linux-kernel - Re: Need help to debug ata errors

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Message-ID: <022c3fad-ca0b-50c9-79f7-2bfa3de75a0d@opensource.wdc.com>
Date:   Mon, 6 Dec 2021 09:12:50 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Ayan Kumar Halder <ayan.kumar.halder@...inx.com>,
        linux-ide@...r.kernel.org
Cc:     axboe@...nel.dk, linux-kernel@...r.kernel.org,
        Stefano Stabellini <sstabellini@...nel.org>,
        Stefano Stabellini <stefano.stabellini@...inx.com>
Subject: Re: Need help to debug ata errors

On 2021/12/03 20:11, Ayan Kumar Halder wrote:
> Hi All,
> 
> I am trying to run linux as a DomU guest on Xen with AHCI assigned to it.
> I can confirm that SATA works (ie able to detect sdb) as a Dom0 guest. 
> However, it does not work as a DomU guest.
> 
> Hardware :- ZCU102 board and it has two sata ports
> Kernel :- 5.10
> 
> I have enabled the debug logs in drivers/ata
> 
> 1. Logs from dom0 (where SATA works) https://pastebin.com/2BhMDq47
> 2. Logs from domU (where SATA does not work) https://pastebin.com/fE8WZnZ0
> 
> Can some help me to answer these questions
> 1. What does this mean "1st FIS failed" ?
> 
> 2. In the dom0 logs, PORT_SCR_ERR = 0x41d0002 whereas in domU logs, 
> PORT_SCR_ERR = 0. Does it give some hints ?
> 
> 3. Any other issues or hints to debug this ?
> 
> I can confirm that in domU scenario, we do not get any interrupts from 
> the device. What might be going wrong here ?

That would be the first thing to check since without interrupts you will not get
any command completion. Commands will timeout and probe will not work.
And this IRQ problem is Xen territory, not ata.

The 1st FIS failed error may be due to some problems with AHCI PCI bar/register
accesses, which may not be working. This I think points again to Xen setup with
domU, which may not have the necessary access rights to get IRQ and PCI bar
accesses ? (I have no experience with Xen)

> 
> Thanks in advance.
> 
> Kind regards,
> Ayan
> 


-- 
Damien Le Moal
Western Digital Research