KVM: x86/mmu: Use raw level to index into MMIO walks' sptes array

mainline inclusion
from mainline-v5.11-rc3
commit dde81f94
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=dde81f9477d018a96fba991c5928c6ab8cc109f8



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Bump the size of the sptes array by one and use the raw level of the
SPTE to index into the sptes array.  Using the SPTE level directly
improves readability by eliminating the need to reason out why the level
is being adjusted when indexing the array.  The array is on the stack
and is not explicitly initialized; bumping its size is nothing more than
a superficial adjustment to the stack frame.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20201218003139.2167891-4-seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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

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