Re: [Xen-devel] [PATCH] tools: libxl: allow permissive qemu-upstream pci passthrough.

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Fri, Jul 3, 2015 at 3:49 PM, Ian Campbell <ian.campbell@xxxxxxxxxx> wrote:
> On Tue, 2015-06-02 at 16:47 +0100, Ian Campbell wrote:
>
> Anyone fancy (n)acking this followup to XSA-131? I think we probably
> want this for 4.6.

As someone who has had dealings with the libxl side of hte
"permissive" flag, I'll certainly Ack the idea of the change:

Acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>

Not qualified to say whether there's anyone on qmp listening, or if
the flag will be ignored properly on older versions of qemu.

 -George



>
>> From c395657b03a1e2b7616d987e7078694874981979 Mon Sep 17 00:00:00 2001
>> From: Ian Campbell <ian.campbell@xxxxxxxxxx>
>> Date: Mon, 1 Jun 2015 11:32:23 +0100
>> Subject: [PATCH] tools: libxl: allow permissive qemu-upstream pci
>>  passthrough.
>>
>> EMBARGOED UNTIL 2015-06-02 12:00 (WITH XSA-131 ET AL)
>>
>> Since XSA-131 qemu-xen now restricts access to PCI cfg by default. In
>> order to allow local configuration of the existing libxl_device_pci
>> "permissive" flag needs to be plumbed through via the new QMP property
>> added by the XSA-131 patches.
>>
>> Versions of QEMU prior to XSA-131 did not support this permissive
>> property, so we only pass it if it is true. Older versions only
>> supported permissive mode.
>>
>> qemu-xen-traditional already supports the permissive mode setting via
>> xenstore.
>>
>> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
>> Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>> Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>
>> ---
>> v2: Only set argument if permissive==true.
>> ---
>>  tools/libxl/libxl_qmp.c |   12 ++++++++++++
>>  1 file changed, 12 insertions(+)
>>
>> diff --git a/tools/libxl/libxl_qmp.c b/tools/libxl/libxl_qmp.c
>> index 9aa7e2e..6484f5e 100644
>> --- a/tools/libxl/libxl_qmp.c
>> +++ b/tools/libxl/libxl_qmp.c
>> @@ -849,6 +849,18 @@ int libxl__qmp_pci_add(libxl__gc *gc, int domid, 
>> libxl_device_pci *pcidev)
>>          QMP_PARAMETERS_SPRINTF(&args, "addr", "%x.%x",
>>                                 PCI_SLOT(pcidev->vdevfn), 
>> PCI_FUNC(pcidev->vdevfn));
>>      }
>> +    /*
>> +     * Version of QEMU prior to the XSA-131 fix did not support this
>> +     * property and were effectively always in permissive mode. The
>> +     * fix for XSA-131 switched the default to be restricted by
>> +     * default and added the permissive property.
>> +     *
>> +     * Therefore in order to support both old and new QEMU we only set
>> +     * the permissive flag if it is true. Users of older QEMU have no
>> +     * reason to set the flag so this is ok.
>> +     */
>> +    if (pcidev->permissive)
>> +        qmp_parameters_add_bool(gc, &args, "permissive", true);
>>
>>      rc = qmp_synchronous_send(qmp, "device_add", args,
>>                                NULL, NULL, qmp->timeout);
>
>
>
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