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KVM: VMX: Remove unneeded __ASM_SIZE usage with POP instruction

PATCH Superseded Uros Bizjak 2 participants 2 messages Apr 26, 2020 – Apr 27, 2020

Subsystems (3)
x86 KVM KVM x86

v1 of 2 Superseded Latest is v2 →

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Uros Bizjak

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#0 lore raw

PATCH 1/1 KVM: VMX: Remove unneeded __ASM_SIZE usage with POP instruction

POP instruction always operates in word size, no need to use __ASM_SIZE macro to force operating mode.

Cc Paolo Bonzini <[email protected]>
Cc Sean Christopherson <[email protected]>
Signed-off-by Uros Bizjak <[email protected]>
---
 arch/x86/kvm/vmx/vmenter.S | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)
arch/x86/kvm/vmx/vmenter.S +7 -7
index 87f3f24fef37..94b8794bdd2a 100644
@@ -163,13 +163,13 @@ SYM_FUNC_START(__vmx_vcpu_run)
 	mov WORD_SIZE(%_ASM_SP), %_ASM_AX
 
 	/* Save all guest registers, including RAX from the stack */
-	__ASM_SIZE(pop) VCPU_RAX(%_ASM_AX)
-	mov %_ASM_CX,   VCPU_RCX(%_ASM_AX)
-	mov %_ASM_DX,   VCPU_RDX(%_ASM_AX)
-	mov %_ASM_BX,   VCPU_RBX(%_ASM_AX)
-	mov %_ASM_BP,   VCPU_RBP(%_ASM_AX)
-	mov %_ASM_SI,   VCPU_RSI(%_ASM_AX)
-	mov %_ASM_DI,   VCPU_RDI(%_ASM_AX)
+	pop           VCPU_RAX(%_ASM_AX)
+	mov %_ASM_CX, VCPU_RCX(%_ASM_AX)
+	mov %_ASM_DX, VCPU_RDX(%_ASM_AX)
+	mov %_ASM_BX, VCPU_RBX(%_ASM_AX)
+	mov %_ASM_BP, VCPU_RBP(%_ASM_AX)
+	mov %_ASM_SI, VCPU_RSI(%_ASM_AX)
+	mov %_ASM_DI, VCPU_RDI(%_ASM_AX)
 #ifdef CONFIG_X86_64
 	mov %r8,  VCPU_R8 (%_ASM_AX)
 	mov %r9,  VCPU_R9 (%_ASM_AX)
Signature · 1 line
2.25.3
Reviewed-by on v1 1/1
#1 lore raw
Quoted 2 lines · Uros Bizjak

POP instruction always operates in word size, no need to use __ASM_SIZE macro to force operating mode.

Nit, "always operates in word size" isn't quite correct, it'd be more accurate to state "POP [mem] defaults to the word size, and the only legal non-default size is 16 bits, e.g. a 32-bit POP will #UD in 64-bit mode and vice versa, no need ...".

With a tweaked changelog:

Reviewed-by Sean Christopherson <[email protected]>
Quoted 35 lines
Cc Paolo Bonzini <[email protected]>
Cc Sean Christopherson <[email protected]>
Signed-off-by Uros Bizjak <[email protected]>
---
 arch/x86/kvm/vmx/vmenter.S | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)
arch/x86/kvm/vmx/vmenter.S +7 -7
index 87f3f24fef37..94b8794bdd2a 100644
@@ -163,13 +163,13 @@ SYM_FUNC_START(__vmx_vcpu_run)
 	mov WORD_SIZE(%_ASM_SP), %_ASM_AX
 
 	/* Save all guest registers, including RAX from the stack */
-	__ASM_SIZE(pop) VCPU_RAX(%_ASM_AX)
-	mov %_ASM_CX,   VCPU_RCX(%_ASM_AX)
-	mov %_ASM_DX,   VCPU_RDX(%_ASM_AX)
-	mov %_ASM_BX,   VCPU_RBX(%_ASM_AX)
-	mov %_ASM_BP,   VCPU_RBP(%_ASM_AX)
-	mov %_ASM_SI,   VCPU_RSI(%_ASM_AX)
-	mov %_ASM_DI,   VCPU_RDI(%_ASM_AX)
+	pop           VCPU_RAX(%_ASM_AX)
+	mov %_ASM_CX, VCPU_RCX(%_ASM_AX)
+	mov %_ASM_DX, VCPU_RDX(%_ASM_AX)
+	mov %_ASM_BX, VCPU_RBX(%_ASM_AX)
+	mov %_ASM_BP, VCPU_RBP(%_ASM_AX)
+	mov %_ASM_SI, VCPU_RSI(%_ASM_AX)
+	mov %_ASM_DI, VCPU_RDI(%_ASM_AX)
 #ifdef CONFIG_X86_64
 	mov %r8,  VCPU_R8 (%_ASM_AX)
 	mov %r9,  VCPU_R9 (%_ASM_AX)
Signature · 1 line
2.25.3