From c87759ce876a7a0b17c2bf4f0b964bd51f0ee871 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Tue, 14 May 2019 14:14:41 -0600 Subject: [PATCH] q35: Revert to kernel irqchip Commit b2fc91db8447 ("q35: set split kernel irqchip as default") changed the default for the pc-q35-4.0 machine type to use split irqchip, which turned out to have disasterous effects on vfio-pci INTx support. KVM resampling irqfds are registered for handling these interrupts, but these are non-functional in split irqchip mode. We can't simply test for split irqchip in QEMU as userspace handling of this interrupt is a significant performance regression versus KVM handling (GeForce GPUs assigned to Windows VMs are non-functional without forcing MSI mode or re-enabling kernel irqchip). The resolution is to revert the change in default irqchip mode in the pc-q35-4.1 machine and create a pc-q35-4.0.1 machine for the 4.0-stable branch. The qemu-q35-4.0 machine type should not be used in vfio-pci configurations for devices requiring legacy INTx support without explicitly modifying the VM configuration to use kernel irqchip. Link: https://bugs.launchpad.net/qemu/+bug/1826422 Fixes: b2fc91db8447 ("q35: set split kernel irqchip as default") Signed-off-by: Alex Williamson Reviewed-by: Peter Xu Message-Id: <155786484688.13873.6037015630912983760.stgit@gimli.home> Signed-off-by: Paolo Bonzini --- hw/core/machine.c | 3 +++ hw/i386/pc.c | 3 +++ hw/i386/pc_q35.c | 16 ++++++++++++++-- include/hw/boards.h | 3 +++ include/hw/i386/pc.h | 3 +++ 5 files changed, 26 insertions(+), 2 deletions(-) diff --git a/hw/core/machine.c b/hw/core/machine.c index 16ba667434..f1a0f45f9c 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -24,6 +24,9 @@ #include "hw/pci/pci.h" #include "hw/mem/nvdimm.h" +GlobalProperty hw_compat_4_0_1[] = {}; +const size_t hw_compat_4_0_1_len = G_N_ELEMENTS(hw_compat_4_0_1); + GlobalProperty hw_compat_4_0[] = {}; const size_t hw_compat_4_0_len = G_N_ELEMENTS(hw_compat_4_0); diff --git a/hw/i386/pc.c b/hw/i386/pc.c index 2632b73f80..edc240bcbf 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -110,6 +110,9 @@ struct hpet_fw_config hpet_cfg = {.count = UINT8_MAX}; /* Physical Address of PVH entry point read from kernel ELF NOTE */ static size_t pvh_start_addr; +GlobalProperty pc_compat_4_0_1[] = {}; +const size_t pc_compat_4_0_1_len = G_N_ELEMENTS(pc_compat_4_0_1); + GlobalProperty pc_compat_4_0[] = {}; const size_t pc_compat_4_0_len = G_N_ELEMENTS(pc_compat_4_0); diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c index 37dd350511..dcddc64662 100644 --- a/hw/i386/pc_q35.c +++ b/hw/i386/pc_q35.c @@ -357,7 +357,7 @@ static void pc_q35_machine_options(MachineClass *m) m->units_per_default_bus = 1; m->default_machine_opts = "firmware=bios-256k.bin"; m->default_display = "std"; - m->default_kernel_irqchip_split = true; + m->default_kernel_irqchip_split = false; m->no_floppy = 1; machine_class_allow_dynamic_sysbus_dev(m, TYPE_AMD_IOMMU_DEVICE); machine_class_allow_dynamic_sysbus_dev(m, TYPE_INTEL_IOMMU_DEVICE); @@ -374,10 +374,22 @@ static void pc_q35_4_1_machine_options(MachineClass *m) DEFINE_Q35_MACHINE(v4_1, "pc-q35-4.1", NULL, pc_q35_4_1_machine_options); -static void pc_q35_4_0_machine_options(MachineClass *m) +static void pc_q35_4_0_1_machine_options(MachineClass *m) { pc_q35_4_1_machine_options(m); m->alias = NULL; + compat_props_add(m->compat_props, hw_compat_4_0_1, hw_compat_4_0_1_len); + compat_props_add(m->compat_props, pc_compat_4_0_1, pc_compat_4_0_1_len); +} + +DEFINE_Q35_MACHINE(v4_0_1, "pc-q35-4.0.1", NULL, + pc_q35_4_0_1_machine_options); + +static void pc_q35_4_0_machine_options(MachineClass *m) +{ + pc_q35_4_0_1_machine_options(m); + m->default_kernel_irqchip_split = true; + m->alias = NULL; compat_props_add(m->compat_props, hw_compat_4_0, hw_compat_4_0_len); compat_props_add(m->compat_props, pc_compat_4_0, pc_compat_4_0_len); } diff --git a/include/hw/boards.h b/include/hw/boards.h index 6f7916f88f..6ff02bf3e4 100644 --- a/include/hw/boards.h +++ b/include/hw/boards.h @@ -292,6 +292,9 @@ struct MachineState { } \ type_init(machine_initfn##_register_types) +extern GlobalProperty hw_compat_4_0_1[]; +extern const size_t hw_compat_4_0_1_len; + extern GlobalProperty hw_compat_4_0[]; extern const size_t hw_compat_4_0_len; diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h index 43df7230a2..5d5636241e 100644 --- a/include/hw/i386/pc.h +++ b/include/hw/i386/pc.h @@ -293,6 +293,9 @@ int e820_add_entry(uint64_t, uint64_t, uint32_t); int e820_get_num_entries(void); bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *); +extern GlobalProperty pc_compat_4_0_1[]; +extern const size_t pc_compat_4_0_1_len; + extern GlobalProperty pc_compat_4_0[]; extern const size_t pc_compat_4_0_len;