Re: [Qemu-devel] [PATCH v2 1/3] s390x/pci: remove idx from msix msg data

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 5 Sep 2017 17:08:14 +0800
Yi Min Zhao <zyimin@linux.vnet.ibm.com> wrote:

> 在 2017/9/5 下午4:50, Cornelia Huck 写道:
> > On Tue, 5 Sep 2017 16:44:37 +0800
> > Yi Min Zhao <zyimin@linux.vnet.ibm.com> wrote:
> >  
> >> 在 2017/9/5 下午4:29, Cornelia Huck 写道:  
> >>> On Fri,  1 Sep 2017 06:22:56 +0200
> >>> Yi Min Zhao <zyimin@linux.vnet.ibm.com> wrote:
> >>>     
> >>>> PCIDevice pointer has been a parameter of kvm_arch_fixup_msi_route().
> >>>> So we don't need to store zpci idx in msix message data to find out the
> >>>> specific zpci device. Instead, we could use pci device id to find its
> >>>> corresponding zpci device.
> >>>>
> >>>> Signed-off-by: Yi Min Zhao <zyimin@linux.vnet.ibm.com>
> >>>> ---
> >>>>    hw/s390x/s390-pci-bus.c  | 16 +++++-----------
> >>>>    hw/s390x/s390-pci-bus.h  |  2 ++
> >>>>    hw/s390x/s390-pci-inst.c | 24 ------------------------
> >>>>    hw/s390x/s390-pci-stub.c |  6 ++++++
> >>>>    target/s390x/kvm.c       |  7 +++++--
> >>>>    5 files changed, 18 insertions(+), 37 deletions(-)
> >>>>

> >>>> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> >>>> index 1338c29528..3d490c5e4b 100644
> >>>> --- a/target/s390x/kvm.c
> >>>> +++ b/target/s390x/kvm.c
> >>>> @@ -2533,10 +2533,13 @@ int kvm_arch_fixup_msi_route(struct kvm_irq_routing_entry *route,
> >>>>                                 uint64_t address, uint32_t data, PCIDevice *dev)
> >>>>    {
> >>>>        S390PCIBusDevice *pbdev;
> >>>> -    uint32_t idx = data >> ZPCI_MSI_VEC_BITS;
> >>>>        uint32_t vec = data & ZPCI_MSI_VEC_MASK;
> >>>>    
> >>>> -    pbdev = s390_pci_find_dev_by_idx(s390_get_phb(), idx);
> >>>> +    if (!dev) {
> >>>> +        return -ENODEV;  
> >>> Can this actually happen?  
> >> I think this cannot happen. But I'm afraid that I miss something.
> >> So I added this to avoid NULL pointer. But from the code and
> >> my test, there has not been NULL pointer happened.  
> > I'm wondering if that is in the same category as the instance I
> > commented on above. Do you want to log something?
> >  
> For the case above, I ensure that zpci device must exist. But here, I'm 
> not sure.
> Because it's called from outside. I'm not sure if the caller might call
> kvm_irqchip_add_msi_route() with NULL as pci device argument.
> 
> Although msix ctrl mr is accessed from outside. But its initialization
> is controled by our code and the pointer to zpci device is saved as
> mr's opaque.

OK. Maybe add a DPRINTF as for the condition below?

> >>>     
> >>>> +    }
> >>>> +
> >>>> +    pbdev = s390_pci_find_dev_by_target(s390_get_phb(), DEVICE(dev)->id);
> >>>>        if (!pbdev) {
> >>>>            DPRINTF("add_msi_route no dev\n");
> >>>>            return -ENODEV;  
> >>>     
> >  
>