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 B77D3C56208 for ; Thu, 6 Aug 2026 10:04:01 +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-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=MWi0NI9m0cyCHv/YKcE74ooCGwGwg2XY1zvoMF0Rkgs=; b=VhBAQr1mZmnFYtc7ISXvT1QZ1b GUmUomsa2e5qf+6ECRrEBrnDML+cxx2Fm/DF3F2lWLFw0OnGj+46Acp87qY82eywXnpMWOiPdQExY /WAZl8nJ2D5oeKgBPT2bKCN6/kSuXWnekTA5sNE6iw+eqXM7POmrOa11ce1RDf5OJ7Gg4mFyzuXmT 4J4WAp1371oWJWBFpvNWeph1QCsYyHSj+CGBWfHItc26/gPaa00r2z/ty9i+mKFOai7q255drM9Sq ekc/dzs4LI6YZG11akdFlMgKHxWHt6VZEbX3KmLcwhRrdyUTLtHCEE/W6/JafqKVGj9BNnKBPJASe 78ua7Vrg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wrux7-00000005UYd-06QM; Thu, 06 Aug 2026 10:03:53 +0000 Received: from out-179.mta1.migadu.com ([95.215.58.179]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wrux4-00000005UXI-1g3X for linux-arm-kernel@lists.infradead.org; Thu, 06 Aug 2026 10:03:51 +0000 X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1786010627; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=MWi0NI9m0cyCHv/YKcE74ooCGwGwg2XY1zvoMF0Rkgs=; b=Ty5O7BPeeLVaIMGJXZp3xJGEA2mnwh1wjVXmlLzlgjj2LEBj8CpEOEdsgWEGQA42Cgf4sj CT531aboWPk63SaGlPDGkRBcWRek2DwgQE1mx1KHu32gBQF1Ay1QCy7IQY8+IAS0jTIKPR yOGYyINxpEkeLq1fsQqSfGFc7snBLZ0= From: Fuad Tabba To: Marc Zyngier , Oliver Upton , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Cc: Will Deacon , Catalin Marinas , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Sascha Bischoff Subject: [PATCH v1 1/4] KVM: arm64: Validate the host-provided vgic model in pKVM Date: Thu, 6 Aug 2026 11:02:53 +0100 Message-Id: <20260806100256.371164-2-fuad.tabba@linux.dev> In-Reply-To: <20260806100256.371164-1-fuad.tabba@linux.dev> References: <20260806100256.371164-1-fuad.tabba@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260806_030350_578904_ECC3D857 X-CRM114-Status: GOOD ( 11.70 ) 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 EL2 copies vgic_model from the host's struct kvm unchecked, and the nVHE world switch dispatches on it with no cpucap guard. A host writing KVM_DEV_TYPE_ARM_VGIC_V5 makes EL2 access GICv5 CPU interface registers, which are UNDEFINED without FEAT_GCIE and panic the hypervisor on any GICv3 machine. Accept only the models pKVM can run, forcing anything else to 0. Fixes: 9b8e3d4ca0e73 ("KVM: arm64: gic-v5: Implement GICv5 load/put and save/restore") Signed-off-by: Fuad Tabba --- arch/arm64/kvm/hyp/nvhe/pkvm.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c index 24d6f164129ac..59bb15efdca42 100644 --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c @@ -340,13 +340,25 @@ static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struc { struct kvm *kvm = &hyp_vm->kvm; unsigned long host_arch_flags = READ_ONCE(host_kvm->arch.flags); + u32 vgic_model = READ_ONCE(host_kvm->arch.vgic.vgic_model); DECLARE_BITMAP(allowed_features, KVM_VCPU_MAX_FEATURES); /* CTR_EL0 is always under host control, even for protected VMs. */ hyp_vm->kvm.arch.ctr_el0 = host_kvm->arch.ctr_el0; - /* Preserve the vgic model so that GICv3 emulation works */ - hyp_vm->kvm.arch.vgic.vgic_model = host_kvm->arch.vgic.vgic_model; + /* + * Preserve the vgic model for GICv3 emulation, but only what pKVM can + * run: the GICv5 world switch touches registers UNDEFINED at EL2 + * without FEAT_GCIE. 0 is not a valid kvm_device_type: "no vgic". + */ + switch (vgic_model) { + case KVM_DEV_TYPE_ARM_VGIC_V2: + case KVM_DEV_TYPE_ARM_VGIC_V3: + break; + default: + vgic_model = 0; + } + hyp_vm->kvm.arch.vgic.vgic_model = vgic_model; /* No restrictions for non-protected VMs. */ if (!kvm_vm_is_protected(kvm)) { -- 2.39.5