KVM/nVMX: Use __vmx_vcpu_run in nested_vmx_check_vmentry_hw

Replace inline assembly in nested_vmx_check_vmentry_hw
with a call to __vmx_vcpu_run. The function is not
performance critical, so (double) GPR save/restore
in __vmx_vcpu_run can be tolerated, as far as performance
effects are concerned.

Cc: Paolo Bonzini <[e-mail]>
Cc: Sean Christopherson <[e-mail]>
Reviewed-and-tested-by: Sean Christopherson <[e-mail]>
Signed-off-by: Uros Bizjak <[e-mail]>
[sean: dropped versioning info from changelog]
Signed-off-by: Sean Christopherson <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Paolo Bonzini <[e-mail]>

arch/x86/kvm/vmx/nested.c

···
 #include "nested.h"
 #include "pmu.h"
 #include "trace.h"
+#include "vmx.h"
 #include "x86.h"
 
 static bool __read_mostly enable_shadow_vmcs = 1;
···
 		vmx->loaded_vmcs->host_state.cr4 = cr4;
 	}
 
-	asm(
-		"sub $%c[wordsize], %%" _ASM_SP "\n\t" /* temporarily adjust RSP for CALL */
-		"cmp %%" _ASM_SP ", %c[host_state_rsp](%[loaded_vmcs]) \n\t"
-		"je 1f \n\t"
-		__ex("vmwrite %%" _ASM_SP ", %[HOST_RSP]") "\n\t"
-		"mov %%" _ASM_SP ", %c[host_state_rsp](%[loaded_vmcs]) \n\t"
-		"1: \n\t"
-		"add $%c[wordsize], %%" _ASM_SP "\n\t" /* un-adjust RSP */
-
-		/* Check if vmlaunch or vmresume is needed */
-		"cmpb $0, %c[launched](%[loaded_vmcs])\n\t"
-
-		/*
-		 * VMLAUNCH and VMRESUME clear RFLAGS.{CF,ZF} on VM-Exit, set
-		 * RFLAGS.CF on VM-Fail Invalid and set RFLAGS.ZF on VM-Fail
-		 * Valid.  vmx_vmenter() directly "returns" RFLAGS, and so the
-		 * results of VM-Enter is captured via CC_{SET,OUT} to vm_fail.
-		 */
-		"call vmx_vmenter\n\t"
-
-		CC_SET(be)
-	      : ASM_CALL_CONSTRAINT, CC_OUT(be) (vm_fail)
-	      :	[HOST_RSP]"r"((unsigned long)HOST_RSP),
-		[loaded_vmcs]"r"(vmx->loaded_vmcs),
-		[launched]"i"(offsetof(struct loaded_vmcs, launched)),
-		[host_state_rsp]"i"(offsetof(struct loaded_vmcs, host_state.rsp)),
-		[wordsize]"i"(sizeof(ulong))
-	      : "memory"
-	);
+	vm_fail = __vmx_vcpu_run(vmx, (unsigned long *)&vcpu->arch.regs,
+				 vmx->loaded_vmcs->launched);
 
 	if (vmx->msr_autoload.host.nr)
 		vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr);

arch/x86/kvm/vmx/vmenter.S

···
  * they VM-Fail, whereas a successful VM-Enter + VM-Exit will jump
  * to vmx_vmexit.
  */
-SYM_FUNC_START(vmx_vmenter)
+SYM_FUNC_START_LOCAL(vmx_vmenter)
 	/* EFLAGS.ZF is set if VMCS.LAUNCHED == 0 */
 	je 2f
 

arch/x86/kvm/vmx/vmx.c

···
 	}
 }
 
-bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
-
 static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
 					struct vcpu_vmx *vmx)
 {

arch/x86/kvm/vmx/vmx.h

···
 struct vmx_uret_msr *vmx_find_uret_msr(struct vcpu_vmx *vmx, u32 msr);
 void pt_update_intercept_for_msr(struct kvm_vcpu *vcpu);
 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);
 int vmx_find_loadstore_msr_slot(struct vmx_msrs *m, u32 msr);
 void vmx_ept_load_pdptrs(struct kvm_vcpu *vcpu);
 void vmx_set_intercept_for_msr(struct kvm_vcpu *vcpu,