diff --git a/docs/specs/ppc-spapr-xive.rst b/docs/specs/ppc-spapr-xive.rst index 7a64c9d049..6159bc6eed 100644 --- a/docs/specs/ppc-spapr-xive.rst +++ b/docs/specs/ppc-spapr-xive.rst @@ -142,8 +142,8 @@ xics XICS KVM XICS emul. XICS KVM (3) QEMU fails at CAS with ``Guest requested unavailable interrupt 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. This - needs to be addressed more cleanly with an error. +(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`` XIVE Device tree properties diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c index 5c4208f430..c7f8f5edd2 100644 --- a/hw/intc/xics_kvm.c +++ b/hw/intc/xics_kvm.c @@ -452,3 +452,33 @@ void xics_kvm_disconnect(SpaprMachineState *spapr, Error **errp) /* Clear the presenter from the VCPUs */ kvm_disable_icps(); } + +/* + * This is a heuristic to detect older KVMs on POWER9 hosts that don't + * support destruction of a KVM XICS device while the VM is running. + * Required to start a spapr machine with ic-mode=dual,kernel-irqchip=on. + */ +bool xics_kvm_has_broken_disconnect(SpaprMachineState *spapr) +{ + int rc; + + rc = kvm_create_device(kvm_state, KVM_DEV_TYPE_XICS, false); + if (rc < 0) { + /* + * The error is ignored on purpose. The KVM XICS setup code + * will catch it again anyway. The goal here is to see if + * close() actually destroys the device or not. + */ + return false; + } + + close(rc); + + rc = kvm_create_device(kvm_state, KVM_DEV_TYPE_XICS, false); + if (rc >= 0) { + close(rc); + return false; + } + + return errno == EEXIST; +} diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c index dfb99f35ea..75654fc67a 100644 --- a/hw/ppc/spapr_irq.c +++ b/hw/ppc/spapr_irq.c @@ -669,6 +669,19 @@ static void spapr_irq_check(SpaprMachineState *spapr, Error **errp) return; } } + + /* + * 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. + */ + if (kvm_enabled() && + spapr->irq == &spapr_irq_dual && + machine_kernel_irqchip_required(machine) && + xics_kvm_has_broken_disconnect(spapr)) { + error_setg(errp, "KVM is too old to support ic-mode=dual,kernel-irqchip=on"); + return; + } } /* diff --git a/include/hw/ppc/xics_spapr.h b/include/hw/ppc/xics_spapr.h index 6c1d9ee559..d968f2499c 100644 --- a/include/hw/ppc/xics_spapr.h +++ b/include/hw/ppc/xics_spapr.h @@ -35,6 +35,7 @@ void spapr_dt_xics(SpaprMachineState *spapr, uint32_t nr_servers, void *fdt, uint32_t phandle); int xics_kvm_init(SpaprMachineState *spapr, Error **errp); void xics_kvm_disconnect(SpaprMachineState *spapr, Error **errp); +bool xics_kvm_has_broken_disconnect(SpaprMachineState *spapr); void xics_spapr_init(SpaprMachineState *spapr); void xics_spapr_connect(SpaprMachineState *spapr);