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

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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: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
This commit is contained in:
Marcelo Tosatti 2013-08-27 23:55:29 -03:00 committed by Gleb Natapov
parent 0912c9771e
commit 2e762ff79f
1 changed files with 24 additions and 23 deletions
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47
arch/x86/kvm/x86.c
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@ -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];