Re: [RFC Patch v4 2/8] ioreq: bump the number of IOREQ page to 4 pages

From: Chao Gao <chao.gao@intel.com>
To: Paul Durrant <Paul.Durrant@citrix.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>,
	Andrew Cooper <Andrew.Cooper3@citrix.com>,
	"Tim (Xen.org)" <tim@xen.org>,
	George Dunlap <George.Dunlap@citrix.com>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
	Jan Beulich <jbeulich@suse.com>,
	Ian Jackson <Ian.Jackson@citrix.com>
Subject: Re: [RFC Patch v4 2/8] ioreq: bump the number of IOREQ page to 4 pages
Date: Wed, 13 Dec 2017 07:39:20 +0800	[thread overview]
Message-ID: <20171212233918.GA36363@op-computing> (raw)
In-Reply-To: <29f1803cb91f44fc86d6832ea44a4f27@AMSPEX02CL03.citrite.net>

On Tue, Dec 12, 2017 at 09:07:46AM +0000, Paul Durrant wrote:
>> -----Original Message-----
>[snip]
>> 
>> Hi, Paul.
>> 
>> I merged the two qemu patches, the privcmd patch [1] and did some tests.
>> I encountered a small issue and report it to you, so you can pay more
>> attention to it when doing some tests. The symptom is that using the new
>> interface to map grant table in xc_dom_gnttab_seed() always fails. After
>> adding some printk in privcmd, I found it is
>> xen_remap_domain_gfn_array() that fails with errcode -16. Mapping ioreq
>> server doesn't have such an issue.
>> 
>> [1]
>> http://xenbits.xen.org/gitweb/?p=people/pauldu/linux.git;a=commit;h=ce5
>> 9a05e6712
>> 
>
>Chao,
>
>  That privcmd patch is out of date. I've just pushed a new one:
>
>http://xenbits.xen.org/gitweb/?p=people/pauldu/linux.git;a=commit;h=9f00199f5f12cef401c6370c94a1140de9b318fc
>
>  Give that a try. I've been using it for a few weeks now.

Mapping ioreq server always fails, while mapping grant table succeeds.

QEMU fails with following log:
xenforeignmemory: error: ioctl failed: Device or resource busy
qemu-system-i386: failed to map ioreq server resources: error 16
handle=0x5614a6df5e00
qemu-system-i386: xen hardware virtual machine initialisation failed

Xen encountered the following error:
(XEN) [13118.909787] mm.c:1003:d0v109 pg_owner d2 l1e_owner d0, but real_pg_owner d0
(XEN) [13118.918122] mm.c:1079:d0v109 Error getting mfn 5da5841 (pfn ffffffffffffffff) from L1 entry 8000005da5841227 for l1e_owner d0, pg_owner d2

I only fixed some obvious issues with a patch to your privcmd patch:

--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -181,7 +181,7 @@ int xen_remap_domain_gfn_range(struct vm_area_struct *vma,
        if (xen_feature(XENFEAT_auto_translated_physmap))
                return -EOPNOTSUPP;
 
-       return do_remap_gfn(vma, addr, &gfn, nr, NULL, prot, domid, pages);
+       return do_remap_pfn(vma, addr, &gfn, nr, NULL, prot, domid, false, pages
 }
 EXPORT_SYMBOL_GPL(xen_remap_domain_gfn_range);
 
@@ -200,8 +200,8 @@ int xen_remap_domain_gfn_array(struct vm_area_struct *vma,
         * cause of "wrong memory was mapped in".
         */
        BUG_ON(err_ptr == NULL);
-        do_remap_pfn(vma, addr, gfn, nr, err_ptr, prot, domid,
-                    false, pages);
+       return do_remap_pfn(vma, addr, gfn, nr, err_ptr, prot, domid,
+                       false, pages);
 }
 EXPORT_SYMBOL_GPL(xen_remap_domain_gfn_array);

Thanks
Chao

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