dev));
> - if (!domain)
> - return 0;
> + bool scalable, found = false;
> + struct dmar_drhd_unit *drhd;
> + struct intel_iommu *iommu;
> + u16 devfn, bus, seg;
>
> - seq_printf(m, "Device %s @0x%llx\n", dev_name(dev),
> - (u64)virt_to_phys(domain->pgd));
> - seq_puts(m, "IOVA_PFN\t\tPML5E\t\t\tPML4E\t\t\tPDPE\t\t\tPDE\t\t\tPTE\n");
> + bus = info->bus;
> + devfn = info->devfn;
> + seg = info->segment;
>
> - pgtable_walk_level(m, domain->pgd, domain->agaw + 2, 0, path);
> - seq_putc(m, '\n');
> + rcu_read_lock();
> + for_each_active_iommu(iommu, drhd) {
> + struct context_entry *context;
> + u64 pgd, path[6] = { 0 };
> + u32 sts, agaw;
>
> - /* Don't iterate */
> - return 1;
> -}
> + if (seg != iommu->segment)
> + continue;
>
> -static int show_device_domain_translation(struct device *dev, void *data)
> -{
> - struct iommu_group *group;
> + sts = dmar_readl(iommu->reg + DMAR_GSTS_REG);
> + if (!(sts & DMA_GSTS_TES)) {
> + seq_printf(m, "DMA Remapping is not enabled on %s\n",
> + iommu->name);
> + continue;
> + }
> + if (dmar_readq(iommu->reg + DMAR_RTADDR_REG) & DMA_RTADDR_SMT)
> + scalable = true;
> + else
> + scalable = false;
>
> - group = iommu_group_get(dev);
> - if (group) {
> /*
> - * The group->mutex is held across the callback, which will
> - * block calls to iommu_attach/detach_group/device. Hence,
> + * The iommu->lock is held across the callback, which will
> + * block calls to domain_attach/domain_detach. Hence,
> * the domain of the device will not change during traversal.
> *
> - * All devices in an iommu group share a single domain, hence
> - * we only dump the domain of the first device. Even though,
> - * this code still possibly races with the iommu_unmap()
> + * Traversing page table possibly races with the iommu_unmap()
> * interface. This could be solved by RCU-freeing the page
> * table pages in the iommu_unmap() path.
> */
> - iommu_group_for_each_dev(group, data,
> - __show_device_domain_translation);
> - iommu_group_put(group);
> + spin_lock(&iommu->lock);
> +
> + context = iommu_context_addr(iommu, bus, devfn, 0);
> + if (!context || !context_present(context))
> + goto iommu_unlock;
> +
> + if (scalable) { /* scalable mode */
> + struct pasid_dir_entry *dir_tbl, *dir_entry;
> + struct pasid_entry *pasid_tbl, *pasid_tbl_entry;
> + u16 pasid_dir_size, dir_idx, tbl_idx, pgtt;
> + u64 pasid_dir_ptr;

0day robot complained:

drivers/iommu/intel/debugfs.c: In function
'domain_translation_struct_show':
>> drivers/iommu/intel/debugfs.c:401:29: warning: variable
'pasid_dir_size' set but not used [-Wunused-but-set-variable]
401 | u16 pasid_dir_size, dir_idx,
tbl_idx, pgtt;
| ^~~~~~~~~~~~~~

I have removed pasid_dir_size and queue the whole series for v6.7.

Thank you!

Best regards,
baolu

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