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List:       linux-s390
Subject:    [PATCH 04/10] KVM: s390: add metric vcpus_in_sie to struct kvm_arch
From:       Michael Mueller <mimu () linux ! ibm ! com>
Date:       2018-10-25 12:37:45
Message-ID: 20181025123751.48809-5-mimu () linux ! ibm ! com
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This metric will allow to identify how many vcpus are currently
running for a given kvm in SIE context. Its value is between 0 and
the number of vcpus defined for the kvm guest, but never lager than
the number of cpus available to the KVM host in total.

This metric is required to decide if the GISA IAM has to be restored
from the kvm arch field of the guest. That will be the case when no
vcpu is in SIE context. (vcpus_in_sie == 0)

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host.h | 1 +
 arch/s390/kvm/kvm-s390.c         | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 01be3b666b11..a9ec2da399b5 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -839,6 +839,7 @@ struct kvm_arch{
 	DECLARE_BITMAP(cpu_feat, KVM_S390_VM_CPU_FEAT_NR_BITS);
 	struct kvm_s390_gisa *gisa;
 	int gib_in_use;
+	atomic_t vcpus_in_sie;
 };
 
 #define KVM_HVA_ERR_BAD		(-1UL)
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index c75b01856092..213d16e5b16a 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -3358,6 +3358,8 @@ static int vcpu_pre_run(struct kvm_vcpu *vcpu)
 		kvm_s390_patch_guest_per_regs(vcpu);
 	}
 
+	atomic_inc(&vcpu->kvm->arch.vcpus_in_sie);
+
 	vcpu->arch.sie_block->icptcode = 0;
 	cpuflags = atomic_read(&vcpu->arch.sie_block->cpuflags);
 	VCPU_EVENT(vcpu, 6, "entering sie flags %x", cpuflags);
@@ -3417,6 +3419,8 @@ static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason)
 	vcpu->run->s.regs.gprs[14] = vcpu->arch.sie_block->gg14;
 	vcpu->run->s.regs.gprs[15] = vcpu->arch.sie_block->gg15;
 
+	atomic_dec(&vcpu->kvm->arch.vcpus_in_sie);
+
 	if (exit_reason == -EINTR) {
 		VCPU_EVENT(vcpu, 3, "%s", "machine check");
 		sie_page = container_of(vcpu->arch.sie_block,
-- 
2.17.0

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