From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailout2.samsung.com (mailout2.samsung.com [203.254.224.25]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 03D6CA47 for ; Tue, 8 Apr 2025 22:30:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.254.224.25 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744151434; cv=none; b=Qui4c5pnHynRmsja+8eXhlubpkw8BPVkAZmD65klgIGeuwYZnyk/eXGRIGpgVZZkrH0gq2iMGwV4AEclo6aw8VInoLtI173XI1VfMPoLgOEjd+QT+rorbZmZR+0g3tMsA8CB+R9yWB54AiU37jvtGqmQ/rK/KxKcmlVmD0TNLkI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744151434; c=relaxed/simple; bh=6iEtmnVy9/oNTMwUdmLOb5G3rvwQgHWh8nU4u7+JlJ8=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:In-Reply-To: Content-Type:References; b=jhqneI/ETz0VHwTHRS0gHpENF62tAvYAc7CIbKeRfFqDt8ItH/SiDosSdWhcuOLJhVE4x5ZfgG67Yl9KNaS/NpTbOB1ZYfrurk6+i2KGjDxg/Goou/47f5RfRIbR27egBLfYDoJ1uo/j5h+z4bFJmNgjXaIGOi6O6oDHTOTcwWo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com; spf=pass smtp.mailfrom=samsung.com; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b=O54uKXsc; arc=none smtp.client-ip=203.254.224.25 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=samsung.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="O54uKXsc" Received: from epcas2p3.samsung.com (unknown [182.195.41.55]) by mailout2.samsung.com (KnoxPortal) with ESMTP id 20250408223028epoutp020019d0dab6e6939ad53d4bee3bc8a3b3~0eHvNbF461735917359epoutp02N for ; Tue, 8 Apr 2025 22:30:28 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout2.samsung.com 20250408223028epoutp020019d0dab6e6939ad53d4bee3bc8a3b3~0eHvNbF461735917359epoutp02N DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1744151428; bh=daTWqN3jpxe4gC1xN/OLC1sxScqhKfxGORcCNJ0vXEk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=O54uKXscZZFj6S40bjZeiRkp9xtVaYplzZ0rjYc44afw6JGLy+MNK4KUuJLuHYDqK HisCgC1y73+rZN+uvY3N1/HCTvJAhvPGApfB6DKOIV4mb0gjoRdcqEw7F7bFX6+eG8 Pl3pXZZLUZWhaJiv2AXo0aYXgRUtoYv7cfL/tVPg= Received: from epsnrtp03.localdomain (unknown [182.195.42.155]) by epcas2p2.samsung.com (KnoxPortal) with ESMTPS id 20250408223028epcas2p25b57e53d0407f0b8150567e1286aeb93~0eHun056R1115911159epcas2p2w; Tue, 8 Apr 2025 22:30:28 +0000 (GMT) Received: from epsmges2p1.samsung.com (unknown [182.195.36.101]) by epsnrtp03.localdomain (Postfix) with ESMTP id 4ZXLPb3VQJz3hhTF; Tue, 8 Apr 2025 22:30:27 +0000 (GMT) Received: from epcas2p2.samsung.com ( [182.195.41.54]) by epsmges2p1.samsung.com (Symantec Messaging Gateway) with SMTP id A7.E0.09787.383A5F76; Wed, 9 Apr 2025 07:30:27 +0900 (KST) Received: from epsmtrp1.samsung.com (unknown [182.195.40.13]) by epcas2p2.samsung.com (KnoxPortal) with ESMTPA id 20250408223026epcas2p220582f5c0401b442921cda2571c595ec~0eHtfGNlY1108211082epcas2p2y; Tue, 8 Apr 2025 22:30:26 +0000 (GMT) Received: from epsmgmcp1.samsung.com (unknown [182.195.42.82]) by epsmtrp1.samsung.com (KnoxPortal) with ESMTP id 20250408223026epsmtrp190cac27ccbda6e1095b0d3de9988e5fc~0eHtdet3W2762627626epsmtrp1L; Tue, 8 Apr 2025 22:30:26 +0000 (GMT) X-AuditID: b6c32a45-9d3ff7000000263b-d8-67f5a38312dc Received: from epsmtip1.samsung.com ( [182.195.34.30]) by epsmgmcp1.samsung.com (Symantec Messaging Gateway) with SMTP id 9D.C1.19478.283A5F76; Wed, 9 Apr 2025 07:30:26 +0900 (KST) Received: from tiffany (unknown [10.229.95.142]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20250408223026epsmtip179dd352b2cf00b65b0d651d4cc0deb9c~0eHtRIngR2246222462epsmtip1D; Tue, 8 Apr 2025 22:30:26 +0000 (GMT) Date: Wed, 9 Apr 2025 07:28:51 +0900 From: Donghyeok Choe To: Marc Zyngier Cc: Youngmin Nam , Sudeep Holla , Thomas Gleixner , Saravana Kannan , Ulf Hansson , Vincent Guittot , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kernel-team@android.com, hajun.sung@samsung.com, joonki.min@samsung.com, ne.yoo@samsung.com, Donghyeok Choe Subject: Re: [GICv3 ITS]S2IDLE framework does not invoke syscore_ops in GICv3 ITS driver Message-ID: <20250408222851.GB2187207@tiffany> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <86tt6zkux7.wl-maz@kernel.org> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrKJsWRmVeSWpSXmKPExsWy7bCmmW7z4q/pBjsXi1pc2zuR3aJp/yVm i6u73zFb7NguYrHp8TVWi8u75rBZ7JxzktVi2fEuVouuQ3/ZLJaf2sFisXnTVGaL42vDLTqO fGO2WHzgE7sDn8e23dtYPdbMW8PosWBTqcemVZ1sHneu7WHzeHfuHLvH5iX1Hn1bVjF6fN4k F8AZlW2TkZqYklqkkJqXnJ+SmZduq+QdHO8cb2pmYKhraGlhrqSQl5ibaqvk4hOg65aZA3S5 kkJZYk4pUCggsbhYSd/Opii/tCRVISO/uMRWKbUgJafAvECvODG3uDQvXS8vtcTK0MDAyBSo MCE74/zNxIIzvBVTdzWyNjDO5O5i5OCQEDCR2LletYuRi0NIYAejxLSGX8xdjJxAzidGiTv/ kiASQPa9hxPYQRIgDb1v/7FCJHYyStyYPp0VouMpo8SVaREgNouAisSa1TuYQGw2AV2JSZ3b 2EBsEQFFiU8XTjKCNDMLnGCWmDe9lxHkDGGBKInH7XEgNbwCehJ/5u9hg7AFJU7OfMICUsIp oC0x7WwJxNFHOCT+uEOc4yJxdet6qNOEJV4d3wJlS0m87G9jB9kkIdDMKDHpxmsmCGcG0JmT PzNBVBlLzHrWzghiMwtkSKyado4VYoGyxJFbLBBhPomOw3/ZIcK8Eh1tQhCdKhLn+x4wwuza MPct1EQPiXUTLzJCgucqs8T+64fYJjDKzULyzSwk22YBjWUW0JRYv0sfIiwv0bx1NjNEWFpi +T8OJBULGNlWMYqlFhTnpqcWGxUYwuM5OT93EyM4PWu57mCc/PaD3iFGJg7GQ4wSHMxKIrxv J35JF+JNSaysSi3Kjy8qzUktPsRoCoylicxSosn5wAyRVxJvaGJpYGJmZmhuZGpgriTOe+jj 03QhgfTEktTs1NSC1CKYPiYOTqkGpj3/4v/+vHr93Rtx3d1pkaycfy8lKe7+ccdHjjvA58P8 6UKv9QLdtCZPqpkt8dz/ld8f5rR7yc6s/zjyyr3fTotWDpvQfUjlcUyicIct36TVeZOuLLk/ rWLT7OPf+k0vZavND362O6f9eb/bFI3U9N1eB/zPfDfSmt2ku3Lh2rmTunLElrzlOiSYqeH6 Yz8fW3SYtEliypONtd82HfbZ9ih2RvRu973MQsHWHvNf1rg4nujenrRYfv0ah59ZP5UdZ0bv nepy7YGYht8u9k/imh+2if0XkeZ6PdHhw+Ibj784lMl4F/70nnwj+Z/H2zXOorPMovk9J6dx rfpn0pbrmdw4U13YTuT/2kfMjkn65kosxRmJhlrMRcWJAKgQJA1YBAAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprJIsWRmVeSWpSXmKPExsWy7bCSnG7T4q/pBnOfmVhc2zuR3aJp/yVm i6u73zFb7NguYrHp8TVWi8u75rBZ7JxzktVi2fEuVouuQ3/ZLJaf2sFisXnTVGaL42vDLTqO fGO2WHzgE7sDn8e23dtYPdbMW8PosWBTqcemVZ1sHneu7WHzeHfuHLvH5iX1Hn1bVjF6fN4k F8AZxWWTkpqTWZZapG+XwJWxcv8atoJ3XBX7fjSxNjBe5+hi5OSQEDCR6H37j7WLkYtDSGA7 o8TEGTNZIRJSEu1bZjJB2MIS91uOQBU9ZpRo/fMArIhFQEVizeodYEVsAroSkzq3sYHYIgKK Ep8unGQEaWAWOMcscfbqXmaQhLBAlMSet9PAGngF9CT+zN/DBjG1nVni8Pk2VoiEoMTJmU9Y QGxmAXWJP/MuATVzANnSEsv/cUCE5SWat84GC3MKaEtMO1sygVFwFpLmWUiaZyE0z0LSvICR ZRWjaGpBcW56bnKBoV5xYm5xaV66XnJ+7iZGcOxpBe1gXLb+r94hRiYOxkOMEhzMSiK8byd+ SRfiTUmsrEotyo8vKs1JLT7EKM3BoiTOq5zTmSIkkJ5YkpqdmlqQWgSTZeLglGpgKpt1keuD 1pSlXJNtAo7+bDle1Mj+0Ph31kqGyg4Rpl8lCfw9r/Wc+vvu7xM2tmaO+pjWHm379MTVgqCG +CbVb1O2eptx2mfITXOXsplcOfNckOqFv32Rs9fE8HaF3fbtvSh5LvQVW72PVOCr6Xeszp84 6+Zh0hjwkyPpgjzHiudenVMdPePlfpavcVkbKlF/PcDwfRPXOv+DW3kyS/rTAmJabHKCuurz Jl0VcVmosMXojq4zd/qUvAN2W+1+ty/wtxDp/fVairdGlIXvvPji4DSB37mSuz582SVe4ur0 ut7i5LmY/++DX/zRfZNmcV0i78OPEukPcVHCtwtj7jgcvnT7sjTz76dHp6gd+a/EUpyRaKjF XFScCAANXZsKLAMAAA== X-CMS-MailID: 20250408223026epcas2p220582f5c0401b442921cda2571c595ec X-Msg-Generator: CA Content-Type: multipart/mixed; boundary="----ieZh69edyBxzv2Y5Ggo8207PwRbI2z7mQ5FWfU8PsFoZKj2n=_bae2f_" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20250408223026epcas2p220582f5c0401b442921cda2571c595ec References: <8634f0mall.wl-maz@kernel.org> <20250402-messy-wild-squid-7b4da9@sudeepholla> <20250403-rare-wasp-of-management-9bce59@sudeepholla> <20250404041323.GA685160@tiffany> <20250407-amiable-perfect-hummingbird-06ad83@sudeepholla> <20250407225146.GA2858456@tiffany> <86tt6zkux7.wl-maz@kernel.org> ------ieZh69edyBxzv2Y5Ggo8207PwRbI2z7mQ5FWfU8PsFoZKj2n=_bae2f_ Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Content-Disposition: inline On Tue, Apr 08, 2025 at 07:51:32AM +0100, Marc Zyngier wrote: > On Mon, 07 Apr 2025 23:51:46 +0100, > Donghyeok Choe wrote: > > > > [1 ] > > On Mon, Apr 07, 2025 at 10:17:43AM +0100, Sudeep Holla wrote: > > > > Do you use any suspend/resume logic in drivers/irqchip/irq-gic-pm.c ? > > No, there are parts of the GIC that require secure access, so the > > GIC save/restore is performed by the firmware. > > Since the GIC-ITS is entirely controlled as a non-secure IP, > > I think it is more efficient to perform save/restore in the kernel. > > More efficient? Give me *one* aspect of this save/restore sequence > that is done in a more efficiently way in the kernel. Dumping MMIO > accesses into memory has the exact same cost at EL1, El2 or EL3, and > splitting things along an arbitrary line to paper over bad firmware is > not a valid argument. If I had to highlight just one efficiency gain — it's that I get to reuse well-tested and well-written save/restore code without reinventing the wheel (or worse, reinventing a square one). And as for bad firmware... I guess it deserves the punishment of handling GIC ITS save/restore. That said, I truly appreciate your insight, and I’ll make an effort to avoid relying on such suboptimal kernel usage going forward. Best regards, Donghyeok Choe ------ieZh69edyBxzv2Y5Ggo8207PwRbI2z7mQ5FWfU8PsFoZKj2n=_bae2f_ Content-Type: text/plain; charset="utf-8" ------ieZh69edyBxzv2Y5Ggo8207PwRbI2z7mQ5FWfU8PsFoZKj2n=_bae2f_--