From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-59.mta0.migadu.com [91.218.175.59]) (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 3CA374AD7ED for ; Tue, 15 Sep 2026 12:38:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.59 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789475942; cv=none; b=Q41EfLZB6nw6OQqBsTa5xLm0KULy/5mTXzQNgfa7F5/17TdIcfPFSlfkoloBNJoM118F1+h152E67gUeAA+Qx+4cFbS6okZ2VsnXcudEJqBx6S5zzHlPcORpHqh7e3jgtQupqtuS7WQNP7SqfQ66riO0Wam+hABuJfkjPDJDsb4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789475942; c=relaxed/simple; bh=tRWMpaS2zOGMIhR9Ho3dwkRGEMdtnMmq18pcvS3WgPs=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Ivgnb9W+Me8LlAU7LJNjsoh55O7Xubc0BTyXD5WLplIpqlCNCIqhb3Q8DG+G2HvnWVLMHtD7JWXkx1RMaZdjPim6YKr3mJcfYCcQvMqmEdLbnBTEzcrhh1uuLzrCE3tEUKgOOSX5cIq+sGwPaue6sXHPZj7LFi7IaXbUf9KQB6o= 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=oGT2/rTV; arc=none smtp.client-ip=91.218.175.59 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="oGT2/rTV" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=tRWMpaS2zOGMIhR9Ho3dwkRGEMdtnMmq18pcvS3WgPs=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1789475937; v=1; x=1790080737; b=oGT2/rTV1ZXXdvjHISk6X8hvyDgUNuQZQlzxdavVhJF4reWxcubYcPw02fXog9f+A1tL7XbQ 27wGSgYVsxFk+kCbqMVfMuSKMwGdMBhZnY0ovcp/DtOeBUJNEJwZPa5vTZioYpRoByIYVkUTPj9 FqM0ueysfvCwDJed7vNWipM4= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 9b55889483332976; Tue, 15 Sep 2026 12:38:57 +0000 X-Mizu-Trace-ID: 9b55889483332976 X-Migadu-Flow: FLOW_OUT From: Fuad Tabba To: maz@kernel.org, oupton@kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: catalin.marinas@arm.com, will@kernel.org, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, mark.rutland@arm.com, vdonnefort@google.com, qperret@google.com, Sascha.Bischoff@arm.com, steven.price@arm.com, tabba@google.com Subject: [PATCH 3/7] KVM: arm64: Validate the host-provided vgic model in pKVM Date: Tue, 15 Sep 2026 13:38:42 +0100 Message-Id: <20260915123846.2317931-4-fuad.tabba@linux.dev> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260915123846.2317931-1-fuad.tabba@linux.dev> References: <20260915123846.2317931-1-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 that are UNDEFINED without FEAT_GCIE, and panics 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 | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c index 459bd9eb7e4bc..4c33c863e90e1 100644 --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c @@ -340,13 +340,19 @@ 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. + */ + 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