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author | Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | 2013-06-20 14:30:19 +0530 |
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committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-06-21 16:01:55 +1000 |
commit | db7cb5b92409b36e4338355fbc3561b3f6801c7b (patch) | |
tree | e9e000cbae80bb0e92742d4bbe10f68352ffe2ff /arch/powerpc/include/asm | |
parent | 12bc9f6fc1d6582b4529ac522d2231bd2584a5f1 (diff) | |
download | op-kernel-dev-db7cb5b92409b36e4338355fbc3561b3f6801c7b.zip op-kernel-dev-db7cb5b92409b36e4338355fbc3561b3f6801c7b.tar.gz |
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>
Diffstat (limited to 'arch/powerpc/include/asm')
-rw-r--r-- | arch/powerpc/include/asm/kvm_book3s_64.h | 58 |
1 files changed, 34 insertions, 24 deletions
diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h index 9c1ff33..a1ecb14 100644 --- a/arch/powerpc/include/asm/kvm_book3s_64.h +++ b/arch/powerpc/include/asm/kvm_book3s_64.h @@ -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; - - /* 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); + + 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); - *p = pte; /* clears _PAGE_BUSY */ + new_pte = pte_mkyoung(old_pte); + if (writing && pte_write(old_pte)) + new_pte = pte_mkdirty(new_pte); - return pte; + if (old_pte == __cmpxchg_u64((unsigned long *)ptep, old_pte, + new_pte)) + break; + } + return new_pte; } + /* Return HPTE cache control bits corresponding to Linux pte bits */ static inline unsigned long hpte_cache_bits(unsigned long pte_val) { |