x86: Add native_[ig]dt_invalidate()

In some places, the native forms of descriptor table invalidation is
required. Rather than open-coding them, add explicitly native functions to
invalidate the GDT and IDT.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210519212154.511983-6-hpa@zytor.com

diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index b8429ae..400c178 100644 (file)
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -224,6 +224,26 @@ static inline void store_idt(struct desc_ptr *dtr)
        asm volatile("sidt %0":"=m" (*dtr));
 }
 
+static inline void native_gdt_invalidate(void)
+{
+       const struct desc_ptr invalid_gdt = {
+               .address = 0,
+               .size = 0
+       };
+
+       native_load_gdt(&invalid_gdt);
+}
+
+static inline void native_idt_invalidate(void)
+{
+       const struct desc_ptr invalid_idt = {
+               .address = 0,
+               .size = 0
+       };
+
+       native_load_idt(&invalid_idt);
+}
+
 /*
  * The LTR instruction marks the TSS GDT entry as busy. On 64-bit, the GDT is
  * a read-only remapping. To prevent a page fault, the GDT is switched to the