Re: [PATCH 1/2] IOMMU/MMU: Adjust top level functions for VT-d Device-TLB flush error.

From: "Jan Beulich" <JBeulich@suse.com>
To: Kevin Tian <kevin.tian@intel.com>
Cc: Feng Wu <feng.wu@intel.com>, Quan Xu <quan.xu@intel.com>,
	George Dunlap <george.dunlap@eu.citrix.com>,
	Liu Jinsong <jinsong.liu@alibaba-inc.com>,
	Dario Faggioli <dario.faggioli@citrix.com>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
	Jun Nakajima <jun.nakajima@intel.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Keir Fraser <keir@xen.org>
Subject: Re: [PATCH 1/2] IOMMU/MMU: Adjust top level functions for VT-d Device-TLB flush error.
Date: Thu, 17 Mar 2016 01:58:50 -0600	[thread overview]
Message-ID: <56EA71CA02000078000DD910@prv-mh.provo.novell.com> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D15F7EC7B1@SHSMSX101.ccr.corp.intel.com>

>>> On 17.03.16 at 08:32, <kevin.tian@intel.com> wrote:
>>  From: Xu, Quan
>> Sent: Thursday, March 17, 2016 2:55 PM
>> --- a/xen/drivers/passthrough/vtd/x86/vtd.c
>> +++ b/xen/drivers/passthrough/vtd/x86/vtd.c
>> @@ -140,8 +140,11 @@ void __hwdom_init vtd_set_hwdom_mapping(struct domain *d)
>> 
>>          tmp = 1 << (PAGE_SHIFT - PAGE_SHIFT_4K);
>>          for ( j = 0; j < tmp; j++ )
>> -            iommu_map_page(d, pfn * tmp + j, pfn * tmp + j,
>> -                           IOMMUF_readable|IOMMUF_writable);
>> +            if ( iommu_map_page(d, pfn * tmp + j, pfn * tmp + j,
>> +                                IOMMUF_readable|IOMMUF_writable) )
>> +                printk(XENLOG_G_ERR
>> +                       "IOMMU: Map page gfn: 0x%lx(mfn: 0x%lx) failed.\n",
>> +                       pfn * tmp + j, pfn * tmp + j);
>> 
>>          if (!(i & (0xfffff >> (PAGE_SHIFT - PAGE_SHIFT_4K))))
>>              process_pending_softirqs();
> 
> Hi, Quan, this patch looks good to me in general. Just double confirm one
> thing. Above doesn't handle error from iommu_map_page, while only
> throwing out warning. Not sure whether it has been discussed before
> as the agreement or not.

For code paths involved in preparing the hardware domain only
I had specifically asked to handle such in a best effort manner,
instead of explicitly rendering a system unbootable.

Jan

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