[libvirt] [PATCH v6 04/17] qemu: set/use proper pciConnectFlags during hotplug

[Andrea Bolognani]

On Mon, 2016-11-07 at 14:50 -0500, Laine Stump wrote:
> Before now, all the qemu hotplug functions assumed that all devices to
> be hotplugged were legacy PCI endpoint devices
> (VIR_PCI_CONNECT_TYPE_PCI_DEVICE). This worked out "okay", because all
> devices *are* legacy PCI endpoint devices on x86/440fx machinetypes,
> and hotplug didn't work properly on machinetypes using PCIe anyway
> (hotplugging onto a legacy PCI slot doesn't work, and until commit
> b87703cf any attempt to manually specify a PCIe address for a
> hotplugged device would be erroneously rejected).
> 
> This patch makes all qemu hotplug operations honor the pciConnectFlags
> set by the single all-knowing function
> qemuDomainDeviceCalculatePCIConnectFlags(). This is done in 3 steps,
> but in a single commit since we would have to touch the other points
> at each step anyway:
> 
> 1) add a flags argument to the hypervisor-agnostic
> virDomainPCIAddressEnsureAddr() (previously it hardcoded
> ..._PCI_DEVICE)
> 
> 2) add a new qemu-specific function qemuDomainEnsurePCIAddress() which
> gets the correct pciConnectFlags for the device from
> qemuDomainDeviceConnectFlags(), then calls
> virDomainPCIAddressEnsureAddr().
> 
> 3) in qemu_hotplug.c replace all calls to
> virDomainPCIAddressEnsureAddr() with calls to
> qemuDomainEnsurePCIAddress()
> 
> So in effect, we're putting a "shim" on top of all calls to
> virDomainPCIAddressEnsureAddr() that sets the right pciConnectFlags.
> ---
>  src/conf/domain_addr.c         | 10 ++--------
>  src/conf/domain_addr.h         |  3 ++-
>  src/qemu/qemu_domain_address.c | 27 +++++++++++++++++++++++++++
>  src/qemu/qemu_domain_address.h |  4 ++++
>  src/qemu/qemu_hotplug.c        | 23 ++++++++++++++++-------
>  5 files changed, 51 insertions(+), 16 deletions(-)

[...]
> +/**
> + * qemuDomainEnsurePCIAddress:
> + *
> + * if @dev should have a PCI address but doesn't, assign an address on
> + * a compatible PCI bus, and set it in @dev->...info. If there is an
> + * address already, validate that it is on a compatible bus, based on
> + * @dev->...info.pciConnectFlags.
> + *
> + * @obj: the virDomainObjPtr for the domain. This will include
> + *       qemuCaps and address cache (if there is one)
> + *
> + * @dev: the device that we need to ensure has a PCI address

Please move the description of the function arguments before
the description of the function itself.

> + * returns 0 on success -1 on failure.
> + */
> +int
> +qemuDomainEnsurePCIAddress(virDomainObjPtr obj,
> +                           virDomainDeviceDefPtr dev)
> +{
> +    qemuDomainObjPrivatePtr priv = obj->privateData;
> +    virDomainDeviceInfoPtr info = virDomainDeviceGetInfo(dev);

virDomainDeviceGetInfo() can return NULL...

> +    qemuDomainFillDevicePCIConnectFlags(obj->def, dev, priv->qemuCaps);
> +
> +    return virDomainPCIAddressEnsureAddr(priv->pciaddrs, info,
> +                                         info->pciConnectFlags);

... but you don't check for that before dereferencing info
here. I guess this function will never be called on a device
that doesn't have a DeviceInfo, but it's probably a good
idea to explicitly check anyways in case the callers change.

ACK once the comments above have been taken care of.

-- 
Andrea Bolognani / Red Hat / Virtualization