x86/efi: Fix kernel panic when CONFIG_DEBUG_VIRTUAL is enabled
When CONFIG_DEBUG_VIRTUAL is enabled, all accesses to __pa(address) are monitored to see whether address falls in direct mapping or kernel text mapping (see Documentation/x86/x86_64/mm.txt for details), if it does not, the kernel panics. During 1:1 mapping of EFI runtime services we access virtual addresses which are == physical addresses, thus the 1:1 mapping and these addresses do not fall in either of the above two regions and hence when passed as arguments to __pa() kernel panics as reported by Dave Hansen here https://lkml.kernel.org/r/5462999A.7090706@intel.com. So, before calling __pa() virtual addresses should be validated which results in skipping call to split_page_count() and that should be fine because it is used to keep track of everything *but* 1:1 mappings. Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> Reported-by: Dave Hansen <dave.hansen@intel.com> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Glenn P Williamson <glenn.p.williamson@intel.com> Cc: Ravi Shankar <ravi.v.shankar@intel.com> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
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@ -648,9 +648,12 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
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for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc)
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set_pte(&pbase[i], pfn_pte(pfn, canon_pgprot(ref_prot)));
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if (pfn_range_is_mapped(PFN_DOWN(__pa(address)),
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PFN_DOWN(__pa(address)) + 1))
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split_page_count(level);
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if (virt_addr_valid(address)) {
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unsigned long pfn = PFN_DOWN(__pa(address));
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if (pfn_range_is_mapped(pfn, pfn + 1))
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split_page_count(level);
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}
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/*
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* Install the new, split up pagetable.
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