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 1E69428DB71; Tue, 21 Oct 2025 07:50:25 +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=1761033026; cv=none; b=usGL4Frrkv4x6R3U1ixg7khmr3+tHzLwnkmdpX/aIHxwcTcLd1s2VTRThaZkFe7ahIqzgcQKsfZGXLRn1/693TDZ1zZHFYqT2avGTLM7KkKdtjkcKUTbUebGuhc8mT5DiONZwpBduKSBWaTEYK9U9ws6y+TXhCMNs34HKepGVUs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761033026; c=relaxed/simple; bh=wcjQXdXyz4a64xPChG6OrBbIDGawzNQC7URHkyMcw9s=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=c01mGMhl+PdCPiySvgOG/z1uzQRTAlS4ycJJ+t+jx8HQKVHggqc9sREhZgak3gv0f0O3bu2rHcaICh0jeBegVrAwOPC5uXTC6LsmjprrN4XUVrECdnVpZbvq4RIlE0ySUSm9mYws5E56CJfL/FYe0sT1OtgdeEgtxjwvoAyisDg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mKp8C6Kk; 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="mKp8C6Kk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99228C4CEF7; Tue, 21 Oct 2025 07:50:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761033025; bh=wcjQXdXyz4a64xPChG6OrBbIDGawzNQC7URHkyMcw9s=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=mKp8C6KkuWJAne+5zLlmaPxKLDRxc161Dmorh/7VwBWhIa4rOhvF+9t5O7TfUkGVN 5J8AZxqfUW3IoY6cvJCxl3akQySI1hE1HTLiqI81hBekdUbevEBVf6wMOpBFCvC4RB fJK80tE4UebXUiYLIb86fa5viFBux7BXSb+APfw2aW6K7hirWZAP5kC5kJQUaDbXEf D3+4ubqnMq76+F5kSiWBuuYzKPsHyGvQM5K+bhGM0B6h9NJq29ui1zi8Kz/6un/Y+W egkYBE9PEBsU0dQDzK+pfmBvipreHtG5jeD0a3d90cYvS/ZpzijvYK7WapUUBhC3kQ wVKrkvEKqxnYA== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1vB78R-0000000FkvS-0gGO; Tue, 21 Oct 2025 07:50:23 +0000 Date: Tue, 21 Oct 2025 08:50:22 +0100 Message-ID: <86frbcwv5t.wl-maz@kernel.org> From: Marc Zyngier To: Mark Brown Cc: Sascha Bischoff , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , nd , "oliver.upton@linux.dev" , Joey Gouly , Suzuki Poulose , "yuzenghui@huawei.com" , Paolo Bonzini , Linus Torvalds , Aishwarya.TCV@arm.com Subject: Re: [PATCH] KVM: arm64: gic-v3: Only set ICH_HCR traps for v2-on-v3 or v3 guests In-Reply-To: <23072856-6b8c-41e2-93d1-ea8a240a7079@sirena.org.uk> References: <20251007160704.1673584-1-sascha.bischoff@arm.com> <23072856-6b8c-41e2-93d1-ea8a240a7079@sirena.org.uk> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: broonie@kernel.org, Sascha.Bischoff@arm.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, nd@arm.com, oliver.upton@linux.dev, Joey.Gouly@arm.com, Suzuki.Poulose@arm.com, yuzenghui@huawei.com, pbonzini@redhat.com, torvalds@linux-foundation.org, Aishwarya.TCV@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Tue, 21 Oct 2025 01:21:56 +0100, Mark Brown wrote: > > On Tue, Oct 07, 2025 at 04:07:13PM +0000, Sascha Bischoff wrote: > > The ICH_HCR_EL2 traps are used when running on GICv3 hardware, or when > > running a GICv3-based guest using FEAT_GCIE_LEGACY on GICv5 > > hardware. When running a GICv2 guest on GICv3 hardware the traps are > > used to ensure that the guest never sees any part of GICv3 (only GICv2 > > is visible to the guest), and when running a GICv3 guest they are used > > to trap in specific scenarios. They are not applicable for a > > GICv2-native guest, and won't be applicable for a(n upcoming) GICv5 > > guest. > > v6.18-rc2 introduces a failure in the KVM no-vgic-v3 selftest on what > appears to be all arm64 platforms with a GICv3 in all of VHE, nVHE and > pKVM modes: > > # selftests: kvm: no-vgic-v3 > # Random seed: 0x6b8b4567 > # ==== Test Assertion Failure ==== > # arm64/no-vgic-v3.c:66: handled > # pid=3469 tid=3469 errno=4 - Interrupted system call > # 1 0x0000000000402ff7: test_run_vcpu at no-vgic-v3.c:128 > # 2 0x0000000000402213: test_guest_no_gicv3 at no-vgic-v3.c:155 > # 3 (inlined by) main at no-vgic-v3.c:174 > # 4 0x0000ffff7fca7543: ?? ??:0 > # 5 0x0000ffff7fca7617: ?? ??:0 > # 6 0x00000000004023af: _start at ??:? > # ICC_PMR_EL1 no read trap > not ok 25 selftests: kvm: no-vgic-v3 # exit=254 > > introduced by this patch, which is commit 3193287ddffb and which never > appeared in -next prior to being merged into mainline. > > It didn't appear in -next since the arm64 KVM fixes tree is not directly > in -next and it was only pulled into Paolo's tree on Saturday, a few > hours before Paolo sent his pull request to Linus, so there was no > opportunity for it to be picked up. As I've previously suggested it > does seem like it would be a good idea to include the fixes branches for > the KVM arch trees in -next (s390 is there, but I don't see the others), As I explained to you more than once, the answer is still no. We keep the two branches separate for good reasons -- for a start, they are manager by different people. If you want to manage a -fixes tree, go for it. If you want to take the -fixes branch in your CI, I have no objection. Do I support this? Absolutely not. M. -- Without deviation from the norm, progress is not possible.