x86/bugs: Add attack vector controls for TSA

Use attack vector controls to determine which TSA mitigation to use.

  [ bp: Simplify the condition in the select function for better
    readability. ]

Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250709155844.3279471-1-david.kaplan@amd.com

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index f41d871f0622025ebb5bfa894d0527a9470bdca9..b9d0509e5e5eec0d6df40d666a200741784f720d 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1657,28 +1657,43 @@ early_param("tsa", tsa_parse_cmdline);
 
 static void __init tsa_select_mitigation(void)
 {
-       if (cpu_mitigations_off() || !boot_cpu_has_bug(X86_BUG_TSA)) {
+       if (!boot_cpu_has_bug(X86_BUG_TSA)) {
                tsa_mitigation = TSA_MITIGATION_NONE;
                return;
        }
 
+       if (tsa_mitigation == TSA_MITIGATION_AUTO) {
+               bool vm = false, uk = false;
+
+               tsa_mitigation = TSA_MITIGATION_NONE;
+
+               if (cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL) ||
+                   cpu_attack_vector_mitigated(CPU_MITIGATE_USER_USER)) {
+                       tsa_mitigation = TSA_MITIGATION_USER_KERNEL;
+                       uk = true;
+               }
+
+               if (cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_HOST) ||
+                   cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_GUEST)) {
+                       tsa_mitigation = TSA_MITIGATION_VM;
+                       vm = true;
+               }
+
+               if (uk && vm)
+                       tsa_mitigation = TSA_MITIGATION_FULL;
+       }
+
        if (tsa_mitigation == TSA_MITIGATION_NONE)
                return;
 
-       if (!boot_cpu_has(X86_FEATURE_VERW_CLEAR)) {
+       if (!boot_cpu_has(X86_FEATURE_VERW_CLEAR))
                tsa_mitigation = TSA_MITIGATION_UCODE_NEEDED;
-               goto out;
-       }
-
-       if (tsa_mitigation == TSA_MITIGATION_AUTO)
-               tsa_mitigation = TSA_MITIGATION_FULL;
 
        /*
         * No need to set verw_clear_cpu_buf_mitigation_selected - it
         * doesn't fit all cases here and it is not needed because this
         * is the only VERW-based mitigation on AMD.
         */
-out:
        pr_info("%s\n", tsa_strings[tsa_mitigation]);
 }