Re: [RFC PATCH v1 1/5] KVM Guest: Add VCPU running/pre-empted statefor guest

From: Raghavendra K T
Date: Mon Apr 30 2012 - 21:04:15 EST


On 04/27/2012 09:53 PM, Nikunj A. Dadhania wrote:
The patch adds guest code for msr between guest and hypervisor. The
msr will export the vcpu running/pre-empted information to the guest
from host. This will enable guest to intelligently send ipi to running
vcpus and set flag for pre-empted vcpus. This will prevent waiting for
vcpus that are not running.

Suggested-by: Peter Zijlstra<a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Nikunj A. Dadhania<nikunj@xxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/kvm_para.h | 10 ++++++++++
arch/x86/kernel/kvm.c | 33 +++++++++++++++++++++++++++++++++
2 files changed, 43 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 77266d3..f57b5cc 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -24,6 +24,7 @@
#define KVM_FEATURE_ASYNC_PF 4
#define KVM_FEATURE_STEAL_TIME 5
#define KVM_FEATURE_PV_UNHALT 6
+#define KVM_FEATURE_VCPU_STATE 7

I think you intended to use KVM_FEATURE_VCPU_STATE to address
guest/host compatibility issue so that host/guest does not break
when one of them run older kernel?

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