From: Keir Fraser <keir.fraser@citrix.com>
Date: Mon, 21 Jun 2010 18:19:25 +0000 (+0100)
Subject: Enable tmem functionality for PV on HVM guests.  Guest kernel
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~11895
X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https:/%22bookmarks://%22/%22http:/www.example.com/cgi/%22https:/%22bookmarks:/%22?a=commitdiff_plain;h=5afab625f400e571b78aaf3b7d2f5644c06d07b3;p=xen.git

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@oracle.com>
---

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 1f1542bc43..b803a30314 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2302,7 +2302,8 @@ static hvm_hypercall_t *hvm_hypercall32_table[NR_hypercalls] = {
     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_table[NR_hypercalls] = {
     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_table[NR_hypercalls] = {
     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 --git a/xen/common/tmem.c b/xen/common/tmem.c
index ffc07669db..a3f236ae0b 100644
--- a/xen/common/tmem.c
+++ b/xen/common/tmem.c
@@ -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 @@ done:
 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 *pool,
         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 @@ static NOINLINE int do_tmem_get(pool_t *pool, uint64_t oid, uint32_t index,
 bad_copy:
     /* this should only happen if the client passed a bad mfn */
     failed_copies++;
-ASSERT(0);
     return -EFAULT;
 
 }
diff --git a/xen/common/tmem_xen.c b/xen/common/tmem_xen.c
index 41c37bc57f..922403297e 100644
--- a/xen/common/tmem_xen.c
+++ b/xen/common/tmem_xen.c
@@ -101,7 +101,7 @@ static inline void *cli_mfn_to_va(tmem_cli_mfn_t cmfn, unsigned long *pcli_mfn)
     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 --git a/xen/include/xen/tmem_xen.h b/xen/include/xen/tmem_xen.h
index 84bb6dd238..f409cbf1a9 100644
--- a/xen/include/xen/tmem_xen.h
+++ b/xen/include/xen/tmem_xen.h
@@ -456,7 +456,9 @@ typedef XEN_GUEST_HANDLE(tmem_op_t) tmem_cli_op_t;
 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;