Re: [PATCH v8 06/10] iommu/vt-d: datatypes and functions used for kdump

[Baoquan He]

On 01/15/15 at 01:45pm, Li, ZhenHua wrote:
> Hi Baoquan,
> Thank you very much for your review. But according to the latest
> discussion, the page tables will not be copied from old kernel. We keep
> using the old page tables before driver is loaded. So there are many
> changes in next version;

Oh, yes. So please ignore this comment.

> 
> See my comments.
> 
> On 01/15/2015 11:28 AM, Baoquan He wrote:
> >On 01/12/15 at 03:06pm, Li, Zhen-Hua wrote:
> >>+/*
> >>+ * Interface to the "copy translation tables" set of functions
> >>+ * from mainline code.
> >>+ */
> >>+static int intel_iommu_load_translation_tables(struct dmar_drhd_unit *drhd,
> >>+		int g_num_of_iommus)
> >
> >The argument g_num_of_iommus is the same as the global variable, it's better
> >to rename it as num_of_iommus. And even it can be removed since you can
> >just use the global variable g_num_of_iommus in this function.
> >
> >Argument drhd can be intel_iommu because no other member variable in
> >drhd is needed.
> 
> This function is no longer used. So forget the parameters.
> 
> >
> >>+{
> >>+	struct intel_iommu *iommu;	/* Virt(iommu hardware registers) */
> >>+	unsigned long long q;		/* quadword scratch */
> >>+	int ret = 0;			/* Integer return code */
> >>+	int i = 0;			/* Loop index */
> >>+	unsigned long flags;
> >>+
> >>+	/* Structure so copy_page_addr() can accumulate things
> >>+	 * over multiple calls and returns
> >>+	 */
> >>+	struct copy_page_addr_parms ppa_parms = copy_page_addr_parms_init;
> >>+	struct copy_page_addr_parms *ppap = &ppa_parms;
> >>+
> >>+
> >>+	iommu = drhd->iommu;
> >>+	q = dmar_readq(iommu->reg + DMAR_RTADDR_REG);
> >>+	if (!q)
> >>+		return -1;
> >>+
> >>+	/* If (list needs initializing) do it here */
> >
> >This initializing should not be here, because it's not only for this
> >drhd. It should be done in init_dmars().
> >
> Yes you are right. Though the variable domain_values_list will not be
> used in next version, I think I need to check if there are any other
> similar problems.
> 
> >>+	if (!domain_values_list) {
> >>+		domain_values_list =
> >>+			 kcalloc(g_num_of_iommus, sizeof(struct list_head),
> >>+					GFP_KERNEL);
> >>+
> >>+		if (!domain_values_list) {
> >>+			pr_err("Allocation failed for domain_values_list array\n");
> >>+			return -ENOMEM;
> >>+		}
> >>+		for (i = 0; i < g_num_of_iommus; i++)
> >>+			INIT_LIST_HEAD(&domain_values_list[i]);
> >>+	}
> >>+
> >>+	spin_lock_irqsave(&iommu->lock, flags);
> >>+
> >>+	/* Load the root-entry table from the old kernel
> >>+	 * foreach context_entry_table in root_entry
> >>+	 *    foreach context_entry in context_entry_table
> >>+	 *       foreach level-1 page_table_entry in context_entry
> >>+	 *          foreach level-2 page_table_entry in level 1 page_table_entry
> >>+	 *             Above pattern continues up to 6 levels of page tables
> >>+	 *                Sanity-check the entry
> >>+	 *                Process the bus, devfn, page_address, page_size
> >>+	 */
> >>+	if (!iommu->root_entry) {
> >>+		iommu->root_entry =
> >>+			(struct root_entry *)alloc_pgtable_page(iommu->node);
> >>+		if (!iommu->root_entry) {
> >>+			spin_unlock_irqrestore(&iommu->lock, flags);
> >>+			return -ENOMEM;
> >>+		}
> >>+	}
> >>+
> >>+	iommu->root_entry_old_phys = q & VTD_PAGE_MASK;
> >>+	if (!iommu->root_entry_old_phys) {
> >>+		pr_err("Could not read old root entry address.");
> >>+		return -1;
> >>+	}
> >>+
> >>+	iommu->root_entry_old_virt = ioremap_cache(iommu->root_entry_old_phys,
> >>+						VTD_PAGE_SIZE);
> >>+	if (!iommu->root_entry_old_virt) {
> >>+		pr_err("Could not map the old root entry.");
> >>+		return -ENOMEM;
> >>+	}
> >>+
> >>+	__iommu_load_old_root_entry(iommu);
> >>+	ret = copy_root_entry_table(iommu, ppap);
> >>+	__iommu_flush_cache(iommu, iommu->root_entry, PAGE_SIZE);
> >>+	__iommu_update_old_root_entry(iommu, -1);
> >>+
> >>+	spin_unlock_irqrestore(&iommu->lock, flags);
> >>+
> >>+	__iommu_free_mapped_mem();
> >>+
> >>+	if (ret)
> >>+		return ret;
> >>+
> >>+	ppa_parms.last = 1;
> >>+	copy_page_addr(0, 0, 0, 0, 0, NULL, ppap);
> >>+
> >>+	return 0;
> >>+}
> >>+
> >>  #endif /* CONFIG_CRASH_DUMP */
> >>--
> >>2.0.0-rc0
> >>
> >>
> >>_______________________________________________
> >>kexec mailing list
> >>kexec@xxxxxxxxxxxxxxxxxxx
> >>http://lists.infradead.org/mailman/listinfo/kexec
> 
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