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Subject[PATCH 06/10] iommu/vt-d: datatypes and functions used for kdump
Date
Populate it with support functions to copy iommu translation tables from
from the panicked kernel into the kdump kernel in the event of a crash.

Functions:
malloc new context table and copy old context table to the new one.
malloc new page table and copy old page table to the new one.

Bill Sumner:
Original version, the creation of the data types and functions.

Li, Zhenhua:
Minor change:
Update the usage of context_get_* and context_put*, use context_*
and context_set_* for replacement.
Update the name of the function that copies root entry table.
Use new function to copy old context entry tables and page tables.

Signed-off-by: Bill Sumner <billsumnerlinux@gmail.com>
Signed-off-by: Li, Zhen-Hua <zhen-hual@hp.com>
---
drivers/iommu/intel-iommu.c | 542 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 542 insertions(+)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 126294db..9b2f725 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -399,6 +399,62 @@ struct iommu_remapped_entry {
static LIST_HEAD(__iommu_remapped_mem);
static DEFINE_MUTEX(__iommu_mem_list_lock);

+/* ========================================================================
+ * Copy iommu translation tables from old kernel into new kernel.
+ * Entry to this set of functions is: intel_iommu_copy_translation_tables()
+ * ------------------------------------------------------------------------
+ */
+
+/*
+ * Lists of domain_values_entry to hold domain values found during the copy.
+ * One list for each iommu in g_number_of_iommus.
+ */
+static struct list_head *domain_values_list;
+
+
+#define RET_BADCOPY -1 /* Return-code: Cannot copy translate tables */
+
+/*
+ * Struct copy_page_addr_parms is used to allow copy_page_addr()
+ * to accumulate values across multiple calls and returns.
+ */
+struct copy_page_addr_parms {
+ u32 first; /* flag: first-time */
+ u32 last; /* flag: last-time */
+ u32 bus; /* last bus number we saw */
+ u32 devfn; /* last devfn we saw */
+ u32 shift; /* last shift we saw */
+ u64 pte; /* Page Table Entry */
+ u64 next_addr; /* next-expected page_addr */
+
+ u64 page_addr; /* page_addr accumulating size */
+ u64 page_size; /* page_size accumulated */
+
+ struct domain_values_entry *dve; /* to accumulate iova ranges */
+};
+
+enum returns_from_copy_context_entry {
+RET_CCE_NOT_PRESENT = 1,
+RET_CCE_NEW_PAGE_TABLES,
+RET_CCE_PASS_THROUGH_1,
+RET_CCE_PASS_THROUGH_2,
+RET_CCE_RESERVED_VALUE,
+RET_CCE_PREVIOUS_DID
+};
+
+static int copy_context_entry(struct intel_iommu *iommu, u32 bus, u32 devfn,
+ void *ppap, struct context_entry *ce);
+
+static int copy_context_entry_table(struct intel_iommu *iommu,
+ u32 bus, void *ppap,
+ struct context_entry **context_new_p,
+ unsigned long context_old_phys);
+
+static int copy_root_entry_table(struct intel_iommu *iommu, void *ppap);
+
+static int intel_iommu_copy_translation_tables(struct dmar_drhd_unit *drhd,
+ int g_num_of_iommus);
+
#endif /* CONFIG_CRASH_DUMP */

/*
@@ -5039,4 +5095,490 @@ static void __iommu_update_old_root_entry(struct intel_iommu *iommu, int index)
memcpy(to + start, from + start, size);
}

+/*
+ * constant for initializing instances of copy_page_addr_parms properly.
+ */
+static struct copy_page_addr_parms copy_page_addr_parms_init = {1, 0};
+
+
+
+/*
+ * Lowest-level function in the 'Copy Page Tables' set
+ * Called once for each page_addr present in an iommu page-address table.
+ *
+ * Because of the depth-first traversal of the page-tables by the
+ * higher-level functions that call 'copy_page_addr', all pages
+ * of a domain will be presented in ascending order of IO Virtual Address.
+ *
+ * This function accumulates each contiguous range of these IOVAs and
+ * reserves it within the proper domain in the crashdump kernel when a
+ * non-contiguous range is detected, as determined by any of the following:
+ * 1. a change in the bus or device owning the presented page
+ * 2. a change in the page-size of the presented page (parameter shift)
+ * 3. a change in the page-table entry of the presented page
+ * 4. a presented IOVA that does not match the expected next-page address
+ * 5. the 'last' flag is set, indicating that all IOVAs have been seen.
+ */
+static int copy_page_addr(u64 page_addr, u32 shift, u32 bus, u32 devfn,
+ u64 pte, struct domain_values_entry *dve,
+ void *parms)
+{
+ struct copy_page_addr_parms *ppap = parms;
+
+ u64 page_size = ((u64)1 << shift); /* page_size */
+ u64 pfn_lo; /* For reserving IOVA range */
+ u64 pfn_hi; /* For reserving IOVA range */
+ struct iova *iova_p; /* For reserving IOVA range */
+
+ if (!ppap) {
+ pr_err("ERROR: ppap is NULL: 0x%3.3x(%3.3d) DevFn: 0x%3.3x(%3.3d) Page: 0x%16.16llx Size: 0x%16.16llx(%lld)\n",
+ bus, bus, devfn, devfn, page_addr,
+ page_size, page_size);
+ return 0;
+ }
+
+ /* If (only extending current addr range) */
+ if (ppap->first == 0 &&
+ ppap->last == 0 &&
+ ppap->bus == bus &&
+ ppap->devfn == devfn &&
+ ppap->shift == shift &&
+ (ppap->pte & ~VTD_PAGE_MASK) == (pte & ~VTD_PAGE_MASK) &&
+ ppap->next_addr == page_addr) {
+
+ /* Update page size and next-expected address */
+ ppap->next_addr += page_size;
+ ppap->page_size += page_size;
+ return 0;
+ }
+
+ if (!ppap->first) {
+ /* Close-out the accumulated IOVA address range */
+
+ if (!ppap->dve) {
+ pr_err("%s ERROR: ppap->dve is NULL -- needed to reserve range for B:D:F=%2.2x:%2.2x:%1.1x\n",
+ __func__,
+ ppap->bus, ppap->devfn >> 3, ppap->devfn & 0x7);
+ return RET_BADCOPY;
+ }
+ pfn_lo = IOVA_PFN(ppap->page_addr);
+ pfn_hi = IOVA_PFN(ppap->page_addr + ppap->page_size);
+ iova_p = reserve_iova(&ppap->dve->iovad, pfn_lo, pfn_hi);
+ }
+
+ /* Prepare for a new IOVA address range */
+ ppap->first = 0; /* Not first-time anymore */
+ ppap->bus = bus;
+ ppap->devfn = devfn;
+ ppap->shift = shift;
+ ppap->pte = pte;
+ ppap->next_addr = page_addr + page_size; /* Next-expected page_addr */
+
+ ppap->page_addr = page_addr; /* Addr(new page) */
+ ppap->page_size = page_size; /* Size(new page) */
+
+ ppap->dve = dve; /* adr(device_values_entry for new range) */
+
+ return 0;
+}
+
+/*
+ * Recursive function to copy the tree of page tables (max 6 recursions)
+ * Parameter 'shift' controls the recursion
+ */
+static int copy_page_table(struct dma_pte **dma_pte_new_p,
+ unsigned long dma_pte_phys,
+ u32 shift, u64 page_addr,
+ struct intel_iommu *iommu,
+ u32 bus, u32 devfn,
+ struct domain_values_entry *dve, void *ppap)
+{
+ int ret; /* Integer return code */
+ struct dma_pte *p; /* Physical adr(each entry) iterator */
+ struct dma_pte *pgt_new_virt; /* Adr(dma_pte in new kernel) */
+ struct dma_pte *dma_pte_next; /* Adr(next table down) */
+ u64 u; /* index(each entry in page_table) */
+
+
+ /* If (already done all levels -- problem) */
+ if (shift < 12) {
+ pr_err("ERROR %s shift < 12 %lx\n", __func__, dma_pte_phys);
+ pr_err("shift %d, page_addr %16.16llu bus %3.3u devfn %3.3u\n",
+ shift, page_addr, bus, devfn);
+ return RET_BADCOPY;
+ }
+
+ /* allocate a page table in the new kernel
+ * copy contents from old kernel
+ * then update each entry in the table in the new kernel
+ */
+
+ pgt_new_virt = (struct dma_pte *)alloc_pgtable_page(iommu->node);
+ if (!pgt_new_virt)
+ return -ENOMEM;
+
+ ret = __iommu_load_from_oldmem(pgt_new_virt,
+ dma_pte_phys,
+ VTD_PAGE_SIZE);
+
+ if (ret <= 0)
+ return ret;
+
+ for (u = 0, p = pgt_new_virt; u < 512; u++, p++) {
+
+ if (((p->val & DMA_PTE_READ) == 0) &&
+ ((p->val & DMA_PTE_WRITE) == 0))
+ continue;
+
+ if (dma_pte_superpage(p) || (shift == 12)) {
+
+ ret = copy_page_addr(page_addr | (u << shift),
+ shift, bus, devfn, p->val, dve, ppap);
+ if (ret)
+ return ret;
+ continue;
+ }
+
+ ret = copy_page_table(&dma_pte_next,
+ (p->val & VTD_PAGE_MASK),
+ shift-9, page_addr | (u << shift),
+ iommu, bus, devfn, dve, ppap);
+ if (ret)
+ return ret;
+
+ p->val &= ~VTD_PAGE_MASK; /* Clear old and set new pgd */
+ p->val |= ((u64)dma_pte_next & VTD_PAGE_MASK);
+ }
+
+ *dma_pte_new_p = (struct dma_pte *)virt_to_phys(pgt_new_virt);
+ __iommu_flush_cache(iommu, pgt_new_virt, VTD_PAGE_SIZE);
+
+ return 0;
+}
+
+
+/*
+ * Called once for each context_entry found in a copied context_entry_table
+ * Each context_entry represents one PCIe device handled by the IOMMU.
+ *
+ * The 'domain_values_list' contains one 'domain_values_entry' for each
+ * unique domain-id found while copying the context entries for each iommu.
+ *
+ * The Intel-iommu spec. requires that every context_entry that contains
+ * the same domain-id point to the same set of page translation tables.
+ * The hardware uses this to improve the use of its translation cache.
+ * In order to insure that the copied translate tables abide by this
+ * requirement, this function keeps a list of domain-ids (dids) that
+ * have already been seen for this iommu. This function checks each entry
+ * already on the list for a domain-id that matches the domain-id in this
+ * context_entry. If found, this function places the address of the previous
+ * context's tree of page translation tables into this context_entry.
+ * If a matching previous entry is not found, a new 'domain_values_entry'
+ * structure is created for the domain-id in this context_entry and
+ * copy_page_table is called to duplicate its tree of page tables.
+ */
+static int copy_context_entry(struct intel_iommu *iommu, u32 bus, u32 devfn,
+ void *ppap, struct context_entry *ce)
+{
+ int ret = 0; /* Integer Return Code */
+ u32 shift = 0; /* bits to shift page_addr */
+ u64 page_addr = 0; /* Address of translated page */
+ unsigned long pgt_old_phys; /* Adr(page_table in the old kernel) */
+ struct dma_pte *pgt_new_phys; /* Adr(page_table in the new kernel) */
+ u8 t; /* Translation-type from context */
+ u8 aw; /* Address-width from context */
+ u32 aw_shift[8] = {
+ 12+9+9, /* [000b] 30-bit AGAW (2-level page table) */
+ 12+9+9+9, /* [001b] 39-bit AGAW (3-level page table) */
+ 12+9+9+9+9, /* [010b] 48-bit AGAW (4-level page table) */
+ 12+9+9+9+9+9, /* [011b] 57-bit AGAW (5-level page table) */
+ 12+9+9+9+9+9+9, /* [100b] 64-bit AGAW (6-level page table) */
+ 0, /* [111b] Reserved */
+ 0, /* [110b] Reserved */
+ 0, /* [111b] Reserved */
+ };
+
+ struct domain_values_entry *dve = NULL;
+
+
+ if (!context_present(ce)) { /* If (context not present) */
+ ret = RET_CCE_NOT_PRESENT; /* Skip it */
+ goto exit;
+ }
+
+ t = context_translation_type(ce);
+ /* If we have seen this domain-id before on this iommu,
+ * give this context the same page-tables and we are done.
+ */
+ list_for_each_entry(dve, &domain_values_list[iommu->seq_id], link) {
+ if (dve->did == (int) context_domain_id(ce)) {
+ switch (t) {
+ case 0: /* page tables */
+ case 1: /* page tables */
+ context_set_address_root(ce,
+ virt_to_phys(dve->pgd));
+ ret = RET_CCE_PREVIOUS_DID;
+ break;
+
+ case 2: /* Pass through */
+ if (dve->pgd == NULL)
+ ret = RET_CCE_PASS_THROUGH_2;
+ else
+ ret = RET_BADCOPY;
+ break;
+
+ default: /* Bad value of 't'*/
+ ret = RET_BADCOPY;
+ break;
+ }
+ goto exit;
+ }
+ }
+
+ /* Since we now know that this is a new domain-id for this iommu,
+ * create a new entry, add it to the list, and handle its
+ * page tables.
+ */
+
+ dve = kcalloc(1, sizeof(struct domain_values_entry), GFP_KERNEL);
+ if (!dve) {
+ ret = -ENOMEM;
+ goto exit;
+ }
+
+ dve->did = (int) context_domain_id(ce);
+ dve->gaw = (int) agaw_to_width(context_address_width(ce));
+ dve->pgd = NULL;
+ init_iova_domain(&dve->iovad, DMA_32BIT_PFN);
+
+ list_add(&dve->link, &domain_values_list[iommu->seq_id]);
+
+
+ if (t == 0 || t == 1) { /* If (context has page tables) */
+ aw = context_address_width(ce);
+ shift = aw_shift[aw];
+
+ pgt_old_phys = context_address_root(ce) << VTD_PAGE_SHIFT;
+
+ ret = copy_page_table(&pgt_new_phys, pgt_old_phys,
+ shift-9, page_addr, iommu, bus, devfn, dve, ppap);
+
+ if (ret) /* if (problem) bail out */
+ goto exit;
+
+ context_set_address_root(ce, (unsigned long)(pgt_new_phys));
+ dve->pgd = phys_to_virt((unsigned long)pgt_new_phys);
+ ret = RET_CCE_NEW_PAGE_TABLES;
+ goto exit;
+ }
+
+ if (t == 2) { /* If (Identity mapped pass-through) */
+ ret = RET_CCE_PASS_THROUGH_1; /* REVISIT: Skip for now */
+ goto exit;
+ }
+
+ ret = RET_CCE_RESERVED_VALUE; /* Else ce->t is a Reserved value */
+ /* Note fall-through */
+
+exit: /* all returns come through here to insure good clean-up */
+ return ret;
+}
+
+
+/*
+ * Called once for each context_entry_table found in the root_entry_table
+ */
+static int copy_context_entry_table(struct intel_iommu *iommu,
+ u32 bus, void *ppap,
+ struct context_entry **context_new_p,
+ unsigned long context_old_phys)
+{
+ int ret = 0; /* Integer return code */
+ struct context_entry *ce; /* Iterator */
+ struct context_entry *context_new_phys; /* adr(table in new kernel) */
+ struct context_entry *context_new_virt; /* adr(table in new kernel) */
+ u32 devfn = 0; /* PCI Device & function */
+
+ /* allocate a context-entry table in the new kernel
+ * copy contents from old kernel
+ * then update each entry in the table in the new kernel
+ */
+ context_new_virt =
+ (struct context_entry *)alloc_pgtable_page(iommu->node);
+ if (!context_new_virt)
+ return -ENOMEM;
+
+ context_new_phys =
+ (struct context_entry *)virt_to_phys(context_new_virt);
+
+ __iommu_load_from_oldmem(context_new_virt,
+ context_old_phys,
+ VTD_PAGE_SIZE);
+
+ for (devfn = 0, ce = context_new_virt; devfn < 256; devfn++, ce++) {
+
+ if (!context_present(ce)) /* If (context not present) */
+ continue; /* Skip it */
+
+ ret = copy_context_entry(iommu, bus, devfn, ppap, ce);
+ if (ret < 0) /* if (problem) */
+ return RET_BADCOPY;
+
+ switch (ret) {
+ case RET_CCE_NOT_PRESENT:
+ continue;
+ case RET_CCE_NEW_PAGE_TABLES:
+ continue;
+ case RET_CCE_PASS_THROUGH_1:
+ continue;
+ case RET_CCE_PASS_THROUGH_2:
+ continue;
+ case RET_CCE_RESERVED_VALUE:
+ return RET_BADCOPY;
+ case RET_CCE_PREVIOUS_DID:
+ continue;
+ default:
+ return RET_BADCOPY;
+ };
+ }
+
+ *context_new_p = context_new_phys;
+ return 0;
+}
+
+
+/*
+ * Highest-level function in the 'copy translation tables' set of functions
+ */
+static int copy_root_entry_table(struct intel_iommu *iommu, void *ppap)
+{
+ int ret = 0; /* Integer return code */
+ u32 bus; /* Index: root-entry-table */
+ struct root_entry *re; /* Virt(iterator: new table) */
+ unsigned long context_old_phys; /* Phys(context table entry) */
+ struct context_entry *context_new_phys; /* Phys(new context_entry) */
+
+ /*
+ * allocate a root-entry table in the new kernel
+ * copy contents from old kernel
+ * then update each entry in the table in the new kernel
+ */
+
+ if (!iommu->root_entry_old_phys)
+ return -ENOMEM;
+
+ for (bus = 0, re = iommu->root_entry; bus < 256; bus += 1, re += 1) {
+ if (!root_present(re))
+ continue;
+
+ context_old_phys = get_context_phys_from_root(re);
+
+ if (!context_old_phys)
+ continue;
+
+ context_new_phys = NULL;
+ ret = copy_context_entry_table(iommu, bus, ppap,
+ &context_new_phys,
+ context_old_phys);
+ if (ret)
+ return ret;
+ __iommu_flush_cache(iommu,
+ phys_to_virt((unsigned long)context_new_phys),
+ VTD_PAGE_SIZE);
+
+ set_root_value(re, (unsigned long)context_new_phys);
+ }
+
+ return 0;
+}
+/*
+ * Interface to the "copy translation tables" set of functions
+ * from mainline code.
+ */
+static int intel_iommu_copy_translation_tables(struct dmar_drhd_unit *drhd,
+ int g_num_of_iommus)
+{
+ 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 */
+ 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_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


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