x86/mm/64: Initialize CR4.PCIDE early

[mirror_ubuntu-jammy-kernel.git] / arch / x86 / kernel / cpu / common.c

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index fb1d3358a4af5bde82e5d8dd751b2db3271a2c82..775f10100d7febac27a84bb9c8deab24e119a8c8 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -169,21 +169,21 @@ static int __init x86_mpx_setup(char *s)
 __setup("nompx", x86_mpx_setup);
 
 #ifdef CONFIG_X86_64
-static int __init x86_pcid_setup(char *s)
+static int __init x86_nopcid_setup(char *s)
 {
-       /* require an exact match without trailing characters */
-       if (strlen(s))
-               return 0;
+       /* nopcid doesn't accept parameters */
+       if (s)
+               return -EINVAL;
 
        /* do not emit a message if the feature is not present */
        if (!boot_cpu_has(X86_FEATURE_PCID))
-               return 1;
+               return 0;
 
        setup_clear_cpu_cap(X86_FEATURE_PCID);
        pr_info("nopcid: PCID feature disabled\n");
-       return 1;
+       return 0;
 }
-__setup("nopcid", x86_pcid_setup);
+early_param("nopcid", x86_nopcid_setup);
 #endif
 
 static int __init x86_noinvpcid_setup(char *s)
@@ -329,38 +329,6 @@ static __always_inline void setup_smap(struct cpuinfo_x86 *c)
        }
 }
 
-static void setup_pcid(struct cpuinfo_x86 *c)
-{
-       if (cpu_has(c, X86_FEATURE_PCID)) {
-               if (cpu_has(c, X86_FEATURE_PGE)) {
-                       /*
-                        * We'd like to use cr4_set_bits_and_update_boot(),
-                        * but we can't.  CR4.PCIDE is special and can only
-                        * be set in long mode, and the early CPU init code
-                        * doesn't know this and would try to restore CR4.PCIDE
-                        * prior to entering long mode.
-                        *
-                        * Instead, we rely on the fact that hotplug, resume,
-                        * etc all fully restore CR4 before they write anything
-                        * that could have nonzero PCID bits to CR3.  CR4.PCIDE
-                        * has no effect on the page tables themselves, so we
-                        * don't need it to be restored early.
-                        */
-                       cr4_set_bits(X86_CR4_PCIDE);
-               } else {
-                       /*
-                        * flush_tlb_all(), as currently implemented, won't
-                        * work if PCID is on but PGE is not.  Since that
-                        * combination doesn't exist on real hardware, there's
-                        * no reason to try to fully support it, but it's
-                        * polite to avoid corrupting data if we're on
-                        * an improperly configured VM.
-                        */
-                       clear_cpu_cap(c, X86_FEATURE_PCID);
-               }
-       }
-}
-
 /*
  * Protection Keys are not available in 32-bit mode.
  */
@@ -1175,9 +1143,6 @@ static void identify_cpu(struct cpuinfo_x86 *c)
        setup_smep(c);
        setup_smap(c);
 
-       /* Set up PCID */
-       setup_pcid(c);
-
        /*
         * The vendor-specific functions might have changed features.
         * Now we do "generic changes."