[v3,31/33] KVM: VMX: Preserve callee-save registers in vCPU-run asm sub-routine

Commit Message

Sean Christopherson Jan. 25, 2019, 3:41 p.m. UTC

...to make it callable from C code.

Note that because KVM chooses to be ultra paranoid about guest register
values, all callee-save registers are still cleared after VM-Exit even
though the host's values are now reloaded from the stack.

Signed-off-by: Sean Christopherson <[e-mail]>
---
 arch/x86/kvm/vmx/vmenter.S | 21 +++++++++++++++++++++
 arch/x86/kvm/vmx/vmx.c     |  5 +----
 2 files changed, 22 insertions(+), 4 deletions(-)

Patch

diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S
index 246404b38b37..900be1d542c8 100644
--- a/arch/x86/kvm/vmx/vmenter.S
+++ b/arch/x86/kvm/vmx/vmenter.S
@@ -95,6 +95,16 @@  ENDPROC(vmx_vmexit)
 ENTRY(__vmx_vcpu_run)
 	push %_ASM_BP
 	mov  %_ASM_SP, %_ASM_BP
+#ifdef CONFIG_X86_64
+	push %r15
+	push %r14
+	push %r13
+	push %r12
+#else
+	push %edi
+	push %esi
+#endif
+	push %_ASM_BX
 
 	/*
 	 * Save @regs, _ASM_ARG2 may be modified by vmx_update_host_rsp() and
@@ -198,6 +208,17 @@  ENTRY(__vmx_vcpu_run)
 
 	/* "POP" @regs. */
 	add $WORD_SIZE, %_ASM_SP
+	pop %_ASM_BX
+
+#ifdef CONFIG_X86_64
+	pop %r12
+	pop %r13
+	pop %r14
+	pop %r15
+#else
+	pop %esi
+	pop %edi
+#endif
 	pop %_ASM_BP
 	ret
 
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 73a1e656b123..b9064b646a85 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6455,10 +6455,7 @@  static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
 #endif
 	      : "cc", "memory"
 #ifdef CONFIG_X86_64
-		, "rbx", "rcx"
-		, "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"
-#else
-		, "ebx", "edi", "esi"
+		, "rcx", "r8", "r9", "r10", "r11"
 #endif
 	      );