linux-kernel - [PATCH 26/62] x86/head/64: Reload GDT after switch to virtual addresses

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Message-Id: <20200211135256.24617-27-joro@8bytes.org>
Date:   Tue, 11 Feb 2020 14:52:20 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     x86@...nel.org
Cc:     hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Joerg Roedel <joro@...tes.org>, Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 26/62] x86/head/64: Reload GDT after switch to virtual addresses

From: Joerg Roedel <jroedel@...e.de>

Reload the GDT after switching to virtual addresses to make sure it will
not go away when the lower mappings are removed.

Signed-off-by: Joerg Roedel <jroedel@...e.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 5a3cde971cb7..a3a9383e8dd6 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -157,6 +157,11 @@ 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_base(%rip)
+	lgdt	boot_gdt_descr(%rip)
+
 	/* Check if nx is implemented */
 	movl	$0x80000001, %eax
 	cpuid
-- 
2.17.1