x86: CPA fix pagetable split
Move the readout of the large entry into the spinlock section to
prevent an unlikely but possible race.
Mark the pmd/pud entry present after the split. We preserved the
non present bit in the new split mapping.
Remove the stale gfp_flags double initialization.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 74446ea..7288099 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -336,7 +336,7 @@
static int split_large_page(pte_t *kpte, unsigned long address)
{
- pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte));
+ pgprot_t ref_prot;
gfp_t gfp_flags = GFP_KERNEL;
unsigned long flags, addr, pfn;
pte_t *pbase, *tmp;
@@ -344,7 +344,6 @@
unsigned int i, level;
#ifdef CONFIG_DEBUG_PAGEALLOC
- gfp_flags = __GFP_HIGH | __GFP_NOFAIL | __GFP_NOWARN;
gfp_flags = GFP_ATOMIC | __GFP_NOWARN;
#endif
base = alloc_pages(gfp_flags, 0);
@@ -368,6 +367,7 @@
#ifdef CONFIG_X86_32
paravirt_alloc_pt(&init_mm, page_to_pfn(base));
#endif
+ ref_prot = pte_pgprot(pte_clrhuge(*kpte));
/*
* Get the target pfn from the original entry:
@@ -377,13 +377,17 @@
set_pte(&pbase[i], pfn_pte(pfn, ref_prot));
/*
- * Install the new, split up pagetable. Important detail here:
+ * Install the new, split up pagetable. Important details here:
*
* On Intel the NX bit of all levels must be cleared to make a
* page executable. See section 4.13.2 of Intel 64 and IA-32
* Architectures Software Developer's Manual).
+ *
+ * Mark the entry present. The current mapping might be
+ * set to not present, which we preserved above.
*/
ref_prot = pte_pgprot(pte_mkexec(pte_clrhuge(*kpte)));
+ pgprot_val(ref_prot) |= _PAGE_PRESENT;
__set_pmd_pte(kpte, address, mk_pte(base, ref_prot));
base = NULL;