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Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tiACX-00000004Fym-0ocZ; Wed, 12 Feb 2025 10:42:41 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id AF6CB300134; Wed, 12 Feb 2025 11:42:39 +0100 (CET) Date: Wed, 12 Feb 2025 11:42:39 +0100 From: Peter Zijlstra To: Rik van Riel Cc: x86@kernel.org, linux-kernel@vger.kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, zhengqi.arch@bytedance.com, nadav.amit@gmail.com, thomas.lendacky@amd.com, kernel-team@meta.com, linux-mm@kvack.org, akpm@linux-foundation.org, jackmanb@google.com, jannh@google.com, mhklinux@outlook.com, andrew.cooper3@citrix.com, Manali Shukla Subject: Re: [PATCH v10 09/12] x86/mm: enable broadcast TLB invalidation for multi-threaded processes Message-ID: <20250212104239.GF19118@noisy.programming.kicks-ass.net> References: <20250211210823.242681-1-riel@surriel.com> <20250211210823.242681-10-riel@surriel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250211210823.242681-10-riel@surriel.com> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 657012000F X-Stat-Signature: o9sofqyimkj8our4rh64ceekmp53pkoj X-Rspam-User: X-HE-Tag: 1739356967-54798 X-HE-Meta: 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 iruhaL9E AppTlrOVNT+MuqUALnBebCn4iJTqcJpp2SOLmEMussJUq99igRXzJHOH4m5VMiNHH89an7ok/iHwomi9Ia/MWP7syCJ5/VO97m0p80vTjosIF1T02sN+F1YiVU8nHpAv3eJcuv5TVYMgeFh54IDvY1w400pSB5+0EqiCu+jItiKmbQmgQQajMuigJ8qTDsGbzEnB7tQ3UbLrbfSLUDBWPczere8QA7mLlAlko08k+DClWc0xWjbRtKX0sbhh53zg8T4wVv2G+NC6tQfg= 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 Tue, Feb 11, 2025 at 04:08:04PM -0500, Rik van Riel wrote: I poked around at this function a little, and ended up with the below. As to your question if any INVLPGB capable hardware needs PTI; the answer is no. No AMD machine needs PTI; but it should still work, just in case someone needs to test something. static void broadcast_tlb_flush(struct flush_tlb_info *info) { unsigned long asid = info->mm->context.global_asid; bool pmd = info->stride_shift == PMD_SHIFT; unsigned long addr = info->start; /* * TLB flushes with INVLPGB are kicked off asynchronously. * The inc_mm_tlb_gen() guarantees page table updates are done * before these TLB flushes happen. */ if (info->end == TLB_FLUSH_ALL) { invlpgb_flush_single_pcid_nosync(kern_pcid(asid)); if (static_cpu_has(X86_FEATURE_PTI)) invlpgb_flush_single_pcid_nosync(user_pcid(asid)); } else do { unsigned long nr = 1; if (info->stride_shift <= PMD_SHIFT) { /* * Calculate how many pages can be flushed at once; if the * remainder of the range is less than one page, flush one. */ nr = (info->end - addr) >> info->stride_shift); nr = clamp_val(nr, 1, invlpgb_count_max); } invlpgb_flush_user_nr_nosync(kern_pcid(asid), addr, nr, pmd); if (static_cpu_has(X86_FEATURE_PTI)) invlpgb_flush_user_nr_nosync(user_pcid(asid), addr, nr, pmd); addr += nr << info->stride_shift; } while (addr < info->end); finish_asid_transition(info); /* Wait for the INVLPGBs kicked off above to finish. */ tlbsync(); }