[Xen-changelog] [xen-unstable] Hypercall continuation cancelation in compat mode for XENMEM_get/set_pod_target

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Jean Guyader <jean.guyader@xxxxxxxxxxxxx>
# Date 1321002862 -3600
# Node ID a095cf28f2b6eeb8f5873c18eb18d4d7e5544e2c
# Parent  6534da595d695a4f2af12a64e46fb06219a0e4bc
Hypercall continuation cancelation in compat mode for XENMEM_get/set_pod_target

If copy_to_guest failed in the compat code after a continuation as been
done in the native code we need to cancel it so we won't reexecute the
hypercall but return from the hypercall with the appropriate error.

Signed-off-by: Jean Guyader <jean.guyader@xxxxxxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Keir Fraser <keir@xxxxxxx>
Committed-by: Jan Beulich <jbeulich@xxxxxxxx>
---


diff -r 6534da595d69 -r a095cf28f2b6 xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c     Fri Nov 11 09:47:40 2011 +0100
+++ b/xen/arch/x86/domain.c     Fri Nov 11 10:14:22 2011 +0100
@@ -1724,6 +1724,24 @@
     __arg;                                                                  \
 })
 
+void hypercall_cancel_continuation(void)
+{
+    struct cpu_user_regs *regs = guest_cpu_user_regs();
+    struct mc_state *mcs = &current->mc_state;
+
+    if ( test_bit(_MCSF_in_multicall, &mcs->flags) )
+    {
+        __clear_bit(_MCSF_call_preempted, &mcs->flags);
+    }
+    else
+    {
+        if ( !is_hvm_vcpu(current) )
+            regs->eip += 2; /* skip re-execute 'syscall' / 'int $xx' */
+        else
+            current->arch.hvm_vcpu.hcall_preempted = 0;
+    }
+}
+
 unsigned long hypercall_create_continuation(
     unsigned int op, const char *format, ...)
 {
diff -r 6534da595d69 -r a095cf28f2b6 xen/arch/x86/x86_64/compat/mm.c
--- a/xen/arch/x86/x86_64/compat/mm.c   Fri Nov 11 09:47:40 2011 +0100
+++ b/xen/arch/x86/x86_64/compat/mm.c   Fri Nov 11 10:14:22 2011 +0100
@@ -133,7 +133,11 @@
         XLAT_pod_target(&cmp, nat);
 
         if ( copy_to_guest(arg, &cmp, 1) )
+        {
+            if ( rc == __HYPERVISOR_memory_op )
+                hypercall_cancel_continuation();
             rc = -EFAULT;
+        }
 
         break;
     }
diff -r 6534da595d69 -r a095cf28f2b6 xen/include/xen/sched.h
--- a/xen/include/xen/sched.h   Fri Nov 11 09:47:40 2011 +0100
+++ b/xen/include/xen/sched.h   Fri Nov 11 10:14:22 2011 +0100
@@ -554,6 +554,7 @@
  */
 unsigned long hypercall_create_continuation(
     unsigned int op, const char *format, ...);
+void hypercall_cancel_continuation(void);
 
 #define hypercall_preempt_check() (unlikely(    \
         softirq_pending(smp_processor_id()) |   \

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