From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] KVM: x86: fix lapic.timer_mode on restore Date: Fri, 05 Jun 2015 21:08:32 +0200 Message-ID: <5571F3B0.9060004@redhat.com> References: <1433530661-31670-1-git-send-email-rkrcmar@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: kvm@vger.kernel.org, stable@vger.kernel.org, Marcelo Tosatti , Linus Torvalds To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , linux-kernel@vger.kernel.org Return-path: In-Reply-To: <1433530661-31670-1-git-send-email-rkrcmar@redhat.com> Sender: stable-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 05/06/2015 20:57, Radim Kr=C4=8Dm=C3=A1=C5=99 wrote: > lapic.timer_mode was not properly initialized after migration, which > broke few useful things, like login, by making every sleep eternal. >=20 > Fix this by calling apic_update_lvtt in kvm_apic_post_state_restore. >=20 > There are other slowpaths that update lvtt, so this patch makes sure > something similar doesn't happen again by calling apic_update_lvtt > after every modification. >=20 > Cc: stable@vger.kernel.org > Fixes: f30ebc312ca9 ("KVM: x86: optimize some accesses to LVTT and SP= IV") > Signed-off-by: Radim Kr=C4=8Dm=C3=A1=C5=99 > --- > arch/x86/kvm/lapic.c | 26 ++++++++++++++++---------- > 1 file changed, 16 insertions(+), 10 deletions(-) >=20 > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index beeef05bb4d9..36e9de1b4127 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -1103,6 +1103,17 @@ static void update_divide_count(struct kvm_lap= ic *apic) > apic->divide_count); > } > =20 > +static void apic_update_lvtt(struct kvm_lapic *apic) > +{ > + u32 timer_mode =3D kvm_apic_get_reg(apic, APIC_LVTT) & > + apic->lapic_timer.timer_mode_mask; > + > + if (apic->lapic_timer.timer_mode !=3D timer_mode) { > + apic->lapic_timer.timer_mode =3D timer_mode; > + hrtimer_cancel(&apic->lapic_timer.timer); > + } > +} > + > static void apic_timer_expired(struct kvm_lapic *apic) > { > struct kvm_vcpu *vcpu =3D apic->vcpu; > @@ -1311,6 +1322,7 @@ static int apic_reg_write(struct kvm_lapic *api= c, u32 reg, u32 val) > apic_set_reg(apic, APIC_LVTT + 0x10 * i, > lvt_val | APIC_LVT_MASKED); > } > + apic_update_lvtt(apic); > atomic_set(&apic->lapic_timer.pending, 0); > =20 > } > @@ -1343,20 +1355,13 @@ static int apic_reg_write(struct kvm_lapic *a= pic, u32 reg, u32 val) > =20 > break; > =20 > - case APIC_LVTT: { > - u32 timer_mode =3D val & apic->lapic_timer.timer_mode_mask; > - > - if (apic->lapic_timer.timer_mode !=3D timer_mode) { > - apic->lapic_timer.timer_mode =3D timer_mode; > - hrtimer_cancel(&apic->lapic_timer.timer); > - } > - > + case APIC_LVTT: > if (!kvm_apic_sw_enabled(apic)) > val |=3D APIC_LVT_MASKED; > val &=3D (apic_lvt_mask[0] | apic->lapic_timer.timer_mode_mask); > apic_set_reg(apic, APIC_LVTT, val); > + apic_update_lvtt(apic); > break; > - } > =20 > case APIC_TMICT: > if (apic_lvtt_tscdeadline(apic)) > @@ -1588,7 +1593,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, boo= l init_event) > =20 > for (i =3D 0; i < APIC_LVT_NUM; i++) > apic_set_reg(apic, APIC_LVTT + 0x10 * i, APIC_LVT_MASKED); > - apic->lapic_timer.timer_mode =3D 0; > + apic_update_lvtt(apic); > if (!(vcpu->kvm->arch.disabled_quirks & KVM_QUIRK_LINT0_REENABLED)) > apic_set_reg(apic, APIC_LVT0, > SET_APIC_DELIVERY_MODE(0, APIC_MODE_EXTINT)); > @@ -1816,6 +1821,7 @@ void kvm_apic_post_state_restore(struct kvm_vcp= u *vcpu, > =20 > apic_update_ppr(apic); > hrtimer_cancel(&apic->lapic_timer.timer); > + apic_update_lvtt(apic); > update_divide_count(apic); > start_apic_timer(apic); > apic->irr_pending =3D true; >=20 Marcelo, if you have some free cycles feel free to apply this to kvm/master and send it to Linus sometime next week. I cannot do it on Monday and I'll be on vacation afterwards. (I'll be back as soon as June 16th so I didn't plan on a formal handoff, but I think it's better to have this in 4.1. The merge window conflicts with Linus's own vacation and might be delayed). And thanks Radim for the fix, it looks good. Paolo