From: Jagannathan Raman <jag.ra...@oracle.com> In some cases, for example MMIO read, QEMU has to wait for the remote to complete a command before proceeding. An eventfd based mechanism is added to synchronize QEMU & remote process.
Signed-off-by: John G Johnson <john.g.john...@oracle.com> Signed-off-by: Jagannathan Raman <jag.ra...@oracle.com> Signed-off-by: Elena Ufimtseva <elena.ufimts...@oracle.com> --- include/io/proxy-link.h | 9 +++++++++ io/proxy-link.c | 26 ++++++++++++++++++++++++++ 2 files changed, 35 insertions(+) diff --git a/include/io/proxy-link.h b/include/io/proxy-link.h index ff602e4..a12c565 100644 --- a/include/io/proxy-link.h +++ b/include/io/proxy-link.h @@ -28,7 +28,9 @@ #include <stddef.h> #include <stdint.h> #include <glib.h> +#include <unistd.h> #include <pthread.h> +#include <sys/eventfd.h> #include "qemu/osdep.h" #include "qom/object.h" @@ -124,11 +126,18 @@ struct ProxyLinkState { proxy_link_callback callback; }; +#define GET_REMOTE_WAIT eventfd(0, 0) +#define PUT_REMOTE_WAIT(wait) close(wait) +#define PROXY_LINK_WAIT_DONE 1 + ProxyLinkState *proxy_link_create(void); void proxy_link_finalize(ProxyLinkState *s); void proxy_proc_send(ProxyLinkState *s, ProcMsg *msg); int proxy_proc_recv(ProxyLinkState *s, ProcMsg *msg); +uint64_t wait_for_remote(int efd); +void notify_proxy(int fd, uint64_t val); + void proxy_link_set_sock(ProxyLinkState *s, int fd); void proxy_link_set_callback(ProxyLinkState *s, proxy_link_callback callback); void start_handler(ProxyLinkState *s); diff --git a/io/proxy-link.c b/io/proxy-link.c index 9ea0ed7..9f6ae77 100644 --- a/io/proxy-link.c +++ b/io/proxy-link.c @@ -31,6 +31,7 @@ #include <sys/socket.h> #include <sys/un.h> #include <unistd.h> +#include <limits.h> #include "qemu/module.h" #include "io/proxy-link.h" @@ -210,6 +211,31 @@ int proxy_proc_recv(ProxyLinkState *s, ProcMsg *msg) return rc; } +uint64_t wait_for_remote(int efd) +{ + uint64_t val; + + if (read(efd, &val, sizeof(val)) == -1) { + qemu_log_mask(LOG_REMOTE_DEBUG, "Error wait_for_remote: %s\n", + strerror(errno)); + return ULLONG_MAX; + } + + val = (val == ULLONG_MAX) ? val : (val - 1); + + return val; +} + +void notify_proxy(int efd, uint64_t val) +{ + val = (val == ULLONG_MAX) ? val : (val + 1); + + if (write(efd, &val, sizeof(val)) == -1) { + qemu_log_mask(LOG_REMOTE_DEBUG, "Error notify_proxy: %s\n", + strerror(errno)); + } +} + static gboolean proxy_link_handler_prepare(GSource *gsrc, gint *timeout) { g_assert(timeout); -- 1.8.3.1