[xen stable-4.17] x86/spec-ctrl: Fix confusion between SPEC_CTRL_EXIT_TO_XEN{,_IST}

[patchbot@xxxxxxx]

commit dc28aba565f226f9bec24cfde993e78478acfb4e
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Tue Sep 12 15:06:49 2023 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Sep 19 19:36:49 2023 +0100

    x86/spec-ctrl: Fix confusion between SPEC_CTRL_EXIT_TO_XEN{,_IST}
    
    c/s 3fffaf9c13e9 ("x86/entry: Avoid using alternatives in NMI/#MC paths")
    dropped the only user, leaving behind the (incorrect) implication that Xen 
had
    split exit paths.
    
    Delete the unused SPEC_CTRL_EXIT_TO_XEN and rename SPEC_CTRL_EXIT_TO_XEN_IST
    to SPEC_CTRL_EXIT_TO_XEN for consistency.
    
    No functional change.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    (cherry picked from commit 1c18d73774533a55ba9d1cbee8bdace03efdb5e7)
---
 xen/arch/x86/include/asm/spec_ctrl_asm.h | 10 ++--------
 xen/arch/x86/x86_64/entry.S              |  2 +-
 2 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/xen/arch/x86/include/asm/spec_ctrl_asm.h 
b/xen/arch/x86/include/asm/spec_ctrl_asm.h
index f23bb105c5..e8fd01243c 100644
--- a/xen/arch/x86/include/asm/spec_ctrl_asm.h
+++ b/xen/arch/x86/include/asm/spec_ctrl_asm.h
@@ -79,7 +79,6 @@
  *  - SPEC_CTRL_ENTRY_FROM_PV
  *  - SPEC_CTRL_ENTRY_FROM_INTR
  *  - SPEC_CTRL_ENTRY_FROM_INTR_IST
- *  - SPEC_CTRL_EXIT_TO_XEN_IST
  *  - SPEC_CTRL_EXIT_TO_XEN
  *  - SPEC_CTRL_EXIT_TO_PV
  *
@@ -268,11 +267,6 @@
     ALTERNATIVE "", __stringify(DO_SPEC_CTRL_ENTRY maybexen=1),         \
         X86_FEATURE_SC_MSR_PV
 
-/* Use when exiting to Xen context. */
-#define SPEC_CTRL_EXIT_TO_XEN                                           \
-    ALTERNATIVE "",                                                     \
-        DO_SPEC_CTRL_EXIT_TO_XEN, X86_FEATURE_SC_MSR_PV
-
 /* Use when exiting to PV guest context. */
 #define SPEC_CTRL_EXIT_TO_PV                                            \
     ALTERNATIVE "",                                                     \
@@ -339,8 +333,8 @@ UNLIKELY_DISPATCH_LABEL(\@_serialise):
     UNLIKELY_END(\@_serialise)
 .endm
 
-/* Use when exiting to Xen in IST context. */
-.macro SPEC_CTRL_EXIT_TO_XEN_IST
+/* Use when exiting to Xen context. */
+.macro SPEC_CTRL_EXIT_TO_XEN
 /*
  * Requires %rbx=stack_end
  * Clobbers %rax, %rcx, %rdx
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index 7675a59ff0..b45a09823a 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -673,7 +673,7 @@ UNLIKELY_START(ne, exit_cr3)
 UNLIKELY_END(exit_cr3)
 
         /* WARNING! `ret`, `call *`, `jmp *` not safe beyond this point. */
-        SPEC_CTRL_EXIT_TO_XEN_IST /* Req: %rbx=end, Clob: acd */
+        SPEC_CTRL_EXIT_TO_XEN     /* Req: %rbx=end, Clob: acd */
 
         RESTORE_ALL adj=8
         iretq
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.17