[tip: x86/urgent] x86/speculation: Use DECLARE_PER_CPU for x86_spec_ctrl_current

[tip-bot2 for Nathan Chancellor]

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     db866d3352ec85e821e730e191481cba3a2bfa6e
Gitweb:        https://git.kernel.org/tip/db866d3352ec85e821e730e191481cba3a2bfa6e
Author:        Nathan Chancellor <nathan@xxxxxxxxxx>
AuthorDate:    Wed, 13 Jul 2022 08:24:37 -07:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Thu, 14 Jul 2022 13:40:21 +02:00

x86/speculation: Use DECLARE_PER_CPU for x86_spec_ctrl_current

Clang warns:

  arch/x86/kernel/cpu/bugs.c:58:21: error: section attribute is specified on redeclared variable [-Werror,-Wsection]
  DEFINE_PER_CPU(u64, x86_spec_ctrl_current);
                      ^
  arch/x86/include/asm/nospec-branch.h:283:12: note: previous declaration is here
  extern u64 x86_spec_ctrl_current;
             ^
  1 error generated.

The declaration should be using DECLARE_PER_CPU instead so all
attributes stay in sync.

Fixes: fc02735b14ff ("KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS")
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Tested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220713152436.2294819-1-nathan@xxxxxxxxxx
---
 arch/x86/include/asm/nospec-branch.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index bb05ed4..10a3bfc 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -11,6 +11,7 @@
 #include <asm/cpufeatures.h>
 #include <asm/msr-index.h>
 #include <asm/unwind_hints.h>
+#include <asm/percpu.h>
 
 #define RETPOLINE_THUNK_SIZE	32
 
@@ -280,7 +281,7 @@ static inline void indirect_branch_prediction_barrier(void)
 
 /* The Intel SPEC CTRL MSR base value cache */
 extern u64 x86_spec_ctrl_base;
-extern u64 x86_spec_ctrl_current;
+DECLARE_PER_CPU(u64, x86_spec_ctrl_current);
 extern void write_spec_ctrl_current(u64 val, bool force);
 extern u64 spec_ctrl_current(void);