Fix S3 resume

Fixes QubesOS/qubes-issues#6066

patch-x86-S3-Fix-Shadow-Stack-resume-path.patch

@@ -0,0 +1,37 @@
+From bd032cbd664a229603592d595ce562dc1a22d158 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
+ <[email protected]>
+Date: Sun, 27 Sep 2020 17:29:35 +0200
+Subject: [PATCH] x86/S3: Fix Shadow Stack resume path
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+Organization: Invisible Things Lab
+Cc: Marek Marczykowski-Górecki <[email protected]>
+
+Fix the resume path to load the shadow stack pointer from saved_ssp (not
+saved_rsp), to match what suspend path does.
+
+Signed-off-by: Marek Marczykowski-Górecki <[email protected]>
+Fixes: 633ecc4a7cb2 ("x86/S3: Save and restore Shadow Stack configuration")
+Backport: 4.14
+---
+ xen/arch/x86/acpi/wakeup_prot.S | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/xen/arch/x86/acpi/wakeup_prot.S b/xen/arch/x86/acpi/wakeup_prot.S
+index a2c41c4f3f26..c6b3fcc93d93 100644
+--- a/xen/arch/x86/acpi/wakeup_prot.S
++++ b/xen/arch/x86/acpi/wakeup_prot.S
+@@ -69,7 +69,7 @@ ENTRY(s3_resume)
+          * so SETSSBSY will successfully load a value useful for us, then
+          * reset MSR_PL0_SSP to its usual value and pop the temporary token.
+          */
+-        mov     saved_rsp(%rip), %rdi
++        mov     saved_ssp(%rip), %rdi
+         cmpq    $1, %rdi
+         je      .L_shstk_done
+
+-- 
+2.25.4
+

xen.spec.in

@@ -126,6 +126,7 @@ Patch622: patch-xen-disable-efi-gettime.patch
 Patch627: patch-libxl-automatically-enable-gfx_passthru-if-IGD-is-as.patch
 Patch628: patch-libxl-workaround-gcc-10.2-maybe-uninitialized-warnin.patch
 Patch629: patch-libxl-fix-Werror-stringop-truncation-in-libxl__prepa.patch
+Patch630: patch-x86-S3-Fix-Shadow-Stack-resume-path.patch
 
 # GCC8 fixes
 Patch714: patch-tools-kdd-mute-spurious-gcc-warning.patch