From: Zengruan Ye yezengruan@huawei.com
virt inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8WMFU CVE: NA
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A new hypercall interface function is provided for the guest to kick WFI state vCPU.
Signed-off-by: Zengruan Ye yezengruan@huawei.com Reviewed-by: Zhanghailiang zhang.zhanghailiang@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com
Signed-off-by: lishusen lishusen2@huawei.com --- Documentation/virt/kvm/arm/pvsched.rst | 16 ++++++++++++++++ include/linux/arm-smccc.h | 6 ++++++ 2 files changed, 22 insertions(+)
diff --git a/Documentation/virt/kvm/arm/pvsched.rst b/Documentation/virt/kvm/arm/pvsched.rst index 8f7112a8a9cd..6ba221e25089 100644 --- a/Documentation/virt/kvm/arm/pvsched.rst +++ b/Documentation/virt/kvm/arm/pvsched.rst @@ -11,6 +11,7 @@ Some SMCCC compatible hypercalls are defined: * PV_SCHED_FEATURES: 0xC5000090 * PV_SCHED_IPA_INIT: 0xC5000091 * PV_SCHED_IPA_RELEASE: 0xC5000092 +* PV_SCHED_KICK_CPU: 0xC5000093
The existence of the PV_SCHED hypercall should be probed using the SMCCC 1.1 ARCH_FEATURES mechanism before calling it. @@ -38,6 +39,13 @@ PV_SCHED_IPA_RELEASE this vCPU's PV data structure is released. ============= ======== ==========
+PV_SCHED_KICK_CPU + ============= ======== ========== + Function ID: (uint32) 0xC5000093 + Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the vCPU is + kicked by the hypervisor. + ============= ======== ========== + PV sched state --------------
@@ -56,3 +64,11 @@ The structure pointed to by the PV_SCHED_IPA hypercall is as follows: The preempted field will be updated to 0 by the hypervisor prior to scheduling a vCPU. When the vCPU is scheduled out, the preempted field will be updated to 1 by the hypervisor. + +A vCPU of a paravirtualized guest that is busywaiting in guest kernel mode for +an event to occur (ex: a spinlock to become available) can execute WFI +instruction once it has busy-waited for more than a threshold time-interval. +Execution of WFI instruction would cause the hypervisor to put the vCPU to sleep +until occurrence of an appropriate event. Another vCPU of the same guest can +wakeup the sleeping vCPU by issuing PV_SCHED_KICK_CPU hypercall, specifying CPU +id (reg1) of the vCPU to be woken up. diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h index daab363d31ae..02b857f44ae8 100644 --- a/include/linux/arm-smccc.h +++ b/include/linux/arm-smccc.h @@ -596,5 +596,11 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1, ARM_SMCCC_OWNER_STANDARD_HYP, \ 0x92)
+#define ARM_SMCCC_HV_PV_SCHED_KICK_CPU \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ + ARM_SMCCC_SMC_64, \ + ARM_SMCCC_OWNER_STANDARD_HYP, \ + 0x93) + #endif /*__ASSEMBLY__*/ #endif /*__LINUX_ARM_SMCCC_H*/