Re: [RFC PATCH 07/10] qemu_interface: Added ebpf helper call.
On 7/28/21 10:17 AM, Andrew Melnychenko wrote:
New function to call "qemu-ebpf-rss-helper".
The helper passes few fds through unix socket.
Technically libvirt should not be aware how many and what those fds.
The helper should return fds that should be passed to the qemu as is and in same order.
Signed-off-by: Andrew Melnychenko <andrew(a)daynix.com>
---
src/qemu/qemu_interface.c | 54 +++++++++++++++++++++++++++++++++++++++
src/qemu/qemu_interface.h | 2 ++
2 files changed, 56 insertions(+)
diff --git a/src/qemu/qemu_interface.c b/src/qemu/qemu_interface.c
index ac0168c80d..76435af94e 100644
--- a/src/qemu/qemu_interface.c
+++ b/src/qemu/qemu_interface.c
@@ -777,3 +777,57 @@ qemuInterfaceOpenVhostNet(virDomainDef *def,
return -1;
}
+
+
+int qemuEbpfRssHelper(const char *helper, int *fds, int nfds)
+{
+ int ret = 0;
+ int err = 0;
+ int unix_fds[2] = { -1, -1 };
+ virCommand *cmd = NULL;
If you'd use:
g_autoptr(virCommand) cmd = NULL;
then you can ditch that explicit virCommandFree() call below.
+
+ if (!helper || !fds || !nfds) {
+ return -1;
+ }
+
+ ret = socketpair(AF_UNIX, SOCK_STREAM, 0, unix_fds);
+ if (ret) {
+ virReportSystemError(errno, "%s", _("failed to create
socket"));
+ return -1;
+ }
+
+ cmd = virCommandNew(helper);
+ if (cmd == NULL) {
This can't really happen. Also, all virCommand* APIs are prepared for
this situation so that we can write simpler code:
cmd = virCommandNew();
virCommandSomething(cmd);
virCommandSomethingElse(cmd);
if (virCommandRunAsync(cmd) < 0) /* This is the point where we learn
about any previous error */
+ VIR_FORCE_CLOSE(unix_fds[1]);
+ ret = -1;
+ goto cleanup;
+ }
+ virCommandAddArgFormat(cmd, "--fd=%d", unix_fds[1]);
+ virCommandPassFD(cmd, unix_fds[1], VIR_COMMAND_PASS_FD_CLOSE_PARENT);
+ virCommandDoAsyncIO(cmd);
+
+ if (virCommandRunAsync(cmd, NULL) < 0) {
+ VIR_FORCE_CLOSE(unix_fds[1]);
This doesn't look right. Even in case of failure virCommandRun* should
have closed all CLOSE_PARENT FDs. So this is effectively a double close.
+ ret = -1;
+ goto cleanup;
+ }
+
+ memset(fds, 0, sizeof(*fds) * nfds);
+
+ ret = virSocketRecvMultipleFDs(unix_fds[0], fds, nfds, 0);
+
+ if (virCommandWait(cmd, &err) < 0) {
+ int i = 0;
+ for (; i < ret; ++i) {
+ if (fds[i]) {
This check seems needless. After successful return from
virSocketRecvMultipleFDs() the @fds array must be filled with only valid
FDs.
+ VIR_FORCE_CLOSE(fds[i]);
+ }
+ }
+ ret = -1;
+ }
+
+cleanup:
+ VIR_FORCE_CLOSE(unix_fds[0]);
+ virCommandFree(cmd);
+ return ret;
+}
diff --git a/src/qemu/qemu_interface.h b/src/qemu/qemu_interface.h
index 438d548065..63d7590035 100644
--- a/src/qemu/qemu_interface.h
+++ b/src/qemu/qemu_interface.h
@@ -61,3 +61,5 @@ int qemuInterfacePrepareSlirp(virQEMUDriver *driver,
qemuSlirp **slirp);
int qemuInterfaceVDPAConnect(virDomainNetDef *net) G_GNUC_NO_INLINE;
+
+int qemuEbpfRssHelper(const char *helper, int *fds, int nfds);
Michal