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powerpc/kvm: Handle transparent hugepage in KVM 

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.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Aneesh Kumar K.V 2013-06-20 14:30:19 +05:30 committed by Benjamin Herrenschmidt
parent 12bc9f6fc1
commit db7cb5b924
3 changed files with 43 additions and 33 deletions
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56
arch/powerpc/include/asm/kvm_book3s_64.h
View File

@ -159,36 +159,46 @@ 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.
* If it's present and writable, atomically set dirty and referenced bits and
* return the PTE, otherwise return 0. If we find a transparent hugepage
* and if it is marked splitting we 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;
pte_t old_pte, new_pte = __pte(0);
/* 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");
while (1) {
old_pte = pte_val(*ptep);
/*
* wait until _PAGE_BUSY is clear then set it atomically
*/
if (unlikely(old_pte & _PAGE_BUSY)) {
cpu_relax();
continue;
}
#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
/* If pte is not present return None */
if (unlikely(!(old_pte & _PAGE_PRESENT)))
return __pte(0);
if (pte_present(pte)) {
pte = pte_mkyoung(pte);
if (writing && pte_write(pte))
pte = pte_mkdirty(pte);
new_pte = pte_mkyoung(old_pte);
if (writing && pte_write(old_pte))
new_pte = pte_mkdirty(new_pte);
if (old_pte == __cmpxchg_u64((unsigned long *)ptep, old_pte,
new_pte))
break;
}
*p = pte; /* clears _PAGE_BUSY */
return 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)
{

8
arch/powerpc/kvm/book3s_64_mmu_hv.c
View File

@ -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 hugepage_shift;
pte_t *ptep, pte;
/*
@ -683,9 +684,10 @@ 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, &hugepage_shift);
if (ptep) {
pte = kvmppc_read_update_linux_pte(ptep, 1,
hugepage_shift);
if (pte_write(pte))
write_ok = 1;
}

12
arch/powerpc/kvm/book3s_hv_rm_mmu.c
View File

@ -139,20 +139,18 @@ static pte_t lookup_linux_pte(pgd_t *pgdir, unsigned long hva,
{
pte_t *ptep;
unsigned long ps = *pte_sizep;
unsigned int shift;
unsigned int hugepage_shift;
ptep = find_linux_pte_or_hugepte(pgdir, hva, &shift);
ptep = find_linux_pte_or_hugepte(pgdir, hva, &hugepage_shift);
if (!ptep)
return __pte(0);
if (shift)
*pte_sizep = 1ul << shift;
if (hugepage_shift)
*pte_sizep = 1ul << hugepage_shift;
else
*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, hugepage_shift);
}
static inline void unlock_hpte(unsigned long *hpte, unsigned long hpte_v)