KVM/x86: Use assembly instruction mnemonics instead of .byte streams

Recently the minimum required version of binutils was changed to 2.20,
which supports all VMX instruction mnemonics. The patch removes
all .byte #defines and uses real instruction mnemonics instead.

The compiler is now able to pass memory operand to the instruction,
so there is no need for memory clobber anymore. Also, the compiler
adds CC register clobber automatically to all extended asm clauses,
so the patch also removes explicit CC clobber.

The immediate benefit of the patch is removal of many unnecesary
register moves, resulting in 1434 saved bytes in vmx.o:

   text    data     bss     dec     hex filename
 151257   18246    8500  178003   2b753 vmx.o
 152691   18246    8500  179437   2bced vmx-old.o

Some examples of improvement include removal of unneeded moves
of %rsp to %rax in front of invept and invvpid instructions:

    a57e:	b9 01 00 00 00       	mov    $0x1,%ecx
    a583:	48 89 04 24          	mov    %rax,(%rsp)
    a587:	48 89 e0             	mov    %rsp,%rax
    a58a:	48 c7 44 24 08 00 00 	movq   $0x0,0x8(%rsp)
    a591:	00 00
    a593:	66 0f 38 80 08       	invept (%rax),%rcx

to:

    a45c:	48 89 04 24          	mov    %rax,(%rsp)
    a460:	b8 01 00 00 00       	mov    $0x1,%eax
    a465:	48 c7 44 24 08 00 00 	movq   $0x0,0x8(%rsp)
    a46c:	00 00
    a46e:	66 0f 38 80 04 24    	invept (%rsp),%rax

and the ability to use more optimal registers and memory operands
in the instruction:

    8faa:	48 8b 44 24 28       	mov    0x28(%rsp),%rax
    8faf:	4c 89 c2             	mov    %r8,%rdx
    8fb2:	0f 79 d0             	vmwrite %rax,%rdx

to:

    8e7c:	44 0f 79 44 24 28    	vmwrite 0x28(%rsp),%r8

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 0 insertions, 13 deletions

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 9527ba5d62da..ade0f153947d 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -503,19 +503,6 @@ enum vmcs_field {
 
 #define VMX_EPT_IDENTITY_PAGETABLE_ADDR		0xfffbc000ul
 
-
-#define ASM_VMX_VMCLEAR_RAX       ".byte 0x66, 0x0f, 0xc7, 0x30"
-#define ASM_VMX_VMLAUNCH          ".byte 0x0f, 0x01, 0xc2"
-#define ASM_VMX_VMRESUME          ".byte 0x0f, 0x01, 0xc3"
-#define ASM_VMX_VMPTRLD_RAX       ".byte 0x0f, 0xc7, 0x30"
-#define ASM_VMX_VMREAD_RDX_RAX    ".byte 0x0f, 0x78, 0xd0"
-#define ASM_VMX_VMWRITE_RAX_RDX   ".byte 0x0f, 0x79, 0xd0"
-#define ASM_VMX_VMWRITE_RSP_RDX   ".byte 0x0f, 0x79, 0xd4"
-#define ASM_VMX_VMXOFF            ".byte 0x0f, 0x01, 0xc4"
-#define ASM_VMX_VMXON_RAX         ".byte 0xf3, 0x0f, 0xc7, 0x30"
-#define ASM_VMX_INVEPT		  ".byte 0x66, 0x0f, 0x38, 0x80, 0x08"
-#define ASM_VMX_INVVPID		  ".byte 0x66, 0x0f, 0x38, 0x81, 0x08"
-
 struct vmx_msr_entry {
 	u32 index;
 	u32 reserved;