From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 CCB8A2D837C; Tue, 26 Aug 2025 16:58:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756227483; cv=none; b=XXhQxg+Z2zJ7Ls0Vfm5yhmEdAzyN7lyg7Rupp/xJ+CY/Qx7MtmI/+Iu7LJ6mJm5ZjpwOMx96WOEevVEQbTbbD63uChgix+YzdBTA201exvr4Z+D2QxGvwQ3oOxUnDtNL7jt8uNGyXA164c1FZ3zKYKVupuYV0ttdg3pYxdFmQJ0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756227483; c=relaxed/simple; bh=fnUtXDAxJfdbxKoWIvjZ0YEMsdquajfs3Wt0vqohrgU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ubMmnoo2oZu9s6x/EePqUAL6yDQNyPSEn9QLVcp1fDTzFKhnPHdwNItf1KrVl76vYqHNUSo0T4xLsZrxMtzfPtxsYoeWBgZVL2BFKsLWS+Gn86AlRsHZVg5MsrA92wClIOcSii+yml4tMhTKqDDFw9xeLeS1jATQ2bfM51G8L/o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fuvpJ+uR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fuvpJ+uR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C82A7C4CEF1; Tue, 26 Aug 2025 16:58:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756227482; bh=fnUtXDAxJfdbxKoWIvjZ0YEMsdquajfs3Wt0vqohrgU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fuvpJ+uRtRM9fzHvRv14jD9ZQo0Z+Ik1UILyoPgPF2jz8dNyPROaEFVvlvQAaXz4X ttXYaAtJGkub4HtTxq/BEINhmPDYT0kc4MO9Pt7hSTntGG0uTTAcFEzDYKdGxtFeT2 qkjkQ9Njb/UFnPIIvb1+17UQA9vp2juzNUYGm3uywq3v8NTkaS1OlNFYQ09AI39lpx YQaZvSP4SUfRf4YlPPa54Y1tNy/wsF7ZVJVKqynCB7t8JfsAtW1Xvl7gh2NjEvVbqY byeS9jwZXrmVRhx6StAaC2vlVi6HX3Ox4JExT2RQEj9zwDNL3tioAysr1mHqOoXhAg 8DUjtPx04KNjg== Date: Tue, 26 Aug 2025 16:58:00 +0000 From: Wei Liu To: Sean Christopherson Cc: Nuno Das Neves , Marc Zyngier , Oliver Upton , Catalin Marinas , Will Deacon , Tianrui Zhao , Bibo Mao , Huacai Chen , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Peter Zijlstra , Andy Lutomirski , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, loongarch@lists.linux.dev, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-hyperv@vger.kernel.org, rcu@vger.kernel.org Subject: Re: [PATCH 0/5] Drivers: hv: Fix NEED_RESCHED_LAZY and use common APIs Message-ID: References: <20250825200622.3759571-1-seanjc@google.com> <3188ca61-2591-4576-9777-1671689b7235@linux.microsoft.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Aug 25, 2025 at 05:27:16PM -0700, Sean Christopherson wrote: > On Mon, Aug 25, 2025, Nuno Das Neves wrote: > > On 8/25/2025 1:06 PM, Sean Christopherson wrote: > > > Fix a bug where MSHV root partitions don't honor NEED_RESCHED_LAZY, and then > > > deduplicate the TIF related MSHV code by turning the "kvm" entry APIs into > > > more generic "virt" APIs (which ideally would have been done when MSHV root > > > support was added). > > > > > > Assuming all is well, maybe this could go through the tip tree? > > > > > > The Hyper-V stuff and non-x86 architectures are compile-tested only. > > > > > > > Thanks Sean, I can test the root partition changes. > > > > A similar change will be needed in mshv_vtl_main.c since it also calls > > mshv_do_pre_guest_mode_work() (hence the "common" in mshv_common.c). > > Oof, more dependencies. I suppose the easiest thing would be to send a series > against > > git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git queue > > and then route everything through there? Our fixes branch is on 6.17-rc1. You can use it as a base if you want to. > > Alternatively, frontload the MSHV fixes (which I'll do regardless) and take those > through hyperv and the rest through the tip tree? That seems like an absurd > amount of juggling though, especially if we want to get the cleanups into 6.18. > And if none of these lands, it's MSHV that'll suffer the most, so betting it all > on the hyperv tree doesn't seem terrible. > I'm happy to do it however the community sees fit. > > Also, is it possible to make all the mshv driver changes in a single patch? > > It's certainly possible, but I'd prefer not do to that. > > > It seems like it would be cleaner than refactoring it in patches 1 & 2 and > > then deleting all the refactored code in patch 5. > > Only if you don't care about backporting fixes, bisection, or maintaining code. > > E.g. if checking NEED_RESCHED_LAZY somehow causes issues, it would be really nice > for that to bisect to exactly that patch, not a patch that also switches to a > completely different set of APIs. > > And if someone is wants the fixes in a pre-6.18 kernel, they don't need to > backport all of the KVM and entry code changes just to get the fix. +1 on this. Thanks, Wei > > As for the maintenance headache, see above.