* Re: [PATCH 2/2] KVM: nVMX: avoid losing the posted notification interrupt when exiting L2
[not found] <20261009205036.672523-3-mlevitsk@redhat.com>
@ 2026-10-10 13:21 ` kernel test robot
0 siblings, 0 replies; only message in thread
From: kernel test robot @ 2026-10-10 13:21 UTC (permalink / raw)
To: Maxim Levitsky, kvm
Cc: llvm, oe-kbuild-all, x86, Sean Christopherson, Paolo Bonzini,
linux-kernel, Maxim Levitsky
Hi Maxim,
kernel test robot noticed the following build warnings:
[auto build test WARNING on kvm/queue]
[also build test WARNING on kvm/next mst-vhost/linux-next linus/master v7.3-rc6 next-20261009]
[cannot apply to kvm/linux-next]
[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#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Maxim-Levitsky/KVM-nVMX-don-t-check-PIR-ON-when-processing-nested-posted-interrupts/20261009-165035
base: https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue
patch link: https://lore.kernel.org/r/20261009205036.672523-3-mlevitsk%40redhat.com
patch subject: [PATCH 2/2] KVM: nVMX: avoid losing the posted notification interrupt when exiting L2
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20261010/202610102131.6oaK34Gm-lkp@intel.com/config)
compiler: clang version 22.1.3 (https://github.com/llvm/llvm-project e9846648fd6183ee6d8cbdb4502213fcf902a211)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261010/202610102131.6oaK34Gm-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202610102131.6oaK34Gm-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> arch/x86/kvm/vmx/nested.c:5167:48: warning: result of comparison of constant -1 with expression of type 'u16' (aka 'unsigned short') is always false [-Wtautological-constant-out-of-range-compare]
5167 | if (!WARN_ON_ONCE(vmx->nested.posted_intr_nv == -1)) {
| ~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~
include/asm-generic/bug.h:120:25: note: expanded from macro 'WARN_ON_ONCE'
120 | int __ret_warn_on = !!(condition); \
| ^~~~~~~~~
1 warning generated.
vim +5167 arch/x86/kvm/vmx/nested.c
5069
5070 /*
5071 * Emulate an exit from nested guest (L2) to L1, i.e., prepare to run L1
5072 * and modify vmcs12 to make it see what it would expect to see there if
5073 * L2 was its real guest. Must only be called when in L2 (is_guest_mode())
5074 */
5075 void __nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 vm_exit_reason,
5076 u32 exit_intr_info, unsigned long exit_qualification,
5077 u32 exit_insn_len)
5078 {
5079 struct vcpu_vmx *vmx = to_vmx(vcpu);
5080 struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
5081
5082 /* Pending MTF traps are discarded on VM-Exit. */
5083 vmx->nested.mtf_pending = false;
5084
5085 /* trying to cancel vmlaunch/vmresume is a bug */
5086 kvm_warn_on_nested_run_pending(vcpu);
5087
5088 /* Note, "checking" the request also clears the request. */
5089 if (kvm_check_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu)) {
5090 #ifdef CONFIG_KVM_HYPERV
5091 /*
5092 * KVM_REQ_GET_NESTED_STATE_PAGES is also used to map
5093 * Enlightened VMCS after migration and we still need to
5094 * do that when something is forcing L2->L1 exit prior to
5095 * the first L2 run.
5096 */
5097 (void)nested_get_evmcs_page(vcpu);
5098 #endif
5099 }
5100
5101 /* Service pending TLB flush requests for L2 before switching to L1. */
5102 kvm_service_local_tlb_flush_requests(vcpu);
5103
5104 /*
5105 * VCPU_REG_PDPTR will be clobbered in arch/x86/kvm/vmx/vmx.h between
5106 * now and the new vmentry. Ensure that the VMCS02 PDPTR fields are
5107 * up-to-date before switching to L1.
5108 */
5109 if (enable_ept && is_pae_paging(vcpu))
5110 vmx_ept_load_pdptrs(vcpu);
5111
5112 leave_guest_mode(vcpu);
5113
5114 if (nested_cpu_has_preemption_timer(vmcs12))
5115 hrtimer_cancel(&to_vmx(vcpu)->nested.preemption_timer);
5116
5117 if (nested_cpu_has(vmcs12, CPU_BASED_USE_TSC_OFFSETTING)) {
5118 vcpu->arch.tsc_offset = vcpu->arch.l1_tsc_offset;
5119 if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_TSC_SCALING))
5120 vcpu->arch.tsc_scaling_ratio = vcpu->arch.l1_tsc_scaling_ratio;
5121 }
5122
5123 if (likely(!vmx->fail)) {
5124 sync_vmcs02_to_vmcs12(vcpu, vmcs12);
5125
5126 if (vm_exit_reason != -1)
5127 prepare_vmcs12(vcpu, vmcs12, vm_exit_reason,
5128 exit_intr_info, exit_qualification,
5129 exit_insn_len);
5130
5131 /*
5132 * Must happen outside of sync_vmcs02_to_vmcs12() as it will
5133 * also be used to capture vmcs12 cache as part of
5134 * capturing nVMX state for snapshot (migration).
5135 *
5136 * Otherwise, this flush will dirty guest memory at a
5137 * point it is already assumed by user-space to be
5138 * immutable.
5139 */
5140 nested_flush_cached_shadow_vmcs12(vcpu, vmcs12);
5141 } else {
5142 /*
5143 * The only expected VM-instruction error is "VM entry with
5144 * invalid control field(s)." Anything else indicates a
5145 * problem with L0.
5146 */
5147 WARN_ON_ONCE(vmcs_read32(VM_INSTRUCTION_ERROR) !=
5148 VMXERR_ENTRY_INVALID_CONTROL_FIELD);
5149
5150 /* VM-Fail at VM-Entry means KVM missed a consistency check. */
5151 WARN_ON_ONCE(warn_on_missed_cc);
5152 }
5153
5154 /*
5155 * Drop events/exceptions that were queued for re-injection to L2
5156 * (picked up via vmx_complete_interrupts()), as well as exceptions
5157 * that were pending for L2. Note, this must NOT be hoisted above
5158 * prepare_vmcs12(), events/exceptions queued for re-injection need to
5159 * be captured in vmcs12 (see vmcs12_save_pending_event()).
5160 */
5161 vcpu->arch.nmi_injected = false;
5162 kvm_clear_exception_queue(vcpu);
5163 kvm_clear_interrupt_queue(vcpu);
5164
5165 if (lapic_in_kernel(vcpu) && vmx->nested.pi_pending) {
5166 vmx->nested.pi_pending = 0;
> 5167 if (!WARN_ON_ONCE(vmx->nested.posted_intr_nv == -1)) {
5168 kvm_lapic_set_irr(vmx->nested.posted_intr_nv, vcpu->arch.apic);
5169 kvm_make_request(KVM_REQ_EVENT, vcpu);
5170 }
5171 }
5172
5173 vmx_switch_vmcs(vcpu, &vmx->vmcs01);
5174
5175 kvm_nested_vmexit_handle_ibrs(vcpu);
5176
5177 /*
5178 * Update any VMCS fields that might have changed while vmcs02 was the
5179 * active VMCS. The tracking is per-vCPU, not per-VMCS.
5180 */
5181 vmcs_write32(VM_EXIT_MSR_STORE_COUNT, vmx->msr_autostore.nr);
5182 vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr);
5183 vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.guest.nr);
5184 vmcs_write64(TSC_OFFSET, vcpu->arch.tsc_offset);
5185 if (kvm_caps.has_tsc_control)
5186 vmcs_write64(TSC_MULTIPLIER, vcpu->arch.tsc_scaling_ratio);
5187
5188 nested_put_vmcs12_pages(vcpu);
5189
5190 if ((vm_exit_reason != -1) &&
5191 (enable_shadow_vmcs || nested_vmx_is_evmptr12_valid(vmx)))
5192 vmx->nested.need_vmcs12_to_shadow_sync = true;
5193
5194 /* in case we halted in L2 */
5195 kvm_set_mp_state(vcpu, KVM_MP_STATE_RUNNABLE);
5196
5197 if (likely(!vmx->fail)) {
5198 if (vm_exit_reason != -1)
5199 trace_kvm_nested_vmexit_inject(vmcs12->vm_exit_reason,
5200 vmcs12->exit_qualification,
5201 vmcs12->idt_vectoring_info_field,
5202 vmcs12->vm_exit_intr_info,
5203 vmcs12->vm_exit_intr_error_code,
5204 KVM_ISA_VMX);
5205
5206 load_vmcs12_host_state(vcpu, vmcs12);
5207
5208 /*
5209 * Process events if an injectable IRQ or NMI is pending, even
5210 * if the event is blocked (RFLAGS.IF is cleared on VM-Exit).
5211 * If an event became pending while L2 was active, KVM needs to
5212 * either inject the event or request an IRQ/NMI window. SMIs
5213 * don't need to be processed as SMM is mutually exclusive with
5214 * non-root mode. INIT/SIPI don't need to be checked as INIT
5215 * is blocked post-VMXON, and SIPIs are ignored.
5216 */
5217 if (kvm_cpu_has_injectable_intr(vcpu) || vcpu->arch.nmi_pending)
5218 kvm_make_request(KVM_REQ_EVENT, vcpu);
5219 return;
5220 }
5221
5222 /*
5223 * After an early L2 VM-entry failure, we're now back
5224 * in L1 which thinks it just finished a VMLAUNCH or
5225 * VMRESUME instruction, so we need to set the failure
5226 * flag and the VM-instruction error field of the VMCS
5227 * accordingly, and skip the emulated instruction.
5228 */
5229 (void)nested_vmx_fail(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD);
5230
5231 /*
5232 * Restore L1's host state to KVM's software model. We're here
5233 * because a consistency check was caught by hardware, which
5234 * means some amount of guest state has been propagated to KVM's
5235 * model and needs to be unwound to the host's state.
5236 */
5237 nested_vmx_restore_host_state(vcpu);
5238
5239 vmx->fail = 0;
5240 }
5241
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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