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 0FE2AC27C52 for ; Tue, 4 Jun 2024 20:18:14 +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-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-Transfer-Encoding:Content-ID:Content-Description:Resent-Date :Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=+XYk4eBsyKSNewmnWxMrIHa00CpHtpOJRqoE+tmXTKk=; b=2nsxNnWlnCCOEUufSDqgJjwRWW XdKW7GHe2ujVyqr5oInlIWYeYNofX3gBLX2XinO4ic+w5Qq3FB6Ef4RfB3teuv13N5b7L0fQWQhC3 WGetL/oLsWT3ObOafMmqOM496LFCaokRrJ9dsJr2MUD+2YcdWeF82zvLVebSx5ifyGJLKBZgXHwE7 dPb3KD8O1qg1rsin9U96EtS12T0DGzo1cRFSZVeK/fV5XXCEV/B4f3QyKTDT1enep8XCCTi+NK9k5 TV/kSJS49odOf4LXcD3IhGRFqtKV62aPWrgoPzZi7/VK+G7DdfuDtXEkQAOhCVPsQFcFl8H8VoXJE YiRjKMPw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sEabc-00000003ha5-3EGB; Tue, 04 Jun 2024 20:18:04 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sEaba-00000003hZf-3sOA; Tue, 04 Jun 2024 20:18:04 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 6C013614E2; Tue, 4 Jun 2024 20:18:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 50DD4C2BBFC; Tue, 4 Jun 2024 20:17:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1717532280; bh=hzO5VxyNboH0UxSA8oeS3DN/P0lxl1+qVDrF4lH35fg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YoZ0l1zC3xE7XjFm6AyGqJGICJLDpBXsff7pMRSlEudgDhIe2FAqUIlZOHMrcDAr3 JFMzUTUWby1raWnTIk9qkVwqwtiz6/Z6smnBNReiuYlHT8eUSl0Z+Aqd5Gb2Mvh34S wAKOpf6ZGKyFw6YsjI3fHnZC+rpMWQawCWhKqPCdn6EmlNin9YkQkOohgJvSm0Jfdq EA1DmGUVMobN6eu67mYDQTP4RfwK6SHx4st2n6F8wStZwJn0RmP6KpiZmkZX3cYHhC s3AwyJtNeSyuaNXCJfi8TiyYPNzftuerF7VkPZyKLtWbcx/eMh95QAsbx5XROxuYBO Zsx5ZvhbZVrFA== Date: Tue, 4 Jun 2024 21:17:54 +0100 From: Conor Dooley To: Alexandre Ghiti Cc: yunhui cui , Catalin Marinas , Will Deacon , Thomas Bogendoerfer , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Paul Walmsley , Palmer Dabbelt , Albert Ou , Andrew Morton , Ved Shanbhogue , Matt Evans , Dylan Jhong , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-mm@kvack.org Subject: Re: [External] [PATCH RFC/RFT v2 3/4] riscv: Stop emitting preventive sfence.vma for new vmalloc mappings Message-ID: <20240604-finalist-screen-c9f35b5cfc56@spud> References: <20240131155929.169961-1-alexghiti@rivosinc.com> <20240131155929.169961-4-alexghiti@rivosinc.com> <20240604-dazzling-envy-1dcf111eb2c5@spud> MIME-Version: 1.0 In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240604_131803_067190_5A2D788A X-CRM114-Status: GOOD ( 23.83 ) 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: multipart/mixed; boundary="===============6907910692179049430==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============6907910692179049430== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="rwD0Txngxq5MBoPY" Content-Disposition: inline --rwD0Txngxq5MBoPY Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jun 04, 2024 at 01:44:15PM +0200, Alexandre Ghiti wrote: > On Tue, Jun 4, 2024 at 10:52=E2=80=AFAM Conor Dooley w= rote: > > > > On Tue, Jun 04, 2024 at 09:17:26AM +0200, Alexandre Ghiti wrote: > > > On Tue, Jun 4, 2024 at 9:15=E2=80=AFAM Alexandre Ghiti wrote: > > > > On Tue, Jun 4, 2024 at 8:21=E2=80=AFAM yunhui cui wrote: > > > > > > > > > > As for the current status of the patch, there are two points that= can > > > > > be optimized: > > > > > 1. Some chip hardware implementations may not cache TLB invalid > > > > > entries, so it doesn't matter whether svvptc is available or not.= Can > > > > > we consider adding a CONFIG_RISCV_SVVPTC to control it? > > > > > > That would produce a non-portable kernel. But I'm not opposed to that > > > at all, let me check how we handle other extensions. Maybe @Conor > > > Dooley has some feedback here? > > > > To be honest, not really sure what to give feedback on. Could you > > elaborate on exactly what the option is going to do? Given the > > portability concern, I guess you were proposing that the option would > > remove the preventative fences, rather than your current patch that > > removes them via an alternative? >=20 > No no, I won't do that, we need a generic kernel for distros so that's > not even a question. What Yunhui was asking about (to me) is: can we > introduce a Kconfig option to always remove the preventive fences, > bypassing the use of alternatives altogether? >=20 > To me, it won't make a difference in terms of performance. But if we > already offer such a possibility for other extensions, well I'll do > it. Otherwise, the question is: should we start doing that? We don't do that for other extensions yet, because currently all the extensions we have options for are additive. There's like 3 alternative patchsites, and they are all just one nop? I don't see the point of having a Kconfig knob for that. --rwD0Txngxq5MBoPY Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZl92cgAKCRB4tDGHoIJi 0jejAP4q4iC1BCvHT6xTV9Sna0UEFmTHPbvuyI/Dr8hN0BftCQEA2HLRmlNNqiPJ abULfaYTpyjXRctzj8H5FL5kCUjY6gs= =929z -----END PGP SIGNATURE----- --rwD0Txngxq5MBoPY-- --===============6907910692179049430== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============6907910692179049430==--