linux-kernel - Re: [PATCH v4 29/30] x86/mm, mm/vmalloc: Defer flush_tlb_kernel_range() targeting NOHZ

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAG48ez1Mh+DOy0ysOo7Qioxh1W7xWQyK9CLGNU9TGOsLXbg=gQ@mail.gmail.com>
Date: Tue, 14 Jan 2025 19:16:44 +0100
From: Jann Horn <jannh@...gle.com>
To: Valentin Schneider <vschneid@...hat.com>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org, 
	virtualization@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
	loongarch@...ts.linux.dev, linux-riscv@...ts.infradead.org, 
	linux-perf-users@...r.kernel.org, xen-devel@...ts.xenproject.org, 
	kvm@...r.kernel.org, linux-arch@...r.kernel.org, rcu@...r.kernel.org, 
	linux-hardening@...r.kernel.org, linux-mm@...ck.org, 
	linux-kselftest@...r.kernel.org, bpf@...r.kernel.org, 
	bcm-kernel-feedback-list@...adcom.com, Juergen Gross <jgross@...e.com>, 
	Ajay Kaher <ajay.kaher@...adcom.com>, Alexey Makhalov <alexey.amakhalov@...adcom.com>, 
	Russell King <linux@...linux.org.uk>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Huacai Chen <chenhuacai@...nel.org>, WANG Xuerui <kernel@...0n.name>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, 
	Peter Zijlstra <peterz@...radead.org>, Arnaldo Carvalho de Melo <acme@...nel.org>, 
	Namhyung Kim <namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	"Liang, Kan" <kan.liang@...ux.intel.com>, Boris Ostrovsky <boris.ostrovsky@...cle.com>, 
	Josh Poimboeuf <jpoimboe@...nel.org>, Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, 
	Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Andy Lutomirski <luto@...nel.org>, Arnd Bergmann <arnd@...db.de>, 
	Frederic Weisbecker <frederic@...nel.org>, "Paul E. McKenney" <paulmck@...nel.org>, 
	Jason Baron <jbaron@...mai.com>, Steven Rostedt <rostedt@...dmis.org>, 
	Ard Biesheuvel <ardb@...nel.org>, Neeraj Upadhyay <neeraj.upadhyay@...nel.org>, 
	Joel Fernandes <joel@...lfernandes.org>, Josh Triplett <josh@...htriplett.org>, 
	Boqun Feng <boqun.feng@...il.com>, Uladzislau Rezki <urezki@...il.com>, 
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Lai Jiangshan <jiangshanlai@...il.com>, 
	Zqiang <qiang.zhang1211@...il.com>, Juri Lelli <juri.lelli@...hat.com>, 
	Clark Williams <williams@...hat.com>, Yair Podemsky <ypodemsk@...hat.com>, 
	Tomas Glozar <tglozar@...hat.com>, Vincent Guittot <vincent.guittot@...aro.org>, 
	Dietmar Eggemann <dietmar.eggemann@....com>, Ben Segall <bsegall@...gle.com>, 
	Mel Gorman <mgorman@...e.de>, Kees Cook <kees@...nel.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, Christoph Hellwig <hch@...radead.org>, 
	Shuah Khan <shuah@...nel.org>, Sami Tolvanen <samitolvanen@...gle.com>, 
	Miguel Ojeda <ojeda@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, 
	"Mike Rapoport (Microsoft)" <rppt@...nel.org>, Samuel Holland <samuel.holland@...ive.com>, Rong Xu <xur@...gle.com>, 
	Nicolas Saenz Julienne <nsaenzju@...hat.com>, Geert Uytterhoeven <geert@...ux-m68k.org>, 
	Yosry Ahmed <yosryahmed@...gle.com>, 
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, 
	"Masami Hiramatsu (Google)" <mhiramat@...nel.org>, Jinghao Jia <jinghao7@...inois.edu>, 
	Luis Chamberlain <mcgrof@...nel.org>, Randy Dunlap <rdunlap@...radead.org>, 
	Tiezhu Yang <yangtiezhu@...ngson.cn>
Subject: Re: [PATCH v4 29/30] x86/mm, mm/vmalloc: Defer flush_tlb_kernel_range()
 targeting NOHZ_FULL CPUs

On Tue, Jan 14, 2025 at 6:51 PM Valentin Schneider <vschneid@...hat.com> wrote:
> vunmap()'s issued from housekeeping CPUs are a relatively common source of
> interference for isolated NOHZ_FULL CPUs, as they are hit by the
> flush_tlb_kernel_range() IPIs.
>
> Given that CPUs executing in userspace do not access data in the vmalloc
> range, these IPIs could be deferred until their next kernel entry.
>
> Deferral vs early entry danger zone
> ===================================
>
> This requires a guarantee that nothing in the vmalloc range can be vunmap'd
> and then accessed in early entry code.

In other words, it needs a guarantee that no vmalloc allocations that
have been created in the vmalloc region while the CPU was idle can
then be accessed during early entry, right?