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Subject[PATCH 19/35] x86: KVM guest: add basic paravirt support
Date
From: Marcelo Tosatti <mtosatti@redhat.com>

Add basic KVM paravirt support. Avoid vm-exits on IO delays.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---
arch/x86/Kconfig | 8 ++++++
arch/x86/kernel/Makefile | 1 +
arch/x86/kernel/kvm.c | 52 ++++++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/setup_32.c | 1 +
arch/x86/kernel/setup_64.c | 2 +
include/linux/kvm_para.h | 6 +++++
6 files changed, 70 insertions(+), 0 deletions(-)
create mode 100644 arch/x86/kernel/kvm.c
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e59ea05..75d2700 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -381,6 +381,14 @@ config KVM_CLOCK
provides the guest with timing infrastructure such as time of day, and
system time

+config KVM_GUEST
+ bool "KVM Guest support"
+ select PARAVIRT
+ depends on !(X86_VISWS || X86_VOYAGER)
+ help
+ This option enables various optimizations for running under the KVM
+ hypervisor.
+
source "arch/x86/lguest/Kconfig"

config PARAVIRT
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index a3379a3..1cc9d42 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -77,6 +77,7 @@ obj-$(CONFIG_DEBUG_RODATA_TEST) += test_rodata.o
obj-$(CONFIG_DEBUG_NX_TEST) += test_nx.o

obj-$(CONFIG_VMI) += vmi_32.o vmiclock_32.o
+obj-$(CONFIG_KVM_GUEST) += kvm.o
obj-$(CONFIG_KVM_CLOCK) += kvmclock.o
obj-$(CONFIG_PARAVIRT) += paravirt.o paravirt_patch_$(BITS).o

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
new file mode 100644
index 0000000..a8e36da
--- /dev/null
+++ b/arch/x86/kernel/kvm.c
@@ -0,0 +1,52 @@
+/*
+ * KVM paravirt_ops implementation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ * Copyright IBM Corporation, 2007
+ * Authors: Anthony Liguori <aliguori@us.ibm.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/kvm_para.h>
+#include <linux/cpu.h>
+#include <linux/mm.h>
+
+/*
+ * No need for any "IO delay" on KVM
+ */
+static void kvm_io_delay(void)
+{
+}
+
+static void paravirt_ops_setup(void)
+{
+ pv_info.name = "KVM";
+ pv_info.paravirt_enabled = 1;
+
+ if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
+ pv_cpu_ops.io_delay = kvm_io_delay;
+
+}
+
+void __init kvm_guest_init(void)
+{
+ if (!kvm_para_available())
+ return;
+
+ paravirt_ops_setup();
+}
diff --git a/arch/x86/kernel/setup_32.c b/arch/x86/kernel/setup_32.c
index 3ef92a2..65f3a23 100644
--- a/arch/x86/kernel/setup_32.c
+++ b/arch/x86/kernel/setup_32.c
@@ -782,6 +782,7 @@ void __init setup_arch(char **cmdline_p)
*/
vmi_init();
#endif
+ kvm_guest_init();

/*
* NOTE: before this point _nobody_ is allowed to allocate
diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c
index 26b676f..10a8ff5 100644
--- a/arch/x86/kernel/setup_64.c
+++ b/arch/x86/kernel/setup_64.c
@@ -452,6 +452,8 @@ void __init setup_arch(char **cmdline_p)
init_apic_mappings();
ioapic_init_mappings();

+ kvm_guest_init();
+
/*
* We trust e820 completely. No explicit ROM probing in memory.
*/
diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
index 5497aac..9c462c9 100644
--- a/include/linux/kvm_para.h
+++ b/include/linux/kvm_para.h
@@ -20,6 +20,12 @@
#include <asm/kvm_para.h>

#ifdef __KERNEL__
+#ifdef CONFIG_KVM_GUEST
+void __init kvm_guest_init(void);
+#else
+#define kvm_guest_init() do { } while (0)
+#endif
+
static inline int kvm_para_has_feature(unsigned int feature)
{
if (kvm_arch_para_features() & (1UL << feature))
--
1.5.4.5


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