From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5846FCCF2E0 for ; Mon, 19 Oct 2026 10:34:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: References:In-Reply-To:Subject:Cc:To:From:Message-ID:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=NMtvbHH/I1g/sQXpRj+No1jY0sXXAfdKFZfF15Bu6bE=; b=FykZg3AF5ZSLtYPbzhFntwnsY1 9R5hbQD8kDWVLeY066dUVcuLUwKxCp2yKm66qAg5rYtAKqsLjmlbwJj98P1mzsK3adVvAT/KjLeoh ewDpxMBMszpvyBi0BgA1a4qGvndlaZg+qGjGQyrVjD/dIBEGauaqNy6YRXN0/h19mZFf7rmioelv5 F0OTKywU9HKeCsATS9GI52VaS9IMg80joV4XIFxM5wRjfqF9A2d0VUbMV1Pq8tsDB2z4Ts38y0vzz fFfHPAiHJ+K8jzTp0wTKU/zkTugskKT70WOBouHZ3HI+K1EwFz3l5dh+1+6W0ZOlBsWQfStVVzIUZ zLXUlY/A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xIkhK-00000007D6J-49Hs; Mon, 19 Oct 2026 10:34:30 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xIkhG-00000007D5X-2zF8 for linux-arm-kernel@lists.infradead.org; Mon, 19 Oct 2026 10:34:26 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 76B3843AF9; Mon, 19 Oct 2026 10:34:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5885A1F000C4; Mon, 19 Oct 2026 10:34:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792406066; bh=NMtvbHH/I1g/sQXpRj+No1jY0sXXAfdKFZfF15Bu6bE=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=M68/nfybPNjbZPiQO8pigg38b3hBoKXHKg+Pa91kYA3owPZ3ebobdyeWdkPPUTvrg adywnocygiCIF3N3KK5qw/goS4vmRDBa/QbV4eXUEFMw6bEOKevvyBQySVbfPBO1aO CNZxhEP5+5oSUbMH7O5qdSOKC6JRY4/XOkFdQRllS3E12XxPcIz/LTzoMBVXazd6kb yLr+2I3FUzSYYEYioLDUz/YXU+Joym1IQjs40U+AAZaMuuqTs1TOqoU9NxkBP9MCAX O+J0ylb4hWFjwAeGD3AoWN+y+ds7I5j72dwntCXEfZTj3Cmhgl3fHS3XtazwvK50zF EZhqoGbpc5SNQ== 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 1xIkhE-00000004b2A-0Ezl; Mon, 19 Oct 2026 10:34:24 +0000 Date: Mon, 19 Oct 2026 11:34:23 +0100 Message-ID: <86y0buyo5s.wl-maz@kernel.org> From: Marc Zyngier To: Fuad Tabba Cc: Oliver Upton , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Mark Rutland , Vincent Donnefort , Quentin Perret , Fuad Tabba , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] KVM: arm64: Track physical CPU number at EL2 In-Reply-To: <20261014125510.2928306-2-fuad.tabba@linux.dev> References: <20261014125510.2928306-1-fuad.tabba@linux.dev> <20261014125510.2928306-2-fuad.tabba@linux.dev> 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) 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: fuad.tabba@linux.dev, oupton@kernel.org, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, vdonnefort@google.com, qperret@google.com, tabba@google.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, 14 Oct 2026 13:55:09 +0100, Fuad Tabba wrote: > > The nVHE hypervisor has no equivalent of smp_processor_id(), so EL2 code > has no index for the CPU it runs on. > > Add a hyp per-CPU hyp_cpu_number, which the host writes in > cpu_prepare_hyp_mode() before it's deprivileged, and a > hyp_smp_processor_id() accessor to read it. The next patch uses it to > index per-CPU state in a hyp VM. > > Signed-off-by: Fuad Tabba > --- > arch/arm64/include/asm/kvm_hyp.h | 3 +++ > arch/arm64/kvm/arm.c | 3 +++ > arch/arm64/kvm/hyp/nvhe/hyp-smp.c | 2 ++ > 3 files changed, 8 insertions(+) > > diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h > index b0e42be3d9eef..6c4169a14b73e 100644 > --- a/arch/arm64/include/asm/kvm_hyp.h > +++ b/arch/arm64/include/asm/kvm_hyp.h > @@ -16,6 +16,9 @@ > DECLARE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt); > DECLARE_PER_CPU(unsigned long, kvm_hyp_vector); > DECLARE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params); > +DECLARE_PER_CPU(int, hyp_cpu_number); > + > +#define hyp_smp_processor_id() (__this_cpu_read(hyp_cpu_number)) > Do we really need this? I was hoping that TPIDR_EL2 would give us a way to compute the CPU number more or less directly, without having to maintain per-CPU variable (which is pretty backward, when you think about it...). M. -- Without deviation from the norm, progress is not possible.