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From: Chao Gao <chao.gao@intel.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: xen-devel@lists.xenproject.org, Wei Liu <wei.liu2@citrix.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>,
	Jan Beulich <jbeulich@suse.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH v3 2/2] libxl: don't reset device when it is accessible by the guest
Date: Thu, 20 Dec 2018 10:47:08 +0800	[thread overview]
Message-ID: <20181220024708.GB10247@gao-cwp> (raw)
In-Reply-To: <20181219090049.lkx5f35jxshuvhw5@mac>

On Wed, Dec 19, 2018 at 10:00:49AM +0100, Roger Pau Monné wrote:
>On Tue, Dec 18, 2018 at 10:43:38PM +0800, Chao Gao wrote:
>> When I destroyed a guest with 'xl destroy', I found the warning
>> in msi_set_mask_bit() in Xen was triggered. After adding "WARN_ON(1)"
>> to that place, I got the call trace below:
>> 
>> (XEN) Xen call trace:
>> (XEN)    [<ffff82d080281a6a>] msi.c#msi_set_mask_bit+0x1da/0x29b
>> (XEN)    [<ffff82d080282e78>] guest_mask_msi_irq+0x1c/0x1e
>> (XEN)    [<ffff82d08030ceb9>] vmsi.c#msixtbl_write+0x173/0x1d4
>> (XEN)    [<ffff82d08030cf30>] vmsi.c#_msixtbl_write+0x16/0x18
>> (XEN)    [<ffff82d0802ffac4>] hvm_process_io_intercept+0x216/0x270
>> (XEN)    [<ffff82d0802ffb45>] hvm_io_intercept+0x27/0x4c
>> (XEN)    [<ffff82d0802f0e86>] emulate.c#hvmemul_do_io+0x273/0x454
>> (XEN)    [<ffff82d0802f10a4>] emulate.c#hvmemul_do_io_buffer+0x3d/0x70
>> (XEN)    [<ffff82d0802f2343>] emulate.c#hvmemul_linear_mmio_access+0x35e/0x436
>> (XEN)    [<ffff82d0802f2640>] emulate.c#linear_write+0xdd/0x13b
>> (XEN)    [<ffff82d0802f3f25>] emulate.c#hvmemul_write+0xbd/0xf1
>> (XEN)    [<ffff82d0802d51df>] x86_emulate+0x2249d/0x23c5c
>> (XEN)    [<ffff82d0802d861f>] x86_emulate_wrapper+0x2b/0x5f
>> (XEN)    [<ffff82d0802f28aa>] emulate.c#_hvm_emulate_one+0x54/0x1b2
>> (XEN)    [<ffff82d0802f2a18>] hvm_emulate_one+0x10/0x12
>> (XEN)    [<ffff82d080300227>] hvm_emulate_one_insn+0x42/0x14a
>> (XEN)    [<ffff82d08030037e>] handle_mmio_with_translation+0x4f/0x51
>> (XEN)    [<ffff82d0802f803b>] hvm_hap_nested_page_fault+0x16c/0x6d8
>> (XEN)    [<ffff82d08032446a>] vmx_vmexit_handler+0x19b0/0x1f2e
>> (XEN)    [<ffff82d08032995a>] vmx_asm_vmexit_handler+0xfa/0x270
>> 
>> It seems to me that guest is trying to mask a msi while the memory decoding
>> of the device is disabled. Performing a device reset without proper method
>> to avoid guest's MSI-X operation would lead to this issue.
>> 
>> The fix is basic - detach pci device before resetting the device.
>
>Seems quite obvious. Do you have any idea why the device was first
>reset and then deassigned?

TBH, I have no idea.

>
>> Signed-off-by: Chao Gao <chao.gao@intel.com>
>
>Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

Thanks
Chao

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  reply	other threads:[~2018-12-20  2:43 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-18 14:43 [PATCH v3 1/2] xen/pt: fix some pass-thru devices don't work across reboot Chao Gao
2018-12-18 14:43 ` [PATCH v3 2/2] libxl: don't reset device when it is accessible by the guest Chao Gao
2018-12-19  9:00   ` Roger Pau Monné
2018-12-20  2:47     ` Chao Gao [this message]
2019-01-02 11:49   ` Wei Liu
2018-12-18 15:53 ` [PATCH v3 1/2] xen/pt: fix some pass-thru devices don't work across reboot Jan Beulich
2018-12-19  4:56   ` Chao Gao
2018-12-19  8:57 ` Roger Pau Monné
2018-12-20  2:46   ` Chao Gao
2018-12-20  9:29     ` Roger Pau Monné
2018-12-20 14:20       ` Chao Gao

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