2015-03-30 22:32+0300, Andrey Korolyov: > On Mon, Mar 30, 2015 at 9:56 PM, Radim Krčmář <rkrcmar@xxxxxxxxxx> wrote: > > 2015-03-27 13:16+0300, Andrey Korolyov: > >> On Fri, Mar 27, 2015 at 12:03 AM, Bandan Das <bsd@xxxxxxxxxx> wrote: > >> > Radim Krčmář <rkrcmar@xxxxxxxxxx> writes: > >> >> I second Bandan -- checking that it reproduces on other machine would be > >> >> great for sanity :) (Although a bug in our APICv is far more likely.) > >> > > >> > If it's APICv related, a run without apicv enabled could give more hints. > >> > > >> > Your "devices not getting reset" hypothesis makes the most sense to me, > >> > maybe the timer vector in the error message is just one part of > >> > the whole story. Another misbehaving interrupt from the dark comes in at the > >> > same time and leads to a double fault. > >> > >> Default trace (APICv enabled, first reboot introduced the issue): > >> http://xdel.ru/downloads/kvm-e5v2-issue/hanged-reboot-apic-on.dat.gz > > > > The relevant part is here, > > prefixed with "qemu-system-x86-4180 [002] 697.111550:" > > > > kvm_exit: reason CR_ACCESS rip 0xd272 info 0 0 > > kvm_cr: cr_write 0 = 0x10 > > kvm_mmu_get_page: existing sp gfn 0 0/4 q0 direct --- !pge !nxe root 0 sync > > kvm_entry: vcpu 0 > > kvm_emulate_insn: f0000:d275: ea 7a d2 00 f0 > > kvm_emulate_insn: f0000:d27a: 2e 0f 01 1e f0 6c > > kvm_emulate_insn: f0000:d280: 31 c0 > > kvm_emulate_insn: f0000:d282: 8e e0 > > kvm_emulate_insn: f0000:d284: 8e e8 > > kvm_emulate_insn: f0000:d286: 8e c0 > > kvm_emulate_insn: f0000:d288: 8e d8 > > kvm_emulate_insn: f0000:d28a: 8e d0 > > kvm_entry: vcpu 0 > > kvm_exit: reason EXTERNAL_INTERRUPT rip 0xd28f info 0 800000f6 > > kvm_entry: vcpu 0 > > kvm_exit: reason EPT_VIOLATION rip 0x8dd0 info 184 0 > > kvm_page_fault: address f8dd0 error_code 184 > > kvm_entry: vcpu 0 > > kvm_exit: reason EXTERNAL_INTERRUPT rip 0x8dd0 info 0 800000f6 > > kvm_entry: vcpu 0 > > kvm_exit: reason EPT_VIOLATION rip 0x76d6 info 184 0 > > kvm_page_fault: address f76d6 error_code 184 > > kvm_entry: vcpu 0 > > kvm_exit: reason EXTERNAL_INTERRUPT rip 0x76d6 info 0 800000f6 > > kvm_entry: vcpu 0 > > kvm_exit: reason PENDING_INTERRUPT rip 0xd331 info 0 0 > > kvm_inj_virq: irq 8 > > kvm_entry: vcpu 0 > > kvm_exit: reason EXTERNAL_INTERRUPT rip 0xfea5 info 0 800000f6 > > kvm_entry: vcpu 0 > > kvm_exit: reason EPT_VIOLATION rip 0xfea5 info 184 0 > > kvm_page_fault: address ffea5 error_code 184 > > kvm_entry: vcpu 0 > > kvm_exit: reason EXTERNAL_INTERRUPT rip 0xfea5 info 0 800000f6 > > kvm_entry: vcpu 0 > > kvm_exit: reason EPT_VIOLATION rip 0xe990 info 184 0 > > kvm_page_fault: address fe990 error_code 184 > > kvm_entry: vcpu 0 > > kvm_exit: reason EXTERNAL_INTERRUPT rip 0xe990 info 0 800000f6 > > kvm_entry: vcpu 0 > > kvm_exit: reason EXCEPTION_NMI rip 0xd334 info 0 80000b0d > > kvm_userspace_exit: reason KVM_EXIT_INTERNAL_ERROR (17) > > > >> Trace without APICv (three reboots, just to make sure to hit the > >> problematic condition of supposed DF, as it still have not one hundred > >> percent reproducibility): > >> http://xdel.ru/downloads/kvm-e5v2-issue/apic-off.dat.gz > > > > The trace here contains a well matching excerpt, just instead of the > > EXCEPTION_NMI, it does > > > > 169.905098: kvm_exit: reason EPT_VIOLATION rip 0xd334 info 181 0 > > 169.905102: kvm_page_fault: address feffd066 error_code 181 > > > > and works. Page fault says we tried to read 0xfeffd066 -- probably IOPB > > of TSS. (I guess it is pre-fetch for following IO instruction.) > > > > Nothing strikes me when looking at it, but some APICv boots don't fail, > > so it would be interesting to compare them ... hosts's 0xf6 interrupt > > (IRQ_WORK_VECTOR) is a possible source of races. (We could look more > > closely. It is fired too often for my liking as well.) > > Thanks Radim, http://xdel.ru/downloads/kvm-e5v2-issue/no-fail-with-apicv.dat.gz > > The related bits looks the same as with enable_apicv=0 for me. Yeah, qemu-system-x86-4201 [007] 159.297337: kvm_exit: reason CR_ACCESS rip 0xd272 info 0 0 kvm_cr: cr_write 0 = 0x10 kvm_mmu_get_page: existing sp gfn 0 0/4 q0 direct --- !pge !nxe root 0 sync kvm_entry: vcpu 0 kvm_emulate_insn: f0000:d275: ea 7a d2 00 f0 kvm_emulate_insn: f0000:d27a: 2e 0f 01 1e f0 6c kvm_emulate_insn: f0000:d280: 31 c0 kvm_emulate_insn: f0000:d282: 8e e0 kvm_emulate_insn: f0000:d284: 8e e8 kvm_emulate_insn: f0000:d286: 8e c0 kvm_emulate_insn: f0000:d288: 8e d8 kvm_emulate_insn: f0000:d28a: 8e d0 kvm_entry: vcpu 0 kvm_exit: reason EPT_VIOLATION rip 0x8dd0 info 184 0 kvm_page_fault: address f8dd0 error_code 184 kvm_entry: vcpu 0 kvm_exit: reason EPT_VIOLATION rip 0x76d6 info 184 0 kvm_page_fault: address f76d6 error_code 184 kvm_entry: vcpu 0 kvm_exit: reason EPT_VIOLATION rip 0xd331 info 181 0 kvm_page_fault: address feffd066 error_code 181 kvm_inj_virq: irq 25 kvm_entry: vcpu 0 kvm_exit: reason EPT_VIOLATION rip 0xe6f2 info 184 0 kvm_page_fault: address fe6f2 error_code 184 kvm_entry: vcpu 0 kvm_exit: reason IO_INSTRUCTION rip 0xd202 info 700040 0 kvm_pio: pio_write at 0x70 size 1 count 1 val 0x8f kvm_userspace_exit: reason KVM_EXIT_IO (2) I noticed three differences from the failing version: 1) Page fault 0xfeffd066 @ 0xd331, KVM also injects vector 0x19 there 2) No PENDING_INTERRUPT irq 8 (not sure why it happened on APICv) 3) No EXTERNAL_INTERRUPT vector 0xf6 (lucky race) Chasing the culprit this way could take a long time, so a new tracepoint that shows if 0xef is set on entry would let us guess the bug faster ... Please provide a failing trace with the following patch: --- diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h index 7c7bc8bef21f..8cf85dcaa1ee 100644 --- a/arch/x86/kvm/trace.h +++ b/arch/x86/kvm/trace.h @@ -742,6 +742,29 @@ TRACE_EVENT(kvm_emulate_insn, #define trace_kvm_emulate_insn_start(vcpu) trace_kvm_emulate_insn(vcpu, 0) #define trace_kvm_emulate_insn_failed(vcpu) trace_kvm_emulate_insn(vcpu, 1) +TRACE_EVENT(kvm_0xef, + TP_PROTO(bool irr, bool isr, u32 vmcs), + TP_ARGS(irr, isr, vmcs), + + TP_STRUCT__entry( + __field(bool, irr ) + __field(bool, isr ) + __field(u32, vmcs) + ), + + TP_fast_assign( + __entry->irr = irr; + __entry->isr = isr; + __entry->vmcs = vmcs; + ), + + TP_printk("irr %s, isr %s, vmcs 0x%x", + __entry->irr ? "set " : "clear", + __entry->isr ? "set " : "clear", + __entry->vmcs + ) + ); + TRACE_EVENT( vcpu_match_mmio, TP_PROTO(gva_t gva, gpa_t gpa, bool write, bool gpa_match), diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index eee63dc33d89..254cca12c2ec 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -8129,6 +8129,13 @@ static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx) msrs[i].host); } +#define VEC_POS(v) ((v) & (32 - 1)) +#define REG_POS(v) (((v) >> 5) << 4) +static inline int apic_test_vector(int vec, void *bitmap) +{ + return test_bit(VEC_POS(vec), (bitmap) + REG_POS(vec)); +} + static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); @@ -8143,6 +8150,10 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu) if (vmx->emulation_required) return; + trace_kvm_0xef(apic_test_vector(0xef, vcpu->arch.apic->regs + APIC_IRR), + apic_test_vector(0xef, vcpu->arch.apic->regs + APIC_ISR), + vmcs_read32(VM_ENTRY_INTR_INFO_FIELD)); + if (vmx->ple_window_dirty) { vmx->ple_window_dirty = false; vmcs_write32(PLE_WINDOW, vmx->ple_window); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 32bf19ef3115..a45fa01bd354 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7881,3 +7881,4 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_nested_intercepts); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_write_tsc_offset); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_ple_window); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_pml_full); +EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_0xef); -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
