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: f4258c991c32 ("KVM: x86: hyper-v: Prepare to meet unallocated Hyper-V context")
Cc: stable@vger.kernel.org
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Huang Le <huangle1@jd.com>
Message-Id: <62115b277dab49ea97da5633f8522daf@jd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5c479ae57693247e9d8915da3bf381563aed679b..2c03b76caf11933dcb5d2c6e82e300a4b5aa57db 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9640,12 +9640,16 @@ 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,