CVE-2023-52659

In the Linux kernel, the following vulnerability has been resolved: x86/mm:
Ensure input to pfn_to_kaddr() is treated as a 64-bit type On 64-bit
platforms, the pfn_to_kaddr() macro requires that the input value is 64
bits in order to ensure that valid address bits don’t get lost when
shifting that input by PAGE_SHIFT to calculate the physical address to
provide a virtual address for. One such example is in pvalidate_pages()
(used by SEV-SNP guests), where the GFN in the struct used for page-state
change requests is a 40-bit bit-field, so attempts to pass this GFN field
directly into pfn_to_kaddr() ends up causing guest crashes when dealing
with addresses above the 1TB range due to the above. Fix this issue with
SEV-SNP guests, as well as any similar cases that might cause issues in
current/future code, by using an inline function, instead of a macro, so
that the input is implicitly cast to the expected 64-bit input type prior
to performing the shift operation. While it might be argued that the issue
is on the caller side, other archs/macros have taken similar approaches to
deal with instances like this, such as ARM explicitly casting the input to
phys_addr_t: e48866647b48 (“ARM: 8396/1: use phys_addr_t in
pfn_to_kaddr()”) A C inline function is even better though. [ mingo:
Refined the changelog some more & added __always_inline. ]