Re: [Xen-devel] iommuu/vt-d issues with LSI MegaSAS (PERC5i)

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Jun 02, 2010 at 03:05:19PM +0800, Weidong Han wrote:
> Pasi Kärkkäinen wrote:
>> On Wed, Jun 02, 2010 at 09:23:37AM +0800, Weidong Han wrote:
>>   
>>> This PCI-x card is not suitable for assignment. It contains an invisible
>>> device 05:08.0 (lspci cannot show it), but this invisible device won't
>>> be mapped by VT-d because VT-d engine doesn't know this device, so you
>>> can see the DMAR faults on it. One workaround is to hard code to map
>>> 05:08.0 when assign 05:0e.0. BTW, PCIe LSI card don't have this problem.
>>>
>>>     
>>
>> Note that this problem happens when booting up dom0..
>>   
> I see. all devices are assigned to dom0 in booting. It just needs to map  
> 05:08.0 as well when map 05:0e.0 in domain_context_mapping.

Hey Weidong,

Thank you the explanation. I am not that familiar with the VT-D chipset,
but it seems that this issue also appears with CardBus controllers:
http://lkml.org/lkml/2010/5/22/69 ?

For this device, the problem should also appear with the newer kernels
without using the Hypervisor and with CONFIG_DMAR enabled, right? 

Am I to understand that the workaround you are proposing is doing
something akin to this:


/*
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License v2.0 as published by
 * the Free Software Foundation
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/module.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/stat.h>
#include <linux/err.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include <linux/limits.h>
#include <linux/device.h>
#include <linux/pci.h>
#include <linux/device.h>

#include <linux/pci.h>

#include <xen/interface/xen.h>
#include <xen/interface/physdev.h>

#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>

#define LSI_HACK  "0.1"

MODULE_AUTHOR("Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>");
MODULE_DESCRIPTION("lsi hack");
MODULE_LICENSE("GPL");
MODULE_VERSION(LSI_HACK);

static int __init lsi_hack_init(void)
{
        int r = 0;

        struct physdev_manage_pci manage_pci = {
                        .bus    = 0x5,
                        .devfn  = PCI_DEVFN(8,0),
                };
        r = HYPERVISOR_physdev_op(PHYSDEVOP_manage_pci_add,
                        &manage_pci);

        return r;
}

static void __exit lsi_hack_exit(void)
{
        int r = 0;
        struct physdev_manage_pci manage_pci;

        manage_pci.bus = 0x5;
        manage_pci.devfn = PCI_DEVFN(8,0);

        r = HYPERVISOR_physdev_op(PHYSDEVOP_manage_pci_remove,
                &manage_pci);
        if (r)
                printk(KERN_ERR "%s: %d\n", __FUNCTION__, r);
}

module_init(lsi_hack_init);
module_exit(lsi_hack_exit);

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