KVM: x86/mmu: Allow zap gfn range to operate under the mmu read lock

mainline inclusion
from mainline-v5.13-rc1
commit 6103bc07
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=6103bc074048876794fa6d21fd8989331690ccbd



----------------------------------------------------------------------

To reduce lock contention and interference with page fault handlers,
allow the TDP MMU function to zap a GFN range to operate under the MMU
read lock.

Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20210401233736.638171-10-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

conflict:
	arch/x86/kvm/mmu/tdp_mmu.c

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