cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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pci.c (1219B)

      1// SPDX-License-Identifier: ISC
      2/*
      3 * Copyright (C) 2019 Lorenzo Bianconi <lorenzo@kernel.org>
      4 */
      5
      6#include "mt76.h"
      7#include <linux/pci.h>
      8
      9void mt76_pci_disable_aspm(struct pci_dev *pdev)
     10{
     11	struct pci_dev *parent = pdev->bus->self;
     12	u16 aspm_conf, parent_aspm_conf = 0;
     13
     14	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &aspm_conf);
     15	aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
     16	if (parent) {
     17		pcie_capability_read_word(parent, PCI_EXP_LNKCTL,
     18					  &parent_aspm_conf);
     19		parent_aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
     20	}
     21
     22	if (!aspm_conf && (!parent || !parent_aspm_conf)) {
     23		/* aspm already disabled */
     24		return;
     25	}
     26
     27	dev_info(&pdev->dev, "disabling ASPM %s %s\n",
     28		 (aspm_conf & PCI_EXP_LNKCTL_ASPM_L0S) ? "L0s" : "",
     29		 (aspm_conf & PCI_EXP_LNKCTL_ASPM_L1) ? "L1" : "");
     30
     31	if (IS_ENABLED(CONFIG_PCIEASPM)) {
     32		int err;
     33
     34		err = pci_disable_link_state(pdev, aspm_conf);
     35		if (!err)
     36			return;
     37	}
     38
     39	/* both device and parent should have the same ASPM setting.
     40	 * disable ASPM in downstream component first and then upstream.
     41	 */
     42	pcie_capability_clear_word(pdev, PCI_EXP_LNKCTL, aspm_conf);
     43	if (parent)
     44		pcie_capability_clear_word(parent, PCI_EXP_LNKCTL,
     45					   aspm_conf);
     46}
     47EXPORT_SYMBOL_GPL(mt76_pci_disable_aspm);