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From afa5b17f385372226de6b0862f12ab39fda16b5c Mon Sep 17 00:00:00 2001
From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Tue, 12 Sep 2023 17:03:16 +0100
Subject: [PATCH 04/30] x86/spec-ctrl: Fold DO_SPEC_CTRL_EXIT_TO_XEN into it's
single user
With the SPEC_CTRL_EXIT_TO_XEN{,_IST} confusion fixed, it's now obvious that
there's only a single EXIT_TO_XEN path. Fold DO_SPEC_CTRL_EXIT_TO_XEN into
SPEC_CTRL_EXIT_TO_XEN to simplify further fixes.
When merging labels, switch the name to .L\@_skip_sc_msr as "skip" on its own
is going to be too generic shortly.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 694bb0f280fd08a4377e36e32b84b5062def4de2)
---
xen/include/asm-x86/spec_ctrl_asm.h | 40 ++++++++++++-----------------
1 file changed, 16 insertions(+), 24 deletions(-)
diff --git a/xen/include/asm-x86/spec_ctrl_asm.h b/xen/include/asm-x86/spec_ctrl_asm.h
index f5110616e4..251c30eee5 100644
--- a/xen/include/asm-x86/spec_ctrl_asm.h
+++ b/xen/include/asm-x86/spec_ctrl_asm.h
@@ -216,27 +216,6 @@
wrmsr
.endm
-.macro DO_SPEC_CTRL_EXIT_TO_XEN
-/*
- * Requires %rbx=stack_end
- * Clobbers %rax, %rcx, %rdx
- *
- * When returning to Xen context, look to see whether SPEC_CTRL shadowing is
- * in effect, and reload the shadow value. This covers race conditions which
- * exist with an NMI/MCE/etc hitting late in the return-to-guest path.
- */
- xor %edx, %edx
-
- testb $SCF_use_shadow, STACK_CPUINFO_FIELD(spec_ctrl_flags)(%rbx)
- jz .L\@_skip
-
- mov STACK_CPUINFO_FIELD(shadow_spec_ctrl)(%rbx), %eax
- mov $MSR_SPEC_CTRL, %ecx
- wrmsr
-
-.L\@_skip:
-.endm
-
.macro DO_SPEC_CTRL_EXIT_TO_GUEST
/*
* Requires %eax=spec_ctrl, %rsp=regs/cpuinfo
@@ -345,11 +324,24 @@ UNLIKELY_DISPATCH_LABEL(\@_serialise):
* Clobbers %rax, %rcx, %rdx
*/
testb $SCF_ist_sc_msr, STACK_CPUINFO_FIELD(spec_ctrl_flags)(%rbx)
- jz .L\@_skip
+ jz .L\@_skip_sc_msr
- DO_SPEC_CTRL_EXIT_TO_XEN
+ /*
+ * When returning to Xen context, look to see whether SPEC_CTRL shadowing
+ * is in effect, and reload the shadow value. This covers race conditions
+ * which exist with an NMI/MCE/etc hitting late in the return-to-guest
+ * path.
+ */
+ xor %edx, %edx
-.L\@_skip:
+ testb $SCF_use_shadow, STACK_CPUINFO_FIELD(spec_ctrl_flags)(%rbx)
+ jz .L\@_skip_sc_msr
+
+ mov STACK_CPUINFO_FIELD(shadow_spec_ctrl)(%rbx), %eax
+ mov $MSR_SPEC_CTRL, %ecx
+ wrmsr
+
+.L\@_skip_sc_msr:
.endm
#endif /* __ASSEMBLY__ */
--
2.43.0
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