Hi David, I love your patch! Perhaps something to improve: [auto build test WARNING on linus/master] [also build test WARNING on v5.16-rc2] [cannot apply to kvm/queue kvms390/next powerpc/topic/ppc-kvm kvmarm/next mst-vhost/linux-next next-20211125] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/David-Woodhouse/KVM-Introduce-CONFIG_HAVE_KVM_DIRTY_RING/20211120-192837 base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git a90af8f15bdc9449ee2d24e1d73fa3f7e8633f81 config: i386-randconfig-c021-20211118 (https://download.01.org/0day-ci/archive/20211126/202111261049.UGt3BQLW-lkp@xxxxxxxxx/config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): # https://github.com/0day-ci/linux/commit/cc99b12d3d722f77f611a364b7a359bb3105ad44 git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review David-Woodhouse/KVM-Introduce-CONFIG_HAVE_KVM_DIRTY_RING/20211120-192837 git checkout cc99b12d3d722f77f611a364b7a359bb3105ad44 # save the config file to linux build tree make W=1 ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@xxxxxxxxx> All warnings (new ones prefixed by >>): arch/x86/kvm/x86.c: In function 'vcpu_enter_guest': >> arch/x86/kvm/x86.c:9743:4: warning: suggest braces around empty body in an 'if' statement [-Wempty-body] 9743 | ; /* Nothing to do. It just wanted to wake us */ | ^ vim +/if +9743 arch/x86/kvm/x86.c 9593 9594 /* 9595 * Returns 1 to let vcpu_run() continue the guest execution loop without 9596 * exiting to the userspace. Otherwise, the value will be returned to the 9597 * userspace. 9598 */ 9599 static int vcpu_enter_guest(struct kvm_vcpu *vcpu) 9600 { 9601 int r; 9602 bool req_int_win = 9603 dm_request_for_irq_injection(vcpu) && 9604 kvm_cpu_accept_dm_intr(vcpu); 9605 fastpath_t exit_fastpath; 9606 9607 bool req_immediate_exit = false; 9608 9609 /* Forbid vmenter if vcpu dirty ring is soft-full */ 9610 if (unlikely(vcpu->kvm->dirty_ring_size && 9611 kvm_dirty_ring_soft_full(&vcpu->dirty_ring))) { 9612 vcpu->run->exit_reason = KVM_EXIT_DIRTY_RING_FULL; 9613 trace_kvm_dirty_ring_exit(vcpu); 9614 r = 0; 9615 goto out; 9616 } 9617 9618 if (kvm_request_pending(vcpu)) { 9619 if (kvm_check_request(KVM_REQ_VM_DEAD, vcpu)) { 9620 r = -EIO; 9621 goto out; 9622 } 9623 if (kvm_check_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu)) { 9624 if (unlikely(!kvm_x86_ops.nested_ops->get_nested_state_pages(vcpu))) { 9625 r = 0; 9626 goto out; 9627 } 9628 } 9629 if (kvm_check_request(KVM_REQ_MMU_RELOAD, vcpu)) 9630 kvm_mmu_unload(vcpu); 9631 if (kvm_check_request(KVM_REQ_MIGRATE_TIMER, vcpu)) 9632 __kvm_migrate_timers(vcpu); 9633 if (kvm_check_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu)) 9634 kvm_update_masterclock(vcpu->kvm); 9635 if (kvm_check_request(KVM_REQ_GLOBAL_CLOCK_UPDATE, vcpu)) 9636 kvm_gen_kvmclock_update(vcpu); 9637 if (kvm_check_request(KVM_REQ_CLOCK_UPDATE, vcpu)) { 9638 r = kvm_guest_time_update(vcpu); 9639 if (unlikely(r)) 9640 goto out; 9641 } 9642 if (kvm_check_request(KVM_REQ_MMU_SYNC, vcpu)) 9643 kvm_mmu_sync_roots(vcpu); 9644 if (kvm_check_request(KVM_REQ_LOAD_MMU_PGD, vcpu)) 9645 kvm_mmu_load_pgd(vcpu); 9646 if (kvm_check_request(KVM_REQ_TLB_FLUSH, vcpu)) { 9647 kvm_vcpu_flush_tlb_all(vcpu); 9648 9649 /* Flushing all ASIDs flushes the current ASID... */ 9650 kvm_clear_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); 9651 } 9652 if (kvm_check_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu)) 9653 kvm_vcpu_flush_tlb_current(vcpu); 9654 if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu)) 9655 kvm_vcpu_flush_tlb_guest(vcpu); 9656 9657 if (kvm_check_request(KVM_REQ_REPORT_TPR_ACCESS, vcpu)) { 9658 vcpu->run->exit_reason = KVM_EXIT_TPR_ACCESS; 9659 r = 0; 9660 goto out; 9661 } 9662 if (kvm_check_request(KVM_REQ_TRIPLE_FAULT, vcpu)) { 9663 if (is_guest_mode(vcpu)) { 9664 kvm_x86_ops.nested_ops->triple_fault(vcpu); 9665 } else { 9666 vcpu->run->exit_reason = KVM_EXIT_SHUTDOWN; 9667 vcpu->mmio_needed = 0; 9668 r = 0; 9669 goto out; 9670 } 9671 } 9672 if (kvm_check_request(KVM_REQ_APF_HALT, vcpu)) { 9673 /* Page is swapped out. Do synthetic halt */ 9674 vcpu->arch.apf.halted = true; 9675 r = 1; 9676 goto out; 9677 } 9678 if (kvm_check_request(KVM_REQ_STEAL_UPDATE, vcpu)) 9679 record_steal_time(vcpu); 9680 if (kvm_check_request(KVM_REQ_SMI, vcpu)) 9681 process_smi(vcpu); 9682 if (kvm_check_request(KVM_REQ_NMI, vcpu)) 9683 process_nmi(vcpu); 9684 if (kvm_check_request(KVM_REQ_PMU, vcpu)) 9685 kvm_pmu_handle_event(vcpu); 9686 if (kvm_check_request(KVM_REQ_PMI, vcpu)) 9687 kvm_pmu_deliver_pmi(vcpu); 9688 if (kvm_check_request(KVM_REQ_IOAPIC_EOI_EXIT, vcpu)) { 9689 BUG_ON(vcpu->arch.pending_ioapic_eoi > 255); 9690 if (test_bit(vcpu->arch.pending_ioapic_eoi, 9691 vcpu->arch.ioapic_handled_vectors)) { 9692 vcpu->run->exit_reason = KVM_EXIT_IOAPIC_EOI; 9693 vcpu->run->eoi.vector = 9694 vcpu->arch.pending_ioapic_eoi; 9695 r = 0; 9696 goto out; 9697 } 9698 } 9699 if (kvm_check_request(KVM_REQ_SCAN_IOAPIC, vcpu)) 9700 vcpu_scan_ioapic(vcpu); 9701 if (kvm_check_request(KVM_REQ_LOAD_EOI_EXITMAP, vcpu)) 9702 vcpu_load_eoi_exitmap(vcpu); 9703 if (kvm_check_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu)) 9704 kvm_vcpu_reload_apic_access_page(vcpu); 9705 if (kvm_check_request(KVM_REQ_HV_CRASH, vcpu)) { 9706 vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT; 9707 vcpu->run->system_event.type = KVM_SYSTEM_EVENT_CRASH; 9708 r = 0; 9709 goto out; 9710 } 9711 if (kvm_check_request(KVM_REQ_HV_RESET, vcpu)) { 9712 vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT; 9713 vcpu->run->system_event.type = KVM_SYSTEM_EVENT_RESET; 9714 r = 0; 9715 goto out; 9716 } 9717 if (kvm_check_request(KVM_REQ_HV_EXIT, vcpu)) { 9718 struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu); 9719 9720 vcpu->run->exit_reason = KVM_EXIT_HYPERV; 9721 vcpu->run->hyperv = hv_vcpu->exit; 9722 r = 0; 9723 goto out; 9724 } 9725 9726 /* 9727 * KVM_REQ_HV_STIMER has to be processed after 9728 * KVM_REQ_CLOCK_UPDATE, because Hyper-V SynIC timers 9729 * depend on the guest clock being up-to-date 9730 */ 9731 if (kvm_check_request(KVM_REQ_HV_STIMER, vcpu)) 9732 kvm_hv_process_stimers(vcpu); 9733 if (kvm_check_request(KVM_REQ_APICV_UPDATE, vcpu)) 9734 kvm_vcpu_update_apicv(vcpu); 9735 if (kvm_check_request(KVM_REQ_APF_READY, vcpu)) 9736 kvm_check_async_pf_completion(vcpu); 9737 if (kvm_check_request(KVM_REQ_MSR_FILTER_CHANGED, vcpu)) 9738 static_call(kvm_x86_msr_filter_changed)(vcpu); 9739 9740 if (kvm_check_request(KVM_REQ_UPDATE_CPU_DIRTY_LOGGING, vcpu)) 9741 static_call(kvm_x86_update_cpu_dirty_logging)(vcpu); 9742 if (kvm_check_request(KVM_REQ_GPC_INVALIDATE, vcpu)) > 9743 ; /* Nothing to do. It just wanted to wake us */ 9744 } 9745 9746 if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win || 9747 kvm_xen_has_interrupt(vcpu)) { 9748 ++vcpu->stat.req_event; 9749 r = kvm_apic_accept_events(vcpu); 9750 if (r < 0) { 9751 r = 0; 9752 goto out; 9753 } 9754 if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) { 9755 r = 1; 9756 goto out; 9757 } 9758 9759 r = inject_pending_event(vcpu, &req_immediate_exit); 9760 if (r < 0) { 9761 r = 0; 9762 goto out; 9763 } 9764 if (req_int_win) 9765 static_call(kvm_x86_enable_irq_window)(vcpu); 9766 9767 if (kvm_lapic_enabled(vcpu)) { 9768 update_cr8_intercept(vcpu); 9769 kvm_lapic_sync_to_vapic(vcpu); 9770 } 9771 } 9772 9773 r = kvm_mmu_reload(vcpu); 9774 if (unlikely(r)) { 9775 goto cancel_injection; 9776 } 9777 9778 preempt_disable(); 9779 9780 static_call(kvm_x86_prepare_guest_switch)(vcpu); 9781 9782 /* 9783 * Disable IRQs before setting IN_GUEST_MODE. Posted interrupt 9784 * IPI are then delayed after guest entry, which ensures that they 9785 * result in virtual interrupt delivery. 9786 */ 9787 local_irq_disable(); 9788 vcpu->mode = IN_GUEST_MODE; 9789 9790 /* 9791 * If the guest requires direct access to mapped L1 pages, check 9792 * the caches are valid. Will raise KVM_REQ_GET_NESTED_STATE_PAGES 9793 * to go and revalidate them, if necessary. 9794 */ 9795 if (is_guest_mode(vcpu) && kvm_x86_ops.nested_ops->check_guest_maps) 9796 kvm_x86_ops.nested_ops->check_guest_maps(vcpu); 9797 9798 srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); 9799 9800 /* 9801 * 1) We should set ->mode before checking ->requests. Please see 9802 * the comment in kvm_vcpu_exiting_guest_mode(). 9803 * 9804 * 2) For APICv, we should set ->mode before checking PID.ON. This 9805 * pairs with the memory barrier implicit in pi_test_and_set_on 9806 * (see vmx_deliver_posted_interrupt). 9807 * 9808 * 3) This also orders the write to mode from any reads to the page 9809 * tables done while the VCPU is running. Please see the comment 9810 * in kvm_flush_remote_tlbs. 9811 */ 9812 smp_mb__after_srcu_read_unlock(); 9813 9814 /* 9815 * This handles the case where a posted interrupt was 9816 * notified with kvm_vcpu_kick. 9817 */ 9818 if (kvm_lapic_enabled(vcpu) && vcpu->arch.apicv_active) 9819 static_call(kvm_x86_sync_pir_to_irr)(vcpu); 9820 9821 if (kvm_vcpu_exit_request(vcpu)) { 9822 vcpu->mode = OUTSIDE_GUEST_MODE; 9823 smp_wmb(); 9824 local_irq_enable(); 9825 preempt_enable(); 9826 vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); 9827 r = 1; 9828 goto cancel_injection; 9829 } 9830 9831 if (req_immediate_exit) { 9832 kvm_make_request(KVM_REQ_EVENT, vcpu); 9833 static_call(kvm_x86_request_immediate_exit)(vcpu); 9834 } 9835 9836 fpregs_assert_state_consistent(); 9837 if (test_thread_flag(TIF_NEED_FPU_LOAD)) 9838 switch_fpu_return(); 9839 9840 if (unlikely(vcpu->arch.switch_db_regs)) { 9841 set_debugreg(0, 7); 9842 set_debugreg(vcpu->arch.eff_db[0], 0); 9843 set_debugreg(vcpu->arch.eff_db[1], 1); 9844 set_debugreg(vcpu->arch.eff_db[2], 2); 9845 set_debugreg(vcpu->arch.eff_db[3], 3); 9846 } else if (unlikely(hw_breakpoint_active())) { 9847 set_debugreg(0, 7); 9848 } 9849 9850 for (;;) { 9851 /* 9852 * Assert that vCPU vs. VM APICv state is consistent. An APICv 9853 * update must kick and wait for all vCPUs before toggling the 9854 * per-VM state, and responsing vCPUs must wait for the update 9855 * to complete before servicing KVM_REQ_APICV_UPDATE. 9856 */ 9857 WARN_ON_ONCE(kvm_apicv_activated(vcpu->kvm) != kvm_vcpu_apicv_active(vcpu)); 9858 9859 exit_fastpath = static_call(kvm_x86_run)(vcpu); 9860 if (likely(exit_fastpath != EXIT_FASTPATH_REENTER_GUEST)) 9861 break; 9862 9863 if (vcpu->arch.apicv_active) 9864 static_call(kvm_x86_sync_pir_to_irr)(vcpu); 9865 9866 if (unlikely(kvm_vcpu_exit_request(vcpu))) { 9867 exit_fastpath = EXIT_FASTPATH_EXIT_HANDLED; 9868 break; 9869 } 9870 } 9871 9872 /* 9873 * Do this here before restoring debug registers on the host. And 9874 * since we do this before handling the vmexit, a DR access vmexit 9875 * can (a) read the correct value of the debug registers, (b) set 9876 * KVM_DEBUGREG_WONT_EXIT again. 9877 */ 9878 if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) { 9879 WARN_ON(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP); 9880 static_call(kvm_x86_sync_dirty_debug_regs)(vcpu); 9881 kvm_update_dr0123(vcpu); 9882 kvm_update_dr7(vcpu); 9883 } 9884 9885 /* 9886 * If the guest has used debug registers, at least dr7 9887 * will be disabled while returning to the host. 9888 * If we don't have active breakpoints in the host, we don't 9889 * care about the messed up debug address registers. But if 9890 * we have some of them active, restore the old state. 9891 */ 9892 if (hw_breakpoint_active()) 9893 hw_breakpoint_restore(); 9894 9895 vcpu->arch.last_vmentry_cpu = vcpu->cpu; 9896 vcpu->arch.last_guest_tsc = kvm_read_l1_tsc(vcpu, rdtsc()); 9897 9898 vcpu->mode = OUTSIDE_GUEST_MODE; 9899 smp_wmb(); 9900 9901 static_call(kvm_x86_handle_exit_irqoff)(vcpu); 9902 9903 /* 9904 * Consume any pending interrupts, including the possible source of 9905 * VM-Exit on SVM and any ticks that occur between VM-Exit and now. 9906 * An instruction is required after local_irq_enable() to fully unblock 9907 * interrupts on processors that implement an interrupt shadow, the 9908 * stat.exits increment will do nicely. 9909 */ 9910 kvm_before_interrupt(vcpu); 9911 local_irq_enable(); 9912 ++vcpu->stat.exits; 9913 local_irq_disable(); 9914 kvm_after_interrupt(vcpu); 9915 9916 /* 9917 * Wait until after servicing IRQs to account guest time so that any 9918 * ticks that occurred while running the guest are properly accounted 9919 * to the guest. Waiting until IRQs are enabled degrades the accuracy 9920 * of accounting via context tracking, but the loss of accuracy is 9921 * acceptable for all known use cases. 9922 */ 9923 vtime_account_guest_exit(); 9924 9925 if (lapic_in_kernel(vcpu)) { 9926 s64 delta = vcpu->arch.apic->lapic_timer.advance_expire_delta; 9927 if (delta != S64_MIN) { 9928 trace_kvm_wait_lapic_expire(vcpu->vcpu_id, delta); 9929 vcpu->arch.apic->lapic_timer.advance_expire_delta = S64_MIN; 9930 } 9931 } 9932 9933 local_irq_enable(); 9934 preempt_enable(); 9935 9936 vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); 9937 9938 /* 9939 * Profile KVM exit RIPs: 9940 */ 9941 if (unlikely(prof_on == KVM_PROFILING)) { 9942 unsigned long rip = kvm_rip_read(vcpu); 9943 profile_hit(KVM_PROFILING, (void *)rip); 9944 } 9945 9946 if (unlikely(vcpu->arch.tsc_always_catchup)) 9947 kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); 9948 9949 if (vcpu->arch.apic_attention) 9950 kvm_lapic_sync_from_vapic(vcpu); 9951 9952 r = static_call(kvm_x86_handle_exit)(vcpu, exit_fastpath); 9953 return r; 9954 9955 cancel_injection: 9956 if (req_immediate_exit) 9957 kvm_make_request(KVM_REQ_EVENT, vcpu); 9958 static_call(kvm_x86_cancel_injection)(vcpu); 9959 if (unlikely(vcpu->arch.apic_attention)) 9960 kvm_lapic_sync_from_vapic(vcpu); 9961 out: 9962 return r; 9963 } 9964 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
