KVM: MMU: load PDPTRs outside mmu_lock

mainline inclusion
from mainline-v5.13-rc1
commit 4a38162e
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I7S3VQ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4a38162ee9f10f5f67c36f4f5aa4f6be2657efd5



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On SVM, reading PDPTRs might access guest memory, which might fault
and thus might sleep.  On the other hand, it is not possible to
release the lock after make_mmu_pages_available has been called.

Therefore, push the call to make_mmu_pages_available and the
mmu_lock critical section within mmu_alloc_direct_roots and
mmu_alloc_shadow_roots.

Reported-by: Wanpeng Li <wanpengli@tencent.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

conflicts:
	arch/x86/kvm/mmu/mmu.c

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>