[PATCH v8 02/11] IOMMU/MMU: enhance the call trees of IOMMU unmapping and mapping

["Xu, Quan" <quan.xu@intel.com>]

From: Quan Xu <quan.xu@intel.com>

When IOMMU mapping is failed, we issue a best effort rollback, stopping
IOMMU mapping, unmapping the previous IOMMU maps and then reporting the
error up to the call trees. When rollback is not feasible (in early
initialization phase or trade-off of complexity) for the hardware domain,
we do things on a best effort basis, only throwing out an error message.

IOMMU unmapping should perhaps continue despite an error, in an attempt
to do best effort cleanup.

Signed-off-by: Quan Xu <quan.xu@intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>

CC: Jan Beulich <jbeulich@suse.com>
CC: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Jun Nakajima <jun.nakajima@intel.com>
CC: Kevin Tian <kevin.tian@intel.com>
CC: George Dunlap <george.dunlap@eu.citrix.com>
CC: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
CC: Feng Wu <feng.wu@intel.com>

v8:
  1. add missing blank
  2. add a brief comment (Jan, if you have a better one, could you help me
     enhance it upon commit?)
---
 xen/arch/x86/mm.c                           | 13 ++++++----
 xen/arch/x86/mm/p2m-ept.c                   | 39 +++++++++++++++++++++++------
 xen/arch/x86/mm/p2m-pt.c                    | 28 ++++++++++++++++++---
 xen/arch/x86/mm/p2m.c                       | 23 ++++++++++++++---
 xen/arch/x86/x86_64/mm.c                    |  9 ++++++-
 xen/drivers/passthrough/amd/pci_amd_iommu.c | 15 +++++++++--
 xen/drivers/passthrough/iommu.c             | 13 +++++++++-
 xen/drivers/passthrough/vtd/x86/vtd.c       | 15 +++++++++--
 xen/include/xen/iommu.h                     |  6 ++---
 9 files changed, 134 insertions(+), 27 deletions(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 8d10a3e..ae7c8ab 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -2467,7 +2467,7 @@ static int __get_page_type(struct page_info *page, unsigned long type,
                            int preemptible)
 {
     unsigned long nx, x, y = page->u.inuse.type_info;
-    int rc = 0;
+    int rc = 0, iommu_ret = 0;
 
     ASSERT(!(type & ~(PGT_type_mask | PGT_pae_xen_l2)));
 
@@ -2578,11 +2578,11 @@ static int __get_page_type(struct page_info *page, unsigned long type,
         if ( d && is_pv_domain(d) && unlikely(need_iommu(d)) )
         {
             if ( (x & PGT_type_mask) == PGT_writable_page )
-                iommu_unmap_page(d, mfn_to_gmfn(d, page_to_mfn(page)));
+                iommu_ret = iommu_unmap_page(d, mfn_to_gmfn(d, page_to_mfn(page)));
             else if ( type == PGT_writable_page )
-                iommu_map_page(d, mfn_to_gmfn(d, page_to_mfn(page)),
-                               page_to_mfn(page),
-                               IOMMUF_readable|IOMMUF_writable);
+                iommu_ret = iommu_map_page(d, mfn_to_gmfn(d, page_to_mfn(page)),
+                                           page_to_mfn(page),
+                                           IOMMUF_readable|IOMMUF_writable);
         }
     }
 
@@ -2599,6 +2599,9 @@ static int __get_page_type(struct page_info *page, unsigned long type,
     if ( (x & PGT_partial) && !(nx & PGT_partial) )
         put_page(page);
 
+    if ( !rc )
+        rc = iommu_ret;
+
     return rc;
 }
 
diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index 1ed5b47..a233194 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -667,6 +667,7 @@ ept_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
     unsigned long gfn_remainder = gfn;
     unsigned int i, target = order / EPT_TABLE_ORDER;
     int ret, rc = 0;
+    bool_t entry_written = 0;
     bool_t direct_mmio = (p2mt == p2m_mmio_direct);
     uint8_t ipat = 0;
     bool_t need_modify_vtd_table = 1;
@@ -812,10 +813,15 @@ ept_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
     rc = atomic_write_ept_entry(ept_entry, new_entry, target);
     if ( unlikely(rc) )
         old_entry.epte = 0;
-    else if ( p2mt != p2m_invalid &&
-              (gfn + (1UL << order) - 1 > p2m->max_mapped_pfn) )
-        /* Track the highest gfn for which we have ever had a valid mapping */
-        p2m->max_mapped_pfn = gfn + (1UL << order) - 1;
+    else
+    {
+        entry_written = 1;
+
+        if ( p2mt != p2m_invalid &&
+             (gfn + (1UL << order) - 1 > p2m->max_mapped_pfn) )
+            /* Track the highest gfn for which we have ever had a valid mapping */
+            p2m->max_mapped_pfn = gfn + (1UL << order) - 1;
+    }
 
 out:
     if ( needs_sync )
@@ -831,10 +837,29 @@ out:
         {
             if ( iommu_flags )
                 for ( i = 0; i < (1 << order); i++ )
-                    iommu_map_page(d, gfn + i, mfn_x(mfn) + i, iommu_flags);
+                {
+                    rc = iommu_map_page(d, gfn + i, mfn_x(mfn) + i, iommu_flags);
+                    if ( unlikely(rc) )
+                    {
+                        while ( i-- )
+                            /*
+                             * IOMMU unmapping should perhaps continue despite an
+                             * error in an attempt to do best effort cleanup, and
+                             * consume the error as __must_check annotation.
+                             */
+                            if ( iommu_unmap_page(p2m->domain, gfn + i) )
+                                continue;
+
+                        break;
+                    }
+                }
             else
                 for ( i = 0; i < (1 << order); i++ )
-                    iommu_unmap_page(d, gfn + i);
+                {
+                    ret = iommu_unmap_page(d, gfn + i);
+                    if ( !rc )
+                        rc = ret;
+                }
         }
     }
 
@@ -847,7 +872,7 @@ out:
     if ( is_epte_present(&old_entry) )
         ept_free_entry(p2m, &old_entry, target);
 
-    if ( rc == 0 && p2m_is_hostp2m(p2m) )
+    if ( entry_written && p2m_is_hostp2m(p2m) )
         p2m_altp2m_propagate_change(d, _gfn(gfn), mfn, order, p2mt, p2ma);
 
     return rc;
diff --git a/xen/arch/x86/mm/p2m-pt.c b/xen/arch/x86/mm/p2m-pt.c
index 3d80612..506e866 100644
--- a/xen/arch/x86/mm/p2m-pt.c
+++ b/xen/arch/x86/mm/p2m-pt.c
@@ -673,6 +673,8 @@ p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
     if ( iommu_enabled && need_iommu(p2m->domain) &&
          (iommu_old_flags != iommu_pte_flags || old_mfn != mfn_x(mfn)) )
     {
+        ASSERT(rc == 0);
+
         if ( iommu_use_hap_pt(p2m->domain) )
         {
             if ( iommu_old_flags )
@@ -680,11 +682,31 @@ p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
         }
         else if ( iommu_pte_flags )
             for ( i = 0; i < (1UL << page_order); i++ )
-                iommu_map_page(p2m->domain, gfn + i, mfn_x(mfn) + i,
-                               iommu_pte_flags);
+            {
+                rc = iommu_map_page(p2m->domain, gfn + i, mfn_x(mfn) + i,
+                                    iommu_pte_flags);
+                if ( unlikely(rc) )
+                {
+                    while ( i-- )
+                        /*
+                         * IOMMU unmapping should perhaps continue despite an
+                         * error in an attempt to do best effort cleanup, and
+                         * consume the error as __must_check annotation.
+                         */
+                        if ( iommu_unmap_page(p2m->domain, gfn + i) )
+                            continue;
+
+                    break;
+                }
+            }
         else
             for ( i = 0; i < (1UL << page_order); i++ )
-                iommu_unmap_page(p2m->domain, gfn + i);
+            {
+                int ret = iommu_unmap_page(p2m->domain, gfn + i);
+
+                if ( !rc )
+                    rc = ret;
+            }
     }
 
     /*
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 9b19769..cabf7c3 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -641,10 +641,20 @@ p2m_remove_page(struct p2m_domain *p2m, unsigned long gfn, unsigned long mfn,
 
     if ( !paging_mode_translate(p2m->domain) )
     {
+        int rc = 0;
+
         if ( need_iommu(p2m->domain) )
+        {
             for ( i = 0; i < (1 << page_order); i++ )
-                iommu_unmap_page(p2m->domain, mfn + i);
-        return 0;
+            {
+                int ret = iommu_unmap_page(p2m->domain, mfn + i);
+
+                if ( !rc )
+                    rc = ret;
+            }
+        }
+
+        return rc;
     }
 
     ASSERT(gfn_locked_by_me(p2m, gfn));
@@ -700,7 +710,14 @@ guest_physmap_add_entry(struct domain *d, unsigned long gfn,
                 if ( rc != 0 )
                 {
                     while ( i-- > 0 )
-                        iommu_unmap_page(d, mfn + i);
+                        /*
+                         * IOMMU unmapping should perhaps continue despite an
+                         * error in an attempt to do best effort cleanup, and
+                         * consume the error as __must_check annotation.
+                         */
+                        if ( iommu_unmap_page(d, mfn + i) )
+                            continue;
+
                     return rc;
                 }
             }
diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index e07e69e..af7102f 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -1436,7 +1436,14 @@ int memory_add(unsigned long spfn, unsigned long epfn, unsigned int pxm)
         if ( i != epfn )
         {
             while (i-- > old_max)
-                iommu_unmap_page(hardware_domain, i);
+                /*
+                 * IOMMU unmapping should perhaps continue despite an
+                 * error in an attempt to do best effort cleanup, and
+                 * consume the error as __must_check annotation.
+                 */
+                if ( iommu_unmap_page(hardware_domain, i) )
+                    continue;
+
             goto destroy_m2p;
         }
     }
diff --git a/xen/drivers/passthrough/amd/pci_amd_iommu.c b/xen/drivers/passthrough/amd/pci_amd_iommu.c
index fce9827..4a860af 100644
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
@@ -282,6 +282,8 @@ static void __hwdom_init amd_iommu_hwdom_init(struct domain *d)
 
     if ( !iommu_passthrough && !need_iommu(d) )
     {
+        int rc = 0;
+
         /* Set up 1:1 page table for dom0 */
         for ( i = 0; i < max_pdx; i++ )
         {
@@ -292,12 +294,21 @@ static void __hwdom_init amd_iommu_hwdom_init(struct domain *d)
              * a pfn_valid() check would seem desirable here.
              */
             if ( mfn_valid(pfn) )
-                amd_iommu_map_page(d, pfn, pfn, 
-                                   IOMMUF_readable|IOMMUF_writable);
+            {
+                int ret = amd_iommu_map_page(d, pfn, pfn,
+                                             IOMMUF_readable|IOMMUF_writable);
+
+                if ( !rc )
+                    rc = ret;
+            }
 
             if ( !(i & 0xfffff) )
                 process_pending_softirqs();
         }
+
+        if ( rc )
+            AMD_IOMMU_DEBUG("d%d: IOMMU mapping failed: %d\n",
+                            d->domain_id, rc);
     }
 
     for_each_amd_iommu ( iommu )
diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 673e126..ec85352 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -171,20 +171,31 @@ void __hwdom_init iommu_hwdom_init(struct domain *d)
     {
         struct page_info *page;
         unsigned int i = 0;
+        int rc = 0;
+
         page_list_for_each ( page, &d->page_list )
         {
             unsigned long mfn = page_to_mfn(page);
             unsigned long gfn = mfn_to_gmfn(d, mfn);
             unsigned int mapping = IOMMUF_readable;
+            int ret;
 
             if ( ((page->u.inuse.type_info & PGT_count_mask) == 0) ||
                  ((page->u.inuse.type_info & PGT_type_mask)
                   == PGT_writable_page) )
                 mapping |= IOMMUF_writable;
-            hd->platform_ops->map_page(d, gfn, mfn, mapping);
+
+            ret = hd->platform_ops->map_page(d, gfn, mfn, mapping);
+            if ( !rc )
+                rc = ret;
+
             if ( !(i++ & 0xfffff) )
                 process_pending_softirqs();
         }
+
+        if ( rc )
+            printk(XENLOG_WARNING "d%d: IOMMU mapping failed: %d\n",
+                   d->domain_id, rc);
     }
 
     return hd->platform_ops->hwdom_init(d);
diff --git a/xen/drivers/passthrough/vtd/x86/vtd.c b/xen/drivers/passthrough/vtd/x86/vtd.c
index c0d6aab..974b537 100644
--- a/xen/drivers/passthrough/vtd/x86/vtd.c
+++ b/xen/drivers/passthrough/vtd/x86/vtd.c
@@ -118,6 +118,8 @@ void __hwdom_init vtd_set_hwdom_mapping(struct domain *d)
 
     for ( i = 0; i < top; i++ )
     {
+        int rc = 0;
+
         /*
          * Set up 1:1 mapping for dom0. Default to use only conventional RAM
          * areas and let RMRRs include needed reserved regions. When set, the
@@ -140,8 +142,17 @@ void __hwdom_init vtd_set_hwdom_mapping(struct domain *d)
 
         tmp = 1 << (PAGE_SHIFT - PAGE_SHIFT_4K);
         for ( j = 0; j < tmp; j++ )
-            iommu_map_page(d, pfn * tmp + j, pfn * tmp + j,
-                           IOMMUF_readable|IOMMUF_writable);
+        {
+            int ret = iommu_map_page(d, pfn * tmp + j, pfn * tmp + j,
+                                     IOMMUF_readable|IOMMUF_writable);
+
+            if ( !rc )
+               rc = ret;
+        }
+
+        if ( rc )
+           printk(XENLOG_WARNING VTDPREFIX " d%d: IOMMU mapping failed: %d\n",
+                  d->domain_id, rc);
 
         if (!(i & (0xfffff >> (PAGE_SHIFT - PAGE_SHIFT_4K))))
             process_pending_softirqs();
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 19ba976..eaa2c77 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -74,9 +74,9 @@ void iommu_teardown(struct domain *d);
 #define IOMMUF_readable  (1u<<_IOMMUF_readable)
 #define _IOMMUF_writable 1
 #define IOMMUF_writable  (1u<<_IOMMUF_writable)
-int iommu_map_page(struct domain *d, unsigned long gfn, unsigned long mfn,
-                   unsigned int flags);
-int iommu_unmap_page(struct domain *d, unsigned long gfn);
+int __must_check iommu_map_page(struct domain *d, unsigned long gfn,
+                                unsigned long mfn, unsigned int flags);
+int __must_check iommu_unmap_page(struct domain *d, unsigned long gfn);
 
 enum iommu_feature
 {
-- 
1.9.1


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