From 7abc0c6d35306a41a48eda7ab2b7b2d51f32f86b Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Thu, 13 Jun 2019 18:45:05 +0200 Subject: xics/spapr: Detect old KVM XICS on POWER9 hosts Older KVMs on POWER9 don't support destroying/recreating a KVM XICS device, which is required by 'dual' interrupt controller mode. This causes QEMU to emit a warning when the guest is rebooted and to fall back on XICS emulation: qemu-system-ppc64: warning: kernel_irqchip allowed but unavailable: Error on KVM_CREATE_DEVICE for XICS: File exists If kernel irqchip is required, QEMU will thus exit when the guest is first rebooted. Failing QEMU this late may be a painful experience for the user. Detect that and exit at machine init instead. Signed-off-by: Greg Kurz Message-Id: <156044430517.125694.6207865998817342638.stgit@bahia.lab.toulouse-stg.fr.ibm.com> Signed-off-by: David Gibson --- hw/intc/xics_kvm.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'hw/intc/xics_kvm.c') 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; +} -- cgit v1.2.3