...and of course actually call it from C now that the assembly code is
in a dedicated sub-routine and has been cleansed of any quirks that
would break compliance with the kernel's x86 calling conventions.
Aside from saving/restoring registers instead of clobbering them, the
only real function difference is that VM-Fail is propagated to EAX
instead of EBX.
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/vmx/vmenter.S | 53 ++++++++++++++++++++++++++------------
arch/x86/kvm/vmx/vmx.c | 23 +++--------------
2 files changed, 40 insertions(+), 36 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S
index ba53409382ce..66dfbe618c9a 100644
--- a/arch/x86/kvm/vmx/vmenter.S
+++ b/arch/x86/kvm/vmx/vmenter.S
@@ -87,17 +87,34 @@ ENDPROC(vmx_vmexit)
* __vmx_vcpu_run - Run a vCPU via a transition to VMX guest mode
* @vmx: struct vcpu_vmx *
* @regs: unsigned long * (to guest registers)
- * %RBX: VMCS launched status (non-zero indicates already launched)
+ * @launched: %true if the VMCS has been launched
*
* Returns:
- * %RBX is 0 on VM-Exit, 1 on VM-Fail
+ * 0 on VM-Exit, 1 on VM-Fail
*/
ENTRY(__vmx_vcpu_run)
- /* Create a stack frame and save @regs. */
push %_ASM_BP
- mov %_ASM_SP, %_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, its register may be modified by vmx_update_host_rsp()
+ * and it's also needed after VM-Exit.
+ */
push %_ASM_ARG2
+ /* Copy @launched to BL, _ASM_ARG3 is volatile. */
+ mov %_ASM_ARG3B, %bl
+
/* Adjust RSP to account for the CALL to vmx_vmenter(). */
lea -WORD_SIZE(%_ASM_SP), %_ASM_ARG2
call vmx_update_host_rsp
@@ -159,8 +176,8 @@ ENTRY(__vmx_vcpu_run)
mov %r15, VCPU_R15(%_ASM_AX)
#endif
- /* Clear EBX to indicate VM-Exit (as opposed to VM-Fail). */
- xor %ebx, %ebx
+ /* Clear RAX to indicate VM-Exit (as opposed to VM-Fail). */
+ xor %eax, %eax
/*
* Clear registers that contain guest values and will not be
@@ -172,10 +189,6 @@ ENTRY(__vmx_vcpu_run)
xor %r9d, %r9d
xor %r10d, %r10d
xor %r11d, %r11d
- xor %r12d, %r12d
- xor %r13d, %r13d
- xor %r14d, %r14d
- xor %r15d, %r15d
#endif
xor %ecx, %ecx
xor %edx, %edx
@@ -184,15 +197,21 @@ ENTRY(__vmx_vcpu_run)
/* "POP" @regs. */
add $WORD_SIZE, %_ASM_SP
- pop %_ASM_BP
+ 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
/* VM-Fail. Out-of-line to avoid a taken Jcc after VM-Exit. */
-2: mov $1, %ebx
- /*
- * RAX holds a guest value and it's not cleared in the common
- * exit path as VM-Exit reloads it with the vcpu_vmx pointer.
- */
- xor %eax, %eax
+2: mov $1, %eax
jmp 1b
ENDPROC(__vmx_vcpu_run)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 0ddd08f9337c..fa75fb8bdaa0 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6370,6 +6370,8 @@ void vmx_update_host_rsp(struct vcpu_vmx *vmx, unsigned long host_rsp)
}
}
+bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
+
static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -6443,25 +6445,8 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
if (vcpu->arch.cr2 != read_cr2())
write_cr2(vcpu->arch.cr2);
- asm(
- "call __vmx_vcpu_run \n\t"
- : ASM_CALL_CONSTRAINT, "=b"(vmx->fail),
-#ifdef CONFIG_X86_64
- "=D"((int){0}), "=S"((int){0})
- : "D"(vmx), "S"(&vcpu->arch.regs),
-#else
- "=a"((int){0}), "=d"((int){0})
- : "a"(vmx), "d"(&vcpu->arch.regs),
-#endif
- "b"(vmx->loaded_vmcs->launched)
- : "cc", "memory"
-#ifdef CONFIG_X86_64
- , "rax", "rcx", "rdx"
- , "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"
-#else
- , "ecx", "edi", "esi"
-#endif
- );
+ vmx->fail = __vmx_vcpu_run(vmx, (unsigned long *)&vcpu->arch.regs,
+ vmx->loaded_vmcs->launched);
vcpu->arch.cr2 = read_cr2();
--
2.20.1
