x86/speculation: Fix SPEC_CTRL write on SMT state change

stable inclusion
from stable-v5.10.133
commit aad83db22e9950577b5b827f57ed7108b3ca5553
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5PTAS
CVE: CVE-2022-29900,CVE-2022-23816,CVE-2022-29901

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=aad83db22e9950577b5b827f57ed7108b3ca5553

--------------------------------

commit 56aa4d22 upstream.

If the SMT state changes, SSBD might get accidentally disabled.  Fix
that.
Signed-off-by: NJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NThadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NLin Yujun <linyujun809@huawei.com>
Reviewed-by: NZhang Jianhua <chris.zjh@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/x86/kernel/cpu/bugs.c

@@ -1414,7 +1414,8 @@ 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. */