From 815fb01b112bf5b3ec6249886cf1f844968721fc Mon Sep 17 00:00:00 2001 From: Chengwen Feng Date: Thu, 5 Mar 2026 16:36:48 +0800 Subject: [PATCH] PCI/TPH: Fix get cpu steer-tag fail on ARM64 platform Currently the pcie_tph_get_cpu_st() has an issue on ARM64 platform: 1. The pcie_tph_get_cpu_st() function directly uses cpu_uid as the input parameter to call the PCI ACPI DSM method. According to the DSM definition, the input value should be the ACPI Processor UID (see [1] for details). 2. In the Broadcom driver implementation [2] (which invokes pcie_tph_get_cpu_st()), cpu_uid is obtained via cpumask_first(irq->cpu_mask) - this is 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. As a result, the current implementation fails to retrieve the correct CPU steer-tag in such cases. 4. The function works on AMD x86 platforms only because the logical CPU ID is identical to the ACPI Processor UID on those systems. This commit fixes it by: 1. Introducing acpi_get_cpu_acpi_id() in all ACPI-enabled platforms. This new API calls get_acpi_id_for_cpu() to retrieve the ACPI Processor UID on arm64/riscv/loongarch arch, and it calls cpu_acpi_id() on x86 arch. 2. Renaming pcie_tph_get_cpu_st()'s input parameter cpu_uid to cpu for clarity, as the parameter now represents a logical CPU ID (not a UID). [1] According to ECN_TPH-ST_Revision_20200924 (https://members.pcisig.com/wg/PCI-SIG/document/15470), the input is defined as: "If the target is a processor, then this field represents the ACPI Processor UID of the processor as specified in the MADT. If the target is a processor container, then this field represents the ACPI Processor UID of the processor container as specified in the PPTT." [2] commit c214410c47d6e ("bnxt_en: Add TPH support in BNXT driver") Fixes: d2e8a34876ce ("PCI/TPH: Add Steering Tag support") Cc: stable@vger.kernel.org Signed-off-by: Chengwen Feng Signed-off-by: Linux RISC-V bot --- Documentation/PCI/tph.rst | 4 ++-- arch/arm64/kernel/acpi.c | 9 +++++++++ arch/loongarch/kernel/acpi.c | 9 +++++++++ arch/riscv/kernel/acpi.c | 10 ++++++++++ arch/x86/kernel/cpu/common.c | 17 +++++++++++++++++ drivers/pci/tph.c | 17 ++++++++++++----- include/linux/acpi.h | 10 ++++++++++ include/linux/pci-tph.h | 4 ++-- 8 files changed, 71 insertions(+), 9 deletions(-) diff --git a/Documentation/PCI/tph.rst b/Documentation/PCI/tph.rst index e8993be64fd64d..b6cf22b9bd90a5 100644 --- a/Documentation/PCI/tph.rst +++ b/Documentation/PCI/tph.rst @@ -79,10 +79,10 @@ To retrieve a Steering Tag for a target memory associated with a specific CPU, use the following function:: int pcie_tph_get_cpu_st(struct pci_dev *pdev, enum tph_mem_type type, - unsigned int cpu_uid, u16 *tag); + unsigned int cpu, u16 *tag); The `type` argument is used to specify the memory type, either volatile -or persistent, of the target memory. The `cpu_uid` argument specifies the +or persistent, of the target memory. The `cpu` argument specifies the CPU where the memory is associated to. After the ST value is retrieved, the device driver can use the following diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index af90128cfed56d..e7d4d9bd30365c 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -29,6 +29,7 @@ #include #include +#include #include #include #include @@ -458,3 +459,11 @@ int acpi_unmap_cpu(int cpu) } EXPORT_SYMBOL(acpi_unmap_cpu); #endif /* CONFIG_ACPI_HOTPLUG_CPU */ + +int acpi_get_cpu_acpi_id(unsigned int cpu) +{ + if (cpu >= nr_cpu_ids || !cpu_possible(cpu)) + return -EINVAL; + return get_acpi_id_for_cpu(cpu); +} +EXPORT_SYMBOL_GPL(acpi_get_cpu_acpi_id); diff --git a/arch/loongarch/kernel/acpi.c b/arch/loongarch/kernel/acpi.c index 1367ca759468f9..db28747a18e84a 100644 --- a/arch/loongarch/kernel/acpi.c +++ b/arch/loongarch/kernel/acpi.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -385,3 +386,11 @@ int acpi_unmap_cpu(int cpu) EXPORT_SYMBOL(acpi_unmap_cpu); #endif /* CONFIG_ACPI_HOTPLUG_CPU */ + +int acpi_get_cpu_acpi_id(unsigned int cpu) +{ + if (cpu >= nr_cpu_ids || !cpu_possible(cpu)) + return -EINVAL; + return get_acpi_id_for_cpu(cpu); +} +EXPORT_SYMBOL_GPL(acpi_get_cpu_acpi_id); diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c index 26c018ebce03c5..343d0403010a15 100644 --- a/arch/riscv/kernel/acpi.c +++ b/arch/riscv/kernel/acpi.c @@ -22,6 +22,8 @@ #include #include +#include + int acpi_noirq = 1; /* skip ACPI IRQ initialization */ int acpi_disabled = 1; EXPORT_SYMBOL(acpi_disabled); @@ -337,3 +339,11 @@ int raw_pci_write(unsigned int domain, unsigned int bus, } #endif /* CONFIG_PCI */ + +int acpi_get_cpu_acpi_id(unsigned int cpu) +{ + if (cpu >= nr_cpu_ids || !cpu_possible(cpu)) + return -EINVAL; + return get_acpi_id_for_cpu(cpu); +} +EXPORT_SYMBOL_GPL(acpi_get_cpu_acpi_id); diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 1c3261cae40c9f..9b06c76d5c0c2f 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -28,6 +28,7 @@ #include #include #include +#include #include #include @@ -57,6 +58,7 @@ #include #include #include +#include #include #include #include @@ -2643,3 +2645,18 @@ void __init arch_cpu_finalize_init(void) */ mem_encrypt_init(); } + +int acpi_get_cpu_acpi_id(unsigned int cpu) +{ + u32 acpi_id; + + if (cpu >= nr_cpu_ids || !cpu_possible(cpu)) + return -EINVAL; + + acpi_id = cpu_acpi_id(cpu); + if (acpi_id == CPU_ACPIID_INVALID) + return -ENODEV; + + return (int)acpi_id; +} +EXPORT_SYMBOL_GPL(acpi_get_cpu_acpi_id); diff --git a/drivers/pci/tph.c b/drivers/pci/tph.c index ca4f97be75389d..3cd38972fcb1c7 100644 --- a/drivers/pci/tph.c +++ b/drivers/pci/tph.c @@ -236,21 +236,28 @@ static int write_tag_to_st_table(struct pci_dev *pdev, int index, u16 tag) * with a specific CPU * @pdev: PCI device * @mem_type: target memory type (volatile or persistent RAM) - * @cpu_uid: associated CPU id + * @cpu: associated CPU id * @tag: Steering Tag to be returned * * Return the Steering Tag for a target memory that is associated with a - * specific CPU as indicated by cpu_uid. + * specific CPU as indicated by cpu. * * Return: 0 if success, otherwise negative value (-errno) */ 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 + unsigned int cpu_uid; struct pci_dev *rp; acpi_handle rp_acpi_handle; union st_info info; + int ret; + + ret = acpi_get_cpu_acpi_id(cpu); + if (ret < 0) + return ret; + cpu_uid = (unsigned int)ret; rp = pcie_find_root_port(pdev); if (!rp || !rp->bus || !rp->bus->bridge) @@ -265,9 +272,9 @@ int pcie_tph_get_cpu_st(struct pci_dev *pdev, enum tph_mem_type mem_type, *tag = tph_extract_tag(mem_type, pdev->tph_req_type, &info); - pci_dbg(pdev, "get steering tag: mem_type=%s, cpu_uid=%d, tag=%#04x\n", + pci_dbg(pdev, "get steering tag: mem_type=%s, cpu=%d, tag=%#04x\n", (mem_type == TPH_MEM_TYPE_VM) ? "volatile" : "persistent", - cpu_uid, *tag); + cpu, *tag); return 0; #else diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 3a412dcebc296d..eca76f21d2e8f4 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -324,6 +324,16 @@ int acpi_unmap_cpu(int cpu); acpi_handle acpi_get_processor_handle(int cpu); +/* + * acpi_get_cpu_acpi_id() - Get ACPI Processor UID of a specified CPU from MADT table + * @cpu: Logical CPU number (0-based) + * + * Return: ACPI Processor ID of the CPU on success (non-negative); + * -EINVAL if the CPU number is invalid or not possible; + * -ENODEV if the ACPI ID of the CPU is invalid. + */ +int acpi_get_cpu_acpi_id(unsigned int cpu); + #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr); #endif diff --git a/include/linux/pci-tph.h b/include/linux/pci-tph.h index ba28140ce67076..be68cd17f2f833 100644 --- a/include/linux/pci-tph.h +++ b/include/linux/pci-tph.h @@ -25,7 +25,7 @@ int pcie_tph_set_st_entry(struct pci_dev *pdev, unsigned int index, u16 tag); int pcie_tph_get_cpu_st(struct pci_dev *dev, enum tph_mem_type mem_type, - unsigned int cpu_uid, u16 *tag); + unsigned int cpu, u16 *tag); void pcie_disable_tph(struct pci_dev *pdev); int pcie_enable_tph(struct pci_dev *pdev, int mode); u16 pcie_tph_get_st_table_size(struct pci_dev *pdev); @@ -36,7 +36,7 @@ static inline int pcie_tph_set_st_entry(struct pci_dev *pdev, { return -EINVAL; } static inline int pcie_tph_get_cpu_st(struct pci_dev *dev, enum tph_mem_type mem_type, - unsigned int cpu_uid, u16 *tag) + unsigned int cpu, u16 *tag) { return -EINVAL; } static inline void pcie_disable_tph(struct pci_dev *pdev) { } static inline int pcie_enable_tph(struct pci_dev *pdev, int mode)