linux-kernel - [PATCH 21/44] x86: asm/virtext.h: add cpu

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Date:	Tue,  9 Dec 2008 22:22:36 +0200
From:	Avi Kivity <avi@...hat.com>
To:	kvm@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Eduardo Habkost <ehabkost@...hat.com>
Subject: [PATCH 21/44] x86: asm/virtext.h: add cpu_vmxoff() inline function

From: Eduardo Habkost <ehabkost@...hat.com>

Unfortunately we can't use exactly the same code from vmx
hardware_disable(), because the KVM function uses the
__kvm_handle_fault_on_reboot() tricks.

Signed-off-by: Eduardo Habkost <ehabkost@...hat.com>
Signed-off-by: Avi Kivity <avi@...hat.com>
---
 arch/x86/include/asm/virtext.h |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/virtext.h b/arch/x86/include/asm/virtext.h
index 298b6a0..7dee5b5 100644
--- a/arch/x86/include/asm/virtext.h
+++ b/arch/x86/include/asm/virtext.h
@@ -18,6 +18,8 @@
 #include <asm/processor.h>
 #include <asm/system.h>
 
+#include <asm/vmx.h>
+
 /*
  * VMX functions:
  */
@@ -28,4 +30,17 @@ static inline int cpu_has_vmx(void)
 	return test_bit(5, &ecx); /* CPUID.1:ECX.VMX[bit 5] -> VT */
 }
 
+
+/** Disable VMX on the current CPU
+ *
+ * vmxoff causes a undefined-opcode exception if vmxon was not run
+ * on the CPU previously. Only call this function if you know VMX
+ * is enabled.
+ */
+static inline void cpu_vmxoff(void)
+{
+	asm volatile (ASM_VMX_VMXOFF : : : "cc");
+	write_cr4(read_cr4() & ~X86_CR4_VMXE);
+}
+
 #endif /* _ASM_X86_VIRTEX_H */
-- 
1.6.0.3

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