@@ -126,6 +126,9 @@ xics XICS KVM XICS emul. XICS KVM
(1) QEMU warns with ``warning: kernel_irqchip requested but unavailable:
IRQ_XIVE capability must be present for KVM``
+ In some cases (old host kernels or KVM nested guests), one may hit a
+ QEMU/KVM incompatibility due to device destruction in reset. QEMU fails
+ with ``KVM is incompatible with ic-mode=dual,kernel-irqchip=on``
(2) QEMU fails with ``kernel_irqchip requested but unavailable:
IRQ_XIVE capability must be present for KVM``
@@ -148,7 +151,7 @@ xics XICS KVM XICS emul. XICS KVM
mode (XICS), either don't set the ic-mode machine property or try
ic-mode=xics or ic-mode=dual``
(4) QEMU/KVM incompatibility due to device destruction in reset. QEMU fails
- with ``KVM is too old to support ic-mode=dual,kernel-irqchip=on``
+ with ``KVM is incompatible with ic-mode=dual,kernel-irqchip=on``
XIVE Device tree properties
@@ -139,6 +139,7 @@ SpaprIrq spapr_irq_dual = {
static int spapr_irq_check(SpaprMachineState *spapr, Error **errp)
{
+ ERRP_GUARD();
MachineState *machine = MACHINE(spapr);
/*
@@ -179,14 +180,19 @@ static int spapr_irq_check(SpaprMachineState *spapr, Error **errp)
/*
* On a POWER9 host, some older KVM XICS devices cannot be destroyed and
- * re-created. Detect that early to avoid QEMU to exit later when the
- * guest reboots.
+ * re-created. Same happens with KVM nested guests. Detect that early to
+ * avoid QEMU to exit later when the guest reboots.
*/
if (kvm_enabled() &&
spapr->irq == &spapr_irq_dual &&
kvm_kernel_irqchip_required() &&
xics_kvm_has_broken_disconnect(spapr)) {
- error_setg(errp, "KVM is too old to support ic-mode=dual,kernel-irqchip=on");
+ error_setg(errp,
+ "KVM is incompatible with ic-mode=dual,kernel-irqchip=on");
+ error_append_hint(errp,
+ "This can happen with an old KVM or in a KVM nested guest.\n");
+ error_append_hint(errp,
+ "Try without kernel-irqchip or with kernel-irqchip=off.\n");
return -1;
}