KVM: x86: Explicitly treat routing entry type changes as changes

commit bcda70c56f3e718465cab2aad260cf34183ce1ce upstream.

Explicitly treat type differences as GSI routing changes, as comparing MSI
data between two entries could get a false negative, e.g. if userspace
changed the type but left the type-specific data as-is.

Fixes: 515a0c79e796 ("kvm: irqfd: avoid update unmodified entries of the routing")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20250404193923.1413163-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2a2dbeb56897d8af3bb9ee7298c2c693d7ddca96..f67fe8a65820c8acfe3a0b44794aed0a922fa734 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -13297,7 +13297,8 @@ int kvm_arch_update_irqfd_routing(struct kvm *kvm, unsigned int host_irq,
 bool kvm_arch_irqfd_route_changed(struct kvm_kernel_irq_routing_entry *old,
                                  struct kvm_kernel_irq_routing_entry *new)
 {
-       if (new->type != KVM_IRQ_ROUTING_MSI)
+       if (old->type != KVM_IRQ_ROUTING_MSI ||
+           new->type != KVM_IRQ_ROUTING_MSI)
                return true;
 
        return !!memcmp(&old->msi, &new->msi, sizeof(new->msi));