diff options
| author | Juergen Gross <jgross@suse.com> | 2025-04-22 15:17:17 +0200 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2025-04-23 07:49:14 -0700 |
| commit | 4ce385f56434f3810ef103e1baea357ddcc6667e (patch) | |
| tree | b0381b54e4246c8bec53dfcf64c1f225b4ce6527 /arch/x86/mm/pgtable.c | |
| parent | 83b2d345e1786fdab96fc2b52942eebde125e7cd (diff) | |
x86/mm: Fix _pgd_alloc() for Xen PV mode
Recently _pgd_alloc() was switched from using __get_free_pages() to
pagetable_alloc_noprof(), which might return a compound page in case
the allocation order is larger than 0.
On x86 this will be the case if CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
is set, even if PTI has been disabled at runtime.
When running as a Xen PV guest (this will always disable PTI), using
a compound page for a PGD will result in VM_BUG_ON_PGFLAGS being
triggered when the Xen code tries to pin the PGD.
Fix the Xen issue together with the not needed 8k allocation for a
PGD with PTI disabled by replacing PGD_ALLOCATION_ORDER with an
inline helper returning the needed order for PGD allocations.
Fixes: a9b3c355c2e6 ("asm-generic: pgalloc: provide generic __pgd_{alloc,free}")
Reported-by: Petr Vaněk <arkamar@atlas.cz>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Petr Vaněk <arkamar@atlas.cz>
Cc:stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250422131717.25724-1-jgross%40suse.com
Diffstat (limited to 'arch/x86/mm/pgtable.c')
| -rw-r--r-- | arch/x86/mm/pgtable.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index a05fcddfc811..f7ae44d3dd9e 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -360,7 +360,7 @@ static inline pgd_t *_pgd_alloc(struct mm_struct *mm) * We allocate one page for pgd. */ if (!SHARED_KERNEL_PMD) - return __pgd_alloc(mm, PGD_ALLOCATION_ORDER); + return __pgd_alloc(mm, pgd_allocation_order()); /* * Now PAE kernel is not running as a Xen domain. We can allocate @@ -380,7 +380,7 @@ static inline void _pgd_free(struct mm_struct *mm, pgd_t *pgd) static inline pgd_t *_pgd_alloc(struct mm_struct *mm) { - return __pgd_alloc(mm, PGD_ALLOCATION_ORDER); + return __pgd_alloc(mm, pgd_allocation_order()); } static inline void _pgd_free(struct mm_struct *mm, pgd_t *pgd) |