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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> 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> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250408_153037_580372_A597408B X-CRM114-Status: GOOD ( 23.03 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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_--