From: Josh Poimboeuf <jpoimboe@kernel.org>

Date: Tue, 14 Jun 2022 23:16:07 +0200

Subject: x86/speculation: Fix SPEC_CTRL write on SMT state change

Git-commit: 56aa4d221f1ee2c3a49b45b800778ec6e0ab73c5

Patch-mainline: v5.19-rc4

References: bsc#1199657 CVE-2022-29900 CVE-2022-29901

If the SMT state changes, SSBD might get accidentally disabled.  Fix

that.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Signed-off-by: Borislav Petkov <bp@suse.de>

---

 arch/x86/kernel/cpu/bugs.c | 3 ++-

 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c

index 108bd74289c5..9b80059c4e02 100644

--- a/arch/x86/kernel/cpu/bugs.c

+++ b/arch/x86/kernel/cpu/bugs.c

@@ -1458,7 +1458,8 @@ static void __init spectre_v2_select_mitigation(void)

 static void update_stibp_msr(void * __unused)

 {

-	write_spec_ctrl_current(x86_spec_ctrl_base, true);

+	u64 val = spec_ctrl_current() | (x86_spec_ctrl_base & SPEC_CTRL_STIBP);

+	write_spec_ctrl_current(val, true);

 }

 /* Update x86_spec_ctrl_base in case SMT state changed. */