From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-194.mta0.migadu.com [91.218.175.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 93DF73AFD16 for ; Mon, 17 Aug 2026 10:32:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.194 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786962761; cv=none; b=Kn7YM2k7hgtrYPp/Xlx5j8PAcd4HmlCEriMMxQYKwNBr+/hGlOXHy9FtxfgjynubemPc6+ZUSb7BiwlPiRSDXyq47ksUG6MpnYERYpRxgJMXBRmNUcw3pMP1ENvyVuq497e50DjX0lsNPD47FDpiBE1bBnKEKf4mg3vXTZmmh7Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786962761; c=relaxed/simple; bh=iOgWnCEhDGyg56J6gm4nwCS3dgCjFHT30oB0fu9Wrzc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=lvee8MmeSeChjnrGhPpOLUJGygItwwDjHqM1J5FGQ6N6cYMhWbbG7tUBjyIjRnXPl2kYpttn21lAlfvV0wN6LSR/etG2HL/M+icbrM5kSzHSCUek6K2iZoIHmndbyNqHEqMVEsal+Usp+aTcnECfOms5JXMZa7j6YyMdZP/YkvI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=P0hIBph8; arc=none smtp.client-ip=91.218.175.194 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="P0hIBph8" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=iOgWnCEhDGyg56J6gm4nwCS3dgCjFHT30oB0fu9Wrzc=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1786962757; v=1; x=1787567557; b=P0hIBph8QvyowagfkE397x6s/R4i/4IuIugcN9foyvrA00O1OFkjuz4YdnxnxKIfCbprQoRt R/5jYwS5xKPhlUZqQLz/ARWELJPusR9nnaLI/3nZS7kyq7Onui07FfZUVOe+1K9RVj3KpWX4TmE AgZNq6Sx4+cqmLlka2c7Opv4= X-Envelope-To: linux-kernel@vger.kernel.org Received: from claudy.lan (37.156.72.212) by smtp.migadu.com with ESMTPS id 0a54397236c5e6e6; Mon, 17 Aug 2026 10:32:37 +0000 X-Migadu-Flow: FLOW_OUT From: Fuad Tabba To: Marc Zyngier , Oliver Upton , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Cc: Fuad Tabba , Will Deacon , Catalin Marinas , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Sascha Bischoff Subject: [PATCH v2 1/4] KVM: arm64: Validate the host-provided vgic model in pKVM Date: Mon, 17 Aug 2026 11:32:25 +0100 Message-Id: <20260817103228.1203140-2-fuad.tabba@linux.dev> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260817103228.1203140-1-fuad.tabba@linux.dev> References: <20260817103228.1203140-1-fuad.tabba@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 GICv3, the one model pKVM supports, 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 | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c index 24d6f164129ac..f41b92c50ad7d 100644 --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c @@ -340,13 +340,20 @@ 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; + /* + * GICv3 is the only model pKVM runs, and the GICv5 world switch + * touches registers UNDEFINED at EL2 without FEAT_GCIE. 0 is not a + * valid kvm_device_type: "no vgic". + */ + if (vgic_model != KVM_DEV_TYPE_ARM_VGIC_V3) + 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