From: Paolo Bonzini <pbonzini@redhat.com>
Date: Mon, 1 Oct 2018 14:07:18 +0000 (+0200)
Subject: kvm/x86: return meaningful value from KVM_SIGNAL_MSI
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=0624fca9512d08cbd9b5d098d904c840d3432404;p=openwrt%2Fstaging%2Fblogic.git

kvm/x86: return meaningful value from KVM_SIGNAL_MSI

If kvm_apic_map_get_dest_lapic() finds a disabled LAPIC,
it will return with bitmap==0 and (*r == -1) will be returned to
userspace.

QEMU may then record "KVM: injection failed, MSI lost
(Operation not permitted)" in its log, which is quite puzzling.

Reported-by: Peng Hao <penghao122@sina.com.cn>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 91ffb63397f5..452eed992aea 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -960,14 +960,14 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
 	map = rcu_dereference(kvm->arch.apic_map);
 
 	ret = kvm_apic_map_get_dest_lapic(kvm, &src, irq, map, &dst, &bitmap);
-	if (ret)
+	if (ret) {
+		*r = 0;
 		for_each_set_bit(i, &bitmap, 16) {
 			if (!dst[i])
 				continue;
-			if (*r < 0)
-				*r = 0;
 			*r += kvm_apic_set_irq(dst[i]->vcpu, irq, dest_map);
 		}
+	}
 
 	rcu_read_unlock();
 	return ret;