From 47ea7263701e85ea03270d34c9a90f3971597e06 Mon Sep 17 00:00:00 2001 From: Matthew Rosato Date: Wed, 8 Oct 2025 16:33:50 -0400 Subject: [PATCH] s390x/pci: set kvm_msi_via_irqfd_allowed Allow irqfd to be used for virtio-pci on s390x if the kernel supports it. This improves s390x virtio-pci performance when using kvm acceleration by allowing kvm to deliver interrupts instead of QEMU. Signed-off-by: Matthew Rosato Reviewed-by: Farhan Ali Reviewed-by: Eric Farman Message-ID: <20251008203350.354121-1-mjrosato@linux.ibm.com> Signed-off-by: Thomas Huth --- hw/s390x/s390-pci-bus.c | 1 + include/hw/s390x/s390-pci-kvm.h | 7 +++++++ 2 files changed, 8 insertions(+) diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c index e8e41c8a9a..52820894fa 100644 --- a/hw/s390x/s390-pci-bus.c +++ b/hw/s390x/s390-pci-bus.c @@ -900,6 +900,7 @@ static void s390_pcihost_realize(DeviceState *dev, Error **errp) s390_pci_init_default_group(); css_register_io_adapters(CSS_IO_ADAPTER_PCI, true, false, S390_ADAPTER_SUPPRESSIBLE, errp); + s390_pcihost_kvm_realize(); } static void s390_pcihost_unrealize(DeviceState *dev) diff --git a/include/hw/s390x/s390-pci-kvm.h b/include/hw/s390x/s390-pci-kvm.h index 933814a402..c33f2833a3 100644 --- a/include/hw/s390x/s390-pci-kvm.h +++ b/include/hw/s390x/s390-pci-kvm.h @@ -14,12 +14,19 @@ #include "hw/s390x/s390-pci-bus.h" #include "hw/s390x/s390-pci-inst.h" +#include "system/kvm.h" #ifdef CONFIG_KVM +static inline void s390_pcihost_kvm_realize(void) +{ + kvm_msi_via_irqfd_allowed = kvm_irqfds_enabled(); +} + bool s390_pci_kvm_interp_allowed(void); int s390_pci_kvm_aif_enable(S390PCIBusDevice *pbdev, ZpciFib *fib, bool assist); int s390_pci_kvm_aif_disable(S390PCIBusDevice *pbdev); #else +static inline void s390_pcihost_kvm_realize(void) {} static inline bool s390_pci_kvm_interp_allowed(void) { return false; -- 2.47.3