drm/i915/gvt: remove detect_host() MPT hook

We only depend on pvinfo register for GVT-g state detection,
not require hypervisor host detect any more.

Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/gvt.c

@@ -68,8 +68,6 @@ static const struct intel_gvt_ops intel_gvt_ops = {
  */
 int intel_gvt_init_host(void)
 {
-	int ret;
-
 	if (intel_gvt_host.initialized)
 		return 0;
 
@@ -103,11 +101,6 @@ int intel_gvt_init_host(void)
 	if (!intel_gvt_host.mpt)
 		return -EINVAL;
 
-	/* Try to detect if we're running in host instead of VM. */
-	ret = intel_gvt_hypervisor_detect_host();
-	if (ret)
-		return -ENODEV;
-
 	gvt_dbg_core("Running with hypervisor %s in host mode\n",
 			supported_hypervisors[intel_gvt_host.hypervisor_type]);
 

drivers/gpu/drm/i915/gvt/hypercall.h

@@ -38,7 +38,6 @@
  * both Xen and KVM by providing dedicated hypervisor-related MPT modules.
  */
 struct intel_gvt_mpt {
-	int (*detect_host)(void);
 	int (*host_init)(struct device *dev, void *gvt, const void *ops);
 	void (*host_exit)(struct device *dev, void *gvt);
 	int (*attach_vgpu)(void *vgpu, unsigned long *handle);

drivers/gpu/drm/i915/gvt/kvmgt.c

@@ -1248,37 +1248,6 @@ static void kvmgt_page_track_flush_slot(struct kvm *kvm,
 	spin_unlock(&kvm->mmu_lock);
 }
 
-static bool kvmgt_check_guest(void)
-{
-	unsigned int eax, ebx, ecx, edx;
-	char s[12];
-	unsigned int *i;
-
-	eax = KVM_CPUID_SIGNATURE;
-	ebx = ecx = edx = 0;
-
-	asm volatile ("cpuid"
-		      : "+a"(eax), "=b"(ebx), "=c"(ecx), "=d"(edx)
-		      :
-		      : "cc", "memory");
-	i = (unsigned int *)s;
-	i[0] = ebx;
-	i[1] = ecx;
-	i[2] = edx;
-
-	return !strncmp(s, "KVMKVMKVM", strlen("KVMKVMKVM"));
-}
-
-/**
- * NOTE:
- * It's actually impossible to check if we are running in KVM host,
- * since the "KVM host" is simply native. So we only dectect guest here.
- */
-static int kvmgt_detect_host(void)
-{
-	return kvmgt_check_guest() ? -ENODEV : 0;
-}
-
 static bool __kvmgt_vgpu_exist(struct intel_vgpu *vgpu, struct kvm *kvm)
 {
 	struct intel_vgpu *itr;
@@ -1453,7 +1422,6 @@ static unsigned long kvmgt_virt_to_pfn(void *addr)
 }
 
 struct intel_gvt_mpt kvmgt_mpt = {
-	.detect_host = kvmgt_detect_host,
 	.host_init = kvmgt_host_init,
 	.host_exit = kvmgt_host_exit,
 	.attach_vgpu = kvmgt_attach_vgpu,

drivers/gpu/drm/i915/gvt/mpt.h

@@ -43,18 +43,6 @@
  * hypervisor.
  */
 
-/**
- * intel_gvt_hypervisor_detect_host - check if GVT-g is running within
- * hypervisor host/privilged domain
- *
- * Returns:
- * Zero on success, -ENODEV if current kernel is running inside a VM
- */
-static inline int intel_gvt_hypervisor_detect_host(void)
-{
-	return intel_gvt_host.mpt->detect_host();
-}
-
 /**
  * intel_gvt_hypervisor_host_init - init GVT-g host side
  *