KVM: x86/mmu: Coalesce TLB flushes across address spaces for gfn range zap

mainline inclusion
from mainline-v5.13-rc1
commit 1a61b7db
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=1a61b7db7a8dc44ce5010926ed48b519dda92d84



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Gather pending TLB flushes across both address spaces when zapping a
given gfn range.  This requires feeding "flush" back into subsequent
calls, but on the plus side sets the stage for further batching
between the legacy MMU and TDP MMU.  It also allows refactoring the
address space iteration to cover the legacy and TDP MMUs without
introducing truly ugly code.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210326021957.1424875-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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

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