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AJvYcCXrwQysoQzC17N5Bsj4SZU/tnGaYaYpQSW7/73gH74rl9WL6ytupiE8d4A3l+ucdIZbd0PJg4tlpGH2Ug==@lists.linux.dev X-Gm-Message-State: AOJu0YyoBr1emfnkM2+W6LmvthxONgdmnN4z9p11i0dNdECkEeerm54v zQ4vHoekvPb+1Wufrm3ERQhtJ9ug1J5Zr+2P99EdYbR0ahyyLNEBSBLlzNa2P6o= X-Google-Smtp-Source: AGHT+IHdEc1RzSfknb4O0tEELFITV1/FMiLC99gVJNOSQQB/c+hZmMPVy98DA8PMYeZcE4ZXSNQJNQ== X-Received: by 2002:a17:902:e80b:b0:1fb:57e7:5bb4 with SMTP id d9443c01a7336-201ca1831c4mr26201755ad.37.1723509934094; Mon, 12 Aug 2024 17:45:34 -0700 (PDT) Received: from ghost ([2601:647:6700:64d0:239c:9f30:d4d6:f989]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-201cd1c86ddsm2537295ad.263.2024.08.12.17.45.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Aug 2024 17:45:33 -0700 (PDT) Date: Mon, 12 Aug 2024 17:45:30 -0700 From: Charlie Jenkins To: Conor Dooley Cc: Rob Herring , Krzysztof Kozlowski , Paul Walmsley , Palmer Dabbelt , Albert Ou , Jisheng Zhang , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , Samuel Holland , Jonathan Corbet , Shuah Khan , Guo Ren , Evan Green , Andy Chiu , Jessica Clarke , Andrew Jones , linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, Conor Dooley , Heiko Stuebner Subject: Re: [PATCH v9 00/13] riscv: Add support for xtheadvector Message-ID: References: <20240806-xtheadvector-v9-0-62a56d2da5d0@rivosinc.com> <20240809-slapping-graph-461287bac506@spud> Precedence: bulk X-Mailing-List: linux-sunxi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240809-slapping-graph-461287bac506@spud> On Fri, Aug 09, 2024 at 11:31:15PM +0100, Conor Dooley wrote: > On Tue, Aug 06, 2024 at 05:31:36PM -0700, Charlie Jenkins wrote: > > xtheadvector is a custom extension that is based upon riscv vector > > version 0.7.1 [1]. All of the vector routines have been modified to > > support this alternative vector version based upon whether xtheadvector > > was determined to be supported at boot. > > > > vlenb is not supported on the existing xtheadvector hardware, so a > > devicetree property thead,vlenb is added to provide the vlenb to Linux. > > > > There is a new hwprobe key RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0 that is > > used to request which thead vendor extensions are supported on the > > current platform. This allows future vendors to allocate hwprobe keys > > for their vendor. > > > > Support for xtheadvector is also added to the vector kselftests. > > So uh, since noone seems to have brought it up, in the light of the issues > with thead's vector implementation, (https://ghostwriteattack.com/) do we > want to enable it at all? I can make it clear in the kconfig that xtheadvector is succeptible to this attack and that it should be enabled with caution. I think we should let people that understand the risk to enable it. - Charlie