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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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72a9b18629
Ever since commit254d1a3f02("xen/pv-on-hvm kexec: shutdown watches from old kernel") using the INTx interrupt from Xen PCI platform device for event channel notification would just lockup the guest during bootup. postcore_initcall now calls xs_reset_watches which will eventually try to read a value from XenStore and will get stuck on read_reply at XenBus forever since the platform driver is not probed yet and its INTx interrupt handler is not registered yet. That means that the guest can not be notified at this moment of any pending event channels and none of the per-event handlers will ever be invoked (including the XenStore one) and the reply will never be picked up by the kernel. The exact stack where things get stuck during xenbus_init: -xenbus_init -xs_init -xs_reset_watches -xenbus_scanf -xenbus_read -xs_single -xs_single -xs_talkv Vector callbacks have always been the favourite event notification mechanism since their introduction in commit38e20b07ef("x86/xen: event channels delivery on HVM.") and the vector callback feature has always been advertised for quite some time by Xen that's why INTx was broken for several years now without impacting anyone. Luckily this also means that event channel notification through INTx is basically dead-code which can be safely removed without impacting anybody since it has been effectively disabled for more than 4 years with nobody complaining about it (at least as far as I'm aware of). This commit removes event channel notification through Xen PCI platform device. Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Cc: Julien Grall <julien.grall@citrix.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Ross Lagerwall <ross.lagerwall@citrix.com> Cc: xen-devel@lists.xenproject.org Cc: linux-kernel@vger.kernel.org Cc: linux-pci@vger.kernel.org Cc: Anthony Liguori <aliguori@amazon.com> Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
133 lines
3.2 KiB
C
133 lines
3.2 KiB
C
/******************************************************************************
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* platform-pci.c
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*
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* Xen platform PCI device driver
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*
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* Authors: ssmith@xensource.com and stefano.stabellini@eu.citrix.com
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*
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* Copyright (c) 2005, Intel Corporation.
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* Copyright (c) 2007, XenSource Inc.
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* Copyright (c) 2010, Citrix
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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* Place - Suite 330, Boston, MA 02111-1307 USA.
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*
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*/
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#include <linux/interrupt.h>
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#include <linux/io.h>
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#include <linux/init.h>
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#include <linux/pci.h>
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#include <xen/platform_pci.h>
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#include <xen/grant_table.h>
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#include <xen/xenbus.h>
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#include <xen/events.h>
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#include <xen/hvm.h>
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#include <xen/xen-ops.h>
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#define DRV_NAME "xen-platform-pci"
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static unsigned long platform_mmio;
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static unsigned long platform_mmio_alloc;
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static unsigned long platform_mmiolen;
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static unsigned long alloc_xen_mmio(unsigned long len)
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{
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unsigned long addr;
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addr = platform_mmio + platform_mmio_alloc;
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platform_mmio_alloc += len;
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BUG_ON(platform_mmio_alloc > platform_mmiolen);
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return addr;
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}
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static int platform_pci_probe(struct pci_dev *pdev,
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const struct pci_device_id *ent)
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{
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int i, ret;
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long ioaddr;
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long mmio_addr, mmio_len;
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unsigned int max_nr_gframes;
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unsigned long grant_frames;
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if (!xen_domain())
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return -ENODEV;
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i = pci_enable_device(pdev);
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if (i)
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return i;
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ioaddr = pci_resource_start(pdev, 0);
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mmio_addr = pci_resource_start(pdev, 1);
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mmio_len = pci_resource_len(pdev, 1);
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if (mmio_addr == 0 || ioaddr == 0) {
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dev_err(&pdev->dev, "no resources found\n");
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ret = -ENOENT;
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goto pci_out;
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}
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ret = pci_request_region(pdev, 1, DRV_NAME);
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if (ret < 0)
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goto pci_out;
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ret = pci_request_region(pdev, 0, DRV_NAME);
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if (ret < 0)
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goto mem_out;
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platform_mmio = mmio_addr;
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platform_mmiolen = mmio_len;
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max_nr_gframes = gnttab_max_grant_frames();
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grant_frames = alloc_xen_mmio(PAGE_SIZE * max_nr_gframes);
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ret = gnttab_setup_auto_xlat_frames(grant_frames);
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if (ret)
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goto out;
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ret = gnttab_init();
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if (ret)
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goto grant_out;
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xenbus_probe(NULL);
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return 0;
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grant_out:
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gnttab_free_auto_xlat_frames();
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out:
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pci_release_region(pdev, 0);
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mem_out:
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pci_release_region(pdev, 1);
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pci_out:
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pci_disable_device(pdev);
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return ret;
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}
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static struct pci_device_id platform_pci_tbl[] = {
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{PCI_VENDOR_ID_XEN, PCI_DEVICE_ID_XEN_PLATFORM,
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PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
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{0,}
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};
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static struct pci_driver platform_driver = {
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.name = DRV_NAME,
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.probe = platform_pci_probe,
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.id_table = platform_pci_tbl,
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};
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static int __init platform_pci_init(void)
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{
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return pci_register_driver(&platform_driver);
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}
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device_initcall(platform_pci_init);
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