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Commit 2e762ff7 authored by Marcelo Tosatti's avatar Marcelo Tosatti Committed by Gleb Natapov
Browse files

KVM: x86: update masterclock when kvmclock_offset is calculated (v2) 



The offset to add to the hosts monotonic time, kvmclock_offset, is
calculated against the monotonic time at KVM_SET_CLOCK ioctl time.

Request a master clock update at this time, to reduce a potentially
unbounded difference between the values of the masterclock and
the clock value used to calculate kvmclock_offset.

Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
parent 0912c977

arch/x86/kvm/x86.c

+24 −23
Original line number Diff line number Diff line
@@ -1447,6 +1447,29 @@ static void pvclock_update_vm_gtod_copy(struct kvm *kvm) 
#endif

}



static void kvm_gen_update_masterclock(struct kvm *kvm)

{

#ifdef CONFIG_X86_64

	int i;

	struct kvm_vcpu *vcpu;

	struct kvm_arch *ka = &kvm->arch;



	spin_lock(&ka->pvclock_gtod_sync_lock);

	kvm_make_mclock_inprogress_request(kvm);

	/* no guest entries from this point */

	pvclock_update_vm_gtod_copy(kvm);



	kvm_for_each_vcpu(i, vcpu, kvm)

		set_bit(KVM_REQ_CLOCK_UPDATE, &vcpu->requests);



	/* guest entries allowed */

	kvm_for_each_vcpu(i, vcpu, kvm)

		clear_bit(KVM_REQ_MCLOCK_INPROGRESS, &vcpu->requests);



	spin_unlock(&ka->pvclock_gtod_sync_lock);

#endif

}



static int kvm_guest_time_update(struct kvm_vcpu *v)

{

	unsigned long flags, this_tsc_khz;
@@ -3796,6 +3819,7 @@ long kvm_arch_vm_ioctl(struct file *filp, 
		delta = user_ns.clock - now_ns;

		local_irq_enable();

		kvm->arch.kvmclock_offset = delta;

		kvm_gen_update_masterclock(kvm);

		break;

	}

	case KVM_GET_CLOCK: {
@@ -5804,29 +5828,6 @@ static void process_nmi(struct kvm_vcpu *vcpu) 
	kvm_make_request(KVM_REQ_EVENT, vcpu);

}



static void kvm_gen_update_masterclock(struct kvm *kvm)

{

#ifdef CONFIG_X86_64

	int i;

	struct kvm_vcpu *vcpu;

	struct kvm_arch *ka = &kvm->arch;



	spin_lock(&ka->pvclock_gtod_sync_lock);

	kvm_make_mclock_inprogress_request(kvm);

	/* no guest entries from this point */

	pvclock_update_vm_gtod_copy(kvm);



	kvm_for_each_vcpu(i, vcpu, kvm)

		set_bit(KVM_REQ_CLOCK_UPDATE, &vcpu->requests);



	/* guest entries allowed */

	kvm_for_each_vcpu(i, vcpu, kvm)

		clear_bit(KVM_REQ_MCLOCK_INPROGRESS, &vcpu->requests);



	spin_unlock(&ka->pvclock_gtod_sync_lock);

#endif

}



static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)

{

	u64 eoi_exit_bitmap[4];