diff options
| author | Mark Johnston <markj@FreeBSD.org> | 2023-03-22 13:02:54 +0000 |
|---|---|---|
| committer | Mark Johnston <markj@FreeBSD.org> | 2023-03-27 12:50:12 +0000 |
| commit | 3b6598f8742cdab079cbce5485e9ddffbacdc1b4 (patch) | |
| tree | 3ceae06c62bb1751fb168ca884827226181dce6e | |
| parent | e6b1b944b5aa1950834f27a8ab9188bcd736844d (diff) | |
| download | src-3b6598f8742cdab079cbce5485e9ddffbacdc1b4.tar.gz src-3b6598f8742cdab079cbce5485e9ddffbacdc1b4.zip | |
bhyve: Sleep briefly in the VMEXIT_DEBUG handler
As of commit 0bda8d3e9f7a ("vmm: permit some IPIs to be handled by
userspace") and commit 9cc9abf409cc ("bhyve: create all vcpus on
startup"), we have a misbehaviour where AP vCPU threads spin until they
receive a SIPI. In particular, since they are "suspended", they simply
call the VMEXIT_DEBUG handler in a loop, but the handler is a no-op by
default.
This is tricky to fix since the gdb stub isn't aware of whether a given
vCPU is supposed to be running. For 13.2's sake, introduce a simple
workaround wherein the VMEXIT_DEBUG handler sleeps for a short period.
This ensures that host CPU usage remains sane when VMs are starting
without penalizing users of VMEXIT_DEBUG too much.
Reviewed by: corvink, jhb
MFC after: 3 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D39174
(cherry picked from commit ef0ac973dbc8c54214ac8c61891abd832cd5b700)
| -rw-r--r-- | usr.sbin/bhyve/bhyverun.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/usr.sbin/bhyve/bhyverun.c b/usr.sbin/bhyve/bhyverun.c index 1becf998b976..5c8265571be9 100644 --- a/usr.sbin/bhyve/bhyverun.c +++ b/usr.sbin/bhyve/bhyverun.c @@ -911,6 +911,11 @@ vmexit_debug(struct vmctx *ctx __unused, struct vm_exit *vme __unused, #ifdef BHYVE_SNAPSHOT checkpoint_cpu_resume(*pvcpu); #endif + /* + * XXX-MJ sleep for a short period to avoid chewing up the CPU in the + * window between activation of the vCPU thread and the STARTUP IPI. + */ + usleep(1000); return (VMEXIT_CONTINUE); } |