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Re: [Qemu-devel] [PATCH v2] xen/pt: Fix a xen passthrough failure
From: |
Zhao Yan |
Subject: |
Re: [Qemu-devel] [PATCH v2] xen/pt: Fix a xen passthrough failure |
Date: |
Tue, 4 Dec 2018 02:32:38 -0500 |
User-agent: |
Mutt/1.9.4 (2018-02-28) |
On Mon, Dec 03, 2018 at 12:20:30PM +0100, Roger Pau Monné wrote:
> Hello,
>
> Thanks for the patch.
>
> The subject should be more descriptive, "Fix a xen passthrough
> failure" is too generic. How about: "allow passthrough of devices with
> bogus interrupt pin" or something similar.
right, thanks for your suggestion. I'll change the subject to this one.
>
> On Mon, Dec 03, 2018 at 12:04:38AM -0500, Zhao Yan wrote:
> > For some pci device, even its PCI_INTERRUPT_PIN is not 0, it actually
> > doesn't support INTx mode, so its machine irq read from host sysfs is 0.
> > In that case, report PCI_INTERRUPT_PIN as 0 to guest and let passthrough
> > continue.
> >
> > v2: fix some coding style issue
>
> The changelog between versions should be below the '---'.
>
got it. thanks :)
> >
> > Cc: Roger Pau Monné <address@hidden>
> > Cc: Jan Beulich <address@hidden>
> > Signed-off-by: Zhao Yan <address@hidden>
> > ---
> > hw/xen/xen_pt.c | 5 +++++
> > hw/xen/xen_pt_config_init.c | 8 +++++++-
> > 2 files changed, 12 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
> > index f1f3a3727c..d601c9979c 100644
> > --- a/hw/xen/xen_pt.c
> > +++ b/hw/xen/xen_pt.c
> > @@ -847,6 +847,11 @@ static void xen_pt_realize(PCIDevice *d, Error **errp)
> > }
> >
> > machine_irq = s->real_device.irq;
> > + if (machine_irq == 0) {
> > + XEN_PT_LOG(d, "machine irq is 0\n");
>
> I would maybe consider disabling INTX assertion here on the command
> register.
>
ok, I'll add that.
Actually I was vacillating on whether to add the disabling of INTx
assertion, as I thought PCI_INTERRUPT_PIN was already reported 0.
But adding the disabling is better.
> > + goto out;
> > + }
> > +
> > rc = xc_physdev_map_pirq(xen_xc, xen_domid, machine_irq, &pirq);
> > if (rc < 0) {
> > error_setg_errno(errp, errno, "Mapping machine irq %u to"
> > diff --git a/hw/xen/xen_pt_config_init.c b/hw/xen/xen_pt_config_init.c
> > index 47f9010c75..1007b6c977 100644
> > --- a/hw/xen/xen_pt_config_init.c
> > +++ b/hw/xen/xen_pt_config_init.c
> > @@ -300,7 +300,13 @@ static int
> > xen_pt_irqpin_reg_init(XenPCIPassthroughState *s,
> > XenPTRegInfo *reg, uint32_t real_offset,
> > uint32_t *data)
> > {
> > - *data = xen_pt_pci_read_intx(s);
> > + if (s->real_device.irq)
> > + *data = xen_pt_pci_read_intx(s);
> > + else {
> > + XEN_PT_LOG(&s->dev,
> > + "machine irq is 0, init guest PCI_INTERRUPT_PIN to 0\n");
> > + *data = 0;
>
> The default value for the register is already zero, so you could drop
> the else branch AFAICT.
ok, I'll drop the else branch. thanks for your review :)
> Thanks, Roger.