mainline inclusion
from mainline-v6.0-rc1
commit 1d5e740d
category: feature
feature: IPI Virtualization
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I5ODSC
CVE: N/A
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1d5e740d518e02cea46325b3d37135bf9c08982a

Intel-SIG: commit 1d5e740d ("KVM: Move kvm_arch_vcpu_precreate() under kvm->lock")

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KVM: Move kvm_arch_vcpu_precreate() under kvm->lock

kvm_arch_vcpu_precreate() targets to handle arch specific VM resource
to be prepared prior to the actual creation of vCPU. For example, x86
platform may need do per-VM allocation based on max_vcpu_ids at the
first vCPU creation. It probably leads to concurrency control on this
allocation as multiple vCPU creation could happen simultaneously. From
the architectual point of view, it's necessary to execute
kvm_arch_vcpu_precreate() under protect of kvm->lock.

Currently only arm64, x86 and s390 have non-nop implementations at the
stage of vCPU pre-creation. Remove the lock acquiring in s390's design
and make sure all architecture can run kvm_arch_vcpu_precreate() safely
under kvm->lock without recrusive lock issue.
Suggested-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NZeng Guang <guang.zeng@intel.com>
Message-Id: <20220419154409.11842-1-guang.zeng@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NJason Zeng <jason.zeng@intel.com>