Re: [libvirt] [PATCH] qemu: avoid double reservation of PCI address when hotplugging interface type='hostdev'
On Sat, 2019-10-19 at 02:18 -0400, Laine Stump wrote:
Commit 01ca4010d86 (libvirt v5.1.0) moved address reservation for
hotplugged interface devices up to an earlier point in
qemuDomainAttachNetDevice() because some function called when
hotplugging on aarch64 needed to know the address type, and failed
when it was "none".
I don't see anything in the original commit suggesting the change
was connected to aarch64? In fact, for the most part I would expect
aarch64/virt guests to go down the very same code paths as x86/q35
guests.
This unfortunately caused a regression, because it also made PCI
address reservation happen before we noticed that the device was a
*hostdev* interface. Those interfaces are hotplugged by just calling
out to qemuDomainAttachHostdevDevice() - that function would then also
attempt to reserve the *same PCI address* that had just been reserved
in qemuDomainAttachNetDevice().
And of course at the time we didn't have, and after this patch still
don't have, test suite coverage for that O:-)
The solution is to move the bit of code that short-circuits out to
virDomainHostdevAttach() up *even earlier* so that no PCI address has
been allocated by the time it's called.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1744523
Signed-off-by: Laine Stump <laine(a)redhat.com>
The prevailing style seems to be
...
been allocated by the time it's called.
https://bugzilla.redhat.com/show_bug.cgi?id=1744523
Signed-off-by: Laine Stump <laine(a)redhat.com>
Feel free to change it or leave it as-is, I personally don't feel
very strongly either way.
+++ b/src/qemu/qemu_hotplug.c
+ case VIR_DOMAIN_NET_TYPE_HOSTDEV:
+ /* this switch is skipped by hostdev interfaces */
Maybe something like
/* hostdev interfaces have been dealt with earlier */
instead?
With at least the reference to aarch64 removed (unless of course I
have misunderstood the situation and the original commit was really
aarch64-related),
Reviewed-by: Andrea Bolognani <abologna(a)redhat.com>
--
Andrea Bolognani / Red Hat / Virtualization