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Peter Anvin" , Paolo Bonzini , Wanpeng Li , Vitaly Kuznetsov , Andy Lutomirski , Frederic Weisbecker , "Paul E. McKenney" , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , Josh Poimboeuf , Jason Baron , 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 , Thomas =?iso-8859-1?Q?Wei=DFschuh?= , Juri Lelli , Marcelo Tosatti , Yair Podemsky , Daniel Wagner , Petr Tesarik , Dave Hansen Subject: Re: [RFC PATCH v3 13/15] context_tracking,x86: Add infrastructure to defer kernel TLBI Message-ID: <20241121111221.GE24774@noisy.programming.kicks-ass.net> References: <20241119153502.41361-1-vschneid@redhat.com> <20241119153502.41361-14-vschneid@redhat.com> <20241120152216.GM19989@noisy.programming.kicks-ass.net> <20241120153221.GM38972@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Queue-Id: 5C78EA0005 X-Rspamd-Server: rspam01 X-Stat-Signature: t7t767sh6jc8hkaktm1u8rhygf3473iy X-HE-Tag: 1732187532-411790 X-HE-Meta: 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 c7Za5O9X dyGdw0Dl+kXjBEmX33JNWL7FFjgT0gq82R/k8rWZilNnD1m61qX1k83ybYfNbIrIJp4G/iwXZZLTbPy6kTS50pJyQ1kgYMX5lyK2PWrIomCJV0Zdl06seLlhHqxt8oaLoeGcX6En3MWYD7Ca/SvHvezcMWKpFxVZyPFWp9SmoA4isayX+MRry6G3ZmC5t/GKjz4+abvAlOE6KCIfWrBebSZsY4mEjvXnVo7nYallPePGiGSS7w3ECMBLl1veMTRSQCR5Im8bmcF4d9UV/hbACXZ/XPhKH83P+b54G1waZPrUkKQNDL6Ou28jmwA== 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: List-Subscribe: List-Unsubscribe: On Wed, Nov 20, 2024 at 06:24:56PM +0100, Valentin Schneider wrote: > > Oh gawd, just having looked at xen_write_cr3() this might not be > > entirely trivial to mark noinstr :/ > > ... I hadn't even seen that. > > AIUI the CR3 RMW is not "enough" if we have PGE enabled, because then > global pages aren't flushed. > > The question becomes: what is held in global pages and do we care about > that when it comes to vmalloc()? I'm starting to think no, but this is x86, > I don't know what surprises are waiting for me. > > 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.