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([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id j20-20020aca1714000000b0037d8c938d62sm893861oii.50.2023.02.12.10.38.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 12 Feb 2023 10:38:29 -0800 (PST) Sender: Guenter Roeck Message-ID: <48d2ac96-abdd-23bc-b167-08dc2c1a1dbe@roeck-us.net> Date: Sun, 12 Feb 2023 10:38:26 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Content-Language: en-US To: Conor Dooley Cc: Jisheng Zhang , Palmer Dabbelt , Paul Walmsley , Albert Ou , Anup Patel , Atish Patra , Heiko Stuebner , Andrew Jones , Conor Dooley , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org References: <20230128172856.3814-1-jszhang@kernel.org> <20230212154333.GA3760469@roeck-us.net> From: Guenter Roeck Subject: Re: [PATCH v5 00/13] riscv: improve boot time isa extensions handling In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/12/23 10:20, Conor Dooley wrote: > On Sun, Feb 12, 2023 at 10:14:13AM -0800, Guenter Roeck wrote: >> On 2/12/23 10:06, Conor Dooley wrote: >>> On Sun, Feb 12, 2023 at 05:06:09PM +0000, Conor Dooley wrote: >>>> On Sun, Feb 12, 2023 at 04:33:58PM +0000, Conor Dooley wrote: >>>>> On Sun, Feb 12, 2023 at 03:59:59PM +0000, Conor Dooley wrote: >>>> >>>> So as not to lead anyone up the garden path, let me correct myself: >>>> >>>>> Hmm, so this appears to be us attempting to patch in alternatives where >>>>> none actually exists - seemingly F & D. >>>> >>>> And of course that's not true, riscv_has_extension_likely() now uses >>>> alternatives as of: >>>> bdda5d554e43 ("riscv: introduce riscv_has_extension_[un]likely()") >>>> >>>> From a quick look, it just happens that the only users are F & D. >>>> >>> >>> Samuel pointed out that this is a lockdep splat on irc. >>> There's a patch on the list that removes the lockdep annotation >>> entirely: >>> https://patchwork.kernel.org/project/linux-riscv/patch/20230202114116.3695793-1-changbin.du@huawei.com/ >>> >>> So ye, no surprises that it was config based! >>> >>> Palmer posted a "better" fix for that lockdep warning a while ago: >>> https://lore.kernel.org/all/20220322022331.32136-1-palmer@rivosinc.com/ >>> >>> So we'd have to duplicate/reuse that for cpufeature/errata patching. >>> >>> >> >> This does not (only) happen in stop_machine(). > > Yah, sorry I meant that it's the same lockdep splat as is being > addressed there. > The first patch deletes the lockdep stuff entirely, so removes the > splat. I was thinking that we'd need to take Palmer's (IMO better) > patch and do the same thing for patching alternatives, but I figure we > can just take the text_mutex itself for alternatives & not have to > dance around the lock. > > I'll go do that I suppose! Thanks a lot for the clarification. That sounds like the backtrace can be largely ignored. However, I still see that the patch series results in boot hangs with the sifive_u qemu emulation, where the log ends with "Oops - illegal instruction". Is that problem being addressed as well ? Thanks, Guenter