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| author | Andrea Parri (Microsoft) <parri.andrea@gmail.com> | 2020-04-06 02:15:04 +0200 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2020-04-23 13:17:11 +0000 |
| commit | 8a857c55420f29da4fc131adc22b12d474c48f4c (patch) | |
| tree | 58e1630f0c8bf8e5d9faef06ae627339ce0c3199 /drivers/hv/hyperv_vmbus.h | |
| parent | 52c7803f9bd4b1f0ac6e2e3e6051415198cc06bd (diff) | |
| download | lwn-8a857c55420f29da4fc131adc22b12d474c48f4c.tar.gz lwn-8a857c55420f29da4fc131adc22b12d474c48f4c.zip | |
Drivers: hv: vmbus: Always handle the VMBus messages on CPU0
A Linux guest have to pick a "connect CPU" to communicate with the
Hyper-V host. This CPU can not be taken offline because Hyper-V does
not provide a way to change that CPU assignment.
Current code sets the connect CPU to whatever CPU ends up running the
function vmbus_negotiate_version(), and this will generate problems if
that CPU is taken offine.
Establish CPU0 as the connect CPU, and add logics to prevents the
connect CPU from being taken offline. We could pick some other CPU,
and we could pick that "other CPU" dynamically if there was a reason to
do so at some point in the future. But for now, #defining the connect
CPU to 0 is the most straightforward and least complex solution.
While on this, add inline comments explaining "why" offer and rescind
messages should not be handled by a same serialized work queue.
Suggested-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20200406001514.19876-2-parri.andrea@gmail.com
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Diffstat (limited to 'drivers/hv/hyperv_vmbus.h')
| -rw-r--r-- | drivers/hv/hyperv_vmbus.h | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h index ab560ac9c040..000740d053a2 100644 --- a/drivers/hv/hyperv_vmbus.h +++ b/drivers/hv/hyperv_vmbus.h @@ -212,12 +212,13 @@ enum vmbus_connect_state { #define MAX_SIZE_CHANNEL_MESSAGE HV_MESSAGE_PAYLOAD_BYTE_COUNT -struct vmbus_connection { - /* - * CPU on which the initial host contact was made. - */ - int connect_cpu; +/* + * The CPU that Hyper-V will interrupt for VMBUS messages, such as + * CHANNELMSG_OFFERCHANNEL and CHANNELMSG_RESCIND_CHANNELOFFER. + */ +#define VMBUS_CONNECT_CPU 0 +struct vmbus_connection { u32 msg_conn_id; atomic_t offer_in_progress; |