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Commit db7cb5b9 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Benjamin Herrenschmidt
Browse files

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: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 12bc9f6f

arch/powerpc/include/asm/kvm_book3s_64.h

+34 −24
Original line number Diff line number Diff line
@@ -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)

{

arch/powerpc/kvm/book3s_64_mmu_hv.c

+5 −3
Original line number Diff line number Diff line
@@ -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;

			}

arch/powerpc/kvm/book3s_hv_rm_mmu.c

+5 −7
Original line number Diff line number Diff line
@@ -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)