From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
We can find pte that are splitting while walking page tables. Return
None pte in that case.
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/kvm_book3s_64.h | 51 ++++++++++++++++++--------------
arch/powerpc/kvm/book3s_64_mmu_hv.c | 7 +++--
arch/powerpc/kvm/book3s_hv_rm_mmu.c | 4 +--
3 files changed, 34 insertions(+), 28 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h
b/arch/powerpc/include/asm/kvm_book3s_64.h
index 9c1ff33..ce20f7e 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -162,33 +162,40 @@ static inline int hpte_cache_flags_ok(unsigned long ptel,
unsigned long io_type)
* Lock and read a linux PTE. If it's present and writable, atomically
* set dirty and referenced bits and return the PTE, otherwise return 0.
*/
-static inline pte_t kvmppc_read_update_linux_pte(pte_t *p, int writing)
+static inline pte_t kvmppc_read_update_linux_pte(pte_t *ptep, int writing,
+ unsigned int hugepage)
{
- pte_t pte, tmp;
-
- /* wait until _PAGE_BUSY is clear then set it atomically */
- __asm__ __volatile__ (
- "1: ldarx %0,0,%3\n"
- " andi. %1,%0,%4\n"
- " bne- 1b\n"
- " ori %1,%0,%4\n"
- " stdcx. %1,0,%3\n"
- " bne- 1b"
- : "=&r" (pte), "=&r" (tmp), "=m" (*p)
- : "r" (p), "i" (_PAGE_BUSY)
- : "cc");
-
- if (pte_present(pte)) {
- pte = pte_mkyoung(pte);
- if (writing && pte_write(pte))
- pte = pte_mkdirty(pte);
- }
+ pte_t old_pte, new_pte = __pte(0);
+repeat:
+ do {
+ old_pte = pte_val(*ptep);
+ /*
+ * wait until _PAGE_BUSY is clear then set it atomically
+ */
+ if (unlikely(old_pte & _PAGE_BUSY))
+ goto repeat;
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ /* If hugepage and is trans splitting return None */
+ if (unlikely(hugepage &&
+ pmd_trans_splitting(pte_pmd(old_pte))))
+ return __pte(0);
+#endif
- *p = pte; /* clears _PAGE_BUSY */
+ /* If pte is not present return None */
+ if (unlikely(!(old_pte & _PAGE_PRESENT)))
+ return __pte(0);
- return pte;
+ new_pte = pte_mkyoung(old_pte);
+ if (writing && pte_write(old_pte))
+ new_pte = pte_mkdirty(new_pte);
+
+ } while (old_pte != __cmpxchg_u64((unsigned long *)ptep,
+ old_pte, new_pte));
+ return new_pte;
}
+
/* Return HPTE cache control bits corresponding to Linux pte bits */
static inline unsigned long hpte_cache_bits(unsigned long pte_val)
{
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c
b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 5880dfb..e1a9415 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -675,6 +675,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct
kvm_vcpu *vcpu,
}
/* if the guest wants write access, see if that is OK */
if (!writing && hpte_is_writable(r)) {
+ unsigned int shift;
pte_t *ptep, pte;
/*
@@ -683,9 +684,9 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct
kvm_vcpu *vcpu,
*/
rcu_read_lock_sched();
ptep = find_linux_pte_or_hugepte(current->mm->pgd,
- hva, NULL);
- if (ptep && pte_present(*ptep)) {
- pte = kvmppc_read_update_linux_pte(ptep, 1);
+ hva, &shift);
+ if (ptep) {
+ pte = kvmppc_read_update_linux_pte(ptep, 1,
shift);
if (pte_write(pte))
write_ok = 1;
}
diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index dcf892d..39ae723 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -150,9 +150,7 @@ static pte_t lookup_linux_pte(pgd_t *pgdir, unsigned long
hva,
*pte_sizep = PAGE_SIZE;
if (ps > *pte_sizep)
return __pte(0);
- if (!pte_present(*ptep))
- return __pte(0);
- return kvmppc_read_update_linux_pte(ptep, writing);
+ return kvmppc_read_update_linux_pte(ptep, writing, shift);
}
static inline void unlock_hpte(unsigned long *hpte, unsigned long hpte_v)
--
1.8.1.2
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