CVE ID:	CVE-2021-47450
Description:	In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Fix host stage-2 PGD refcount The KVM page-table library refcounts the pages of concatenated stage-2 PGDs individually. However, when running KVM in protected mode, the host's stage-2 PGD is currently managed by EL2 as a single high-order compound page, which can cause the refcount of the tail pages to reach 0 when they shouldn't, hence corrupting the page-table. Fix this by introducing a new hyp_split_page() helper in the EL2 page allocator (matching the kernel's split_page() function), and make use of it from host_s2_zalloc_pages_exact().
Test IDs:	None available
Cross References:	Common Vulnerability Exposure (CVE) ID: CVE-2021-47450 https://git.kernel.org/stable/c/1d58a17ef54599506d44c45ac95be27273a4d2b1 https://git.kernel.org/stable/c/1d58a17ef54599506d44c45ac95be27273a4d2b1 https://git.kernel.org/stable/c/b372264c66ef78f2cab44e877fbd765ad6d24c39 https://git.kernel.org/stable/c/b372264c66ef78f2cab44e877fbd765ad6d24c39