| Message ID | 1495279472-4576-1-git-send-email-jschoenh@amazon.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
2017-05-20 19:24 GMT+08:00 Jan H. Schönherr <jschoenh@amazon.de>: > Intel SDM says, that at most one LAPIC should be configured with ExtINT > delivery. KVM configures all LAPICs this way. This causes pic_unlock() > to kick the first available vCPU from the internal KVM data structures. > If this vCPU is not the BSP, but some not-yet-booted AP, the BSP may > never realize that there is an interrupt. > > Fix that by enabling ExtINT delivery only for the BSP. > > This allows booting a Linux guest without a TSC in the above situation. > Otherwise the BSP gets stuck in calibrate_delay_converge(). > > Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de> Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com> > --- > arch/x86/kvm/lapic.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index c329d28..df1b865 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -1934,7 +1934,8 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event) > for (i = 0; i < KVM_APIC_LVT_NUM; i++) > kvm_lapic_set_reg(apic, APIC_LVTT + 0x10 * i, APIC_LVT_MASKED); > apic_update_lvtt(apic); > - if (kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_LINT0_REENABLED)) > + if (kvm_vcpu_is_reset_bsp(vcpu) && > + kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_LINT0_REENABLED)) > kvm_lapic_set_reg(apic, APIC_LVT0, > SET_APIC_DELIVERY_MODE(0, APIC_MODE_EXTINT)); > apic_manage_nmi_watchdog(apic, kvm_lapic_get_reg(apic, APIC_LVT0)); > -- > 2.3.1.dirty >
On 05/22/2017 09:19 AM, Xiao Guangrong wrote: > > > On 05/20/2017 07:24 PM, Jan H. Schönherr wrote: >> Intel SDM says, that at most one LAPIC should be configured with ExtINT >> delivery. KVM configures all LAPICs this way. This causes pic_unlock() >> to kick the first available vCPU from the internal KVM data structures. >> If this vCPU is not the BSP, but some not-yet-booted AP, the BSP may >> never realize that there is an interrupt. >> >> Fix that by enabling ExtINT delivery only for the BSP. >> >> This allows booting a Linux guest without a TSC in the above situation. >> Otherwise the BSP gets stuck in calibrate_delay_converge(). > > Patch looks good to me. > > BTW, what benefit do you want to get from notsc? > None. I just want my guest to boot in case it does that. :) Regards Jan Amazon Development Center Germany GmbH Berlin - Dresden - Aachen main office: Krausenstr. 38, 10117 Berlin Geschaeftsfuehrer: Dr. Ralf Herbrich, Christian Schlaeger Ust-ID: DE289237879 Eingetragen am Amtsgericht Charlottenburg HRB 149173 B
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index c329d28..df1b865 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1934,7 +1934,8 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event) for (i = 0; i < KVM_APIC_LVT_NUM; i++) kvm_lapic_set_reg(apic, APIC_LVTT + 0x10 * i, APIC_LVT_MASKED); apic_update_lvtt(apic); - if (kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_LINT0_REENABLED)) + if (kvm_vcpu_is_reset_bsp(vcpu) && + kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_LINT0_REENABLED)) kvm_lapic_set_reg(apic, APIC_LVT0, SET_APIC_DELIVERY_MODE(0, APIC_MODE_EXTINT)); apic_manage_nmi_watchdog(apic, kvm_lapic_get_reg(apic, APIC_LVT0));
Intel SDM says, that at most one LAPIC should be configured with ExtINT delivery. KVM configures all LAPICs this way. This causes pic_unlock() to kick the first available vCPU from the internal KVM data structures. If this vCPU is not the BSP, but some not-yet-booted AP, the BSP may never realize that there is an interrupt. Fix that by enabling ExtINT delivery only for the BSP. This allows booting a Linux guest without a TSC in the above situation. Otherwise the BSP gets stuck in calibrate_delay_converge(). Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de> --- arch/x86/kvm/lapic.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)