diff options
| -rw-r--r-- | src/arch/x86/include/bits/xen.h | 19 | ||||
| -rw-r--r-- | src/interface/xen/xenstore.c | 4 |
2 files changed, 23 insertions, 0 deletions
diff --git a/src/arch/x86/include/bits/xen.h b/src/arch/x86/include/bits/xen.h index 3433cea1..fc065ea3 100644 --- a/src/arch/x86/include/bits/xen.h +++ b/src/arch/x86/include/bits/xen.h @@ -161,4 +161,23 @@ xen_hypercall_5 ( struct xen_hypervisor *xen, unsigned int hypercall, return retval; } +/** + * Test and clear pending event + * + * @v xen Xen hypervisor + * @v port Event channel port + * @ret pending Event was pending + */ +static inline __attribute__ (( always_inline )) uint8_t +xenevent_pending ( struct xen_hypervisor *xen, evtchn_port_t port ) { + uint8_t pending; + + __asm__ __volatile__ ( "lock btr %2, %0\n\t" + "setc %1\n\t" + : "+m" ( xen->shared->evtchn_pending ), + "=a" ( pending ) + : "Ir" ( port ) ); + return pending; +} + #endif /* _BITS_XEN_H */ diff --git a/src/interface/xen/xenstore.c b/src/interface/xen/xenstore.c index 731af779..23424a92 100644 --- a/src/interface/xen/xenstore.c +++ b/src/interface/xen/xenstore.c @@ -242,6 +242,10 @@ static int xenstore_response ( struct xen_hypervisor *xen, uint32_t req_id, char *string; int rc; + /* Wait for response to become available */ + while ( ! xenevent_pending ( xen, xen->store.port ) ) + cpu_nap(); + /* Receive message header */ xenstore_recv ( xen, &msg, sizeof ( msg ) ); *len = msg.len; |