[Xen-devel] [PATCH V4 2/3] x86/mm: allocate logdirty_ranges for altp2ms

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

This patch is a pre-requisite for the one fixing VGA logdirty
freezes when using altp2m. It only concerns itself with the
ranges allocation / deallocation / initialization part. While
touching the code, I've switched global_logdirty from bool_t
to bool.

Signed-off-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>

---
CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>

---
Changes since V3:
- Removed all added p2m_free_logdirty() calls happening before
  p2m_free_one(), since p2m_free_one() already calls
  p2m_free_logdirty().
- Removed the p2m_free_logdirty() call from p2m_reset_altp2m().
  Jan has rightly asked about its placement, and on further review
  it was plain wrong: the rangeset would have been freed but not
  re-allocated in this case, so a p2m_reset_altp2m() would have
  just led to using a NULL logdirty_ranges pointer.
---
 xen/arch/x86/mm/p2m.c     | 76 ++++++++++++++++++++++++++++++++++++-----------
 xen/include/asm-x86/p2m.h |  2 +-
 2 files changed, 60 insertions(+), 18 deletions(-)

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 42b9ef4..bc6e543 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -59,6 +59,28 @@ static void p2m_nestedp2m_init(struct p2m_domain *p2m)
 #endif
 }
 
+static int p2m_init_logdirty(struct p2m_domain *p2m)
+{
+    if ( p2m->logdirty_ranges )
+        return 0;
+
+    p2m->logdirty_ranges = rangeset_new(p2m->domain, "log-dirty",
+                                        RANGESETF_prettyprint_hex);
+    if ( !p2m->logdirty_ranges )
+        return -ENOMEM;
+
+    return 0;
+}
+
+static void p2m_free_logdirty(struct p2m_domain *p2m)
+{
+    if ( !p2m->logdirty_ranges )
+        return;
+
+    rangeset_destroy(p2m->logdirty_ranges);
+    p2m->logdirty_ranges = NULL;
+}
+
 /* Init the datastructures for later use by the p2m code */
 static int p2m_initialise(struct domain *d, struct p2m_domain *p2m)
 {
@@ -108,7 +130,10 @@ free_p2m:
 static void p2m_free_one(struct p2m_domain *p2m)
 {
     if ( hap_enabled(p2m->domain) && cpu_has_vmx )
+    {
+        p2m_free_logdirty(p2m);
         ept_p2m_uninit(p2m);
+    }
     free_cpumask_var(p2m->dirty_cpumask);
     xfree(p2m);
 }
@@ -116,19 +141,19 @@ static void p2m_free_one(struct p2m_domain *p2m)
 static int p2m_init_hostp2m(struct domain *d)
 {
     struct p2m_domain *p2m = p2m_init_one(d);
+    int rc;
 
-    if ( p2m )
-    {
-        p2m->logdirty_ranges = rangeset_new(d, "log-dirty",
-                                            RANGESETF_prettyprint_hex);
-        if ( p2m->logdirty_ranges )
-        {
-            d->arch.p2m = p2m;
-            return 0;
-        }
+    if ( !p2m )
+        return -ENOMEM;
+
+    rc = p2m_init_logdirty(p2m);
+
+    if ( !rc )
+        d->arch.p2m = p2m;
+    else
         p2m_free_one(p2m);
-    }
-    return -ENOMEM;
+
+    return rc;
 }
 
 static void p2m_teardown_hostp2m(struct domain *d)
@@ -138,7 +163,6 @@ static void p2m_teardown_hostp2m(struct domain *d)
 
     if ( p2m )
     {
-        rangeset_destroy(p2m->logdirty_ranges);
         p2m_free_one(p2m);
         d->arch.p2m = NULL;
     }
@@ -2279,6 +2303,18 @@ void p2m_flush_altp2m(struct domain *d)
     altp2m_list_unlock(d);
 }
 
+static int p2m_init_altp2m_logdirty(struct p2m_domain *p2m)
+{
+    struct p2m_domain *hostp2m = p2m_get_hostp2m(p2m->domain);
+    int rc = p2m_init_logdirty(p2m);
+
+    if ( rc )
+        return rc;
+
+    /* The following is really just a rangeset copy. */
+    return rangeset_merge(p2m->logdirty_ranges, hostp2m->logdirty_ranges);
+}
+
 int p2m_init_altp2m_by_id(struct domain *d, unsigned int idx)
 {
     int rc = -EINVAL;
@@ -2290,8 +2326,9 @@ int p2m_init_altp2m_by_id(struct domain *d, unsigned int 
idx)
 
     if ( d->arch.altp2m_eptp[idx] == mfn_x(INVALID_MFN) )
     {
-        p2m_init_altp2m_ept(d, idx);
-        rc = 0;
+        rc = p2m_init_altp2m_logdirty(d->arch.altp2m_p2m[idx]);
+        if ( !rc )
+            p2m_init_altp2m_ept(d, idx);
     }
 
     altp2m_list_unlock(d);
@@ -2310,9 +2347,13 @@ int p2m_init_next_altp2m(struct domain *d, uint16_t *idx)
         if ( d->arch.altp2m_eptp[i] != mfn_x(INVALID_MFN) )
             continue;
 
-        p2m_init_altp2m_ept(d, i);
-        *idx = i;
-        rc = 0;
+        rc = p2m_init_altp2m_logdirty(d->arch.altp2m_p2m[i]);
+
+        if ( !rc )
+        {
+            p2m_init_altp2m_ept(d, i);
+            *idx = i;
+        }
 
         break;
     }
@@ -2341,6 +2382,7 @@ int p2m_destroy_altp2m_by_id(struct domain *d, unsigned 
int idx)
         {
             p2m_flush_table(d->arch.altp2m_p2m[idx]);
             /* Uninit and reinit ept to force TLB shootdown */
+            p2m_free_logdirty(d->arch.altp2m_p2m[idx]);
             ept_p2m_uninit(d->arch.altp2m_p2m[idx]);
             ept_p2m_init(d->arch.altp2m_p2m[idx]);
             d->arch.altp2m_eptp[idx] = mfn_x(INVALID_MFN);
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index d08c595..e905c65 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -223,7 +223,7 @@ struct p2m_domain {
     struct rangeset   *logdirty_ranges;
 
     /* Host p2m: Global log-dirty mode enabled for the domain. */
-    bool_t             global_logdirty;
+    bool               global_logdirty;
 
     /* Host p2m: when this flag is set, don't flush all the nested-p2m 
      * tables on every host-p2m change.  The setter of this flag 
-- 
2.7.4


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