diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -1830,6 +1830,56 @@
 	    : "cc", "memory");
 }
 
+extern const char wrmsr_early_safe_gp_handler[];
+static uint64_t orig_gp_handler;
+
+static struct gate_descriptor *
+wrmsr_early_get_gp_descr(void)
+{
+	struct region_descriptor efi_idt;
+	struct gate_descriptor *gpf_descr;
+
+	lidt(&efi_idt);
+	return ((void *)(uintptr_t)(efi_idt.rd_base +
+	    sizeof(*gpf_descr) * IDT_GP));
+}
+
+static void
+wrmsr_early_set_gp_handler(uint64_t h)
+{
+	struct gate_descriptor *gpf_descr;
+
+	gpf_descr = wrmsr_early_get_gp_descr();
+	gpf_descr->gd_looffset = h;
+	gpf_descr->gd_hioffset = h >> 16;
+}
+
+static uint64_t
+wrmsr_early_get_gp_handler(void)
+{
+	struct gate_descriptor *gpf_descr;
+	uint64_t res;
+
+	gpf_descr = wrmsr_early_get_gp_descr();
+	res = gpf_descr->gd_hioffset;
+	res <<= 16;
+	res |= gpf_descr->gd_looffset;
+	return (res);
+}
+
+void
+wrmsr_early_safe_start(void)
+{
+	orig_gp_handler = wrmsr_early_get_gp_handler();
+	wrmsr_early_set_gp_handler((uintptr_t)wrmsr_early_safe_gp_handler);
+}
+
+void
+wrmsr_early_safe_end(void)
+{
+	wrmsr_early_set_gp_handler(orig_gp_handler);
+}
+
 #ifdef KDB
 
 /*
diff --git a/sys/amd64/amd64/support.S b/sys/amd64/amd64/support.S
--- a/sys/amd64/amd64/support.S
+++ b/sys/amd64/amd64/support.S
@@ -1565,6 +1565,25 @@
 	POP_FRAME_POINTER
 	ret
 
+ENTRY(wrmsr_early_safe)
+	movl	%edi,%ecx
+	movl	%esi,%eax
+	sarq	$32,%rsi
+	movl	%esi,%edx
+wrmsrF:	wrmsr
+	xorl	%eax,%eax
+	POP_FRAME_POINTER
+	ret
+
+ENTRY(wrmsr_early_faulted)
+	movl	$EFAULT,%eax
+	POP_FRAME_POINTER
+	ret
+
+ENTRY(wrmsr_early_safe_gp_handler)
+	movq	$wrmsr_early_faulted,8(%rsp)
+	iretq
+
 /*
  * void pmap_pti_pcid_invalidate(uint64_t ucr3, uint64_t kcr3);
  * Invalidates address space addressed by ucr3, then returns to kcr3.
diff --git a/sys/amd64/include/md_var.h b/sys/amd64/include/md_var.h
--- a/sys/amd64/include/md_var.h
+++ b/sys/amd64/include/md_var.h
@@ -100,6 +100,10 @@
 int	set_fpcontext(struct thread *td, struct __mcontext *mcp,
 	    char *xfpustate, size_t xfpustate_len);
 
+void	wrmsr_early_safe_start(void);
+void	wrmsr_early_safe_end(void);
+int	wrmsr_early_safe(u_int msr, uint64_t data);
+
 #endif /* !_MACHINE_MD_VAR_H_ */
 
 #endif /* __i386__ */