This is a note to let you know that I've just added the patch titled

kaiser: x86_cr3_pcid_noflush and x86_cr3_pcid_user

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: kaiser-x86_cr3_pcid_noflush-and-x86_cr3_pcid_user.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Wed Jan 3 18:58:12 CET 2018

From: Hugh Dickins hughd@google.com Date: Sun, 27 Aug 2017 16:24:27 -0700 Subject: kaiser: x86_cr3_pcid_noflush and x86_cr3_pcid_user

From: Hugh Dickins hughd@google.com

Mostly this commit is just unshouting X86_CR3_PCID_KERN_VAR and X86_CR3_PCID_USER_VAR: we usually name variables in lower-case.

But why does x86_cr3_pcid_noflush need to be __aligned(PAGE_SIZE)? Ah, it's a leftover from when kaiser_add_user_map() once complained about mapping the same page twice. Make it __read_mostly instead. (I'm a little uneasy about all the unrelated data which shares its page getting user-mapped too, but that was so before, and not a big deal: though we call it user-mapped, it's not mapped with _PAGE_USER.)

And there is a little change around the two calls to do_nmi(). Previously they set the NOFLUSH bit (if PCID supported) when forcing to kernel context before do_nmi(); now they also have the NOFLUSH bit set (if PCID supported) when restoring context after: nothing done in do_nmi() should require a TLB to be flushed here.

Signed-off-by: Hugh Dickins hughd@google.com Acked-by: Jiri Kosina jkosina@suse.cz Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/entry/entry_64.S | 8 ++++---- arch/x86/include/asm/kaiser.h | 11 +++++------ arch/x86/mm/kaiser.c | 13 +++++++------ 3 files changed, 16 insertions(+), 16 deletions(-)

--- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1290,11 +1290,11 @@ ENTRY(nmi) /* Unconditionally use kernel CR3 for do_nmi() */ /* %rax is saved above, so OK to clobber here */ movq %cr3, %rax + /* If PCID enabled, NOFLUSH now and NOFLUSH on return */ + orq x86_cr3_pcid_noflush, %rax pushq %rax /* mask off "user" bit of pgd address and 12 PCID bits: */ andq $(~(X86_CR3_PCID_ASID_MASK | KAISER_SHADOW_PGD_OFFSET)), %rax - /* Add back kernel PCID and "no flush" bit */ - orq X86_CR3_PCID_KERN_VAR, %rax movq %rax, %cr3 #endif call do_nmi @@ -1534,11 +1534,11 @@ end_repeat_nmi: /* Unconditionally use kernel CR3 for do_nmi() */ /* %rax is saved above, so OK to clobber here */ movq %cr3, %rax + /* If PCID enabled, NOFLUSH now and NOFLUSH on return */ + orq x86_cr3_pcid_noflush, %rax pushq %rax /* mask off "user" bit of pgd address and 12 PCID bits: */ andq $(~(X86_CR3_PCID_ASID_MASK | KAISER_SHADOW_PGD_OFFSET)), %rax - /* Add back kernel PCID and "no flush" bit */ - orq X86_CR3_PCID_KERN_VAR, %rax movq %rax, %cr3 #endif

--- a/arch/x86/include/asm/kaiser.h +++ b/arch/x86/include/asm/kaiser.h @@ -25,7 +25,7 @@ .macro _SWITCH_TO_KERNEL_CR3 reg movq %cr3, \reg andq $(~(X86_CR3_PCID_ASID_MASK | KAISER_SHADOW_PGD_OFFSET)), \reg -orq X86_CR3_PCID_KERN_VAR, \reg +orq x86_cr3_pcid_noflush, \reg movq \reg, %cr3 .endm

@@ -37,11 +37,10 @@ movq \reg, %cr3 * not enabled): so that the one register can update both memory and cr3. */ movq %cr3, \reg -andq $(~(X86_CR3_PCID_ASID_MASK | KAISER_SHADOW_PGD_OFFSET)), \reg -orq PER_CPU_VAR(X86_CR3_PCID_USER_VAR), \reg +orq PER_CPU_VAR(x86_cr3_pcid_user), \reg js 9f /* FLUSH this time, reset to NOFLUSH for next time (if PCID enabled) */ -movb \regb, PER_CPU_VAR(X86_CR3_PCID_USER_VAR+7) +movb \regb, PER_CPU_VAR(x86_cr3_pcid_user+7) 9: movq \reg, %cr3 .endm @@ -94,8 +93,8 @@ movq PER_CPU_VAR(unsafe_stack_register_b */ DECLARE_PER_CPU_USER_MAPPED(unsigned long, unsafe_stack_register_backup);

-extern unsigned long X86_CR3_PCID_KERN_VAR; -DECLARE_PER_CPU(unsigned long, X86_CR3_PCID_USER_VAR); +extern unsigned long x86_cr3_pcid_noflush; +DECLARE_PER_CPU(unsigned long, x86_cr3_pcid_user);

extern char __per_cpu_user_mapped_start[], __per_cpu_user_mapped_end[];

--- a/arch/x86/mm/kaiser.c +++ b/arch/x86/mm/kaiser.c @@ -29,8 +29,8 @@ DEFINE_PER_CPU_USER_MAPPED(unsigned long * This is also handy because systems that do not support PCIDs * just end up or'ing a 0 into their CR3, which does no harm. */ -__aligned(PAGE_SIZE) unsigned long X86_CR3_PCID_KERN_VAR; -DEFINE_PER_CPU(unsigned long, X86_CR3_PCID_USER_VAR); +unsigned long x86_cr3_pcid_noflush __read_mostly; +DEFINE_PER_CPU(unsigned long, x86_cr3_pcid_user);

/* * At runtime, the only things we map are some things for CPU @@ -304,7 +304,8 @@ void __init kaiser_init(void) sizeof(gate_desc) * NR_VECTORS, __PAGE_KERNEL);

- kaiser_add_user_map_early(&X86_CR3_PCID_KERN_VAR, PAGE_SIZE, + kaiser_add_user_map_early(&x86_cr3_pcid_noflush, + sizeof(x86_cr3_pcid_noflush), __PAGE_KERNEL); }

@@ -384,8 +385,8 @@ void kaiser_setup_pcid(void) * These variables are used by the entry/exit * code to change PCID and pgd and TLB flushing. */ - X86_CR3_PCID_KERN_VAR = kern_cr3; - this_cpu_write(X86_CR3_PCID_USER_VAR, user_cr3); + x86_cr3_pcid_noflush = kern_cr3; + this_cpu_write(x86_cr3_pcid_user, user_cr3); }

/* @@ -395,7 +396,7 @@ void kaiser_setup_pcid(void) */ void kaiser_flush_tlb_on_return_to_user(void) { - this_cpu_write(X86_CR3_PCID_USER_VAR, + this_cpu_write(x86_cr3_pcid_user, X86_CR3_PCID_USER_FLUSH | KAISER_SHADOW_PGD_OFFSET); } EXPORT_SYMBOL(kaiser_flush_tlb_on_return_to_user);

Patches currently in stable-queue which might be from hughd@google.com are

queue-4.4/kaiser-vmstat-show-nr_kaisertable-as-nr_overhead.patch queue-4.4/kaiser-add-nokaiser-boot-option-using-alternative.patch queue-4.4/kaiser-fix-unlikely-error-in-alloc_ldt_struct.patch queue-4.4/kaiser-_pgd_alloc-without-__gfp_repeat-to-avoid-stalls.patch queue-4.4/kaiser-kaiser_flush_tlb_on_return_to_user-check-pcid.patch queue-4.4/x86-paravirt-dont-patch-flush_tlb_single.patch queue-4.4/kaiser-merged-update.patch queue-4.4/kaiser-delete-kaiser_real_switch-option.patch queue-4.4/kaiser-kaiser_remove_mapping-move-along-the-pgd.patch queue-4.4/kaiser-fix-perf-crashes.patch queue-4.4/kaiser-drop-is_atomic-arg-to-kaiser_pagetable_walk.patch queue-4.4/kaiser-load_new_mm_cr3-let-switch_user_cr3-flush-user.patch queue-4.4/kaiser-enhanced-by-kernel-and-user-pcids.patch queue-4.4/kaiser-x86_cr3_pcid_noflush-and-x86_cr3_pcid_user.patch queue-4.4/kaiser-use-alternative-instead-of-x86_cr3_pcid_noflush.patch queue-4.4/kaiser-stack-map-page_size-at-thread_size-page_size.patch queue-4.4/kaiser-name-that-0x1000-kaiser_shadow_pgd_offset.patch queue-4.4/kaiser-fix-regs-to-do_nmi-ifndef-config_kaiser.patch queue-4.4/kaiser-do-not-set-_page_nx-on-pgd_none.patch queue-4.4/kaiser-tidied-up-asm-kaiser.h-somewhat.patch queue-4.4/kaiser-cleanups-while-trying-for-gold-link.patch queue-4.4/kaiser-tidied-up-kaiser_add-remove_mapping-slightly.patch queue-4.4/kaiser-fix-build-and-fixme-in-alloc_ldt_struct.patch queue-4.4/kaiser-kernel-address-isolation.patch queue-4.4/kaiser-enomem-if-kaiser_pagetable_walk-null.patch queue-4.4/kaiser-asm-tlbflush.h-handle-nopge-at-lower-level.patch queue-4.4/kaiser-paranoid_entry-pass-cr3-need-to-paranoid_exit.patch queue-4.4/kaiser-kaiser-depends-on-smp.patch queue-4.4/kaiser-pcid-0-for-kernel-and-128-for-user.patch