From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 85BB6C10F1A for ; Tue, 7 May 2024 11:45:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=kYkbx0wSABtHYjD0tST2q4R3Tm5RjkyXdWsJneg2Ks0=; b=EQC1a/maPE4jbu QFfIOiDer+PvOuXjqfIt/LLZr9uFrTN7vVOfoUDTOGqR3xWFsiXZKr7m5GGNCLjL1rFt49yNo7+gg 8sgORUIjj5s9zhcvuSdTdsVxm6vWGV99Ml7Af54yeCepiLuuZZUIuGFKW+wcsaRq5oHLpBLov9Iqe rCsRy58nvtjYTyQ50G9FyqXMfwWQ+Mv/4jBKPLVgWjiAn1mazkiFvw1WB1Ekee2rL3ilVe48FtXCV 0LKSqvhf5LpzL4zQgwqu4sTp/veOQBboHk+7G3Rx5btKKeP0i54VC+HmjX8xdoINjeeSSj1vKNrT2 9rvV+Vq71jzMB0gMWTaA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s4JG8-0000000Alsu-238a; Tue, 07 May 2024 11:45:24 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1s4JG5-0000000AlrS-2mQV for linux-arm-kernel@lists.infradead.org; Tue, 07 May 2024 11:45:23 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 769F861142; Tue, 7 May 2024 11:45:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F356CC2BBFC; Tue, 7 May 2024 11:45:16 +0000 (UTC) Date: Tue, 7 May 2024 12:45:14 +0100 From: Catalin Marinas To: Ryan Roberts Cc: Will Deacon , Joey Gouly , Ard Biesheuvel , Mark Rutland , Anshuman Khandual , David Hildenbrand , Peter Xu , Mike Rapoport , Shivansh Vij , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 0/4] arm64/mm: Enable userfaultfd write-protect Message-ID: References: <20240503144604.151095-1-ryan.roberts@arm.com> <20240507110750.GA22289@willie-the-truck> <3764382b-9fa6-4e94-ad5b-2e22e3e7c71a@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <3764382b-9fa6-4e94-ad5b-2e22e3e7c71a@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240507_044521_766625_F0315A7A X-CRM114-Status: GOOD ( 23.68 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, May 07, 2024 at 12:17:18PM +0100, Ryan Roberts wrote: > On 07/05/2024 12:07, Will Deacon wrote: > > On Fri, May 03, 2024 at 03:45:58PM +0100, Ryan Roberts wrote: > >> This series adds uffd write-protect support for arm64. > >> > >> Previous attempts to add uffd-wp (and soft-dirty) have failed because of a > >> perceived lack of available PTE SW bits. However it actually turns out that > >> there are 2 available but they are hidden. PTE_PROT_NONE was previously > >> occupying a SW bit, but can be moved, freeing up the SW bit. Bit 63 is marked as > >> "IGNORED" in the Arm ARM, but it does not currently indicate "reserved for SW > >> use" like it does for the other SW bits. I've confirmed with the spec owner that > >> this is an oversight; the bit is intended to be reserved for SW use and the spec > >> will clarify this in a future update. > >> > >> So now we have two spare bits; patch 4 enables uffd-wp on arm64, using the SW > >> bit freed up by moving PTE_PROT_NONE. This leaves bit 63 spare for future use > >> (e.g. soft-dirty - see RFC at [4] - or some other usage). > >> > >> --- > >> > >> This applies on top of v6.9-rc5. > > > > I chucked this into the CI on Friday and it looks to have survived the > > long weekend, so I've gone ahead and merged it into for-next/core. Short > > of any last minute failures (touch wood), this should land in 6.10. > > Oh great - thanks! > > Catalin was previously proposing to hold this until 6.11 - I'll leave you two to > fight it out in case that's still his preference ;-) Fine by me as well to go in 6.10. Will is taking the blame if it all falls apart ;). -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel