From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout07.his.huawei.com (canpmsgout07.his.huawei.com [113.46.200.222]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8A38E2868B5; Wed, 11 Mar 2026 03:00:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.222 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773198010; cv=none; b=r2B2jtdlS8LPfpbojXZP9TCgg97CKHFEWD4sVdtoVBICOSCBF0fQEIHhN4c3CrVUNgamKxl3pc4YnkFRb06e1q1DFrVWrhxvmOBFOpFsXF5jRRdEk9Pk555JEqNI/TWJ0j1duYei0b1hdzG0Ci4dJ114H6qFdi+SX0phiSh4PyE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773198010; c=relaxed/simple; bh=ZVNRdZOlzeflVbYT5vXQDtqpMaNUZi2VFbF2LUVNHBY=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=uooMZMzvm+9QtcxRJHnoRy+yySxcTYX1uUmvguXmrTJHhwsr2/TS42k4wK4PoQvKPNOnYEzwG2d7JW4NyqEcNJywz/Pd1UgmjUwHf1OM8z1lXAUikJNP8e9t2YD1QhletZxajT1hqFEWozyZHJQhbRWUQklVN9xBo145vUE+79M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b=UIuMwL2Z; arc=none smtp.client-ip=113.46.200.222 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b="UIuMwL2Z" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=DUKycpPzpFIpG0env8jwSvfK5sQZJJ1YY0eqvDa9Ls4=; b=UIuMwL2ZnQBHKt0OSz5st4Og2VYIGREkqW4SE+XsyKkbHXGhNjJEsAWrxVSqy6OOZJ3NLbK9Z kP8s3Xd0pnLT2F4QMacoWnfn19/NxFuvNNLMkzdoJPW46wBbTVsZOQsEtjgpquwRCBs94A0/o7e g1HUZD+aWdwNP2wFTTnfWEY= Received: from mail.maildlp.com (unknown [172.19.163.214]) by canpmsgout07.his.huawei.com (SkyGuard) with ESMTPS id 4fVwMy3T5lzLlSf; Wed, 11 Mar 2026 10:55:10 +0800 (CST) Received: from kwepemk500009.china.huawei.com (unknown [7.202.194.94]) by mail.maildlp.com (Postfix) with ESMTPS id 7FEF34056C; Wed, 11 Mar 2026 11:00:05 +0800 (CST) Received: from [10.67.121.161] (10.67.121.161) by kwepemk500009.china.huawei.com (7.202.194.94) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Wed, 11 Mar 2026 11:00:03 +0800 Message-ID: <9ef9b529-839b-4cf0-a294-5b68fe8aa768@huawei.com> Date: Wed, 11 Mar 2026 11:00:02 +0800 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 2/2] PCI/TPH: Fix get cpu steer-tag fail on ARM64 platform To: Bjorn Helgaas , Jeremy Linton CC: Bjorn Helgaas , Catalin Marinas , Will Deacon , "Rafael J . Wysocki" , Jonathan Corbet , Shuah Khan , Huacai Chen , WANG Xuerui , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , , "H . Peter Anvin" , Juergen Gross , Boris Ostrovsky , Len Brown , Sunil V L , Mark Rutland , Jonathan Cameron , Kees Cook , Yanteng Si , Sean Christopherson , Kai Huang , Tom Lendacky , Thomas Huth , Thorsten Blum , Kevin Loughlin , Zheyun Shen , Peter Zijlstra , Pawan Gupta , Xin Li , "Ahmed S . Darwish" , Sohil Mehta , Ilkka Koskinen , Robin Murphy , James Clark , Besar Wicaksono , Ma Ke , Ajit Khaparde , Wei Huang , Andy Gospodarek , Somnath Kotur , , , , , , , , , , , , , , Wathsala Vithanage References: <20260310220920.GA826995@bhelgaas> Content-Language: en-US From: fengchengwen In-Reply-To: <20260310220920.GA826995@bhelgaas> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: kwepems500001.china.huawei.com (7.221.188.70) To kwepemk500009.china.huawei.com (7.202.194.94) On 3/11/2026 6:09 AM, Bjorn Helgaas wrote: > On Tue, Mar 10, 2026 at 10:58:49AM -0500, Jeremy Linton wrote: >> On 3/9/26 10:20 PM, Chengwen Feng wrote: >>> pcie_tph_get_cpu_st() is broken on ARM64: >>> 1. pcie_tph_get_cpu_st() passes cpu_uid to the PCI ACPI DSM method. >>> cpu_uid should be the ACPI Processor UID [1]. >>> 2. In BNXT, pcie_tph_get_cpu_st() is passed a cpu_uid obtained via >>> cpumask_first(irq->cpu_mask) - the logical CPU ID of a CPU core, >>> generated and managed by kernel (e.g., [0,255] for a system with 256 >>> logical CPU cores). >>> 3. On ARM64 platforms, ACPI assigns Processor UID to cores listed in the >>> MADT table, and this UID may not match the kernel's logical CPU ID. >>> When this occurs, the mismatch results in the wrong CPU steer-tag. >>> 4. On AMD x86 the logical CPU ID is identical to the ACPI Processor UID >>> so the mismatch is not seen. > >>> int pcie_tph_get_cpu_st(struct pci_dev *pdev, enum tph_mem_type mem_type, >>> - unsigned int cpu_uid, u16 *tag) >>> + unsigned int cpu, u16 *tag) >>> { >>> #ifdef CONFIG_ACPI >>> + u32 cpu_uid = acpi_get_cpu_acpi_id(cpu); > > From AI review (gemini/gemini-3.1-pro-preview): > > Does this code need to validate that `cpu` is within bounds before > using it? Before this change, the `cpu_uid` parameter was passed > opaquely to the ACPI firmware via `tph_invoke_dsm()`, which would > gracefully handle invalid values. > > Now, `cpu` is treated as a logical CPU index and passed to > `acpi_get_cpu_acpi_id(cpu)`. On architectures like arm64 and riscv, > `acpi_get_cpu_acpi_id()` uses `cpu` directly as an array index > (`&cpu_madt_gicc[cpu]` and `&cpu_madt_rintc[cpu]`). On x86, it uses > `per_cpu(x86_cpu_to_acpiid, cpu)`. > > If a caller passes an out-of-bounds `cpu` index (for example, if an > IRQ affinity mask is empty and `cpumask_first()` returns > `nr_cpu_ids`, or if userspace passes an arbitrary ID via > `mlx5_st_alloc_index()`), this will result in an out-of-bounds > memory read. > > Consider adding a bounds check: > > if (cpu >= nr_cpu_ids) > return -EINVAL; > > I agree that this is an issue, and I think implementations of > acpi_get_cpu_acpi_id() should validate their inputs. > > I don't know if there's a value that can never be a valid ACPI CPU UID > and could be used as an error value from acpi_get_cpu_acpi_id(). I do > see a few mentions of a ~0 value meaning "all processors" (ACPI r6.6, > sec 5.2.12.13). I only have the ACPI Specification Version 6.5, so I will use v6.5 as an example. The ACPI specification does not define invalid value ranges for the ACPI UID. For the arm64 platform (Section 5.2.12.14): ACPI Processor UID: The OS associates this GICC Structure with a processor device object in the namespace when the _UID child object of the processor device evaluates to a numeric value that matches the numeric value in this field. I am concerned that we cannot implement it like this: int acpi_get_cpu_uid(unsigned int cpu) { if (cpu >= nr_cpu_ids) return -EINVAL; ... } or: u32 acpi_get_cpu_uid(unsigned int cpu) { if (cpu >= nr_cpu_ids) return U32_MAX; ... } How about implementing it as follows: s64 acpi_get_cpu_uid(unsigned int cpu) { if (cpu >= nr_cpu_ids) return -EINVAL; ... } or int acpi_get_cpu_uid(unsigned int cpu, u32 *uid) { if (cpu >= nr_cpu_ids) return -EINVAL; *uid = xxx; return 0; } Another issue: This commit also provides an implementation for the x86 platform. However, further code analysis revealed a potential problem in the implementation: The acpi_get_cpu_acpi_id() retrieves uid from x86_cpu_to_acpiid in SMP, and x86_cpu_to_acpiid is set through the call chain: acpi_parse_lapic() -> topology_register_apic() -> topo_register_apic() -> topo_set_cpuids() -> x86_cpu_to_acpiid. It appears to retrieve the "ACPI Processor UID" from ACPI Section 5.2.12.2, but the problem is that this field is only one byte in length, which may cause issues in huge-core systems. Therefore, I suggest re-implementing the acpi_get_cpu_uid function for the x86 platform. Either I provide a default implementation (shown below), or x86 guys contribute to the implementation: s64 acpi_get_cpu_uid(unsigned int cpu) { if (cpu >= nr_cpu_ids) return -EINVAL; return cpu; } Thanks >