From: Dave Hansen <dave.hansen@intel.com>
To: Peter Zijlstra <peterz@infradead.org>,
Valentin Schneider <vschneid@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
kvm@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org,
x86@kernel.org, rcu@vger.kernel.org,
linux-kselftest@vger.kernel.org,
"Steven Rostedt" <rostedt@goodmis.org>,
"Masami Hiramatsu" <mhiramat@kernel.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Wanpeng Li" <wanpengli@tencent.com>,
"Vitaly Kuznetsov" <vkuznets@redhat.com>,
"Andy Lutomirski" <luto@kernel.org>,
"Frederic Weisbecker" <frederic@kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
"Neeraj Upadhyay" <quic_neeraju@quicinc.com>,
"Joel Fernandes" <joel@joelfernandes.org>,
"Josh Triplett" <josh@joshtriplett.org>,
"Boqun Feng" <boqun.feng@gmail.com>,
"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
"Lai Jiangshan" <jiangshanlai@gmail.com>,
Zqiang <qiang.zhang1211@gmail.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Uladzislau Rezki" <urezki@gmail.com>,
"Christoph Hellwig" <hch@infradead.org>,
"Lorenzo Stoakes" <lstoakes@gmail.com>,
"Josh Poimboeuf" <jpoimboe@kernel.org>,
"Jason Baron" <jbaron@akamai.com>,
"Kees Cook" <keescook@chromium.org>,
"Sami Tolvanen" <samitolvanen@google.com>,
"Ard Biesheuvel" <ardb@kernel.org>,
"Nicholas Piggin" <npiggin@gmail.com>,
"Juerg Haefliger" <juerg.haefliger@canonical.com>,
"Nicolas Saenz Julienne" <nsaenz@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
"Nadav Amit" <namit@vmware.com>,
"Dan Carpenter" <error27@gmail.com>,
"Chuang Wang" <nashuiliang@gmail.com>,
"Yang Jihong" <yangjihong1@huawei.com>,
"Petr Mladek" <pmladek@suse.com>,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
"Song Liu" <song@kernel.org>,
"Julian Pidancet" <julian.pidancet@oracle.com>,
"Tom Lendacky" <thomas.lendacky@amd.com>,
"Dionna Glaze" <dionnaglaze@google.com>,
"Thomas Weißschuh" <linux@weissschuh.net>,
"Juri Lelli" <juri.lelli@redhat.com>,
"Marcelo Tosatti" <mtosatti@redhat.com>,
"Yair Podemsky" <ypodemsk@redhat.com>,
"Daniel Wagner" <dwagner@suse.de>,
"Petr Tesarik" <ptesarik@suse.com>
Subject: Re: [RFC PATCH v3 13/15] context_tracking,x86: Add infrastructure to defer kernel TLBI
Date: Thu, 21 Nov 2024 07:07:44 -0800 [thread overview]
Message-ID: <4b562cd0-7500-4b3a-8f5c-e6acfea2896e@intel.com> (raw)
In-Reply-To: <20241121111221.GE24774@noisy.programming.kicks-ass.net>
On 11/21/24 03:12, Peter Zijlstra wrote:
>> I see e.g. ds_clear_cea() clears PTEs that can have the _PAGE_GLOBAL flag,
>> and it correctly uses the non-deferrable flush_tlb_kernel_range().
>
> I always forget what we use global pages for, dhansen might know, but
> let me try and have a look.
>
> I *think* we only have GLOBAL on kernel text, and that only sometimes.
I think you're remembering how _PAGE_GLOBAL gets used when KPTI is in play.
Ignoring KPTI for a sec... We use _PAGE_GLOBAL for all kernel mappings.
Before PCIDs, global mappings let the kernel TLB entries live across CR3
writes. When PCIDs are in play, global mappings let two different ASIDs
share TLB entries.
When KPTI is around, the kernel writes CR3 at user/kernel switches to
make sure secrets are unmapped and can't be leaked by Meltdown. But
unmapping those secrets doesn't do squat if they were mapped globally
since they'll still be in the TLB and quite usable. There, we're more
judicious and only mark performance-sensitive things that are not secret
to be global, like kernel text.
next prev parent reply other threads:[~2024-11-21 15:07 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-19 15:34 [RFC PATCH v3 00/15] context_tracking,x86: Defer some IPIs until a user->kernel transition Valentin Schneider
2024-11-19 15:34 ` [RFC PATCH v3 01/15] objtool: Make validate_call() recognize indirect calls to pv_ops[] Valentin Schneider
2024-11-19 20:38 ` Josh Poimboeuf
2024-11-19 15:34 ` [RFC PATCH v3 02/15] objtool: Flesh out warning related to pv_ops[] calls Valentin Schneider
2024-11-19 20:38 ` Josh Poimboeuf
2024-11-19 15:34 ` [RFC PATCH v3 03/15] sched/clock: Make sched_clock_running __ro_after_init Valentin Schneider
2024-11-19 15:34 ` [RFC PATCH v3 04/15] rcu: Add a small-width RCU watching counter debug option Valentin Schneider
2024-11-20 14:50 ` Peter Zijlstra
2024-11-20 16:15 ` Valentin Schneider
2024-11-22 12:53 ` Paul E. McKenney
2024-11-22 13:56 ` Valentin Schneider
2024-11-19 15:34 ` [RFC PATCH v3 05/15] rcutorture: Make TREE04 use CONFIG_RCU_DYNTICKS_TORTURE Valentin Schneider
2024-11-22 12:54 ` Paul E. McKenney
2024-11-19 15:34 ` [RFC PATCH v3 06/15] jump_label: Add forceful jump label type Valentin Schneider
2024-11-19 23:39 ` Josh Poimboeuf
2024-11-20 14:56 ` Peter Zijlstra
2024-11-20 14:57 ` Peter Zijlstra
2024-11-20 16:55 ` Josh Poimboeuf
2024-11-21 11:00 ` Peter Zijlstra
2024-11-21 15:38 ` Josh Poimboeuf
2024-11-21 15:51 ` Valentin Schneider
2024-11-21 20:21 ` Josh Poimboeuf
2024-11-22 10:17 ` Valentin Schneider
2024-11-20 16:24 ` Valentin Schneider
2024-11-20 0:05 ` Josh Poimboeuf
2024-11-20 10:22 ` Peter Zijlstra
2024-11-19 15:34 ` [RFC PATCH v3 07/15] x86/speculation/mds: Make mds_idle_clear forceful Valentin Schneider
2024-11-19 15:34 ` [RFC PATCH v3 08/15] sched/clock, x86: Make __sched_clock_stable forceful Valentin Schneider
2024-11-20 14:59 ` Peter Zijlstra
2024-11-20 16:34 ` Valentin Schneider
2024-11-21 11:02 ` Peter Zijlstra
2024-11-19 15:34 ` [RFC PATCH v3 09/15] objtool: Warn about non __ro_after_init static key usage in .noinstr Valentin Schneider
2024-11-20 17:13 ` Josh Poimboeuf
2024-11-19 15:34 ` [RFC PATCH v3 10/15] x86/alternatives: Record text_poke's of JUMP_TYPE_FORCEFUL labels Valentin Schneider
2024-11-19 15:34 ` [RFC PATCH v3 11/15] context-tracking: Introduce work deferral infrastructure Valentin Schneider
2024-11-20 10:54 ` Frederic Weisbecker
2024-11-20 14:23 ` Frederic Weisbecker
2024-11-20 17:10 ` Valentin Schneider
2024-11-20 17:30 ` Frederic Weisbecker
2024-11-22 14:56 ` Valentin Schneider
2024-11-24 21:46 ` Frederic Weisbecker
2024-11-29 16:40 ` Valentin Schneider
2024-11-29 22:19 ` Frederic Weisbecker
2024-11-19 15:34 ` [RFC PATCH v3 12/15] context_tracking,x86: Defer kernel text patching IPIs Valentin Schneider
2024-11-20 15:13 ` Peter Zijlstra
2024-11-19 15:35 ` [RFC PATCH v3 13/15] context_tracking,x86: Add infrastructure to defer kernel TLBI Valentin Schneider
2024-11-20 15:22 ` Peter Zijlstra
2024-11-20 15:32 ` Peter Zijlstra
2024-11-20 17:24 ` Valentin Schneider
2024-11-21 11:12 ` Peter Zijlstra
2024-11-21 15:07 ` Dave Hansen [this message]
2024-11-21 15:30 ` Peter Zijlstra
2024-12-05 17:31 ` Petr Tesarik
2024-12-09 12:04 ` Valentin Schneider
2024-12-09 12:12 ` Peter Zijlstra
2024-12-09 14:42 ` Petr Tesarik
2024-12-10 13:53 ` Valentin Schneider
2024-12-10 14:42 ` Petr Tesarik
2024-12-09 12:33 ` Petr Tesarik
2024-11-21 16:26 ` Peter Zijlstra
2024-11-19 15:35 ` [RFC PATCH v3 14/15] x86/mm, mm/vmalloc: Defer flush_tlb_kernel_range() targeting NOHZ_FULL CPUs Valentin Schneider
2024-11-19 15:35 ` [RFC PATCH v3 15/15] context-tracking: Add a Kconfig to enable IPI deferral for NO_HZ_IDLE Valentin Schneider
2024-11-19 16:45 ` [RFC PATCH v3 00/15] context_tracking,x86: Defer some IPIs until a user->kernel transition Steven Rostedt
2024-11-19 22:51 ` Valentin Schneider
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4b562cd0-7500-4b3a-8f5c-e6acfea2896e@intel.com \
--to=dave.hansen@intel.com \
--cc=Jason@zx2c4.com \
--cc=akpm@linux-foundation.org \
--cc=ardb@kernel.org \
--cc=boqun.feng@gmail.com \
--cc=bp@alien8.de \
--cc=bpf@vger.kernel.org \
--cc=corbet@lwn.net \
--cc=dave.hansen@linux.intel.com \
--cc=dionnaglaze@google.com \
--cc=dwagner@suse.de \
--cc=error27@gmail.com \
--cc=frederic@kernel.org \
--cc=hch@infradead.org \
--cc=hpa@zytor.com \
--cc=jbaron@akamai.com \
--cc=jiangshanlai@gmail.com \
--cc=joel@joelfernandes.org \
--cc=josh@joshtriplett.org \
--cc=jpoimboe@kernel.org \
--cc=juerg.haefliger@canonical.com \
--cc=julian.pidancet@oracle.com \
--cc=juri.lelli@redhat.com \
--cc=keescook@chromium.org \
--cc=kirill.shutemov@linux.intel.com \
--cc=kvm@vger.kernel.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux@weissschuh.net \
--cc=lstoakes@gmail.com \
--cc=luto@kernel.org \
--cc=mathieu.desnoyers@efficios.com \
--cc=mhiramat@kernel.org \
--cc=mingo@redhat.com \
--cc=mtosatti@redhat.com \
--cc=namit@vmware.com \
--cc=nashuiliang@gmail.com \
--cc=npiggin@gmail.com \
--cc=nsaenz@kernel.org \
--cc=paulmck@kernel.org \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=pmladek@suse.com \
--cc=ptesarik@suse.com \
--cc=qiang.zhang1211@gmail.com \
--cc=quic_neeraju@quicinc.com \
--cc=rcu@vger.kernel.org \
--cc=rostedt@goodmis.org \
--cc=samitolvanen@google.com \
--cc=song@kernel.org \
--cc=tglx@linutronix.de \
--cc=thomas.lendacky@amd.com \
--cc=urezki@gmail.com \
--cc=vkuznets@redhat.com \
--cc=vschneid@redhat.com \
--cc=wanpengli@tencent.com \
--cc=x86@kernel.org \
--cc=yangjihong1@huawei.com \
--cc=ypodemsk@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox