From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Thomas Lamprecht <t.lamprecht@proxmox.com>

Date: Mon, 6 Apr 2020 12:16:54 +0200

Subject: [PATCH] PVE: [Compat]: 4.0 used balloon qemu-4-0-config-size false

 here

The underlying issue why this change from upstream to us arised in

the first place is that QEMU 4.0 was already released at the point we

run into this migration issue, so we did the then obvious fallback to

false for virtio-balloon-device qemu-4-0-config-size.

QEMU made that switch back in 4.1, where it now uses a backward

compatible mechanism to detect if the bigger CFG sizes should be

used, i.e., checking the VIRTIO_BALLOON_F_PAGE_POISON or

VIRTIO_BALLOON_F_FREE_PAGE_HINT balloon feature flags.

As for them, upstream released version 4.0 had this to true they keep

it to true in their compatibility record for the 4.0 machine, to

allow live migrations from 4.0 to 4.1.

As for us, downstream released version 4.0 (first public release of

this QEMU) had this to false, we change it back to false again, for

the same reason.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

---

 hw/core/machine.c | 3 ++-

 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c

index 2cf2f321f9..e0f857820d 100644

--- a/hw/core/machine.c

+++ b/hw/core/machine.c

@@ -107,7 +107,8 @@ GlobalProperty hw_compat_4_0[] = {

     { "virtio-vga",     "edid", "false" },

     { "virtio-gpu-device", "edid", "false" },

     { "virtio-device", "use-started", "false" },

-    { "virtio-balloon-device", "qemu-4-0-config-size", "true" },

+    // PVE differed from upstream for 4.0 balloon cfg size

+    { "virtio-balloon-device", "qemu-4-0-config-size", "false" },

     { "pl031", "migrate-tick-offset", "false" },

 };

 const size_t hw_compat_4_0_len = G_N_ELEMENTS(hw_compat_4_0);