x86/boot/compressed/64: Call set_sev_encryption_mask() earlier

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

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index fb6c039..42190c0 100644 (file)
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -543,9 +543,16 @@ 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 62e42c1..b4f2a5f 100644 (file)
--- 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;