[Xen-changelog] [xen-unstable] Enable tmem functionality for PV on HVM guests. Guest kernel

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1277144365 -3600
# Node ID 72c6228b5f0ffa1ad08d2868ec3678eae6ba70ba
# Parent  cfba1560054a6d8349eacb94631b7529afffd766
Enable tmem functionality for PV on HVM guests.  Guest kernel
must still be tmem-enabled to use this functionality (e.g.
won't work for Windows), but upstream Linux tmem (aka
cleancache and frontswap) patches apply cleanly on top
of PV on HVM patches.

Also, fix up some ASSERTS and code used only when bad guest
mfns are passed to tmem.  Previous code could crash Xen
if a buggy/malicious guest passes bad gmfns.

Signed-off-by: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c     |    9 ++++++---
 xen/common/tmem.c          |   24 ++++++++++++------------
 xen/common/tmem_xen.c      |    2 +-
 xen/include/xen/tmem_xen.h |    4 +++-
 4 files changed, 22 insertions(+), 17 deletions(-)

diff -r cfba1560054a -r 72c6228b5f0f xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c    Mon Jun 21 19:18:27 2010 +0100
+++ b/xen/arch/x86/hvm/hvm.c    Mon Jun 21 19:19:25 2010 +0100
@@ -2302,7 +2302,8 @@ static hvm_hypercall_t *hvm_hypercall32_
     HYPERCALL(event_channel_op),
     HYPERCALL(sched_op),
     HYPERCALL(set_timer_op),
-    HYPERCALL(hvm_op)
+    HYPERCALL(hvm_op),
+    HYPERCALL(tmem_op)
 };
 
 #else /* defined(__x86_64__) */
@@ -2355,7 +2356,8 @@ static hvm_hypercall_t *hvm_hypercall64_
     HYPERCALL(event_channel_op),
     HYPERCALL(sched_op),
     HYPERCALL(set_timer_op),
-    HYPERCALL(hvm_op)
+    HYPERCALL(hvm_op),
+    HYPERCALL(tmem_op)
 };
 
 static hvm_hypercall_t *hvm_hypercall32_table[NR_hypercalls] = {
@@ -2366,7 +2368,8 @@ static hvm_hypercall_t *hvm_hypercall32_
     HYPERCALL(event_channel_op),
     HYPERCALL(sched_op),
     HYPERCALL(set_timer_op),
-    HYPERCALL(hvm_op)
+    HYPERCALL(hvm_op),
+    HYPERCALL(tmem_op)
 };
 
 #endif /* defined(__x86_64__) */
diff -r cfba1560054a -r 72c6228b5f0f xen/common/tmem.c
--- a/xen/common/tmem.c Mon Jun 21 19:18:27 2010 +0100
+++ b/xen/common/tmem.c Mon Jun 21 19:19:25 2010 +0100
@@ -1483,6 +1483,7 @@ copy_uncompressed:
         pgp_free_data(pgp, pool);
     if ( ( pgp->pfp = tmem_page_alloc(pool) ) == NULL )
         goto failed_dup;
+    pgp->size = 0;
     /* tmh_copy_from_client properly handles len==0 and offsets != 0 */
     ret = tmh_copy_from_client(pgp->pfp,cmfn,tmem_offset,pfn_offset,len,0);
     if ( ret == -EFAULT )
@@ -1492,7 +1493,6 @@ copy_uncompressed:
         if ( pcd_associate(pgp,NULL,0) == -ENOMEM )
             goto failed_dup;
     }
-    pgp->size = 0;
 
 done:
     /* successfully replaced data, clean up and return success */
@@ -1509,12 +1509,14 @@ bad_copy:
 bad_copy:
     /* this should only happen if the client passed a bad mfn */
     failed_copies++;
-ASSERT(0);
-    return -EFAULT;
+    ret = -EFAULT;
+    goto cleanup;
 
 failed_dup:
    /* couldn't change out the data, flush the old data and return
     * -ENOSPC instead of -ENOMEM to differentiate failed _dup_ put */
+    ret = -ENOSPC;
+cleanup:
     pgpfound = pgp_delete_from_obj(obj, pgp->index);
     ASSERT(pgpfound == pgp);
     pgp_delete(pgpfound,0);
@@ -1528,7 +1530,7 @@ failed_dup:
         tmem_spin_unlock(&obj->obj_spinlock);
     }
     pool->dup_puts_flushed++;
-    return -ENOSPC;
+    return ret;
 }
 
 
@@ -1579,6 +1581,7 @@ static NOINLINE int do_tmem_put(pool_t *
         goto free;
     ASSERT(ret != -EEXIST);
     pgp->index = index;
+    pgp->size = 0;
 
     if ( len != 0 && client->compress )
     {
@@ -1615,7 +1618,6 @@ copy_uncompressed:
         if ( pcd_associate(pgp,NULL,0) == -ENOMEM )
             goto delete_and_free;
     }
-    pgp->size = 0;
 
 insert_page:
     if ( is_ephemeral(pool) )
@@ -1648,6 +1650,11 @@ insert_page:
         tot_good_eph_puts++;
     return 1;
 
+bad_copy:
+    /* this should only happen if the client passed a bad mfn */
+    ret = -EFAULT;
+    failed_copies++;
+
 delete_and_free:
     ASSERT((obj != NULL) && (pgp != NULL) && (pgp->index != -1));
     pgpdel = pgp_delete_from_obj(obj, pgp->index);
@@ -1669,12 +1676,6 @@ free:
     }
     pool->no_mem_puts++;
     return ret;
-
-bad_copy:
-    /* this should only happen if the client passed a bad mfn */
-    failed_copies++;
-ASSERT(0);
-    goto free;
 }
 
 static NOINLINE int do_tmem_get(pool_t *pool, uint64_t oid, uint32_t index,
@@ -1758,7 +1759,6 @@ bad_copy:
 bad_copy:
     /* this should only happen if the client passed a bad mfn */
     failed_copies++;
-ASSERT(0);
     return -EFAULT;
 
 }
diff -r cfba1560054a -r 72c6228b5f0f xen/common/tmem_xen.c
--- a/xen/common/tmem_xen.c     Mon Jun 21 19:18:27 2010 +0100
+++ b/xen/common/tmem_xen.c     Mon Jun 21 19:19:25 2010 +0100
@@ -101,7 +101,7 @@ static inline void *cli_mfn_to_va(tmem_c
     p2m_type_t t;
 
     cli_mfn = mfn_x(gfn_to_mfn(current->domain, cmfn, &t));
-    if (t != p2m_ram_rw)
+    if (t != p2m_ram_rw || cli_mfn == INVALID_MFN)
         return NULL;
     if (pcli_mfn != NULL)
         *pcli_mfn = cli_mfn;
diff -r cfba1560054a -r 72c6228b5f0f xen/include/xen/tmem_xen.h
--- a/xen/include/xen/tmem_xen.h        Mon Jun 21 19:18:27 2010 +0100
+++ b/xen/include/xen/tmem_xen.h        Mon Jun 21 19:19:25 2010 +0100
@@ -456,7 +456,9 @@ static inline int tmh_get_tmemop_from_cl
 static inline int tmh_get_tmemop_from_client(tmem_op_t *op, tmem_cli_op_t uops)
 {
 #ifdef CONFIG_COMPAT
-    if ( is_pv_32on64_vcpu(current) )
+    if ( is_hvm_vcpu(current) ?
+         hvm_guest_x86_mode(current) != 8 :
+         is_pv_32on64_vcpu(current) )
     {
         int rc;
         enum XLAT_tmem_op_u u;

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog