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x86/speculation: Fix firmware entry SPEC_CTRL handling

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The firmware entry code may accidentally clear STIBP or SSBD. Fix that.

Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
This commit is contained in:
Josh Poimboeuf authored and Borislav Petkov committed 2022-06-27 10:34:00 +02:00
1 parent b2620facef
commit e6aa13622e
1 file changed
+4 -6
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arch/x86/include/asm/nospec-branch.h
+4 -6
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@@ -285,18 +285,16 @@ extern u64 spec_ctrl_current(void);
*/
#define firmware_restrict_branch_speculation_start() \
do { \
u64 val = x86_spec_ctrl_base | SPEC_CTRL_IBRS; \
\
preempt_disable(); \
alternative_msr_write(MSR_IA32_SPEC_CTRL, val, \
alternative_msr_write(MSR_IA32_SPEC_CTRL, \
spec_ctrl_current() | SPEC_CTRL_IBRS, \
X86_FEATURE_USE_IBRS_FW); \
} while (0)
#define firmware_restrict_branch_speculation_end() \
do { \
u64 val = x86_spec_ctrl_base; \
\
alternative_msr_write(MSR_IA32_SPEC_CTRL, val, \
alternative_msr_write(MSR_IA32_SPEC_CTRL, \
spec_ctrl_current(), \
X86_FEATURE_USE_IBRS_FW); \
preempt_enable(); \
} while (0)