[SRU][Q:linux-oracle][PATCH 0/1] oracle: set enable_virt_at_load default to false on kernels > 6.8

[Vinicius Peixoto]

BugLink: https://bugs.launchpad.net/bugs/2139360

[Impact]

OCI uses live migration to migrate VM instances from hosts to hosts.
That feature is currently not possible if nested virtualisation is
enabled. However, in commit b4886fab6fb62 ("KVM: Add a module param to
allow enabling virtualization when KVM is loaded"), the
enable_virt_at_load parameter was introduced for the KVM module, and was
set to true by default, making it such that the kvm module sets the
EFER.SVME bit at load time, rather than when a guest is started. This is
a breaking change for the OCI live migration use case.

[Fix]

Change the default value of enable_virt_at_load to false in our Oracle
kernels > 6.8 in order to support the live migration use case. This is
implemented as a sauce patch within the Oracle kernels only, since the
justification is specific to the OCI use case and unlikely to be
accepted by upstream.

[Test plan]

Oracle has validated this fix on their side using packages provided by
Phil Cox in this PPA (thanks Phil!):
https://launchpad.net/~philcox/+archive/ubuntu/oracle-sf00417471-disable-enable-virt-at-load

[Where problems could occur]

This change is relatively harmless, with the only downside (currently,
on the 6.17 Oracle kernel) being that TDX requires
enable_virt_at_load=true since fcdbdf63431c9 ("KVM: VMX: Initialize TDX
during KVM module load"); however, this limitation is not currently
relevant to the OCI use case.

[Other info]
SF #00417471

Philip Cox (1):
  UBUNTU: SAUCE: kvm: set `enable_virt_at_load` default to false

 virt/kvm/kvm_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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