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| author | Chris Co <chrco@microsoft.com> | 2020-11-10 20:01:18 +0100 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2020-11-11 11:58:09 +0100 |
| commit | 92e4dc8b05663d6539b1b8375f3b1cf7b204cfe9 (patch) | |
| tree | 8778ca9385173a90f1994713a044473fccace400 /drivers/hv | |
| parent | x86/hyperv: Clarify comment on x2apic mode (diff) | |
| download | linux-92e4dc8b05663d6539b1b8375f3b1cf7b204cfe9.tar.xz linux-92e4dc8b05663d6539b1b8375f3b1cf7b204cfe9.zip | |
Drivers: hv: vmbus: Allow cleanup of VMBUS_CONNECT_CPU if disconnected
When invoking kexec() on a Linux guest running on a Hyper-V host, the
kernel panics.
RIP: 0010:cpuhp_issue_call+0x137/0x140
Call Trace:
__cpuhp_remove_state_cpuslocked+0x99/0x100
__cpuhp_remove_state+0x1c/0x30
hv_kexec_handler+0x23/0x30 [hv_vmbus]
hv_machine_shutdown+0x1e/0x30
machine_shutdown+0x10/0x20
kernel_kexec+0x6d/0x96
__do_sys_reboot+0x1ef/0x230
__x64_sys_reboot+0x1d/0x20
do_syscall_64+0x6b/0x3d8
entry_SYSCALL_64_after_hwframe+0x44/0xa9
This was due to hv_synic_cleanup() callback returning -EBUSY to
cpuhp_issue_call() when tearing down the VMBUS_CONNECT_CPU, even
if the vmbus_connection.conn_state = DISCONNECTED. hv_synic_cleanup()
should succeed in the case where vmbus_connection.conn_state
is DISCONNECTED.
Fix is to add an extra condition to test for
vmbus_connection.conn_state == CONNECTED on the VMBUS_CONNECT_CPU and
only return early if true. This way the kexec() path can still shut
everything down while preserving the initial behavior of preventing
CPU offlining on the VMBUS_CONNECT_CPU while the VM is running.
Fixes: 8a857c55420f29 ("Drivers: hv: vmbus: Always handle the VMBus messages on CPU0")
Signed-off-by: Chris Co <chrco@microsoft.com>
Reviewed-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201110190118.15596-1-chrco@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Diffstat (limited to 'drivers/hv')
| -rw-r--r-- | drivers/hv/hv.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c index da69338f92f5..75a8638ff68b 100644 --- a/drivers/hv/hv.c +++ b/drivers/hv/hv.c @@ -244,9 +244,13 @@ int hv_synic_cleanup(unsigned int cpu) /* * Hyper-V does not provide a way to change the connect CPU once - * it is set; we must prevent the connect CPU from going offline. + * it is set; we must prevent the connect CPU from going offline + * while the VM is running normally. But in the panic or kexec() + * path where the vmbus is already disconnected, the CPU must be + * allowed to shut down. */ - if (cpu == VMBUS_CONNECT_CPU) + if (cpu == VMBUS_CONNECT_CPU && + vmbus_connection.conn_state == CONNECTED) return -EBUSY; /* |