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KVM: x86: Fix uninitialized eoi_exit_bitmap usage in vcpu_load_eoi_exitmap()

PATCH Applied 黄乐 2 participants 2 messages Nov 15, 2021 – Nov 16, 2021

Subsystems (4)
Stable branch x86 KVM KVM x86
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黄乐

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#0 lore raw

PATCH v2 1/1 KVM: x86: Fix uninitialized eoi_exit_bitmap usage in vcpu_load_eoi_exitmap()

In vcpu_load_eoi_exitmap(), currently the eoi_exit_bitmap[4] array is initialized only when Hyper-V context is available, in other path it is just passed to kvm_x86_ops.load_eoi_exitmap() directly from on the stack, which would cause unexpected interrupt delivery/handling issues, e.g. an *old* linux kernel that relies on PIT to do clock calibration on KVM might randomly fail to boot.

Fix it by passing ioapic_handled_vectors to load_eoi_exitmap() when Hyper-V context is not available.

Fixes f2bc14b69c38 ("KVM: x86: hyper-v: Prepare to meet unallocated Hyper-V context")
Cc [email protected]
Reviewed-by Vitaly Kuznetsov <[email protected]>
Signed-off-by Huang Le <[email protected]>

---

arch/x86/kvm/x86.c +6 -2
index dc7eb5fddfd3..26466f94e31a 100644
@@ -9547,12 +9547,16 @@ static void vcpu_load_eoi_exitmap(struct kvm_vcpu *vcpu)
 	if (!kvm_apic_hw_enabled(vcpu->arch.apic))
 		return;
 
-	if (to_hv_vcpu(vcpu))
+	if (to_hv_vcpu(vcpu)) {
 		bitmap_or((ulong *)eoi_exit_bitmap,
 			  vcpu->arch.ioapic_handled_vectors,
 			  to_hv_synic(vcpu)->vec_bitmap, 256);
+		static_call(kvm_x86_load_eoi_exitmap)(vcpu, eoi_exit_bitmap);
+		return;
+	}
 
-	static_call(kvm_x86_load_eoi_exitmap)(vcpu, eoi_exit_bitmap);
+	static_call(kvm_x86_load_eoi_exitmap)(
+		vcpu, (u64 *)vcpu->arch.ioapic_handled_vectors);
 }
 
 void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,
maintainer Applied
#1 lore raw
Quoted 29 lines · 黄乐

In vcpu_load_eoi_exitmap(), currently the eoi_exit_bitmap[4] array is initialized only when Hyper-V context is available, in other path it is just passed to kvm_x86_ops.load_eoi_exitmap() directly from on the stack, which would cause unexpected interrupt delivery/handling issues, e.g. an *old* linux kernel that relies on PIT to do clock calibration on KVM might randomly fail to boot.

Fix it by passing ioapic_handled_vectors to load_eoi_exitmap() when Hyper-V context is not available.

Fixes f2bc14b69c38 ("KVM: x86: hyper-v: Prepare to meet unallocated Hyper-V context")
Cc [email protected]
Reviewed-by Vitaly Kuznetsov <[email protected]>
Signed-off-by Huang Le <[email protected]>

---

arch/x86/kvm/x86.c +1 -1
index dc7eb5fddfd3..26466f94e31a 100644
@@ -9547,12 +9547,16 @@ static void vcpu_load_eoi_exitmap(struct kvm_vcpu *vcpu)
  	if (!kvm_apic_hw_enabled(vcpu->arch.apic))
  		return;
 
-	if (to_hv_vcpu(vcpu))
+	if (to_hv_vcpu(vcpu)) {
  		bitmap_or((ulong *)eoi_exit_bitmap,
  			  vcpu->arch.ioapic_handled_vectors,
  			  to_hv_synic(vcpu)->vec_bitmap, 256);

arch/x86/kvm/x86.c static void vcpu_load_eoi_exitmap(struct kvm_vcpu *vcpu) · line 9562

Quoted 10 lines
arch/x86/kvm/x86.c +5 -1
+		static_call(kvm_x86_load_eoi_exitmap)(vcpu, eoi_exit_bitmap);
+		return;
+	}
 
-	static_call(kvm_x86_load_eoi_exitmap)(vcpu, eoi_exit_bitmap);
+	static_call(kvm_x86_load_eoi_exitmap)(
+		vcpu, (u64 *)vcpu->arch.ioapic_handled_vectors);
  }
 
  void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,

Queued, thanks.

Paolo