x86/microcode: Dont abuse the TLB-flush interface

commit 23cb7d46f371844c004784ad9552a57446f73e5a upstream.

Commit:

  ec400ddeff20 ("x86/microcode_intel_early.c: Early update ucode on Intel's CPU")

... grubbed into tlbflush internals without coherent explanation.

Since it says its a precaution and the SDM doesn't mention anything like
this, take it out back.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: fenghua.yu@intel.com
Cc: hughd@google.com
Cc: keescook@google.com
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 509046c..c2e45da 100644 (file)
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -246,20 +246,9 @@ static inline void __native_flush_tlb(void)
        preempt_enable();
 }
 
-static inline void __native_flush_tlb_global_irq_disabled(void)
-{
-       unsigned long cr4;
-
-       cr4 = this_cpu_read(cpu_tlbstate.cr4);
-       /* clear PGE */
-       native_write_cr4(cr4 & ~X86_CR4_PGE);
-       /* write old PGE again and flush TLBs */
-       native_write_cr4(cr4);
-}
-
 static inline void __native_flush_tlb_global(void)
 {
-       unsigned long flags;
+       unsigned long cr4, flags;
 
        if (static_cpu_has(X86_FEATURE_INVPCID)) {
                /*
@@ -277,7 +266,11 @@ static inline void __native_flush_tlb_global(void)
         */
        raw_local_irq_save(flags);
 
-       __native_flush_tlb_global_irq_disabled();
+       cr4 = this_cpu_read(cpu_tlbstate.cr4);
+       /* toggle PGE */
+       native_write_cr4(cr4 ^ X86_CR4_PGE);
+       /* write old PGE again and flush TLBs */
+       native_write_cr4(cr4);
 
        raw_local_irq_restore(flags);
 }

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 7dbcb7a..8ccdca6 100644 (file)
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -565,15 +565,6 @@ static void print_ucode(struct ucode_cpu_info *uci)
 }
 #else
 
-/*
- * Flush global tlb. We only do this in x86_64 where paging has been enabled
- * already and PGE should be enabled as well.
- */
-static inline void flush_tlb_early(void)
-{
-       __native_flush_tlb_global_irq_disabled();
-}
-
 static inline void print_ucode(struct ucode_cpu_info *uci)
 {
        struct microcode_intel *mc;
@@ -602,10 +593,6 @@ static int apply_microcode_early(struct ucode_cpu_info *uci, bool early)
        if (rev != mc->hdr.rev)
                return -1;
 
-#ifdef CONFIG_X86_64
-       /* Flush global tlb. This is precaution. */
-       flush_tlb_early();
-#endif
        uci->cpu_sig.rev = rev;
 
        if (early)