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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8A987C531DC for ; Tue, 20 Aug 2024 17:56:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2185A6B0088; Tue, 20 Aug 2024 13:56:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1C7F36B0089; Tue, 20 Aug 2024 13:56:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 08F8D6B008A; Tue, 20 Aug 2024 13:56:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id DEA356B0088 for ; Tue, 20 Aug 2024 13:56:31 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 8DFF640409 for ; Tue, 20 Aug 2024 17:56:31 +0000 (UTC) X-FDA: 82473378582.24.BB746F9 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf14.hostedemail.com (Postfix) with ESMTP id CBD3110001C for ; Tue, 20 Aug 2024 17:56:29 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=kMBNHgu8; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf14.hostedemail.com: domain of broonie@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=broonie@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1724176501; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=e11pN2BdH2hSkSs+MwLNCsr30fsWEsmDq6STmO8Srtw=; b=F4GJTXqlqi7a3MthPPzfR6HRFIMggQYIstS4rvQT7GicHSUsPouGI4+GRpOqmEKhqj/LDH BkCUJ6nUIHcFrQ+H4GYfwZaXDvPpNi7cFKqMThLBAye/5od7sPdayjP+ogMasg11jfmaNx qHnwJvvQbeNTf+OIommJXI4iVIG0sII= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1724176501; a=rsa-sha256; cv=none; b=xbVYiTfxxzivSolo2OoJTkhCy3DVx9iGgG9QrhsZ1lFQBHTqKAymdwK50ISmrx74WzEVjz y4s1VyS4uhimTE6D+ifTctfN0z0HpwPMfEpB21BR+ybxXN+CFFhf46HtV19B7LKYVjzxS9 jbyHVEAkXSgAKwo7WT8ScAiFZQjAJjo= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=kMBNHgu8; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf14.hostedemail.com: domain of broonie@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=broonie@kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id C44D160E86; Tue, 20 Aug 2024 17:56:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA60CC4AF63; Tue, 20 Aug 2024 17:56:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724176588; bh=gZbF78Vf8hQyyvrqZwyllYGTMkZkFUc2boH3xNoj3xg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kMBNHgu8QiEUNr6Dj0H9OBOYNtuyoJmzRNKbBHyDLb+AJcBwiuh2LgJrzteoMvVsx 5LXnhtvTMAUrTQWGO8C4/3pUWw0n2Ty4gAoWYmAT+yBC5FbQ2efuWgCCm9W086xLv1 Zz0YOIynNZ511iDRjmQKgI/z2W0DSwrGpMHtyIFX7gsM+jxsuh0nwza7zZ/cUCLkch 5kByC8ltUO3h9EBYmOklMwhN2gyHbUmRzoURFqk+UuCaO0bvG1QT+x0RnLV4jkxDZv rOQIythKgjlcvs2q9paWHNJINWO8TqkFa8qlRlL1CfSG4cDj+KBmcAFn41ujrmw+M5 1HSxxSLa5whtA== Date: Tue, 20 Aug 2024 18:56:19 +0100 From: Mark Brown To: Catalin Marinas Cc: Will Deacon , Jonathan Corbet , Andrew Morton , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Arnd Bergmann , Oleg Nesterov , Eric Biederman , Shuah Khan , "Rick P. Edgecombe" , Deepak Gupta , Ard Biesheuvel , Szabolcs Nagy , Kees Cook , "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Florian Weimer , Christian Brauner , Thiago Jung Bauermann , Ross Burton , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH v10 19/40] arm64/gcs: Context switch GCS state for EL0 Message-ID: <3b316422-7f88-4f5d-a691-eb9209ec4ba9@sirena.org.uk> References: <20240801-arm64-gcs-v10-0-699e2bd2190b@kernel.org> <20240801-arm64-gcs-v10-19-699e2bd2190b@kernel.org> <0f6fd3ec-2481-4507-af0e-3cbbb7406b54@sirena.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="3PN7G0mWO4eG7H9j" Content-Disposition: inline In-Reply-To: <0f6fd3ec-2481-4507-af0e-3cbbb7406b54@sirena.org.uk> X-Cookie: You are false data. X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: CBD3110001C X-Stat-Signature: h7wsa4tbfecwn64zukufp3cmc5x44biy X-Rspam-User: X-HE-Tag: 1724176589-639764 X-HE-Meta: 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 lrCa33WN Sy3xtUifQDCFKr4ReZrIs/Q8K3nV3rywZRtPoHJXEyPSiW62pJ948ch6OGerK397U+C6p5V5W7/wLbzTkHApycDT/PDcXmOonw3ReIAhsw7SBMpYCMR/dzwGKuTbGEmYKxGX0lRpkpRjox2DsM0HeGEkSSVD2NleL9qy5KAfgtpLTFMwSo5cm8T3v6nu6htB3aLJWqdJ+VHsxanGLQpFRlKmksOsoh0PEt5O52d8LSAOu84+Z3E2brZ3QBg1pz+7od4m23zc4pryI4nrZQyIRjHmnEU6YnKhLTCaUW6KKUGOzKdX9VKrvSZo5KDuj2Q06C82yAMdXpLdumYukxfUA9om5QqGZ3U9IcagTzXQafYS7IbKqgZ9G51KjaCx8wfzRw2v8 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: --3PN7G0mWO4eG7H9j Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Aug 19, 2024 at 04:44:52PM +0100, Mark Brown wrote: > On Mon, Aug 19, 2024 at 12:46:13PM +0100, Catalin Marinas wrote: > > On Thu, Aug 01, 2024 at 01:06:46PM +0100, Mark Brown wrote: > > > + /* > > > + * Ensure that GCS changes are observable by/from other PEs in > > > + * case of migration. > > > + */ > > > + if (task_gcs_el0_enabled(current) || task_gcs_el0_enabled(next)) > > > + gcsb_dsync(); > > Could we do the sysreg writing under this 'if' block? If no app is using > > GCS (which would be the case for a while), it looks like unnecessary > > sysreg accesses. > Yes, that should be fine I think. I forgot when writing the above that we always allow reads from GCSPR_EL0 in order to avoid corner cases for unwinders in the case of asynchronous disable. I'd expect that to be cheap to access though. --3PN7G0mWO4eG7H9j Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmbE2MIACgkQJNaLcl1U h9DGLQf+N5+bf9wgOIIzNX1vkURDnQUEK8nayHI+jFDZJUtCwgCR7dnbVvAybutt pxS7u/jQBZvRrPuIk4JAvlPy/uRMzwfk9ooJ/US3OA2OmcbLQX+k4cNNxkx4uJiN XP2g8aMT14h2hwKkusxr8dUCwyB55hTlFvHPsLZQ24dqsLp2FMZOXqIjEhjPth/I qtq8/NVfk4nBuJ2M9HAMVMTiB9RxjE0dkqvWrD11wiWoD4oxozxMWze93JijR2LZ 2DkwdCLX0oezojVLBNXak0Qyw5JCKP+y1UDdtsLfN2kKyEljQp9lr5+hTUdEjv+N JBdNzCm5oAI+cdBJ0+S4fqr7zDDDLg== =Yb1u -----END PGP SIGNATURE----- --3PN7G0mWO4eG7H9j--