[PATCH v8 04/20] powerpc: mm: Add p?d_large() definitions

[PATCH v8 04/20] powerpc: mm: Add p?d_large() definitions

[Steven Price]

walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information is provided by the
p?d_large() functions/macros.

For powerpc pmd_large() was already implemented, so hoist it out of the
CONFIG_TRANSPARENT_HUGEPAGE condition and implement the other levels.

CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Michael Ellerman <mpe@ellerman.id.au>
CC: linuxppc-dev@lists.ozlabs.org
CC: kvm-ppc@vger.kernel.org
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/powerpc/include/asm/book3s/64/pgtable.h | 30 ++++++++++++++------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 581f91be9dd4..f6d1ac8b832e 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -897,6 +897,12 @@ static inline int pud_present(pud_t pud)
 	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PRESENT));
 }
 
+#define pud_large	pud_large
+static inline int pud_large(pud_t pud)
+{
+	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
+}
+
 extern struct page *pud_page(pud_t pud);
 extern struct page *pmd_page(pmd_t pmd);
 static inline pte_t pud_pte(pud_t pud)
@@ -940,6 +946,12 @@ static inline int pgd_present(pgd_t pgd)
 	return !!(pgd_raw(pgd) & cpu_to_be64(_PAGE_PRESENT));
 }
 
+#define pgd_large	pgd_large
+static inline int pgd_large(pgd_t pgd)
+{
+	return !!(pgd_raw(pgd) & cpu_to_be64(_PAGE_PTE));
+}
+
 static inline pte_t pgd_pte(pgd_t pgd)
 {
 	return __pte_raw(pgd_raw(pgd));
@@ -1093,6 +1105,15 @@ static inline bool pmd_access_permitted(pmd_t pmd, bool write)
 	return pte_access_permitted(pmd_pte(pmd), write);
 }
 
+#define pmd_large	pmd_large
+/*
+ * returns true for pmd migration entries, THP, devmap, hugetlb
+ */
+static inline int pmd_large(pmd_t pmd)
+{
+	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
+}
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 extern pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot);
 extern pmd_t mk_pmd(struct page *page, pgprot_t pgprot);
@@ -1119,15 +1140,6 @@ pmd_hugepage_update(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp,
 	return hash__pmd_hugepage_update(mm, addr, pmdp, clr, set);
 }
 
-/*
- * returns true for pmd migration entries, THP, devmap, hugetlb
- * But compile time dependent on THP config
- */
-static inline int pmd_large(pmd_t pmd)
-{
-	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
-}
-
 static inline pmd_t pmd_mknotpresent(pmd_t pmd)
 {
 	return __pmd(pmd_val(pmd) & ~_PAGE_PRESENT);
-- 
2.20.1

[PATCH v8 05/20] KVM: PPC: Book3S HV: Remove pmd_is_leaf()

[Steven Price]

Since pmd_large() is now always available, pmd_is_leaf() is redundant.
Replace all uses with calls to pmd_large().

CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Michael Ellerman <mpe@ellerman.id.au>
CC: Paul Mackerras <paulus@ozlabs.org>
CC: kvm-ppc@vger.kernel.org
CC: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/powerpc/kvm/book3s_64_mmu_radix.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index f55ef071883f..1b57b4e3f819 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -363,12 +363,6 @@ static void kvmppc_pte_free(pte_t *ptep)
 	kmem_cache_free(kvm_pte_cache, ptep);
 }
 
-/* Like pmd_huge() and pmd_large(), but works regardless of config options */
-static inline int pmd_is_leaf(pmd_t pmd)
-{
-	return !!(pmd_val(pmd) & _PAGE_PTE);
-}
-
 static pmd_t *kvmppc_pmd_alloc(void)
 {
 	return kmem_cache_alloc(kvm_pmd_cache, GFP_KERNEL);
@@ -460,7 +454,7 @@ static void kvmppc_unmap_free_pmd(struct kvm *kvm, pmd_t *pmd, bool full,
 	for (im = 0; im < PTRS_PER_PMD; ++im, ++p) {
 		if (!pmd_present(*p))
 			continue;
-		if (pmd_is_leaf(*p)) {
+		if (pmd_large(*p)) {
 			if (full) {
 				pmd_clear(p);
 			} else {
@@ -593,7 +587,7 @@ int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgtable, pte_t pte,
 	else if (level <= 1)
 		new_pmd = kvmppc_pmd_alloc();
 
-	if (level == 0 && !(pmd && pmd_present(*pmd) && !pmd_is_leaf(*pmd)))
+	if (level == 0 && !(pmd && pmd_present(*pmd) && !pmd_large(*pmd)))
 		new_ptep = kvmppc_pte_alloc();
 
 	/* Check if we might have been invalidated; let the guest retry if so */
@@ -662,7 +656,7 @@ int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgtable, pte_t pte,
 		new_pmd = NULL;
 	}
 	pmd = pmd_offset(pud, gpa);
-	if (pmd_is_leaf(*pmd)) {
+	if (pmd_large(*pmd)) {
 		unsigned long lgpa = gpa & PMD_MASK;
 
 		/* Check if we raced and someone else has set the same thing */
-- 
2.20.1

Re: [PATCH v8 05/20] KVM: PPC: Book3S HV: Remove pmd_is_leaf()

[Paul Mackerras]

On Wed, Apr 03, 2019 at 03:16:12PM +0100, Steven Price wrote:
> Since pmd_large() is now always available, pmd_is_leaf() is redundant.
> Replace all uses with calls to pmd_large().

NAK.  I don't want to do this, because pmd_is_leaf() is purely about
the guest page tables (the "partition-scoped" radix tree which
specifies the guest physical to host physical translation), not about
anything to do with the Linux process page tables.  The guest page
tables have the same format as the Linux process page tables, but they
are managed separately.

If it makes things clearer, I could rename it to "guest_pmd_is_leaf()"
or something similar.

Paul.

Re: [PATCH v8 05/20] KVM: PPC: Book3S HV: Remove pmd_is_leaf()

[Steven Price]

On 29/04/2019 03:05, Paul Mackerras wrote:
> On Wed, Apr 03, 2019 at 03:16:12PM +0100, Steven Price wrote:
>> Since pmd_large() is now always available, pmd_is_leaf() is redundant.
>> Replace all uses with calls to pmd_large().
> 
> NAK.  I don't want to do this, because pmd_is_leaf() is purely about
> the guest page tables (the "partition-scoped" radix tree which
> specifies the guest physical to host physical translation), not about
> anything to do with the Linux process page tables.  The guest page
> tables have the same format as the Linux process page tables, but they
> are managed separately.

Fair enough, I'll drop this patch in the next posting.

> If it makes things clearer, I could rename it to "guest_pmd_is_leaf()"
> or something similar.

I'll leave that decision up to you - it might prevent similar confusion
in the future.

Steve