From: Joerg Roedel <jroedel@suse.de>
Date: Mon, 7 Sep 2020 15:15:21 +0200
Subject: x86/boot/compressed/64: Call set_sev_encryption_mask() earlier
Git-commit: c2a0304a286f386e45cea3f4b0617f0813de67fd
Patch-mainline: v5.10-rc1
References: jsc#SLE-14337

Call set_sev_encryption_mask() while still on the stage 1 #VC-handler
because the stage 2 handler needs the kernel's own page tables to be
set up, to which calling set_sev_encryption_mask() is a prerequisite.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-21-joro@8bytes.org
---
 arch/x86/boot/compressed/head_64.S      |    9 ++++++++-
 arch/x86/boot/compressed/ident_map_64.c |    3 ---
 2 files changed, 8 insertions(+), 4 deletions(-)

--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -546,9 +546,16 @@ relocated:
 	lgdt	gdt64(%rip)
 
 /*
- * Load stage2 IDT and switch to our own page-table
+ * If running as an SEV guest, the encryption mask is required in the
+ * page-table setup code below. When the guest also has SEV-ES enabled
+ * set_sev_encryption_mask() will cause #VC exceptions, but the stage2
+ * handler can't map its GHCB because the page-table is not set up yet.
+ * So set up the encryption mask here while still on the stage1 #VC
+ * handler. Then load stage2 IDT and switch to the kernel's own
+ * page-table.
  */
 	pushq	%rsi
+	call	set_sev_encryption_mask
 	call	load_stage2_idt
 	call	initialize_identity_maps
 	popq	%rsi
--- a/arch/x86/boot/compressed/ident_map_64.c
+++ b/arch/x86/boot/compressed/ident_map_64.c
@@ -108,9 +108,6 @@ static void add_identity_map(unsigned lo
 /* Locates and clears a region for a new top level page table. */
 void initialize_identity_maps(void)
 {
-	/* If running as an SEV guest, the encryption mask is required. */
-	set_sev_encryption_mask();
-
 	/* Exclude the encryption mask from __PHYSICAL_MASK */
 	physical_mask &= ~sme_me_mask;