[Xen-changelog] [xen-unstable] PoD: Allow pod_set_cache_target hypercall to be preempted

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User George Dunlap <george.dunlap@xxxxxxxxxxxxx>
# Date 1295274253 0
# Node ID 97ab84aca65cdcbce2ddccc51629fb24adb056cf
# Parent  d1631540bcc4d369d7e7ec1d87e54e1a8f5d5f78
PoD: Allow pod_set_cache_target hypercall to be preempted

For very large VMs, setting the cache target can take long enough that
dom0 complains of soft lockups.  Allow the hypercall to be preempted.

Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Acked-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
---
 xen/arch/x86/domain.c           |    4 ++--
 xen/arch/x86/mm.c               |   26 +++++++++++++++++---------
 xen/arch/x86/mm/p2m.c           |   18 +++++++++++++++---
 xen/arch/x86/x86_64/compat/mm.c |    3 +++
 4 files changed, 37 insertions(+), 14 deletions(-)

diff -r d1631540bcc4 -r 97ab84aca65c xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c     Tue Jan 18 17:23:24 2011 +0000
+++ b/xen/arch/x86/domain.c     Mon Jan 17 14:24:13 2011 +0000
@@ -1653,8 +1653,8 @@ int hypercall_xlat_continuation(unsigned
     unsigned long nval = 0;
     va_list args;
 
-    BUG_ON(*id > 5);
-    BUG_ON(mask & (1U << *id));
+    BUG_ON(id && *id > 5);
+    BUG_ON(id && (mask & (1U << *id)));
 
     va_start(args, mask);
 
diff -r d1631540bcc4 -r 97ab84aca65c xen/arch/x86/mm.c
--- a/xen/arch/x86/mm.c Tue Jan 18 17:23:24 2011 +0000
+++ b/xen/arch/x86/mm.c Mon Jan 17 14:24:13 2011 +0000
@@ -4799,15 +4799,23 @@ long arch_memory_op(int op, XEN_GUEST_HA
             rc = p2m_pod_set_mem_target(d, target.target_pages);
         }
 
-        p2m = p2m_get_hostp2m(d);
-        target.tot_pages       = d->tot_pages;
-        target.pod_cache_pages = p2m->pod.count;
-        target.pod_entries     = p2m->pod.entry_count;
-
-        if ( copy_to_guest(arg, &target, 1) )
-        {
-            rc= -EFAULT;
-            goto pod_target_out_unlock;
+        if ( rc == -EAGAIN )
+        {
+            rc = hypercall_create_continuation(
+                __HYPERVISOR_memory_op, "lh", op, arg);
+        }
+        else if ( rc >= 0 )
+        {
+            p2m = p2m_get_hostp2m(d);
+            target.tot_pages       = d->tot_pages;
+            target.pod_cache_pages = p2m->pod.count;
+            target.pod_entries     = p2m->pod.entry_count;
+
+            if ( copy_to_guest(arg, &target, 1) )
+            {
+                rc= -EFAULT;
+                goto pod_target_out_unlock;
+            }
         }
         
     pod_target_out_unlock:
diff -r d1631540bcc4 -r 97ab84aca65c xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c     Tue Jan 18 17:23:24 2011 +0000
+++ b/xen/arch/x86/mm/p2m.c     Mon Jan 17 14:24:13 2011 +0000
@@ -435,7 +435,7 @@ static struct page_info * p2m_pod_cache_
 
 /* Set the size of the cache, allocating or freeing as necessary. */
 static int
-p2m_pod_set_cache_target(struct p2m_domain *p2m, unsigned long pod_target)
+p2m_pod_set_cache_target(struct p2m_domain *p2m, unsigned long pod_target, int 
preemptible)
 {
     struct domain *d = p2m->domain;
     int ret = 0;
@@ -468,6 +468,12 @@ p2m_pod_set_cache_target(struct p2m_doma
         }
 
         p2m_pod_cache_add(p2m, page, order);
+
+        if ( hypercall_preempt_check() && preemptible )
+        {
+            ret = -EAGAIN;
+            goto out;
+        }
     }
 
     /* Decreasing the target */
@@ -512,6 +518,12 @@ p2m_pod_set_cache_target(struct p2m_doma
                 put_page(page+i);
 
             put_page(page+i);
+
+            if ( hypercall_preempt_check() && preemptible )
+            {
+                ret = -EAGAIN;
+                goto out;
+            }
         }
     }
 
@@ -589,7 +601,7 @@ p2m_pod_set_mem_target(struct domain *d,
 
     ASSERT( pod_target >= p2m->pod.count );
 
-    ret = p2m_pod_set_cache_target(p2m, pod_target);
+    ret = p2m_pod_set_cache_target(p2m, pod_target, 1/*preemptible*/);
 
 out:
     p2m_unlock(p2m);
@@ -753,7 +765,7 @@ out_entry_check:
     /* If we've reduced our "liabilities" beyond our "assets", free some */
     if ( p2m->pod.entry_count < p2m->pod.count )
     {
-        p2m_pod_set_cache_target(p2m, p2m->pod.entry_count);
+        p2m_pod_set_cache_target(p2m, p2m->pod.entry_count, 0/*can't 
preempt*/);
     }
 
 out_unlock:
diff -r d1631540bcc4 -r 97ab84aca65c xen/arch/x86/x86_64/compat/mm.c
--- a/xen/arch/x86/x86_64/compat/mm.c   Tue Jan 18 17:23:24 2011 +0000
+++ b/xen/arch/x86/x86_64/compat/mm.c   Mon Jan 17 14:24:13 2011 +0000
@@ -126,6 +126,9 @@ int compat_arch_memory_op(int op, XEN_GU
         rc = arch_memory_op(op, guest_handle_from_ptr(nat, void));
         if ( rc < 0 )
             break;
+
+        if ( rc == __HYPERVISOR_memory_op )
+            hypercall_xlat_continuation(NULL, 0x2, nat, arg);
 
         XLAT_pod_target(&cmp, nat);
 

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