+ drivers-pci-intel-iommuc-errors-with-smaller-iommu-widths.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     drivers/pci/intel-iommu.c: errors with smaller iommu widths
has been added to the -mm tree.  Its filename is
     drivers-pci-intel-iommuc-errors-with-smaller-iommu-widths.patch

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------------------------------------------------------
Subject: drivers/pci/intel-iommu.c: errors with smaller iommu widths
From: "Tom Lyon" <pugs@cisco.com>

When using iommu_domain_alloc with the Intel iommu, the domain address
width is always initialized to 48 bits (agaw 2).   This domain->agaw
value is then used by pfn_to_dma_pte to (always) build a 4 level page
table.   However, not all systems support iommu width of 48 or 4 level
page tables.   In particular, the Core i5-660 and i5-670 support an
address width of 36 bits (not 39!), an agaw of only 1, and only 3 level
page tables.

This version of the patch simply lops off extra levels of the page tables
if the agaw value of the iommu is less than what is currently allocated
for the domain (in intel_iommu_attach_device).  If there were already
allocated addresses above what the new iommu can handle, EFAULT is
returned.

A related bug in intel_iommu_map_range() didn't allow allocation at the
very end of the address space, that code has been simplified and
corrected.

Signed-off-by: Tom Lyon <pugs@cisco.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/pci/intel-iommu.c |   51 ++++++++++++++++--------------------
 1 file changed, 24 insertions(+), 27 deletions(-)

diff -puN drivers/pci/intel-iommu.c~drivers-pci-intel-iommuc-errors-with-smaller-iommu-widths drivers/pci/intel-iommu.c
--- a/drivers/pci/intel-iommu.c~drivers-pci-intel-iommuc-errors-with-smaller-iommu-widths
+++ a/drivers/pci/intel-iommu.c
@@ -3433,19 +3433,6 @@ static void vm_domain_remove_all_dev_inf
 /* domain id for virtual machine, it won't be set in context */
 static unsigned long vm_domid;
 
-static int vm_domain_min_agaw(struct dmar_domain *domain)
-{
-	int i;
-	int min_agaw = domain->agaw;
-
-	for_each_set_bit(i, &domain->iommu_bmp, g_num_of_iommus) {
-		if (min_agaw > g_iommus[i]->agaw)
-			min_agaw = g_iommus[i]->agaw;
-	}
-
-	return min_agaw;
-}
-
 static struct dmar_domain *iommu_alloc_vm_domain(void)
 {
 	struct dmar_domain *domain;
@@ -3574,7 +3561,6 @@ static int intel_iommu_attach_device(str
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct intel_iommu *iommu;
 	int addr_width;
-	u64 end;
 
 	/* normally pdev is not mapped */
 	if (unlikely(domain_context_mapped(pdev))) {
@@ -3597,14 +3583,30 @@ static int intel_iommu_attach_device(str
 
 	/* check if this iommu agaw is sufficient for max mapped address */
 	addr_width = agaw_to_width(iommu->agaw);
-	end = DOMAIN_MAX_ADDR(addr_width);
-	end = end & VTD_PAGE_MASK;
-	if (end < dmar_domain->max_addr) {
-		printk(KERN_ERR "%s: iommu agaw (%d) is not "
+	if (addr_width > cap_mgaw(iommu->cap))
+		addr_width = cap_mgaw(iommu->cap);
+
+	if (dmar_domain->max_addr > (1LL << addr_width)) {
+		printk(KERN_ERR "%s: iommu width (%d) is not "
 		       "sufficient for the mapped address (%llx)\n",
-		       __func__, iommu->agaw, dmar_domain->max_addr);
+		       __func__, addr_width, dmar_domain->max_addr);
 		return -EFAULT;
 	}
+	dmar_domain->gaw = addr_width;
+
+	/*
+	 * Knock out extra levels of page tables if necessary
+	 */
+	while (iommu->agaw < dmar_domain->agaw) {
+		struct dma_pte *pte;
+
+		pte = dmar_domain->pgd;
+		if (dma_pte_present(pte)) {
+			free_pgtable_page(dmar_domain->pgd);
+			dmar_domain->pgd = (struct dma_pte *)dma_pte_addr(pte);
+		}
+		dmar_domain->agaw--;
+	}
 
 	return domain_add_dev_info(dmar_domain, pdev, CONTEXT_TT_MULTI_LEVEL);
 }
@@ -3624,7 +3626,6 @@ static int intel_iommu_map_range(struct 
 {
 	struct dmar_domain *dmar_domain = domain->priv;
 	u64 max_addr;
-	int addr_width;
 	int prot = 0;
 	int ret;
 
@@ -3637,18 +3638,14 @@ static int intel_iommu_map_range(struct 
 
 	max_addr = iova + size;
 	if (dmar_domain->max_addr < max_addr) {
-		int min_agaw;
 		u64 end;
 
 		/* check if minimum agaw is sufficient for mapped address */
-		min_agaw = vm_domain_min_agaw(dmar_domain);
-		addr_width = agaw_to_width(min_agaw);
-		end = DOMAIN_MAX_ADDR(addr_width);
-		end = end & VTD_PAGE_MASK;
+		end = __DOMAIN_MAX_ADDR(dmar_domain->gaw) + 1;
 		if (end < max_addr) {
-			printk(KERN_ERR "%s: iommu agaw (%d) is not "
+			printk(KERN_ERR "%s: iommu width (%d) is not "
 			       "sufficient for the mapped address (%llx)\n",
-			       __func__, min_agaw, max_addr);
+			       __func__, dmar_domain->gaw, max_addr);
 			return -EFAULT;
 		}
 		dmar_domain->max_addr = max_addr;
_

Patches currently in -mm which might be from pugs@cisco.com are

drivers-pci-intel-iommuc-errors-with-smaller-iommu-widths.patch

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