KVM: SVM: Disable AVIC before setting V_IRQ

The commit 64b5bd270426 ("KVM: nSVM: ignore L1 interrupt window
while running L2 with V_INTR_MASKING=1") introduced a WARN_ON,
which checks if AVIC is enabled when trying to set V_IRQ
in the VMCB for enabling irq window.

The following warning is triggered because the requesting vcpu
(to deactivate AVIC) does not get to process APICv update request
for itself until the next #vmexit.

WARNING: CPU: 0 PID: 118232 at arch/x86/kvm/svm/svm.c:1372 enable_irq_window+0x6a/0xa0 [kvm_amd]
 RIP: 0010:enable_irq_window+0x6a/0xa0 [kvm_amd]
 Call Trace:
  kvm_arch_vcpu_ioctl_run+0x6e3/0x1b50 [kvm]
  ? kvm_vm_ioctl_irq_line+0x27/0x40 [kvm]
  ? _copy_to_user+0x26/0x30
  ? kvm_vm_ioctl+0xb3e/0xd90 [kvm]
  ? set_next_entity+0x78/0xc0
  kvm_vcpu_ioctl+0x236/0x610 [kvm]
  ksys_ioctl+0x8a/0xc0
  __x64_sys_ioctl+0x1a/0x20
  do_syscall_64+0x58/0x210
  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes by sending APICV update request to all other vcpus, and
immediately update APIC for itself.

Signed-off-by: Suravee Suthikulpanit <[email protected]>
Link: https://lkml.org/lkml/2020/5/2/167
Fixes: 64b5bd270426 ("KVM: nSVM: ignore L1 interrupt window while running L2 with V_INTR_MASKING=1")
Message-Id: <1588818939[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ba8edf3b89f65d1a1618852b7faaccfffb7c98dc..98176b80c481f521d2cfe867a9ee5b966a0326a1 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8060,6 +8060,7 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_update_apicv);
  */
 void kvm_request_apicv_update(struct kvm *kvm, bool activate, ulong bit)
 {
+       struct kvm_vcpu *except;
        unsigned long old, new, expected;
 
        if (!kvm_x86_ops.check_apicv_inhibit_reasons ||
@@ -8084,7 +8085,17 @@ void kvm_request_apicv_update(struct kvm *kvm, bool activate, ulong bit)
        trace_kvm_apicv_update_request(activate, bit);
        if (kvm_x86_ops.pre_update_apicv_exec_ctrl)
                kvm_x86_ops.pre_update_apicv_exec_ctrl(kvm, activate);
-       kvm_make_all_cpus_request(kvm, KVM_REQ_APICV_UPDATE);
+
+       /*
+        * Sending request to update APICV for all other vcpus,
+        * while update the calling vcpu immediately instead of
+        * waiting for another #VMEXIT to handle the request.
+        */
+       except = kvm_get_running_vcpu();
+       kvm_make_all_cpus_request_except(kvm, KVM_REQ_APICV_UPDATE,
+                                        except);
+       if (except)
+               kvm_vcpu_update_apicv(except);
 }
 EXPORT_SYMBOL_GPL(kvm_request_apicv_update);