x86/ioreq server: asynchronously reset outstanding p2m_ioreq_server entries

After an ioreq server has unmapped, the remaining p2m_ioreq_server
entries need to be reset back to p2m_ram_rw. This patch does this
asynchronously with the current p2m_change_entry_type_global()
interface.

New field entry_count is introduced in struct p2m_domain, to record
the number of p2m_ioreq_server p2m page table entries. One nature of
these entries is that they only point to 4K sized page frames, because
all p2m_ioreq_server entries are originated from p2m_ram_rw ones in
p2m_change_type_one(). We do not need to worry about the counting for
2M/1G sized pages.

This patch disallows mapping of an ioreq server, when there's still
p2m_ioreq_server entry left, in case another mapping occurs right after
the current one being unmapped, releases its lock, with p2m table not
synced yet.

This patch also disallows live migration, when there's remaining
p2m_ioreq_server entry in p2m table. The core reason is our current
implementation of p2m_change_entry_type_global() lacks information
to resync p2m_ioreq_server entries correctly if global_logdirty is
on.

We still need to handle other recalculations, however; which means
that when doing a recalculation, if the current type is
p2m_ioreq_server, we check to see if p2m->ioreq.server is valid or
not.  If it is, we leave it as type p2m_ioreq_server; if not, we reset
it to p2m_ram as appropriate.

To avoid code duplication, lift recalc_type() out of p2m-pt.c and use
it for all type recalculations (both in p2m-pt.c and p2m-ept.c).

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
index 5bf3b6dc7a3f5e5a3063acbda98f7d3f39c33305..07a6c2679b6c3f7e462498e80c88313a440ceaa5 100644 (file)
--- a/xen/arch/x86/hvm/ioreq.c
+++ b/xen/arch/x86/hvm/ioreq.c
@@ -955,6 +955,14 @@ int hvm_map_mem_type_to_ioreq_server(struct domain *d, ioservid_t id,
 
     spin_unlock_recursive(&d->arch.hvm_domain.ioreq_server.lock);
 
+    if ( rc == 0 && flags == 0 )
+    {
+        struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+        if ( read_atomic(&p2m->ioreq.entry_count) )
+            p2m_change_entry_type_global(d, p2m_ioreq_server, p2m_ram_rw);
+    }
+
     return rc;
 }
 

diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c
index c0610c5ea030b357b67bd79f931c57ff40b0108e..b9814321c6522bcbfe64c23f55161c7c12796e67 100644 (file)
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -187,6 +187,15 @@ out:
  */
 static int hap_enable_log_dirty(struct domain *d, bool_t log_global)
 {
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+    /*
+     * Refuse to turn on global log-dirty mode if
+     * there are outstanding p2m_ioreq_server pages.
+     */
+    if ( log_global && read_atomic(&p2m->ioreq.entry_count) )
+        return -EBUSY;
+
     /* turn on PG_log_dirty bit in paging mode */
     paging_lock(d);
     d->arch.paging.mode |= PG_log_dirty;

diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index cc1eb217baf5c0b0f117ab5ccb8f5009aae82cdf..f37a1f2f282c6e1b5a97c5bb755801d0d13a99f8 100644 (file)
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -533,6 +533,8 @@ static int resolve_misconfig(struct p2m_domain *p2m, unsigned long gfn)
             {
                 for ( gfn -= i, i = 0; i < EPT_PAGETABLE_ENTRIES; ++i )
                 {
+                    p2m_type_t nt;
+
                     e = atomic_read_ept_entry(&epte[i]);
                     if ( e.emt == MTRR_NUM_TYPES )
                         e.emt = 0;
@@ -542,11 +544,18 @@ static int resolve_misconfig(struct p2m_domain *p2m, unsigned long gfn)
                                                _mfn(e.mfn), 0, &ipat,
                                                e.sa_p2mt == p2m_mmio_direct);
                     e.ipat = ipat;
-                    if ( e.recalc && p2m_is_changeable(e.sa_p2mt) )
+
+                    nt = p2m_recalc_type(e.recalc, e.sa_p2mt, p2m, gfn + i);
+                    if ( nt != e.sa_p2mt )
                     {
-                         e.sa_p2mt = p2m_is_logdirty_range(p2m, gfn + i, gfn + i)
-                                     ? p2m_ram_logdirty : p2m_ram_rw;
-                         ept_p2m_type_to_flags(p2m, &e, e.sa_p2mt, e.access);
+                        if ( e.sa_p2mt == p2m_ioreq_server )
+                        {
+                            ASSERT(p2m->ioreq.entry_count > 0);
+                            p2m->ioreq.entry_count--;
+                        }
+
+                        e.sa_p2mt = nt;
+                        ept_p2m_type_to_flags(p2m, &e, e.sa_p2mt, e.access);
                     }
                     e.recalc = 0;
                     wrc = atomic_write_ept_entry(&epte[i], e, level);
@@ -562,23 +571,24 @@ static int resolve_misconfig(struct p2m_domain *p2m, unsigned long gfn)
 
                 if ( recalc && p2m_is_changeable(e.sa_p2mt) )
                 {
-                     unsigned long mask = ~0UL << (level * EPT_TABLE_ORDER);
-
-                     switch ( p2m_is_logdirty_range(p2m, gfn & mask,
-                                                    gfn | ~mask) )
-                     {
-                     case 0:
-                          e.sa_p2mt = p2m_ram_rw;
-                          e.recalc = 0;
-                          break;
-                     case 1:
-                          e.sa_p2mt = p2m_ram_logdirty;
-                          e.recalc = 0;
-                          break;
-                     default: /* Force split. */
-                          emt = -1;
-                          break;
-                     }
+                    unsigned long mask = ~0UL << (level * EPT_TABLE_ORDER);
+
+                    ASSERT(e.sa_p2mt != p2m_ioreq_server);
+                    switch ( p2m_is_logdirty_range(p2m, gfn & mask,
+                                                   gfn | ~mask) )
+                    {
+                    case 0:
+                         e.sa_p2mt = p2m_ram_rw;
+                         e.recalc = 0;
+                         break;
+                    case 1:
+                         e.sa_p2mt = p2m_ram_logdirty;
+                         e.recalc = 0;
+                         break;
+                    default: /* Force split. */
+                         emt = -1;
+                         break;
+                    }
                 }
                 if ( unlikely(emt < 0) )
                 {
@@ -816,6 +826,23 @@ ept_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
         new_entry.suppress_ve = is_epte_valid(&old_entry) ?
                                     old_entry.suppress_ve : 1;
 
+    /*
+     * p2m_ioreq_server is only used for 4K pages, so the
+     * count is only done on ept page table entries.
+     */
+    if ( p2mt == p2m_ioreq_server )
+    {
+        ASSERT(i == 0);
+        p2m->ioreq.entry_count++;
+    }
+
+    if ( ept_entry->sa_p2mt == p2m_ioreq_server )
+    {
+        ASSERT(i == 0);
+        ASSERT(p2m->ioreq.entry_count > 0);
+        p2m->ioreq.entry_count--;
+    }
+
     rc = atomic_write_ept_entry(ept_entry, new_entry, target);
     if ( unlikely(rc) )
         old_entry.epte = 0;
@@ -964,12 +991,8 @@ static mfn_t ept_get_entry(struct p2m_domain *p2m,
 
     if ( is_epte_valid(ept_entry) )
     {
-        if ( (recalc || ept_entry->recalc) &&
-             p2m_is_changeable(ept_entry->sa_p2mt) )
-            *t = p2m_is_logdirty_range(p2m, gfn, gfn) ? p2m_ram_logdirty
-                                                      : p2m_ram_rw;
-        else
-            *t = ept_entry->sa_p2mt;
+        *t = p2m_recalc_type(recalc || ept_entry->recalc,
+                             ept_entry->sa_p2mt, p2m, gfn);
         *a = ept_entry->access;
         if ( sve )
             *sve = ept_entry->suppress_ve;

diff --git a/xen/arch/x86/mm/p2m-pt.c b/xen/arch/x86/mm/p2m-pt.c
index c0055f3ab5e55b395fcbdd73c32cd05b2f9af2e9..5079b59af35d6d66002d6ec95f9970fe4eaad55c 100644 (file)
--- a/xen/arch/x86/mm/p2m-pt.c
+++ b/xen/arch/x86/mm/p2m-pt.c
@@ -389,6 +389,7 @@ static int do_recalc(struct p2m_domain *p2m, unsigned long gfn)
         {
             unsigned long mask = ~0UL << (level * PAGETABLE_ORDER);
 
+            ASSERT(p2m_flags_to_type(l1e_get_flags(*pent)) != p2m_ioreq_server);
             if ( !needs_recalc(l1, *pent) ||
                  !p2m_is_changeable(p2m_flags_to_type(l1e_get_flags(*pent))) ||
                  p2m_is_logdirty_range(p2m, gfn & mask, gfn | ~mask) >= 0 )
@@ -436,17 +437,18 @@ static int do_recalc(struct p2m_domain *p2m, unsigned long gfn)
          needs_recalc(l1, *pent) )
     {
         l1_pgentry_t e = *pent;
+        p2m_type_t ot, nt;
+        unsigned long mask = ~0UL << (level * PAGETABLE_ORDER);
 
         if ( !valid_recalc(l1, e) )
             P2M_DEBUG("bogus recalc leaf at d%d:%lx:%u\n",
                       p2m->domain->domain_id, gfn, level);
-        if ( p2m_is_changeable(p2m_flags_to_type(l1e_get_flags(e))) )
+        ot = p2m_flags_to_type(l1e_get_flags(e));
+        nt = p2m_recalc_type_range(true, ot, p2m, gfn & mask, gfn | ~mask);
+        if ( nt != ot )
         {
-            unsigned long mask = ~0UL << (level * PAGETABLE_ORDER);
-            p2m_type_t p2mt = p2m_is_logdirty_range(p2m, gfn & mask, gfn | ~mask)
-                              ? p2m_ram_logdirty : p2m_ram_rw;
             unsigned long mfn = l1e_get_pfn(e);
-            unsigned long flags = p2m_type_to_flags(p2m, p2mt,
+            unsigned long flags = p2m_type_to_flags(p2m, nt,
                                                     _mfn(mfn), level);
 
             if ( level )
@@ -460,9 +462,17 @@ static int do_recalc(struct p2m_domain *p2m, unsigned long gfn)
                      mfn &= ~((unsigned long)_PAGE_PSE_PAT >> PAGE_SHIFT);
                 flags |= _PAGE_PSE;
             }
+
+            if ( ot == p2m_ioreq_server )
+            {
+                ASSERT(p2m->ioreq.entry_count > 0);
+                ASSERT(level == 0);
+                p2m->ioreq.entry_count--;
+            }
+
             e = l1e_from_pfn(mfn, flags);
             p2m_add_iommu_flags(&e, level,
-                                (p2mt == p2m_ram_rw)
+                                (nt == p2m_ram_rw)
                                 ? IOMMUF_readable|IOMMUF_writable : 0);
             ASSERT(!needs_recalc(l1, e));
         }
@@ -582,6 +592,7 @@ p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
             }
         }
 
+        ASSERT(p2m_flags_to_type(flags) != p2m_ioreq_server);
         ASSERT(!mfn_valid(mfn) || p2mt != p2m_mmio_direct);
         l3e_content = mfn_valid(mfn) || p2m_allows_invalid_mfn(p2mt)
             ? l3e_from_pfn(mfn_x(mfn),
@@ -606,6 +617,8 @@ p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
 
     if ( page_order == PAGE_ORDER_4K )
     {
+        p2m_type_t p2mt_old;
+
         rc = p2m_next_level(p2m, &table, &gfn_remainder, gfn,
                             L2_PAGETABLE_SHIFT - PAGE_SHIFT,
                             L2_PAGETABLE_ENTRIES, PGT_l1_page_table, 1);
@@ -629,6 +642,21 @@ p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
         if ( entry_content.l1 != 0 )
             p2m_add_iommu_flags(&entry_content, 0, iommu_pte_flags);
 
+        p2mt_old = p2m_flags_to_type(l1e_get_flags(*p2m_entry));
+
+        /*
+         * p2m_ioreq_server is only used for 4K pages, so
+         * the count is only done for level 1 entries.
+         */
+        if ( p2mt == p2m_ioreq_server )
+            p2m->ioreq.entry_count++;
+
+        if ( p2mt_old == p2m_ioreq_server )
+        {
+            ASSERT(p2m->ioreq.entry_count > 0);
+            p2m->ioreq.entry_count--;
+        }
+
         /* level 1 entry */
         p2m->write_p2m_entry(p2m, gfn, p2m_entry, entry_content, 1);
         /* NB: paging_write_p2m_entry() handles tlb flushes properly */
@@ -655,7 +683,8 @@ p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
                 intermediate_entry = *p2m_entry;
             }
         }
-        
+
+        ASSERT(p2m_flags_to_type(flags) != p2m_ioreq_server);
         ASSERT(!mfn_valid(mfn) || p2mt != p2m_mmio_direct);
         if ( mfn_valid(mfn) || p2m_allows_invalid_mfn(p2mt) )
             l2e_content = l2e_from_pfn(mfn_x(mfn),
@@ -726,15 +755,6 @@ p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
     return rc;
 }
 
-static inline p2m_type_t recalc_type(bool_t recalc, p2m_type_t t,
-                                     struct p2m_domain *p2m, unsigned long gfn)
-{
-    if ( !recalc || !p2m_is_changeable(t) )
-        return t;
-    return p2m_is_logdirty_range(p2m, gfn, gfn) ? p2m_ram_logdirty
-                                                : p2m_ram_rw;
-}
-
 static mfn_t
 p2m_pt_get_entry(struct p2m_domain *p2m, unsigned long gfn,
                  p2m_type_t *t, p2m_access_t *a, p2m_query_t q,
@@ -820,8 +840,8 @@ pod_retry_l3:
             mfn = _mfn(l3e_get_pfn(*l3e) +
                        l2_table_offset(addr) * L1_PAGETABLE_ENTRIES +
                        l1_table_offset(addr));
-            *t = recalc_type(recalc || _needs_recalc(flags),
-                             p2m_flags_to_type(flags), p2m, gfn);
+            *t = p2m_recalc_type(recalc || _needs_recalc(flags),
+                                 p2m_flags_to_type(flags), p2m, gfn);
             unmap_domain_page(l3e);
 
             ASSERT(mfn_valid(mfn) || !p2m_is_ram(*t));
@@ -859,8 +879,8 @@ pod_retry_l2:
     if ( flags & _PAGE_PSE )
     {
         mfn = _mfn(l2e_get_pfn(*l2e) + l1_table_offset(addr));
-        *t = recalc_type(recalc || _needs_recalc(flags),
-                         p2m_flags_to_type(flags), p2m, gfn);
+        *t = p2m_recalc_type(recalc || _needs_recalc(flags),
+                             p2m_flags_to_type(flags), p2m, gfn);
         unmap_domain_page(l2e);
         
         ASSERT(mfn_valid(mfn) || !p2m_is_ram(*t));
@@ -896,7 +916,7 @@ pod_retry_l1:
         return INVALID_MFN;
     }
     mfn = _mfn(l1e_get_pfn(*l1e));
-    *t = recalc_type(recalc || _needs_recalc(flags), l1t, p2m, gfn);
+    *t = p2m_recalc_type(recalc || _needs_recalc(flags), l1t, p2m, gfn);
     unmap_domain_page(l1e);
 
     ASSERT(mfn_valid(mfn) || !p2m_is_ram(*t) || p2m_is_paging(*t));

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index b84add035eab7c3e364765877df93262be579bc1..4169d18ddadfa02c57f13af65dcc009efe8d5af8 100644 (file)
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -317,6 +317,15 @@ int p2m_set_ioreq_server(struct domain *d,
         if ( p2m->ioreq.server != NULL )
             goto out;
 
+        /*
+         * It is possible that an ioreq server has just been unmapped,
+         * released the spin lock, with some p2m_ioreq_server entries
+         * in p2m table remained. We shall refuse another ioreq server
+         * mapping request in such case.
+         */
+        if ( read_atomic(&p2m->ioreq.entry_count) )
+            goto out;
+
         p2m->ioreq.server = s;
         p2m->ioreq.flags = flags;
     }

diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 452162072dcf15241c8b373fc89d10b7c0803a38..f27b3a6844c3f0089106ba0d647b45e3435bbccd 100644 (file)
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -120,7 +120,8 @@ typedef unsigned int p2m_query_t;
 
 /* Types that can be subject to bulk transitions. */
 #define P2M_CHANGEABLE_TYPES (p2m_to_mask(p2m_ram_rw) \
-                              | p2m_to_mask(p2m_ram_logdirty) )
+                              | p2m_to_mask(p2m_ram_logdirty) \
+                              | p2m_to_mask(p2m_ioreq_server) )
 
 #define P2M_POD_TYPES (p2m_to_mask(p2m_populate_on_demand))
 
@@ -349,6 +350,7 @@ struct p2m_domain {
           * are to be emulated by an ioreq server.
           */
          unsigned int flags;
+         unsigned long entry_count;
      } ioreq;
 };
 
@@ -744,6 +746,28 @@ static inline p2m_type_t p2m_flags_to_type(unsigned long flags)
     return (flags >> 12) & 0x7f;
 }
 
+static inline p2m_type_t p2m_recalc_type_range(bool recalc, p2m_type_t t,
+                                               struct p2m_domain *p2m,
+                                               unsigned long gfn_start,
+                                               unsigned long gfn_end)
+{
+    if ( !recalc || !p2m_is_changeable(t) )
+        return t;
+
+    if ( t == p2m_ioreq_server && p2m->ioreq.server != NULL )
+        return t;
+
+    return p2m_is_logdirty_range(p2m, gfn_start, gfn_end) ? p2m_ram_logdirty
+                                                          : p2m_ram_rw;
+}
+
+static inline p2m_type_t p2m_recalc_type(bool recalc, p2m_type_t t,
+                                         struct p2m_domain *p2m,
+                                         unsigned long gfn)
+{
+    return p2m_recalc_type_range(recalc, t, p2m, gfn, gfn);
+}
+
 int p2m_pt_handle_deferred_changes(uint64_t gpa);
 
 /*