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Peter Anvin" , Paolo Bonzini , Wanpeng Li , Vitaly Kuznetsov , Andy Lutomirski , Peter Zijlstra , Frederic Weisbecker , "Paul E. McKenney" , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , Josh Poimboeuf , Kees Cook , Sami Tolvanen , Ard Biesheuvel , Nicholas Piggin , Juerg Haefliger , Nicolas Saenz Julienne , "Kirill A. Shutemov" , Nadav Amit , Dan Carpenter , Chuang Wang , Yang Jihong , Petr Mladek , "Jason A. Donenfeld" , Song Liu , Julian Pidancet , Tom Lendacky , Dionna Glaze , =?utf-8?q?Thomas_Wei=C3=9Fschuh?= , Juri Lelli , Daniel Bristot de Oliveira , Marcelo Tosatti , Yair Podemsky Subject: [RFC PATCH 13/14] context_tracking,x86: Add infrastructure to defer kernel TLBI Date: Wed, 5 Jul 2023 19:12:55 +0100 Message-Id: <20230705181256.3539027-14-vschneid@redhat.com> In-Reply-To: <20230705181256.3539027-1-vschneid@redhat.com> References: <20230705181256.3539027-1-vschneid@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 836B18000A X-Stat-Signature: 6icstk9yape8nimypy8gut8dwdwggt3h X-HE-Tag: 1688581041-376475 X-HE-Meta: U2FsdGVkX18ur8AUUvC9IOc5yb/VXTgqW4azYJMUSyEcabz/sW1U9+FWM/eHpbNSFoNbQ6JXIM+jdaoEyX8IBin0KDdmKIn2acotT9aDNbmc7dPgzkltjxJJWEVB3Ojy/++YRHtmcD0v9bMSlPXphTy2h6wYN6b+iqmlysJX6gC/T6lraSjopR8mmNq8SKnLimDBVzspAucGo96TU9PJQHZPxW2ys+K3mIgw5hncs7YuGUmZnvhE+tKFouB6w1q1IIxHuaPlO9GUR8If4Q9Mxx7vGK89A+V1BeiOFOVKOgDdUasx9ANJUXJ7LIOC9BfHiWPaZM2s/iVoOwtdWf+BqWHKvUwMLZHV69wEzxxhEWVKowYF4IpmM9KYbvPQcVraXq1Mh3AE53/g4Q25B9aHuv10qOxcNHkOeByJjplpxvyP5opqALWeN/I+rxRggSxXDGQZYvI32qUHlGTMYTZl8TQyhp3ih7A3mtiZrQf/tTY9S7r2+RaPUBraWMYbVAPa8A7Zfp2aCeK2c+GJ34pR+q2qWx3CG449RK9BaRUIMCd7oJINYk74QIKjjCASkrJysaCOkJx+5dw7jLBpnXVgp0tJnRAXkbzXXV1WlyhLckBxeoqj9MbfCts1FqXMYnv0w4V4DtqhQ2LQnpv5no8b0tjSRHou4hrx2AUYgkllDMunKZQHS1dJN1I2pLg8iw82Y2JPbpBuOqtzG94jt2xQncRKFSnbL6Iqcujp7jEhBzkEvsXFPk4QYHiIbr0uDLcz7Pcvb0jKEDNOesYMwFssi4aVpCIOhBUCeHCCuYhLiOWo+ZkmHWboKCSoC4Z1mKxHd6BnwcnIAbsv0WquantEYTdJbMLegqyj9tpxuej/zKWZFi3YaZU2lvEuvb7tTKdXumQ/JYkmLBPSqWtW0DQVqU6N0P4CmUAT2ArsyCyxSPbQs2oHylyjlTpfXCj8Fy4zfNxl/HYZ5C2gLVqW281 RlpEOLI5 5UHCbDlwJFZxwQ5WpLPWQOKYeni6jvRMmK7MC98yBpa+OcvPkD4Vjf33l2zdjm1gF1MgiEcUE+8/MMrOxqRp9jtTwUbop/ERuYlDVubFtu/Frki2ahBCPCs/z+QMueFY6osAG5jFIOaYivdhjiN+lu1MX0uTJDlEJaqcKlEWyhpi+sC5gl5BNJFKs61Tb89P1QIi6wSSbS4ywx3wArwU4+dj3RL7tHrsJ4XWp X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Kernel TLB invalidation IPIs are a common source of interference on NOHZ_FULL CPUs. Given NOHZ_FULL CPUs executing in userspace are not accessing any kernel addresses, these invalidations do not need to happen immediately, and can be deferred until the next user->kernel transition. Rather than make __flush_tlb_all() noinstr, add a minimal noinstr variant that doesn't try to leverage INVPCID. FIXME: not fully noinstr compliant XXX: same issue as with ins patching, when do we access data that should be invalidated? Signed-off-by: Valentin Schneider --- arch/x86/include/asm/context_tracking_work.h | 4 ++++ arch/x86/include/asm/tlbflush.h | 1 + arch/x86/mm/tlb.c | 17 +++++++++++++++++ include/linux/context_tracking_work.h | 2 ++ 4 files changed, 24 insertions(+) diff --git a/arch/x86/include/asm/context_tracking_work.h b/arch/x86/include/asm/context_tracking_work.h index 2c66687ce00e2..9d4f021b5a45b 100644 --- a/arch/x86/include/asm/context_tracking_work.h +++ b/arch/x86/include/asm/context_tracking_work.h @@ -3,6 +3,7 @@ #define _ASM_X86_CONTEXT_TRACKING_WORK_H #include +#include static __always_inline void arch_context_tracking_work(int work) { @@ -10,6 +11,9 @@ static __always_inline void arch_context_tracking_work(int work) case CONTEXT_WORK_SYNC: sync_core(); break; + case CONTEXT_WORK_TLBI: + __flush_tlb_all_noinstr(); + break; } } diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 75bfaa4210303..9064aa0027d05 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -15,6 +15,7 @@ #include void __flush_tlb_all(void); +void noinstr __flush_tlb_all_noinstr(void); #define TLB_FLUSH_ALL -1UL #define TLB_GENERATION_INVALID 0 diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 267acf27480af..631df9189ded4 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -1237,6 +1237,23 @@ void __flush_tlb_all(void) } EXPORT_SYMBOL_GPL(__flush_tlb_all); +void noinstr __flush_tlb_all_noinstr(void) +{ + /* + * This is for invocation in early entry code that cannot be + * instrumented. A RMW to CR4 works for most cases, but relies on + * being able to flip either of the PGE or PCIDE bits. Flipping CR4.PCID + * would require also resetting CR3.PCID, so just try with CR4.PGE, else + * do the CR3 write. + * + * TODO: paravirt + */ + if (cpu_feature_enabled(X86_FEATURE_PGE)) + __native_tlb_flush_global(this_cpu_read(cpu_tlbstate.cr4)); + else + flush_tlb_local(); +} + void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch) { struct flush_tlb_info *info; diff --git a/include/linux/context_tracking_work.h b/include/linux/context_tracking_work.h index b0c7463048b60..c084a60d2fec5 100644 --- a/include/linux/context_tracking_work.h +++ b/include/linux/context_tracking_work.h @@ -7,12 +7,14 @@ enum { CONTEXT_WORK_DISABLED_OFFSET, CONTEXT_WORK_SYNC_OFFSET, + CONTEXT_WORK_TLBI_OFFSET, CONTEXT_WORK_MAX_OFFSET }; enum ct_work { CONTEXT_WORK_DISABLED = BIT(CONTEXT_WORK_DISABLED_OFFSET), CONTEXT_WORK_SYNC = BIT(CONTEXT_WORK_SYNC_OFFSET), + CONTEXT_WORK_TLBI = BIT(CONTEXT_WORK_TLBI_OFFSET), CONTEXT_WORK_MAX = BIT(CONTEXT_WORK_MAX_OFFSET) };