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authorthomas knych <thomaswk@google.com>2014-01-09 13:14:23 -0800
committerPaolo Bonzini <pbonzini@redhat.com>2014-01-15 12:58:41 +0100
commit94ccff133820552a859c0fb95e33a539e0b90a75 (patch)
tree0fbf9538748867da53e5b72e6235f94784c51c0c /kvm-all.c
parent2ba82852894c762299b7d05e9a2be184116b80f0 (diff)
downloadfocaccia-qemu-94ccff133820552a859c0fb95e33a539e0b90a75.tar.gz
focaccia-qemu-94ccff133820552a859c0fb95e33a539e0b90a75.zip
KVM: Retry KVM_CREATE_VM on EINTR
Upstreaming this change from Android (https://android-review.googlesource.com/54211).

On heavily loaded machines with many VM instances we see KVM_CREATE_VM
failing with EINTR on this path:

kvm_dev_ioctl_create_vm -> kvm_create_vm -> kvm_init_mmu_notifier -> mmu_notifier_register ->  do_mmu_notifier_register -> mm_take_all_locks

which checks if any signals have been raised while it was attaining locks
and returns EINTR.  Retrying the system call greatly improves reliability.

Cc: qemu-stable@nongnu.org
Signed-off-by: thomas knych <thomaswk@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'kvm-all.c')
-rw-r--r--kvm-all.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/kvm-all.c b/kvm-all.c
index 393775459d..6df2ee1635 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -1442,16 +1442,22 @@ int kvm_init(void)
         nc++;
     }
 
-    s->vmfd = kvm_ioctl(s, KVM_CREATE_VM, 0);
-    if (s->vmfd < 0) {
+    do {
+        ret = kvm_ioctl(s, KVM_CREATE_VM, 0);
+    } while (ret == -EINTR);
+
+    if (ret < 0) {
+        fprintf(stderr, "ioctl(KVM_CREATE_VM) failed: %d %s\n", -s->vmfd,
+                strerror(-ret));
+
 #ifdef TARGET_S390X
         fprintf(stderr, "Please add the 'switch_amode' kernel parameter to "
                         "your host kernel command line\n");
 #endif
-        ret = s->vmfd;
         goto err;
     }
 
+    s->vmfd = ret;
     missing_cap = kvm_check_extension_list(s, kvm_required_capabilites);
     if (!missing_cap) {
         missing_cap =