From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-247.mta0.migadu.com [91.218.175.247]) (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 6E5824E73CC for ; Mon, 28 Sep 2026 15:25:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.247 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790609144; cv=none; b=fryFj6mmWK+7H1BWSGldVrJFoa5n9RTJ2/56LsagJOJkS/kqnpP3jh0ZNCEQKhPqgrKbYahnAIOArPJ3a8zZXH6ATb91RGMbSIRRczsj+UsEuKxcDKw9IYWFzetnbdzM3992bGclKwEoTPXbjSNE7an2ZRe+lkEFWcdxXXNgBmg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790609144; c=relaxed/simple; bh=P0RVNuENs3vpENd0HRdOYdMiYWEyBhUlAVznVoI9ctM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Hjuodz4NKX+YtMeeEoJAOUhen0cq84NQxSp+uSdxk2NAOPwwqfW5CfwvGJaXNbHqwbNzIqCF+sdMer0LwDWPn05MZXvo6GrVY65gXU5QJFmal8abILoPUie5xLgjT+CZYAb/l+W+JfASnWjmH6FwZd6okE4x3aC9Ub59CgsQq3c= 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=ZRQLRpgS; arc=none smtp.client-ip=91.218.175.247 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="ZRQLRpgS" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=P0RVNuENs3vpENd0HRdOYdMiYWEyBhUlAVznVoI9ctM=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1790609140; v=1; x=1791213940; b=ZRQLRpgShNNXptQTnoo4geZPAESCFlaXdtTyBZGmZvRv7slOY508pIK0WglY3qge1J5D0ZNf 7Pt18O2rA+qfSwCEV4isbB1s8GwLQ3Imr04gcSlmwwe3UEXWU8B+CQrjk8oJXFTI9Q9mqRa+zDt j+wE2DdWydpDT9aOfDRagLT4= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 7f3a0b0fc5a4363a; Mon, 28 Sep 2026 15:25:40 +0000 X-Mizu-Trace-ID: 7f3a0b0fc5a4363a X-Migadu-Flow: FLOW_OUT From: Fuad Tabba To: Marc Zyngier , Oliver Upton , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: Joey Gouly , Suzuki K Poulose , Zenghui Yu , Steffen Eiden , Catalin Marinas , Will Deacon , Mark Rutland , Jing Zhang , Karl Mehltretter , Fuad Tabba , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v1 03/10] KVM: arm64: nv: Don't loop on AT S12E{0,1}{R,W} with an invalid VTCR_EL2 Date: Mon, 28 Sep 2026 16:25:00 +0100 Message-Id: <20260928152507.2116110-4-fuad.tabba@linux.dev> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260928152507.2116110-1-fuad.tabba@linux.dev> References: <20260928152507.2116110-1-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 When KVM walks an L1 guest's stage-2 tables, a positive return means the walk faulted with the syndrome in out->esr, and a negative one means KVM couldn't complete it and the caller has to retry. The VTCR_EL2.T0SZ and SL0 checks return -EFAULT for what is the guest's own misconfiguration: an invalid SL0 is a stage-2 level 0 Translation fault (AArch64_S2InvalidSL()), and so is an out of range T0SZ that the implementation doesn't clamp (AArch64_S2TxSZFaults()). An L1 guest that programs either value therefore executes AT S12E{0,1}{R,W} forever, since the AT is never retired, and on an L2 abort KVM injects the fault and then returns -EFAULT from KVM_RUN. The T0SZ check also left the syndrome unset, so where a fault was reported at all, on an L2 abort or in PAR_EL1 after a stage-1 AT, it was an Address size fault. Return 1 with a level 0 Translation fault from both checks, as the walk does for the guest's other stage-2 faults. Fixes: fd276e71d1e7b ("KVM: arm64: nv: Handle shadow stage 2 page faults") Fixes: 92c6443222ca4 ("KVM: arm64: Propagate PTW errors up to AT emulation") Signed-off-by: Fuad Tabba --- arch/arm64/kvm/nested.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index 98c1f8c193319..a67be19e73250 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -275,13 +275,10 @@ static int walk_nested_s2_pgd(struct kvm_vcpu *vcpu, phys_addr_t ipa, stride = wi->pgshift - 3; input_size = get_ia_size(wi); - if (input_size > 48 || input_size < 25) - return -EFAULT; - - ret = check_base_s2_limits(vcpu, wi, level, input_size, stride); - if (ret) { + if (input_size > 48 || input_size < 25 || + check_base_s2_limits(vcpu, wi, level, input_size, stride)) { out->esr = compute_fsc(0, ESR_ELx_FSC_FAULT); - return ret; + return 1; } base_lower_bound = 3 + input_size - ((3 - level) * stride + -- 2.39.5