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 C275D43C05B for ; Tue, 10 Mar 2026 08:56:51 +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=1773133011; cv=none; b=sS9jhFo83scsafzQXNq2vxdAUUsvTL0lFLCPeuVCb4wcJC+F05GALwqPxMx6nabi99DoseSfQCTI8gseytWIn0U4beV77RqRjJ+sYWF0IFol5L32VUL8E+iPhVZzX5+H7b71gmO5nc6WamS8rkzwd/K1wopE9MtyFse4YfUIDFw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773133011; c=relaxed/simple; bh=j4VJOlhEknG6bMkHk1YimyiS2IexRdXTWAVCoIkrRqw=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=Mh0dxFMCVvhMQk5EG2nItrHrVW4sDYma3qtbx73Irh4buZtADEPeB1PKe9XNUr7gVCKjC11j/2kdmo4EQyL4PTmZkz+vo4n6BNJewGPTZaGGecUvK+tqThz5rhV5992ZTwZk+DNYOMUNXyvLDdY726fMlQlTwNAj9lqTlj3AprU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=npF78254; 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="npF78254" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 963C4C19423; Tue, 10 Mar 2026 08:56:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773133011; bh=j4VJOlhEknG6bMkHk1YimyiS2IexRdXTWAVCoIkrRqw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=npF78254cnnPUrOff1mK5nolouVzLkrHEqRX18KjjjopVS38NODo/rLFd9WoQthEc yaVAqwChnF0eM5NjfwFCDmwd6goHzKnfI2Pr7w/oOGqJBejchc2jqOo5C+H8kIsKgk wASeOAWMvtGwPCBwD5/8xvQJaoQLGNMKtF1qBo/do3dYumXQQT7TAgsOxcOo/puX3G IzhPmrfXuscu2tVvCbnZvhEQ1KXjhGQCGd3DgiaqXZSwzCcY9x8Lyb3zu2AuuCjO6m wh4K2kBshnkjOJVIZcgES5LVerURAb+NSuGFCtu6gVfv7KH9z+hTNuysl6wP+DL5QD k/7FL6pxJEBYw== 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 1vzstV-00000000Lru-1h7v; Tue, 10 Mar 2026 08:56:49 +0000 Date: Tue, 10 Mar 2026 08:56:48 +0000 Message-ID: <86ecls6p0v.wl-maz@kernel.org> From: Marc Zyngier To: Vincent Donnefort Cc: oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, qperret@google.com, tabba@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kernel-team@android.com Subject: Re: [PATCH] KVM: arm64: Fix ICV_DIR_EL1 trapping detection for pKVM In-Reply-To: References: <20260309160450.2610295-1-vdonnefort@google.com> <86h5qo7vr9.wl-maz@kernel.org> 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: kvmarm@lists.linux.dev 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: vdonnefort@google.com, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, qperret@google.com, tabba@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Mon, 09 Mar 2026 18:07:45 +0000, Vincent Donnefort wrote: > > [...] > > > > diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c > > > index e7790097db93..0432852228f9 100644 > > > --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c > > > +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c > > > @@ -463,6 +463,11 @@ static void handle___vgic_v3_get_gic_config(struct kvm_cpu_context *host_ctxt) > > > cpu_reg(host_ctxt, 1) = __vgic_v3_get_gic_config(); > > > } > > > > > > +static void handle___vgic_v3_get_ich_vtr_el2(struct kvm_cpu_context *host_ctxt) > > > +{ > > > + cpu_reg(host_ctxt, 1) = read_sysreg_s(SYS_ICH_VTR_EL2); > > > +} > > > + > > > static void handle___vgic_v3_init_lrs(struct kvm_cpu_context *host_ctxt) > > > { > > > __vgic_v3_init_lrs(); > > > @@ -622,6 +627,7 @@ static const hcall_t host_hcall[] = { > > > HANDLE_FUNC(__kvm_timer_set_cntvoff), > > > HANDLE_FUNC(__vgic_v3_save_aprs), > > > HANDLE_FUNC(__vgic_v3_restore_vmcr_aprs), > > > + HANDLE_FUNC(__vgic_v3_get_ich_vtr_el2), > > > HANDLE_FUNC(__pkvm_reserve_vm), > > > HANDLE_FUNC(__pkvm_unreserve_vm), > > > HANDLE_FUNC(__pkvm_init_vm), > > > > > > > This looks incredibly complicated. Since pKVM forbids late onlining of > > CPUs, you are absolutely sure that you have already seen the CPU being > > hot-plugged on. > > > > So it would make a lot more sense to just return the current value of > > the property you are trying to re-evaluate: you know for sure it > > cannot change under your feet. > > > > I have quickly tested the following hack: > > > > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > > index c31f8e17732a3..947ff71b3b66b 100644 > > --- a/arch/arm64/kernel/cpufeature.c > > +++ b/arch/arm64/kernel/cpufeature.c > > @@ -2345,6 +2345,9 @@ static bool can_trap_icv_dir_el1(const struct arm64_cpu_capabilities *entry, > > !is_midr_in_range_list(has_vgic_v3)) > > return false; > > > > + if (system_capabilities_finalized() && is_protected_kvm_enabled()) > > + return cpus_have_final_cap(ARM64_HAS_ICH_HCR_EL2_TDIR); > > + > > if (is_kernel_in_hyp_mode()) > > res.a1 = read_sysreg_s(SYS_ICH_VTR_EL2); > > else > > > > which works for me. Could you please give it a go? > > That works! I can spin a V2 with that if you want. I've sent what I had written yesterday. Tested-by appreciated! Thanks, M. -- Without deviation from the norm, progress is not possible.