From e80edf9b45a0465ce8fbded75f6d5f218039a67c Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 5 Dec 2017 13:34:51 +0100 Subject: [PATCH 175/231] x86/microcode: Dont abuse the TLB-flush interface MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit CVE-2017-5754 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) Signed-off-by: Thomas Gleixner Cc: Andy Lutomirski Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: David Laight Cc: Denys Vlasenko Cc: Eduardo Valentin Cc: Greg KH Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Will Deacon 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 (cherry picked from commit 23cb7d46f371844c004784ad9552a57446f73e5a) Signed-off-by: Andy Whitcroft Signed-off-by: Kleber Sacilotto de Souza (cherry picked from commit 0f3d96d1e5aa4d9538ab1a918fb49f2c57ebb6f5) Signed-off-by: Fabian Grünbichler --- arch/x86/include/asm/tlbflush.h | 19 ++++++------------- arch/x86/kernel/cpu/microcode/intel.c | 13 ------------- 2 files changed, 6 insertions(+), 26 deletions(-) diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 6533da3036c9..6d2688a6fda0 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -234,20 +234,9 @@ 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)) { /* @@ -265,7 +254,11 @@ 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 636a5fcfdeb7..d9a8f69101aa 100644 --- a/arch/x86/kernel/cpu/microcode/intel.c +++ b/arch/x86/kernel/cpu/microcode/intel.c @@ -564,15 +564,6 @@ 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; @@ -601,10 +592,6 @@ 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) -- 2.14.2