From: Sai Praneeth <sai.praneeth.prakhya@xxxxxxxxx>
Since EFI page tables can be treated as kernel page tables they should
be global. All the other page mapping functions in pageattr.c set the
_PAGE_GLOBAL bit and we want to avoid inconsistencies when we map a page
in the EFI code paths, for example when that page is split in
__split_large_page(), etc. It also makes it easier to validate that the
EFI region mappings have the correct attributes because there are fewer
differences compared with regular kernel mappings.
Cc: Ricardo Neri <ricardo.neri@xxxxxxxxx>
Cc: Ravi Shankar <ravi.v.shankar@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>
---
arch/x86/mm/pageattr.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 3052e72fa9f5..9256f6406a3c 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -904,6 +904,20 @@ static void populate_pte(struct cpa_data *cpa,
pte = pte_offset_kernel(pmd, start);
+ /*
+ * Set the GLOBAL flags only if the PRESENT flag is
+ * set otherwise pte_present will return true even on
+ * a non present pte. The canon_pgprot will clear
+ * _PAGE_GLOBAL for the ancient hardware that doesn't
+ * support it.
+ */
+ if (pgprot_val(pgprot) & _PAGE_PRESENT)
+ pgprot_val(pgprot) |= _PAGE_GLOBAL;
+ else
+ pgprot_val(pgprot) &= ~_PAGE_GLOBAL;
+
+ pgprot = canon_pgprot(pgprot);
+
while (num_pages-- && start < end) {
set_pte(pte, pfn_pte(cpa->pfn, pgprot));
--
2.1.4
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