[PATCH v7 20/72] x86/boot/compressed/64: Call set_sev_encryption_mask() earlier

Joerg Roedel
2020-09-07T13:15:21Z

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 at suse.de>
---
 arch/x86/boot/compressed/head_64.S      | 9 ++++++++-
 arch/x86/boot/compressed/ident_map_64.c | 3 ---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/boot/compressed/head_64.S
b/arch/x86/boot/compressed/head_64.S
index 37c8c2c8f8b6..1c80f1738fd9 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -533,9 +533,16 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
 	rep	stosq

 /*
- * 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
diff --git a/arch/x86/boot/compressed/ident_map_64.c
b/arch/x86/boot/compressed/ident_map_64.c
index 62e42c11a336..b4f2a5f503cd 100644
--- a/arch/x86/boot/compressed/ident_map_64.c
+++ b/arch/x86/boot/compressed/ident_map_64.c
@@ -105,9 +105,6 @@ static void add_identity_map(unsigned long start, unsigned
long end)
 /* 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;

--
2.28.0