From 58593f4340d766fb7639de542f3b21463d5b98ef Mon Sep 17 00:00:00 2001
Message-Id: <58593f4340d766fb7639de542f3b21463d5b98ef@dist-git>
From: Laine Stump <laine@laine.org>
Date: Mon, 12 Sep 2016 16:25:25 -0400
Subject: [PATCH] conf: allow hotplugging "legacy PCI" device to manually
 addressed PCIe slot

In a full domain config, libvirt allows overriding the normal PCI
vs. PCI Express rules when a device address is explicitly provided
(so, e.g., you can force a legacy PCI device to plug into a PCIe port,
although libvirt would never do that on its own). However, due to a
bug libvirt doesn't give this same leeway when hotplugging devices. On
top of that, current libvirt assumes that *all* devices are legacy
PCI. The result of all this is that it's impossible to hotplug a
device into a PCIe port, even if you manually add the PCI address.

This can all be traced to the function
virDomainPCIAddressEnsureAddr(), and the fact that it calls
virDomainPCIaddressReserveSlot() for manually set addresses, and that
function hardcodes the argument "fromConfig" to false (meaning "this
address was auto-assigned, so it should be subject to stricter
validation").

Since virDomainPCIAddressReserveSlot() is just a one line simple
wrapper around virDomainPCIAddressReserveAddr() (adding in a hardcoded
reserveEntireSlot = true and fromConfig = false), all that's needed to
solve the problem with no unwanted side effects is to replace that
call for virDomainPCIAddressReserveSlot() with a direct call to
virDomainPCIAddressReserveAddr(), but with reserveEntireSlot = true,
fromConfig = true. That's what this patch does.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1337490
(cherry picked from commit b87703cf79559157404667628802d7fe8f9f19a6)
---
 src/conf/domain_addr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/conf/domain_addr.c b/src/conf/domain_addr.c
index 7f4f4d8..cad1c27 100644
--- a/src/conf/domain_addr.c
+++ b/src/conf/domain_addr.c
@@ -507,7 +507,8 @@ virDomainPCIAddressEnsureAddr(virDomainPCIAddressSetPtr addrs,
                                          addrStr, flags, true))
             goto cleanup;
 
-        ret = virDomainPCIAddressReserveSlot(addrs, &dev->addr.pci, flags);
+        ret = virDomainPCIAddressReserveAddr(addrs, &dev->addr.pci, flags,
+                                             true, true);
     } else {
         ret = virDomainPCIAddressReserveNextSlot(addrs, dev, flags);
     }
-- 
2.10.0