[PATCH 4/6] mm: New XENMEM space, XENMAPSPACE_gmfn_range

[Jean Guyader <jean.guyader@eu.citrix.com>]

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XENMAPSPACE_gmfn_range is like XENMAPSPACE_gmfn but it runs on
a range of pages. The size of the range is defined in a new field.

This new field .size is located in the 16 bits padding between .domid
and .space in struct xen_add_to_physmap to stay compatible with older
versions.

Signed-off-by: Jean Guyader <jean.guyader@eu.citrix.com>
---
 xen/arch/x86/mm.c               |  164 ++++++++++++++++++++++-----------------
 xen/arch/x86/x86_64/compat/mm.c |    4 +
 xen/include/public/memory.h     |    4 +
 3 files changed, 102 insertions(+), 70 deletions(-)


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diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index f75011e..2417fe9 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4598,93 +4598,112 @@ static int xenmem_add_to_physmap(struct domain *d, struct xen_add_to_physmap xat
     unsigned long prev_mfn, mfn = 0, gpfn;
     int rc;
 
-    switch ( xatp.space )
-    {
-    case XENMAPSPACE_shared_info:
-        if ( xatp.idx == 0 )
-            mfn = virt_to_mfn(d->shared_info);
-        break;
-    case XENMAPSPACE_grant_table:
-        spin_lock(&d->grant_table->lock);
+    if ( xatp.space != XENMAPSPACE_gmfn_range )
+        xatp.size = 1;
 
-        if ( d->grant_table->gt_version == 0 )
-            d->grant_table->gt_version = 1;
-
-        if ( d->grant_table->gt_version == 2 &&
-             (xatp.idx & XENMAPIDX_grant_table_status) )
+    while ( xatp.size > 0 )
+    {
+        if ( hypercall_preempt_check() )
         {
-            xatp.idx &= ~XENMAPIDX_grant_table_status;
-            if ( xatp.idx < nr_status_frames(d->grant_table) )
-                mfn = virt_to_mfn(d->grant_table->status[xatp.idx]);
+            rc = -EAGAIN;
+            break;
         }
-        else
+
+        switch ( xatp.space )
         {
-            if ( (xatp.idx >= nr_grant_frames(d->grant_table)) &&
-                 (xatp.idx < max_nr_grant_frames) )
-                gnttab_grow_table(d, xatp.idx + 1);
+        case XENMAPSPACE_shared_info:
+            if ( xatp.idx == 0 )
+                mfn = virt_to_mfn(d->shared_info);
+            break;
+        case XENMAPSPACE_grant_table:
+            spin_lock(&d->grant_table->lock);
 
-            if ( xatp.idx < nr_grant_frames(d->grant_table) )
-                mfn = virt_to_mfn(d->grant_table->shared_raw[xatp.idx]);
-        }
+            if ( d->grant_table->gt_version == 0 )
+                d->grant_table->gt_version = 1;
 
-        spin_unlock(&d->grant_table->lock);
-        break;
-    case XENMAPSPACE_gmfn:
-    {
-        p2m_type_t p2mt;
+            if ( d->grant_table->gt_version == 2 &&
+                 (xatp.idx & XENMAPIDX_grant_table_status) )
+            {
+                xatp.idx &= ~XENMAPIDX_grant_table_status;
+                if ( xatp.idx < nr_status_frames(d->grant_table) )
+                    mfn = virt_to_mfn(d->grant_table->status[xatp.idx]);
+            }
+            else
+            {
+                if ( (xatp.idx >= nr_grant_frames(d->grant_table)) &&
+                     (xatp.idx < max_nr_grant_frames) )
+                    gnttab_grow_table(d, xatp.idx + 1);
+
+                if ( xatp.idx < nr_grant_frames(d->grant_table) )
+                    mfn = virt_to_mfn(d->grant_table->shared_raw[xatp.idx]);
+            }
 
-        xatp.idx = mfn_x(gfn_to_mfn_unshare(d, xatp.idx, &p2mt));
-        /* If the page is still shared, exit early */
-        if ( p2m_is_shared(p2mt) )
+            spin_unlock(&d->grant_table->lock);
+            break;
+        case XENMAPSPACE_gmfn:
         {
-            rcu_unlock_domain(d);
-            return -ENOMEM;
+            p2m_type_t p2mt;
+
+            xatp.idx = mfn_x(gfn_to_mfn_unshare(d, xatp.idx, &p2mt));
+            /* If the page is still shared, exit early */
+            if ( p2m_is_shared(p2mt) )
+            {
+                rcu_unlock_domain(d);
+                return -ENOMEM;
+            }
+            if ( !get_page_from_pagenr(xatp.idx, d) )
+                break;
+            mfn = xatp.idx;
+            page = mfn_to_page(mfn);
+            break;
         }
-        if ( !get_page_from_pagenr(xatp.idx, d) )
+        default:
             break;
-        mfn = xatp.idx;
-        page = mfn_to_page(mfn);
-        break;
-    }
-    default:
-        break;
-    }
+        }
+
+        if ( !paging_mode_translate(d) || (mfn == 0) )
+        {
+            if ( page )
+                put_page(page);
+            rcu_unlock_domain(d);
+            return -EINVAL;
+        }
+
+        domain_lock(d);
 
-    if ( !paging_mode_translate(d) || (mfn == 0) )
-    {
         if ( page )
             put_page(page);
-        rcu_unlock_domain(d);
-        return -EINVAL;
-    }
 
-    domain_lock(d);
+        /* Remove previously mapped page if it was present. */
+        prev_mfn = gmfn_to_mfn(d, xatp.gpfn);
+        if ( mfn_valid(prev_mfn) )
+        {
+            if ( is_xen_heap_mfn(prev_mfn) )
+                /* Xen heap frames are simply unhooked from this phys slot. */
+                guest_physmap_remove_page(d, xatp.gpfn, prev_mfn, 0);
+            else
+                /* Normal domain memory is freed, to avoid leaking memory. */
+                guest_remove_page(d, xatp.gpfn);
+        }
 
-    if ( page )
-        put_page(page);
+        /* Unmap from old location, if any. */
+        gpfn = get_gpfn_from_mfn(mfn);
+        ASSERT( gpfn != SHARED_M2P_ENTRY );
+        if ( gpfn != INVALID_M2P_ENTRY )
+            guest_physmap_remove_page(d, gpfn, mfn, 0);
 
-    /* Remove previously mapped page if it was present. */
-    prev_mfn = gmfn_to_mfn(d, xatp.gpfn);
-    if ( mfn_valid(prev_mfn) )
-    {
-        if ( is_xen_heap_mfn(prev_mfn) )
-            /* Xen heap frames are simply unhooked from this phys slot. */
-            guest_physmap_remove_page(d, xatp.gpfn, prev_mfn, 0);
-        else
-            /* Normal domain memory is freed, to avoid leaking memory. */
-            guest_remove_page(d, xatp.gpfn);
-    }
+        /* Map at new location. */
+        rc = guest_physmap_add_page(d, xatp.gpfn, mfn, 0);
 
-    /* Unmap from old location, if any. */
-    gpfn = get_gpfn_from_mfn(mfn);
-    ASSERT( gpfn != SHARED_M2P_ENTRY );
-    if ( gpfn != INVALID_M2P_ENTRY )
-        guest_physmap_remove_page(d, gpfn, mfn, 0);
+        domain_unlock(d);
 
-    /* Map at new location. */
-    rc = guest_physmap_add_page(d, xatp.gpfn, mfn, 0);
+        xatp.idx++;
+        xatp.gpfn++;
+        xatp.size--;
 
-    domain_unlock(d);
+        if ( rc != 0 )
+            break;
+    }
 
     return rc;
 }
@@ -4714,10 +4733,15 @@ long arch_memory_op(int op, XEN_GUEST_HANDLE(void) arg)
             return -EPERM;
         }
 
-        xenmem_add_to_physmap(d, xatp);
-
+        rc = xenmem_add_to_physmap(d, xatp);
         rcu_unlock_domain(d);
 
+        if ( rc == -EAGAIN )
+        {
+            rc = hypercall_create_continuation(
+                    __HYPERVISOR_memory_op, "ih", op, arg);
+        }
+
         return rc;
     }
 
diff --git a/xen/arch/x86/x86_64/compat/mm.c b/xen/arch/x86/x86_64/compat/mm.c
index 2c05099..05c3098 100644
--- a/xen/arch/x86/x86_64/compat/mm.c
+++ b/xen/arch/x86/x86_64/compat/mm.c
@@ -63,6 +63,10 @@ int compat_arch_memory_op(int op, XEN_GUEST_HANDLE(void) arg)
 
         XLAT_add_to_physmap(nat, &cmp);
         rc = arch_memory_op(op, guest_handle_from_ptr(nat, void));
+        XLAT_add_to_physmap(&cmp, nat);
+
+        if ( copy_to_guest(arg, &cmp, 1) )
+            return -EFAULT;
 
         break;
     }
diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index 08355e3..c5b78a8 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -208,10 +208,14 @@ struct xen_add_to_physmap {
     /* Which domain to change the mapping for. */
     domid_t domid;
 
+    /* Number of pages to go through for gmfn_range */
+    uint16_t    size;
+
     /* Source mapping space. */
 #define XENMAPSPACE_shared_info 0 /* shared info page */
 #define XENMAPSPACE_grant_table 1 /* grant table page */
 #define XENMAPSPACE_gmfn        2 /* GMFN */
+#define XENMAPSPACE_gmfn_range  3 /* GMFN range */
     unsigned int space;
 
 #define XENMAPIDX_grant_table_status 0x80000000

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