x86/pti: Add attack vector controls for PTI

Disable PTI mitigation if user->kernel attack vector mitigations are
disabled.

Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250707183316.1349127-20-david.kaplan@amd.com

diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 190299834011640fcfa74a93273b178d81a8da01..6dba18f8c7155df92a1da772e014ad6841bf5376 100644 (file)
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -38,6 +38,7 @@
 #include <asm/desc.h>
 #include <asm/sections.h>
 #include <asm/set_memory.h>
+#include <asm/bugs.h>
 
 #undef pr_fmt
 #define pr_fmt(fmt)     "Kernel/User page tables isolation: " fmt
@@ -84,7 +85,8 @@ void __init pti_check_boottime_disable(void)
                return;
        }
 
-       if (cpu_mitigations_off())
+       if (pti_mode == PTI_AUTO &&
+           !cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL))
                pti_mode = PTI_FORCE_OFF;
        if (pti_mode == PTI_FORCE_OFF) {
                pti_print_if_insecure("disabled on command line.");