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Commit 93f95106 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Greg Kroah-Hartman
Browse files

x86/speculation: Fix firmware entry SPEC_CTRL handling 



commit e6aa13622ea8283cc699cac5d018cc40a2ba2010 upstream.

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

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarThadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: default avatarSuleiman Souhlal <suleiman@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ca47b5c5

arch/x86/include/asm/nospec-branch.h

+4 −6
Original line number Diff line number Diff line
@@ -317,18 +317,16 @@ 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)