2016-01-26 20:56 GMT+08:00 Jan Beulich <jbeul...@suse.com>:
> >>> On 26.01.16 at 02:34, <chang...@gmail.com> wrote:
> > There are some problems when msi guest_masked is set to 1 by default.
> > When guest os is windows 2008 r2 server,
> > the device(eg X540-AT2 vf) is not initialized correctly.
> > Host will always receive message like this :"VF Reset msg received from
> vf".
> > Guest has network connectivity issues,
> > and can not correctly receive/send the packet.
> > So, guest_masked is set to 0 by default.
>
> You describe a problem and half of your change, but there's no
> connection between the two: What is actually wrong with current
> behavior (matching the hardware's - MSI-X mask bits are set when
> coming out of reset).
>
> > --- a/xen/arch/x86/msi.c
> > +++ b/xen/arch/x86/msi.c
> > @@ -512,7 +512,7 @@ void guest_mask_msi_irq(struct irq_desc *desc,
> bool_t mask)
> >
> > static unsigned int startup_msi_irq(struct irq_desc *desc)
> > {
> > - if ( unlikely(!msi_set_mask_bit(desc, 0, !!(desc->status &
> IRQ_GUEST))) )
> > + if ( unlikely(!msi_set_mask_bit(desc, 0, 0) ))
> > WARN();
> > return 0;
> > }
>
> Whether this part can go under "set ... by default" is highly
> questionable. Plus, while this affects MSI and MSI-X, ...
>
> If irq is owned by guest,in function msi_set_mask_bit():
...
bool_t flag = host || guest; //The flag should be true.
...
writel(flag, entry->mask_base + PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET);
...
PCI device can not generate interrrupt.
windows guest can not change vector_ctrl_mask, guest os get abnormal status
of nic.
> > @@ -972,7 +972,7 @@ static int msix_capability_init(struct pci_dev *dev,
> > entry->msi_attrib.entry_nr = msi->entry_nr;
> > entry->msi_attrib.maskbit = 1;
> > entry->msi_attrib.host_masked = 1;
> > - entry->msi_attrib.guest_masked = 1;
> > + entry->msi_attrib.guest_masked = 0;
> > entry->msi_attrib.pos = pos;
> > entry->irq = msi->irq;
> > entry->dev = dev;
>
> ... this change affect MSI-X only, and doing some guessing from
> what you write above I suspect you only really tested one of the
> two cases.
>
> So while the change _may_ be necessary, you'll need to do a
> better job at explaining why you what you do.
>
Msi guest_masked is set to 0 in the original code, only msi-x guest_masked
is modifed in msix_capability_init() function by patch.
>
> Jan
>
>
This issue appears after commited the variable guest_mask.
Initialization operations of pci device may be changed in windows
guest,or Xen need to change the initial state of vtd pci device.
--
Jianzhong,Chang
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