From 1144c6fa17e7d3fca1e2940c8bd0da966c74e4c5 Mon Sep 17 00:00:00 2001 From: Eduardo Habkost Date: Mon, 20 Jan 2014 19:05:30 +0100 Subject: [PATCH 33/34] pc: Enable x2apic by default on more recent CPU models (v2) RH-Author: Eduardo Habkost Message-id: <1390244730-31038-3-git-send-email-ehabkost@redhat.com> Patchwork-id: 56848 O-Subject: [RHEL7 qemu-kvm PATCH 2/2] pc: Enable x2apic by default on more recent CPU models (v2) Bugzilla: 1049706 RH-Acked-by: Paolo Bonzini RH-Acked-by: Bandan Das RH-Acked-by: Laszlo Ersek Bugzilla: 1049706 Brew scratch build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=6900764 Upstream status: not applicable (see notes below) On RHEL-6 we already enabled x2apic by default on Conroe, Penryn, Nehalem, Westmere, SandyBridge, Haswell, Opteron_G{1,2,3}. To not introduce performance regressions, this patch changes the rhel7 machine-types to enable x2apic by default on all those models and also on Opteron_G{4,5}. Quoting the patch I sent upstream[1]: > Normally we try to keep the CPU model definitions as close as the real > CPUs as possible, but x2apic can be emulated by KVM without host CPU > support for x2apic, and it improves performance by reducing APIC access > overhead. x2apic emulation is available on KVM since 2009 (Linux > 2.6.32-rc1), there's no reason for not enabling x2apic by default when > running KVM. Upstream status is "not applicable" because this patch touches only the rhel7-specific PC code. I am doing this because my plan is to enable x2apic by default even if upstream rejects my patch, and I want to get this done as soon as possible to get more testing exposure. [1] A patch was submitted to change cpu.c to add x2apic to those CPU models upstream, and can be seen at: Message-Id: <1390228618-21663-1-git-send-email-ehabkost@redhat.com> http://article.gmane.org/gmane.comp.emulators.qemu/251492 The upstream patch is a resend. A similar patch was sent in September 2013, was ACKed by Gleb, but was ignored by all maintainers. Changes v2: * Use the new pc_compat_rhel*() functions * Disable x2apic explicitly on Opteron_G{4,5} on pc_compat_rhel650() Signed-off-by: Eduardo Habkost --- hw/i386/pc_piix.c | 12 ++++++++++++ hw/i386/pc_q35.c | 10 ++++++++++ 2 files changed, 22 insertions(+) Signed-off-by: Miroslav Rezanina --- hw/i386/pc_piix.c | 12 ++++++++++++ hw/i386/pc_q35.c | 10 ++++++++++ 2 files changed, 22 insertions(+), 0 deletions(-) diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c index 769571c..663c9d5 100644 --- a/hw/i386/pc_piix.c +++ b/hw/i386/pc_piix.c @@ -745,6 +745,16 @@ machine_init(pc_machine_init); static void pc_compat_rhel700(QEMUMachineInitArgs *args) { + x86_cpu_compat_set_features("Conroe", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Penryn", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Nehalem", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Westmere", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + /* SandyBridge and Haswell already have x2apic enabled */ + x86_cpu_compat_set_features("Opteron_G1", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Opteron_G2", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Opteron_G3", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Opteron_G4", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Opteron_G5", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); } static void pc_init_rhel700(QEMUMachineInitArgs *args) @@ -899,6 +909,8 @@ static void pc_compat_rhel650(QEMUMachineInitArgs *args) x86_cpu_compat_set_features("Opteron_G1", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); x86_cpu_compat_set_features("Opteron_G2", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); x86_cpu_compat_set_features("Opteron_G3", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Opteron_G4", FEAT_1_ECX, 0, CPUID_EXT_X2APIC); + x86_cpu_compat_set_features("Opteron_G5", FEAT_1_ECX, 0, CPUID_EXT_X2APIC); x86_cpu_compat_set_features("phenom", FEAT_8000_0001_EDX, 0, CPUID_EXT2_RDTSCP); diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c index 0280a95..232c62d 100644 --- a/hw/i386/pc_q35.c +++ b/hw/i386/pc_q35.c @@ -270,6 +270,16 @@ machine_init(pc_q35_machine_init); static void pc_q35_compat_rhel700(QEMUMachineInitArgs *args) { + x86_cpu_compat_set_features("Conroe", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Penryn", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Nehalem", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Westmere", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + /* SandyBridge and Haswell already have x2apic enabled */ + x86_cpu_compat_set_features("Opteron_G1", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Opteron_G2", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Opteron_G3", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Opteron_G4", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); + x86_cpu_compat_set_features("Opteron_G5", FEAT_1_ECX, CPUID_EXT_X2APIC, 0); } static void pc_q35_init_rhel700(QEMUMachineInitArgs *args) -- 1.7.1