[PATCH v4 31/75] x86/head/64: Reload GDT after switch to virtual addresses

Joerg Roedel
Tue, 14 Jul 2020 12:08:33 -0000

Reload the GDT after switching to virtual addresses to make sure it will
not go away when the lower mappings are removed. This will also reload
the GDT for booting APs, which will need a working GDT too to handle #VC
exceptions.

Signed-off-by: Joerg Roedel <jroedel at suse.de>
---
 arch/x86/kernel/head_64.S | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 473e60a12e2f..87ea9f540608 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -164,6 +164,11 @@ SYM_CODE_START(secondary_startup_64)
 1:
 	UNWIND_HINT_EMPTY

+	/* Setup boot GDT descriptor and load boot GDT */
+	leaq	boot_gdt(%rip), %rax
+	movq	%rax, boot_gdt_descr+2(%rip)
+	lgdt	boot_gdt_descr(%rip)
+
 	/* Check if nx is implemented */
 	movl	$0x80000001, %eax
 	cpuid
--
2.27.0