Backport of QEMU v4.1 commit for stable v4.0.1 release commit c87759ce876a7a0b17c2bf4f0b964bd51f0ee871 Author: Alex Williamson Date: Tue May 14 14:14:41 2019 -0600 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") Cc: address@hidden Reviewed-by: Peter Xu Signed-off-by: Alex Williamson --- Same code as v1, just updating the commit log as a formal backport of the merged 4.1 commit. 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 743fef28982c..5d046a43e3d2 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[] = {}; +const size_t hw_compat_4_0_len = G_N_ELEMENTS(hw_compat_4_0); + GlobalProperty hw_compat_3_1[] = { { "pcie-root-port", "x-speed", "2_5" }, { "pcie-root-port", "x-width", "1" }, diff --git a/hw/i386/pc.c b/hw/i386/pc.c index f2c15bf1f2c3..d98b737b8f3b 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -115,6 +115,9 @@ 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[] = {}; +const size_t pc_compat_4_0_len = G_N_ELEMENTS(pc_compat_4_0); + GlobalProperty pc_compat_3_1[] = { { "intel-iommu", "dma-drain", "off" }, { "Opteron_G3" "-" TYPE_X86_CPU, "rdtscp", "off" }, diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c index 372c6b73bebd..45cc29d1adb7 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); @@ -365,12 +365,24 @@ static void pc_q35_machine_options(MachineClass *m) m->max_cpus = 288; } -static void pc_q35_4_0_machine_options(MachineClass *m) +static void pc_q35_4_0_1_machine_options(MachineClass *m) { pc_q35_machine_options(m); m->alias = "q35"; } +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); +} + DEFINE_Q35_MACHINE(v4_0, "pc-q35-4.0", NULL, pc_q35_4_0_machine_options); diff --git a/include/hw/boards.h b/include/hw/boards.h index e231860666a1..fe1885cbffa0 100644 --- a/include/hw/boards.h +++ b/include/hw/boards.h @@ -293,6 +293,9 @@ struct MachineState { } \ type_init(machine_initfn##_register_types) +extern GlobalProperty hw_compat_4_0[]; +extern const size_t hw_compat_4_0_len; + extern GlobalProperty hw_compat_3_1[]; extern const size_t hw_compat_3_1_len; diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h index ca65ef18afb4..43df7230a22b 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[]; +extern const size_t pc_compat_4_0_len; + extern GlobalProperty pc_compat_3_1[]; extern const size_t pc_compat_3_1_len;