Messages in this thread Patch in this message | | | From | Nadav Amit <> | Subject | [RFC PATCH 11/14] x86/mm: use relaxed TLB flushes when protection is removed | Date | Mon, 18 Jul 2022 05:02:09 -0700 |
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From: Nadav Amit <namit@vmware.com>
When checking x86 PTE flags to determine whether a TLB flush is needed, determine whether a relaxed TLB flush is sufficient. If protection is added (NX removed or W added), indicate that a relaxed TLB flush would suffice.
Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will@kernel.org> Cc: Yu Zhao <yuzhao@google.com> Cc: Nick Piggin <npiggin@gmail.com> Signed-off-by: Nadav Amit <namit@vmware.com> --- arch/x86/include/asm/tlbflush.h | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 230cd1d24fe6..4f98735ab07a 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -271,18 +271,23 @@ static inline enum pte_flush_type pte_flags_flush_type(unsigned long oldflags, * dirty/access bit if needed without a fault. */ const pteval_t flush_on_clear = _PAGE_DIRTY | _PAGE_PRESENT | - _PAGE_ACCESSED; + _PAGE_ACCESSED | _PAGE_RW; + const pteval_t flush_on_set = _PAGE_NX; + const pteval_t flush_on_set_relaxed = _PAGE_RW; + const pteval_t flush_on_clear_relaxed = _PAGE_NX; const pteval_t software_flags = _PAGE_SOFTW1 | _PAGE_SOFTW2 | _PAGE_SOFTW3 | _PAGE_SOFTW4; - const pteval_t flush_on_change = _PAGE_RW | _PAGE_USER | _PAGE_PWT | + const pteval_t flush_on_change = _PAGE_USER | _PAGE_PWT | _PAGE_PCD | _PAGE_PSE | _PAGE_GLOBAL | _PAGE_PAT | _PAGE_PAT_LARGE | _PAGE_PKEY_BIT0 | _PAGE_PKEY_BIT1 | - _PAGE_PKEY_BIT2 | _PAGE_PKEY_BIT3 | _PAGE_NX; + _PAGE_PKEY_BIT2 | _PAGE_PKEY_BIT3; unsigned long diff = oldflags ^ newflags; BUILD_BUG_ON(flush_on_clear & software_flags); BUILD_BUG_ON(flush_on_clear & flush_on_change); BUILD_BUG_ON(flush_on_change & software_flags); + BUILD_BUG_ON(flush_on_change & flush_on_clear_relaxed); + BUILD_BUG_ON(flush_on_change & flush_on_set_relaxed); /* Ignore software flags */ diff &= ~software_flags; @@ -301,9 +306,16 @@ static inline enum pte_flush_type pte_flags_flush_type(unsigned long oldflags, if (diff & flush_on_change) return PTE_FLUSH_STRICT; + if (diff & oldflags & flush_on_clear_relaxed) + return PTE_FLUSH_RELAXED; + + if (diff & newflags & flush_on_set_relaxed) + return PTE_FLUSH_RELAXED; + /* Ensure there are no flags that were left behind */ if (IS_ENABLED(CONFIG_DEBUG_VM) && - (diff & ~(flush_on_clear | software_flags | flush_on_change))) { + (diff & ~(flush_on_clear | flush_on_set | + software_flags | flush_on_change))) { VM_WARN_ON_ONCE(1); return PTE_FLUSH_STRICT; } -- 2.25.1
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