Commit c2c647f9 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: x86: reduce pvclock_gtod_sync_lock critical sections 



There is no need to include changes to vcpu->requests into
the pvclock_gtod_sync_lock critical section.  The changes to
the shared data structures (in pvclock_update_vm_gtod_copy)
already occur under the lock.

Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 6ebae23c

arch/x86/kvm/x86.c

+4 −6
Original line number Diff line number Diff line
@@ -2561,10 +2561,12 @@ static void kvm_gen_update_masterclock(struct kvm *kvm) 


	kvm_hv_invalidate_tsc_page(kvm);



	spin_lock(&ka->pvclock_gtod_sync_lock);

	kvm_make_mclock_inprogress_request(kvm);



	/* no guest entries from this point */

	spin_lock(&ka->pvclock_gtod_sync_lock);

	pvclock_update_vm_gtod_copy(kvm);

	spin_unlock(&ka->pvclock_gtod_sync_lock);



	kvm_for_each_vcpu(i, vcpu, kvm)

		kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
@@ -2572,8 +2574,6 @@ static void kvm_gen_update_masterclock(struct kvm *kvm) 
	/* guest entries allowed */

	kvm_for_each_vcpu(i, vcpu, kvm)

		kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu);



	spin_unlock(&ka->pvclock_gtod_sync_lock);

#endif

}
@@ -7739,16 +7739,14 @@ static void kvm_hyperv_tsc_notifier(void) 
		struct kvm_arch *ka = &kvm->arch;



		spin_lock(&ka->pvclock_gtod_sync_lock);



		pvclock_update_vm_gtod_copy(kvm);

		spin_unlock(&ka->pvclock_gtod_sync_lock);



		kvm_for_each_vcpu(cpu, vcpu, kvm)

			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);



		kvm_for_each_vcpu(cpu, vcpu, kvm)

			kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu);



		spin_unlock(&ka->pvclock_gtod_sync_lock);

	}

	mutex_unlock(&kvm_lock);

}