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Re: [Qemu-devel] [PATCH RFC v11 4/4] vfio: add 'aer' property to expose
From: |
Alex Williamson |
Subject: |
Re: [Qemu-devel] [PATCH RFC v11 4/4] vfio: add 'aer' property to expose aercap |
Date: |
Fri, 20 Jan 2017 11:01:01 -0700 |
On Fri, 20 Jan 2017 14:04:08 +0800
Cao jin <address@hidden> wrote:
> On 01/19/2017 06:36 AM, Alex Williamson wrote:
> > On Sat, 31 Dec 2016 17:13:08 +0800
> > Cao jin <address@hidden> wrote:
> >
> >> From: Chen Fan <address@hidden>
> >>
> >> Add 'aer' property, let user choose whether expose the aer capability
> >> or not.
> >
> > But that's not what it does, it only controls the behavior in response
> > to non-fatal errors, the capability is exposed regardless.
> >
>
> This commit log is legacy, and defaults to off is a result of the
> configuration restriction & your previous discussion, right?
>
> In current version, if 'aer' property is off, we just allocate the
> config space via pcie_add_capability(), we don't init the AER
> capability, the value is all 0s there, so does that still mean
> "capability is exposed regardless"?
The design has changed, we no longer require a matching host and guest
topology, we can more easily transparently enable non-fatal error
correction. We need to reevaluate whether previous decisions are still
valid, we cannot blindly assume that a requirement for a previous
design still applies. Thanks,
Alex
> >> Should disable aer feature by default, because only non-fatal
> >> error is supported now.
> >
> > Why does that mean it should be disabled by default? What bad thing
> > happens if we enable this opportunistically?
> >
> >> Signed-off-by: Chen Fan <address@hidden>
> >> Signed-off-by: Dou Liyang <address@hidden>
> >> Signed-off-by: Cao jin <address@hidden>
> >> ---
> >> hw/vfio/pci.c | 2 ++
> >> 1 file changed, 2 insertions(+)
> >>
> >> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> >> index 9861f72..fc9db66 100644
> >> --- a/hw/vfio/pci.c
> >> +++ b/hw/vfio/pci.c
> >> @@ -3057,6 +3057,8 @@ static Property vfio_pci_dev_properties[] = {
> >> DEFINE_PROP_UINT32("x-pci-sub-device-id", VFIOPCIDevice,
> >> sub_device_id, PCI_ANY_ID),
> >> DEFINE_PROP_UINT32("x-igd-gms", VFIOPCIDevice, igd_gms, 0),
> >> + DEFINE_PROP_BIT("aer", VFIOPCIDevice, features,
> >> + VFIO_FEATURE_ENABLE_AER_BIT, false),
> >> /*
> >> * TODO - support passed fds... is this necessary?
> >> * DEFINE_PROP_STRING("vfiofd", VFIOPCIDevice, vfiofd_name),
> >
> >
> >
> > .
> >
>