[PATCH 2/2] kvm tools: Don't use ioeventfds if no KVM_CAP_IOEVENTFD

[Sasha Levin]

Check KVM_CAP_IOEVENTFD before using ioeventfds.

Signed-off-by: Sasha Levin <levinsasha...@gmail.com>
---
 tools/kvm/builtin-run.c           |    2 +-
 tools/kvm/include/kvm/ioeventfd.h |    2 +-
 tools/kvm/ioeventfd.c             |   16 +++++++++++++++-
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/tools/kvm/builtin-run.c b/tools/kvm/builtin-run.c
index 76f1a8c..47e4ea8 100644
--- a/tools/kvm/builtin-run.c
+++ b/tools/kvm/builtin-run.c
@@ -932,7 +932,7 @@ int kvm_cmd_run(int argc, const char **argv, const char 
*prefix)
 
        kvm->single_step = single_step;
 
-       ioeventfd__init();
+       ioeventfd__init(kvm);
 
        max_cpus = kvm__max_cpus(kvm);
        recommended_cpus = kvm__recommended_cpus(kvm);
diff --git a/tools/kvm/include/kvm/ioeventfd.h 
b/tools/kvm/include/kvm/ioeventfd.h
index df01750..3a95788 100644
--- a/tools/kvm/include/kvm/ioeventfd.h
+++ b/tools/kvm/include/kvm/ioeventfd.h
@@ -19,7 +19,7 @@ struct ioevent {
        struct list_head        list;
 };
 
-void ioeventfd__init(void);
+void ioeventfd__init(struct kvm *kvm);
 void ioeventfd__start(void);
 void ioeventfd__add_event(struct ioevent *ioevent);
 void ioeventfd__del_event(u64 addr, u64 datamatch);
diff --git a/tools/kvm/ioeventfd.c b/tools/kvm/ioeventfd.c
index 3a240e4..75dd3f2 100644
--- a/tools/kvm/ioeventfd.c
+++ b/tools/kvm/ioeventfd.c
@@ -18,9 +18,14 @@
 static struct  epoll_event events[IOEVENTFD_MAX_EVENTS];
 static int     epoll_fd;
 static LIST_HEAD(used_ioevents);
+static bool    ioeventfd_avail;
 
-void ioeventfd__init(void)
+void ioeventfd__init(struct kvm *kvm)
 {
+       ioeventfd_avail = kvm__has_cap(kvm, KVM_CAP_IOEVENTFD);
+       if (!ioeventfd_avail)
+               return;
+
        epoll_fd = epoll_create(IOEVENTFD_MAX_EVENTS);
        if (epoll_fd < 0)
                die("Failed creating epoll fd");
@@ -33,6 +38,9 @@ void ioeventfd__add_event(struct ioevent *ioevent)
        struct ioevent *new_ioevent;
        int event;
 
+       if (!ioeventfd_avail)
+               return;
+
        new_ioevent = malloc(sizeof(*new_ioevent));
        if (new_ioevent == NULL)
                die("Failed allocating memory for new ioevent");
@@ -68,6 +76,9 @@ void ioeventfd__del_event(u64 addr, u64 datamatch)
        struct ioevent *ioevent;
        u8 found = 0;
 
+       if (!ioeventfd_avail)
+               return;
+
        list_for_each_entry(ioevent, &used_ioevents, list) {
                if (ioevent->io_addr == addr) {
                        found = 1;
@@ -123,6 +134,9 @@ void ioeventfd__start(void)
 {
        pthread_t thread;
 
+       if (!ioeventfd_avail)
+               return;
+
        if (pthread_create(&thread, NULL, ioeventfd__thread, NULL) != 0)
                die("Failed starting ioeventfd thread");
 }
-- 
1.7.8

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