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x86/mm: Ensure input to pfn_to_kaddr() is treated as a 64-bit type
[ Upstream commit8e5647a723
] 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:e48866647b
("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. ] Fixes:6c32117963
("x86/sev: Add SNP-specific unaccepted memory support") Suggested-by: Dave Hansen <dave.hansen@intel.com> Suggested-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Michael Roth <michael.roth@amd.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20231122163700.400507-1-michael.roth@amd.com Cc: Andy Lutomirski <luto@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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1 changed files with 5 additions and 1 deletions
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@ -66,10 +66,14 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
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* virt_addr_valid(kaddr) returns true.
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*/
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#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
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#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
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extern bool __virt_addr_valid(unsigned long kaddr);
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#define virt_addr_valid(kaddr) __virt_addr_valid((unsigned long) (kaddr))
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static __always_inline void *pfn_to_kaddr(unsigned long pfn)
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{
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return __va(pfn << PAGE_SHIFT);
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}
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static __always_inline u64 __canonical_address(u64 vaddr, u8 vaddr_bits)
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{
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return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits);
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