Re: [PATCH] KVM: x86: fix xen guest panic due to lack of KVM_REQ_EVENT
On Mon, Aug 25, 2014 at 11:16:16AM +0200, Paolo Bonzini wrote: >Il 25/08/2014 11:08, Wanpeng Li ha scritto: >> Hi Paolo, >> On Mon, Aug 25, 2014 at 11:01:07AM +0200, Paolo Bonzini wrote: >>> Il 25/08/2014 09:58, Wanpeng Li ha scritto: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c10408e..b7c0073 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4928,6 +4928,8 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask) if (!mask) kvm_make_request(KVM_REQ_EVENT, vcpu); } + if (!(int_shadow || mask)) + kvm_make_request(KVM_REQ_EVENT, vcpu); } static void inject_emulated_exception(struct kvm_vcpu *vcpu) >>> >>> No, this patch undoes the optimization in the buggy patch. >>> >>> A KVM_REQ_EVENT must be missing somewhere else. >>> >> >> Could you give some tips in order that I can figure it out? > >I have no idea right now (I was planning to debug it this week). > >(BTW, look at the original commit that introduced KVM_REQ_EVENT -- >https://git.kernel.org/cgit/virt/kvm/kvm.git/commit/?id=3842d135 -- and >compare the patch and the commit message. You can see that it was added >to the emulator because it is a "place that can set EFLAGS" and this >idea is preserved in the buggy patch). > >From xen codes which report panic: check_timer timer_irq_works local_save_flags(flags); => pushf;pop local_irq_enable(); => sti delay local_irq_restore(flags); => pushfq;andq;orq;popfq Regards, Wanpeng Li >The important thing is that (despite Xen being involved) this is not >related to nested virtualization. So I would first of all try to see if >some module parameter makes it go away (apicv and unrestricted mode >especially), then capture a trace of the panic. At least this is how I >was planning to start... :) > >Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] KVM: x86: fix xen guest panic due to lack of KVM_REQ_EVENT
Hi Paolo, On Mon, Aug 25, 2014 at 11:16:16AM +0200, Paolo Bonzini wrote: >Il 25/08/2014 11:08, Wanpeng Li ha scritto: >> Hi Paolo, >> On Mon, Aug 25, 2014 at 11:01:07AM +0200, Paolo Bonzini wrote: >>> Il 25/08/2014 09:58, Wanpeng Li ha scritto: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c10408e..b7c0073 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4928,6 +4928,8 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask) if (!mask) kvm_make_request(KVM_REQ_EVENT, vcpu); } + if (!(int_shadow || mask)) + kvm_make_request(KVM_REQ_EVENT, vcpu); } static void inject_emulated_exception(struct kvm_vcpu *vcpu) >>> >>> No, this patch undoes the optimization in the buggy patch. >>> >>> A KVM_REQ_EVENT must be missing somewhere else. >>> >> >> Could you give some tips in order that I can figure it out? > >I have no idea right now (I was planning to debug it this week). > >(BTW, look at the original commit that introduced KVM_REQ_EVENT -- >https://git.kernel.org/cgit/virt/kvm/kvm.git/commit/?id=3842d135 -- and >compare the patch and the commit message. You can see that it was added >to the emulator because it is a "place that can set EFLAGS" and this >idea is preserved in the buggy patch). > >The important thing is that (despite Xen being involved) this is not >related to nested virtualization. So I would first of all try to see if >some module parameter makes it go away (apicv and unrestricted mode This bug can be reproduced w/o apicv. >especially), then capture a trace of the panic. At least this is how I >was planning to start... :) Great, I will also continue to debug it. ;-) Regards, Wanpeng Li > >Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] KVM: x86: fix xen guest panic due to lack of KVM_REQ_EVENT
Il 25/08/2014 11:08, Wanpeng Li ha scritto: > Hi Paolo, > On Mon, Aug 25, 2014 at 11:01:07AM +0200, Paolo Bonzini wrote: >> Il 25/08/2014 09:58, Wanpeng Li ha scritto: >>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >>> index c10408e..b7c0073 100644 >>> --- a/arch/x86/kvm/x86.c >>> +++ b/arch/x86/kvm/x86.c >>> @@ -4928,6 +4928,8 @@ static void toggle_interruptibility(struct kvm_vcpu >>> *vcpu, u32 mask) >>> if (!mask) >>> kvm_make_request(KVM_REQ_EVENT, vcpu); >>> } >>> + if (!(int_shadow || mask)) >>> + kvm_make_request(KVM_REQ_EVENT, vcpu); >>> } >>> >>> static void inject_emulated_exception(struct kvm_vcpu *vcpu) >> >> No, this patch undoes the optimization in the buggy patch. >> >> A KVM_REQ_EVENT must be missing somewhere else. >> > > Could you give some tips in order that I can figure it out? I have no idea right now (I was planning to debug it this week). (BTW, look at the original commit that introduced KVM_REQ_EVENT -- https://git.kernel.org/cgit/virt/kvm/kvm.git/commit/?id=3842d135 -- and compare the patch and the commit message. You can see that it was added to the emulator because it is a "place that can set EFLAGS" and this idea is preserved in the buggy patch). The important thing is that (despite Xen being involved) this is not related to nested virtualization. So I would first of all try to see if some module parameter makes it go away (apicv and unrestricted mode especially), then capture a trace of the panic. At least this is how I was planning to start... :) Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] KVM: x86: fix xen guest panic due to lack of KVM_REQ_EVENT
Hi Paolo, On Mon, Aug 25, 2014 at 11:01:07AM +0200, Paolo Bonzini wrote: >Il 25/08/2014 09:58, Wanpeng Li ha scritto: >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index c10408e..b7c0073 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -4928,6 +4928,8 @@ static void toggle_interruptibility(struct kvm_vcpu >> *vcpu, u32 mask) >> if (!mask) >> kvm_make_request(KVM_REQ_EVENT, vcpu); >> } >> +if (!(int_shadow || mask)) >> +kvm_make_request(KVM_REQ_EVENT, vcpu); >> } >> >> static void inject_emulated_exception(struct kvm_vcpu *vcpu) > >No, this patch undoes the optimization in the buggy patch. > >A KVM_REQ_EVENT must be missing somewhere else. > Could you give some tips in order that I can figure it out? Regards, Wanpeng Li >Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] KVM: x86: fix xen guest panic due to lack of KVM_REQ_EVENT
Il 25/08/2014 09:58, Wanpeng Li ha scritto: > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index c10408e..b7c0073 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -4928,6 +4928,8 @@ static void toggle_interruptibility(struct kvm_vcpu > *vcpu, u32 mask) > if (!mask) > kvm_make_request(KVM_REQ_EVENT, vcpu); > } > + if (!(int_shadow || mask)) > + kvm_make_request(KVM_REQ_EVENT, vcpu); > } > > static void inject_emulated_exception(struct kvm_vcpu *vcpu) No, this patch undoes the optimization in the buggy patch. A KVM_REQ_EVENT must be missing somewhere else. Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH] KVM: x86: fix xen guest panic due to lack of KVM_REQ_EVENT
This patch fix bug https://bugzilla.kernel.org/show_bug.cgi?id=82211
(XEN) ..MP-BIOS bug: 8254 timer not connected to IO-APIC
(XEN) ...trying to set up timer (IRQ0) through the 8259A ... failed.
(XEN) ...trying to set up timer as Virtual Wire IRQ... failed.
(XEN) ...trying to set up timer as ExtINT IRQ... failed :(.
(XEN)
(XEN)
(XEN) Panic on CPU 0:
(XEN) IO-APIC + timer doesn't work! Boot with apic_verbosity=debug and send a
report.
(XEN)
Commit 6addfc42992b ("KVM: x86: avoid useless set of KVM_REQ_EVENT after
emulation") sets a KVM_REQ_EVENT if an interrupt could be injected, which
happens a) if an interrupt shadow bit (STI or MOV SS) has gone away; b)
if the interrupt flag has just been set. However, a KVM_REQ_EVENT should
be set if there is no sti sequence. This patch fix it by set a KVM_REQ_EVENT
if both the first and the second instructions are not sti.
Signed-off-by: Wanpeng Li
---
arch/x86/kvm/x86.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c10408e..b7c0073 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4928,6 +4928,8 @@ static void toggle_interruptibility(struct kvm_vcpu
*vcpu, u32 mask)
if (!mask)
kvm_make_request(KVM_REQ_EVENT, vcpu);
}
+ if (!(int_shadow || mask))
+ kvm_make_request(KVM_REQ_EVENT, vcpu);
}
static void inject_emulated_exception(struct kvm_vcpu *vcpu)
--
1.9.1
--
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Please read the FAQ at http://www.tux.org/lkml/
[PATCH] KVM: x86: fix xen guest panic due to lack of KVM_REQ_EVENT
This patch fix bug https://bugzilla.kernel.org/show_bug.cgi?id=82211 (XEN) ..MP-BIOS bug: 8254 timer not connected to IO-APIC (XEN) ...trying to set up timer (IRQ0) through the 8259A ... failed. (XEN) ...trying to set up timer as Virtual Wire IRQ... failed. (XEN) ...trying to set up timer as ExtINT IRQ... failed :(. (XEN) (XEN) (XEN) Panic on CPU 0: (XEN) IO-APIC + timer doesn't work! Boot with apic_verbosity=debug and send a report. (XEN) Commit 6addfc42992b (KVM: x86: avoid useless set of KVM_REQ_EVENT after emulation) sets a KVM_REQ_EVENT if an interrupt could be injected, which happens a) if an interrupt shadow bit (STI or MOV SS) has gone away; b) if the interrupt flag has just been set. However, a KVM_REQ_EVENT should be set if there is no sti sequence. This patch fix it by set a KVM_REQ_EVENT if both the first and the second instructions are not sti. Signed-off-by: Wanpeng Li wanpeng...@linux.intel.com --- arch/x86/kvm/x86.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c10408e..b7c0073 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4928,6 +4928,8 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask) if (!mask) kvm_make_request(KVM_REQ_EVENT, vcpu); } + if (!(int_shadow || mask)) + kvm_make_request(KVM_REQ_EVENT, vcpu); } static void inject_emulated_exception(struct kvm_vcpu *vcpu) -- 1.9.1 -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] KVM: x86: fix xen guest panic due to lack of KVM_REQ_EVENT
Il 25/08/2014 09:58, Wanpeng Li ha scritto: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c10408e..b7c0073 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4928,6 +4928,8 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask) if (!mask) kvm_make_request(KVM_REQ_EVENT, vcpu); } + if (!(int_shadow || mask)) + kvm_make_request(KVM_REQ_EVENT, vcpu); } static void inject_emulated_exception(struct kvm_vcpu *vcpu) No, this patch undoes the optimization in the buggy patch. A KVM_REQ_EVENT must be missing somewhere else. Paolo -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] KVM: x86: fix xen guest panic due to lack of KVM_REQ_EVENT
Hi Paolo, On Mon, Aug 25, 2014 at 11:01:07AM +0200, Paolo Bonzini wrote: Il 25/08/2014 09:58, Wanpeng Li ha scritto: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c10408e..b7c0073 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4928,6 +4928,8 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask) if (!mask) kvm_make_request(KVM_REQ_EVENT, vcpu); } +if (!(int_shadow || mask)) +kvm_make_request(KVM_REQ_EVENT, vcpu); } static void inject_emulated_exception(struct kvm_vcpu *vcpu) No, this patch undoes the optimization in the buggy patch. A KVM_REQ_EVENT must be missing somewhere else. Could you give some tips in order that I can figure it out? Regards, Wanpeng Li Paolo -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] KVM: x86: fix xen guest panic due to lack of KVM_REQ_EVENT
Il 25/08/2014 11:08, Wanpeng Li ha scritto: Hi Paolo, On Mon, Aug 25, 2014 at 11:01:07AM +0200, Paolo Bonzini wrote: Il 25/08/2014 09:58, Wanpeng Li ha scritto: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c10408e..b7c0073 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4928,6 +4928,8 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask) if (!mask) kvm_make_request(KVM_REQ_EVENT, vcpu); } + if (!(int_shadow || mask)) + kvm_make_request(KVM_REQ_EVENT, vcpu); } static void inject_emulated_exception(struct kvm_vcpu *vcpu) No, this patch undoes the optimization in the buggy patch. A KVM_REQ_EVENT must be missing somewhere else. Could you give some tips in order that I can figure it out? I have no idea right now (I was planning to debug it this week). (BTW, look at the original commit that introduced KVM_REQ_EVENT -- https://git.kernel.org/cgit/virt/kvm/kvm.git/commit/?id=3842d135 -- and compare the patch and the commit message. You can see that it was added to the emulator because it is a place that can set EFLAGS and this idea is preserved in the buggy patch). The important thing is that (despite Xen being involved) this is not related to nested virtualization. So I would first of all try to see if some module parameter makes it go away (apicv and unrestricted mode especially), then capture a trace of the panic. At least this is how I was planning to start... :) Paolo -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] KVM: x86: fix xen guest panic due to lack of KVM_REQ_EVENT
Hi Paolo, On Mon, Aug 25, 2014 at 11:16:16AM +0200, Paolo Bonzini wrote: Il 25/08/2014 11:08, Wanpeng Li ha scritto: Hi Paolo, On Mon, Aug 25, 2014 at 11:01:07AM +0200, Paolo Bonzini wrote: Il 25/08/2014 09:58, Wanpeng Li ha scritto: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c10408e..b7c0073 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4928,6 +4928,8 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask) if (!mask) kvm_make_request(KVM_REQ_EVENT, vcpu); } + if (!(int_shadow || mask)) + kvm_make_request(KVM_REQ_EVENT, vcpu); } static void inject_emulated_exception(struct kvm_vcpu *vcpu) No, this patch undoes the optimization in the buggy patch. A KVM_REQ_EVENT must be missing somewhere else. Could you give some tips in order that I can figure it out? I have no idea right now (I was planning to debug it this week). (BTW, look at the original commit that introduced KVM_REQ_EVENT -- https://git.kernel.org/cgit/virt/kvm/kvm.git/commit/?id=3842d135 -- and compare the patch and the commit message. You can see that it was added to the emulator because it is a place that can set EFLAGS and this idea is preserved in the buggy patch). The important thing is that (despite Xen being involved) this is not related to nested virtualization. So I would first of all try to see if some module parameter makes it go away (apicv and unrestricted mode This bug can be reproduced w/o apicv. especially), then capture a trace of the panic. At least this is how I was planning to start... :) Great, I will also continue to debug it. ;-) Regards, Wanpeng Li Paolo -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] KVM: x86: fix xen guest panic due to lack of KVM_REQ_EVENT
On Mon, Aug 25, 2014 at 11:16:16AM +0200, Paolo Bonzini wrote: Il 25/08/2014 11:08, Wanpeng Li ha scritto: Hi Paolo, On Mon, Aug 25, 2014 at 11:01:07AM +0200, Paolo Bonzini wrote: Il 25/08/2014 09:58, Wanpeng Li ha scritto: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c10408e..b7c0073 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4928,6 +4928,8 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask) if (!mask) kvm_make_request(KVM_REQ_EVENT, vcpu); } + if (!(int_shadow || mask)) + kvm_make_request(KVM_REQ_EVENT, vcpu); } static void inject_emulated_exception(struct kvm_vcpu *vcpu) No, this patch undoes the optimization in the buggy patch. A KVM_REQ_EVENT must be missing somewhere else. Could you give some tips in order that I can figure it out? I have no idea right now (I was planning to debug it this week). (BTW, look at the original commit that introduced KVM_REQ_EVENT -- https://git.kernel.org/cgit/virt/kvm/kvm.git/commit/?id=3842d135 -- and compare the patch and the commit message. You can see that it was added to the emulator because it is a place that can set EFLAGS and this idea is preserved in the buggy patch). From xen codes which report panic: check_timer timer_irq_works local_save_flags(flags); = pushf;pop local_irq_enable(); = sti delay local_irq_restore(flags); = pushfq;andq;orq;popfq Regards, Wanpeng Li The important thing is that (despite Xen being involved) this is not related to nested virtualization. So I would first of all try to see if some module parameter makes it go away (apicv and unrestricted mode especially), then capture a trace of the panic. At least this is how I was planning to start... :) Paolo -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
