!854 [sync] PR-793: LoongArch: kvm: add pv ipi support

Merge Pull Request from: @openeuler-sync-bot 
 

Origin pull request: 
https://gitee.com/openeuler/kernel/pulls/793 
 
PV IPI with less VM exit can improve performance than
iocsr emulation when sending ipi interrupt to multi cpus.
    
This patch supports:
1. sending PV IPI by hypercall
2. recording and updating steal time for VM
 
 
Link:https://gitee.com/openeuler/kernel/pulls/854

 

Reviewed-by: Jialin Zhang <zhangjialin11@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>