bitkeeper revision 1.1159.187.15 (41a61537tODn12flBND8W6jum0b79Q)

Fix hypercall preemption. At the same time I reimplemented most of the
multi-hypercall in arch-independent C code.

1 files changed, 76 insertions, 0 deletions

diff --git a/xen/common/multicall.c b/xen/common/multicall.c
new file mode 100644
index 0000000000..04b5a7bdd2
--- /dev/null
+++ b/xen/common/multicall.c
@@ -0,0 +1,76 @@
+/******************************************************************************
+ * multicall.c
+ */
+
+#include <xen/config.h>
+#include <xen/types.h>
+#include <xen/lib.h>
+#include <xen/mm.h>
+#include <xen/perfc.h>
+#include <xen/sched.h>
+#include <xen/event.h>
+#include <xen/multicall.h>
+
+struct mc_state mc_state[NR_CPUS];
+
+long do_multicall(multicall_entry_t *call_list, unsigned int nr_calls)
+{
+    struct mc_state *mcs = &mc_state[smp_processor_id()];
+    unsigned int     i;
+
+    if ( unlikely(__test_and_set_bit(_MCSF_in_multicall, &mcs->flags)) )
+    {
+        DPRINTK("Multicall reentry is disallowed.\n");
+        return -EINVAL;
+    }
+
+    if ( unlikely(!array_access_ok(VERIFY_WRITE, call_list, 
+                                   nr_calls, sizeof(*call_list))) )
+    {
+        DPRINTK("Bad memory range %p for %u*%u bytes.\n",
+                call_list, nr_calls, sizeof(*call_list));
+        goto fault;
+    }
+
+    for ( i = 0; i < nr_calls; i++ )
+    {
+        if ( unlikely(__copy_from_user(&mcs->call, &call_list[i], 
+                                       sizeof(*call_list))) )
+        {
+            DPRINTK("Error copying from user range %p for %u bytes.\n",
+                    &call_list[i], sizeof(*call_list));
+            goto fault;
+        }
+
+        do_multicall_call(&mcs->call);
+
+        if ( unlikely(__put_user(mcs->call.args[5], &call_list[i].args[5])) )
+        {
+            DPRINTK("Error writing result back to multicall block.\n");
+            goto fault;
+        }
+
+        if ( hypercall_preempt_check() )
+        {
+            /* If the sub-call wasn't preempted, skip over it. */
+            if ( !test_bit(_MCSF_call_preempted, &mcs->flags) )
+                i++;
+
+            /* Only create a continuation if there is work left to be done. */
+            if ( i < nr_calls )
+            {
+                mcs->flags = 0;
+                hypercall_create_continuation(
+                    __HYPERVISOR_multicall, 2, &call_list[i], nr_calls-i);
+                return __HYPERVISOR_multicall;
+            }
+        }
+    }
+
+    mcs->flags = 0;
+    return 0;
+
+ fault:
+    mcs->flags = 0;
+    return -EFAULT;
+}