[PATCH v3 0/4] KVM: Support PUD hugepages at stage 2

[PATCH v3 0/4] KVM: Support PUD hugepages at stage 2

[Punit Agrawal]

Hi,

This patchset adds support for PUD hugepages at stage 2. This feature
is useful on cores that have support for large sized TLB mappings
(e.g., 1GB for 4K granule). Previous postings can be found at
[0][1][2].

Support is added to code that is shared between arm and arm64. Dummy
helpers for arm are provided as the port does not support PUD hugepage
sizes.

There is a small conflict with the series to add support for 52 bit
IPA[3]. The patches have been functionally tested on an A57 based
system. The patchset is based on v4.17-rc5 and incorporates feedback
received on the previous version.

Thanks,
Punit

v2 -> v3:
* Update vma_pagesize directly if THP [1/4]. Previsouly this was done
  indirectly via hugetlb
* Added review tag [4/4]

v1 -> v2:
* Create helper to check if the page should have exec permission [1/4]
* Fix broken condition to detect THP hugepage [1/4]
* Fix in-correct hunk resulting from a rebase [4/4]

[0] https://www.spinics.net/lists/arm-kernel/msg628053.html
[1] https://lkml.org/lkml/2018/4/20/566
[2] https://lkml.org/lkml/2018/5/1/133
[3] https://lwn.net/Articles/750176/


Punit Agrawal (4):
  KVM: arm/arm64: Share common code in user_mem_abort()
  KVM: arm/arm64: Introduce helpers to manupulate page table entries
  KVM: arm64: Support dirty page tracking for PUD hugepages
  KVM: arm64: Add support for PUD hugepages at stage 2

 arch/arm/include/asm/kvm_mmu.h         |  40 ++++++++
 arch/arm64/include/asm/kvm_mmu.h       |  30 ++++++
 arch/arm64/include/asm/pgtable-hwdef.h |   4 +
 arch/arm64/include/asm/pgtable.h       |   2 +
 virt/kvm/arm/mmu.c                     | 121 +++++++++++++++++--------
 5 files changed, 161 insertions(+), 36 deletions(-)

-- 
2.17.0

[PATCH v3 1/4] KVM: arm/arm64: Share common code in user_mem_abort()

[Punit Agrawal]

The code for operations such as marking the pfn as dirty, and
dcache/icache maintenance during stage 2 fault handling is duplicated
between normal pages and PMD hugepages.

Instead of creating another copy of the operations when we introduce
PUD hugepages, let's share them across the different pagesizes.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
---
 virt/kvm/arm/mmu.c | 69 +++++++++++++++++++++++++++-------------------
 1 file changed, 40 insertions(+), 29 deletions(-)

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 7f6a944db23d..07ae1e003762 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1396,6 +1396,21 @@ static void invalidate_icache_guest_page(kvm_pfn_t pfn, unsigned long size)
 	__invalidate_icache_guest_page(pfn, size);
 }
 
+static bool stage2_should_exec(struct kvm *kvm, phys_addr_t addr,
+			       bool exec_fault, unsigned long fault_status)
+{
+	/*
+	 * If we took an execution fault we will have made the
+	 * icache/dcache coherent and should now let the s2 mapping be
+	 * executable.
+	 *
+	 * Write faults (!exec_fault && FSC_PERM) are orthogonal to
+	 * execute permissions, and we preserve whatever we have.
+	 */
+	return exec_fault ||
+		(fault_status == FSC_PERM && stage2_is_exec(kvm, addr));
+}
+
 static void kvm_send_hwpoison_signal(unsigned long address,
 				     struct vm_area_struct *vma)
 {
@@ -1428,7 +1443,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	kvm_pfn_t pfn;
 	pgprot_t mem_type = PAGE_S2;
 	bool logging_active = memslot_is_logging(memslot);
-	unsigned long flags = 0;
+	unsigned long vma_pagesize, flags = 0;
 
 	write_fault = kvm_is_write_fault(vcpu);
 	exec_fault = kvm_vcpu_trap_is_iabt(vcpu);
@@ -1448,7 +1463,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 		return -EFAULT;
 	}
 
-	if (vma_kernel_pagesize(vma) == PMD_SIZE && !logging_active) {
+	vma_pagesize = vma_kernel_pagesize(vma);
+	if (vma_pagesize == PMD_SIZE && !logging_active) {
 		hugetlb = true;
 		gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT;
 	} else {
@@ -1517,28 +1533,33 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	if (mmu_notifier_retry(kvm, mmu_seq))
 		goto out_unlock;
 
-	if (!hugetlb && !force_pte)
-		hugetlb = transparent_hugepage_adjust(&pfn, &fault_ipa);
+	if (!hugetlb && !force_pte) {
+		/*
+		 * Only PMD_SIZE transparent hugepages(THP) are
+		 * currently supported. This code will need to be
+		 * updated to support other THP sizes.
+		 */
+		if (transparent_hugepage_adjust(&pfn, &fault_ipa))
+			vma_pagesize = PMD_SIZE;
+	}
+
+	if (writable)
+		kvm_set_pfn_dirty(pfn);
 
-	if (hugetlb) {
+	if (fault_status != FSC_PERM)
+		clean_dcache_guest_page(pfn, vma_pagesize);
+
+	if (exec_fault)
+		invalidate_icache_guest_page(pfn, vma_pagesize);
+
+	if (vma_pagesize == PMD_SIZE) {
 		pmd_t new_pmd = pfn_pmd(pfn, mem_type);
 		new_pmd = pmd_mkhuge(new_pmd);
-		if (writable) {
+		if (writable)
 			new_pmd = kvm_s2pmd_mkwrite(new_pmd);
-			kvm_set_pfn_dirty(pfn);
-		}
 
-		if (fault_status != FSC_PERM)
-			clean_dcache_guest_page(pfn, PMD_SIZE);
-
-		if (exec_fault) {
+		if (stage2_should_exec(kvm, fault_ipa, exec_fault, fault_status))
 			new_pmd = kvm_s2pmd_mkexec(new_pmd);
-			invalidate_icache_guest_page(pfn, PMD_SIZE);
-		} else if (fault_status == FSC_PERM) {
-			/* Preserve execute if XN was already cleared */
-			if (stage2_is_exec(kvm, fault_ipa))
-				new_pmd = kvm_s2pmd_mkexec(new_pmd);
-		}
 
 		ret = stage2_set_pmd_huge(kvm, memcache, fault_ipa, &new_pmd);
 	} else {
@@ -1546,21 +1567,11 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 
 		if (writable) {
 			new_pte = kvm_s2pte_mkwrite(new_pte);
-			kvm_set_pfn_dirty(pfn);
 			mark_page_dirty(kvm, gfn);
 		}
 
-		if (fault_status != FSC_PERM)
-			clean_dcache_guest_page(pfn, PAGE_SIZE);
-
-		if (exec_fault) {
+		if (stage2_should_exec(kvm, fault_ipa, exec_fault, fault_status))
 			new_pte = kvm_s2pte_mkexec(new_pte);
-			invalidate_icache_guest_page(pfn, PAGE_SIZE);
-		} else if (fault_status == FSC_PERM) {
-			/* Preserve execute if XN was already cleared */
-			if (stage2_is_exec(kvm, fault_ipa))
-				new_pte = kvm_s2pte_mkexec(new_pte);
-		}
 
 		ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte, flags);
 	}
-- 
2.17.0

[PATCH v3 2/4] KVM: arm/arm64: Introduce helpers to manupulate page table entries

[Punit Agrawal]

Introduce helpers to abstract architectural handling of the conversion
of pfn to page table entries and marking a PMD page table entry as a
block entry.

The helpers are introduced in preparation for supporting PUD hugepages
at stage 2 - which are supported on arm64 but do not exist on arm.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
 arch/arm/include/asm/kvm_mmu.h   | 5 +++++
 arch/arm64/include/asm/kvm_mmu.h | 5 +++++
 virt/kvm/arm/mmu.c               | 7 ++++---
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 707a1f06dc5d..5907a81ad5c1 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -75,6 +75,11 @@ phys_addr_t kvm_get_idmap_vector(void);
 int kvm_mmu_init(void);
 void kvm_clear_hyp_idmap(void);
 
+#define kvm_pfn_pte(pfn, prot)	pfn_pte(pfn, prot)
+#define kvm_pfn_pmd(pfn, prot)	pfn_pmd(pfn, prot)
+
+#define kvm_pmd_mkhuge(pmd)	pmd_mkhuge(pmd)
+
 static inline void kvm_set_pmd(pmd_t *pmd, pmd_t new_pmd)
 {
 	*pmd = new_pmd;
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 082110993647..d962508ce4b3 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -173,6 +173,11 @@ void kvm_clear_hyp_idmap(void);
 #define	kvm_set_pte(ptep, pte)		set_pte(ptep, pte)
 #define	kvm_set_pmd(pmdp, pmd)		set_pmd(pmdp, pmd)
 
+#define kvm_pfn_pte(pfn, prot)		pfn_pte(pfn, prot)
+#define kvm_pfn_pmd(pfn, prot)		pfn_pmd(pfn, prot)
+
+#define kvm_pmd_mkhuge(pmd)		pmd_mkhuge(pmd)
+
 static inline pte_t kvm_s2pte_mkwrite(pte_t pte)
 {
 	pte_val(pte) |= PTE_S2_RDWR;
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 07ae1e003762..0beefcc5e090 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1553,8 +1553,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 		invalidate_icache_guest_page(pfn, vma_pagesize);
 
 	if (vma_pagesize == PMD_SIZE) {
-		pmd_t new_pmd = pfn_pmd(pfn, mem_type);
-		new_pmd = pmd_mkhuge(new_pmd);
+		pmd_t new_pmd = kvm_pfn_pmd(pfn, mem_type);
+
+		new_pmd = kvm_pmd_mkhuge(new_pmd);
 		if (writable)
 			new_pmd = kvm_s2pmd_mkwrite(new_pmd);
 
@@ -1563,7 +1564,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 
 		ret = stage2_set_pmd_huge(kvm, memcache, fault_ipa, &new_pmd);
 	} else {
-		pte_t new_pte = pfn_pte(pfn, mem_type);
+		pte_t new_pte = kvm_pfn_pte(pfn, mem_type);
 
 		if (writable) {
 			new_pte = kvm_s2pte_mkwrite(new_pte);
-- 
2.17.0

[PATCH v3 3/4] KVM: arm64: Support dirty page tracking for PUD hugepages

[Punit Agrawal]

In preparation for creating PUD hugepages at stage 2, add support for
write protecting PUD hugepages when they are encountered. Write
protecting guest tables is used to track dirty pages when migrating
VMs.

Also, provide trivial implementations of required kvm_s2pud_* helpers
to allow sharing of code with arm32.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
 arch/arm/include/asm/kvm_mmu.h   | 16 ++++++++++++++++
 arch/arm64/include/asm/kvm_mmu.h | 10 ++++++++++
 virt/kvm/arm/mmu.c               |  9 ++++++---
 3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 5907a81ad5c1..224c22c0a69c 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -80,6 +80,22 @@ void kvm_clear_hyp_idmap(void);
 
 #define kvm_pmd_mkhuge(pmd)	pmd_mkhuge(pmd)
 
+/*
+ * The following kvm_*pud*() functionas are provided strictly to allow
+ * sharing code with arm64. They should never be called in practice.
+ */
+static inline void kvm_set_s2pud_readonly(pud_t *pud)
+{
+	BUG();
+}
+
+static inline bool kvm_s2pud_readonly(pud_t *pud)
+{
+	BUG();
+	return false;
+}
+
+
 static inline void kvm_set_pmd(pmd_t *pmd, pmd_t new_pmd)
 {
 	*pmd = new_pmd;
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index d962508ce4b3..f440cf216a23 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -240,6 +240,16 @@ static inline bool kvm_s2pmd_exec(pmd_t *pmdp)
 	return !(READ_ONCE(pmd_val(*pmdp)) & PMD_S2_XN);
 }
 
+static inline void kvm_set_s2pud_readonly(pud_t *pudp)
+{
+	kvm_set_s2pte_readonly((pte_t *)pudp);
+}
+
+static inline bool kvm_s2pud_readonly(pud_t *pudp)
+{
+	return kvm_s2pte_readonly((pte_t *)pudp);
+}
+
 static inline bool kvm_page_empty(void *ptr)
 {
 	struct page *ptr_page = virt_to_page(ptr);
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 0beefcc5e090..671d3c0825f2 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1286,9 +1286,12 @@ static void  stage2_wp_puds(pgd_t *pgd, phys_addr_t addr, phys_addr_t end)
 	do {
 		next = stage2_pud_addr_end(addr, end);
 		if (!stage2_pud_none(*pud)) {
-			/* TODO:PUD not supported, revisit later if supported */
-			BUG_ON(stage2_pud_huge(*pud));
-			stage2_wp_pmds(pud, addr, next);
+			if (stage2_pud_huge(*pud)) {
+				if (!kvm_s2pud_readonly(pud))
+					kvm_set_s2pud_readonly(pud);
+			} else {
+				stage2_wp_pmds(pud, addr, next);
+			}
 		}
 	} while (pud++, addr = next, addr != end);
 }
-- 
2.17.0

[PATCH v3 4/4] KVM: arm64: Add support for PUD hugepages at stage 2

[Punit Agrawal]

KVM only supports PMD hugepages at stage 2. Extend the stage 2 fault
handling to add support for PUD hugepages.

Addition of pud hugepage support enables additional hugepage
sizes (e.g., 1G with 4K granule) which can be useful on cores that
support mapping larger block sizes in the TLB entries.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
 arch/arm/include/asm/kvm_mmu.h         | 19 ++++++++++++
 arch/arm64/include/asm/kvm_mmu.h       | 15 ++++++++++
 arch/arm64/include/asm/pgtable-hwdef.h |  4 +++
 arch/arm64/include/asm/pgtable.h       |  2 ++
 virt/kvm/arm/mmu.c                     | 40 ++++++++++++++++++++++++--
 5 files changed, 77 insertions(+), 3 deletions(-)

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 224c22c0a69c..155916dbdd7e 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -77,8 +77,11 @@ void kvm_clear_hyp_idmap(void);
 
 #define kvm_pfn_pte(pfn, prot)	pfn_pte(pfn, prot)
 #define kvm_pfn_pmd(pfn, prot)	pfn_pmd(pfn, prot)
+#define kvm_pfn_pud(pfn, prot)	(__pud(0))
 
 #define kvm_pmd_mkhuge(pmd)	pmd_mkhuge(pmd)
+/* No support for pud hugepages */
+#define kvm_pud_mkhuge(pud)	(pud)
 
 /*
  * The following kvm_*pud*() functionas are provided strictly to allow
@@ -95,6 +98,22 @@ static inline bool kvm_s2pud_readonly(pud_t *pud)
 	return false;
 }
 
+static inline void kvm_set_pud(pud_t *pud, pud_t new_pud)
+{
+	BUG();
+}
+
+static inline pud_t kvm_s2pud_mkwrite(pud_t pud)
+{
+	BUG();
+	return pud;
+}
+
+static inline pud_t kvm_s2pud_mkexec(pud_t pud)
+{
+	BUG();
+	return pud;
+}
 
 static inline void kvm_set_pmd(pmd_t *pmd, pmd_t new_pmd)
 {
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index f440cf216a23..f49a68fcbf26 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -172,11 +172,14 @@ void kvm_clear_hyp_idmap(void);
 
 #define	kvm_set_pte(ptep, pte)		set_pte(ptep, pte)
 #define	kvm_set_pmd(pmdp, pmd)		set_pmd(pmdp, pmd)
+#define kvm_set_pud(pudp, pud)		set_pud(pudp, pud)
 
 #define kvm_pfn_pte(pfn, prot)		pfn_pte(pfn, prot)
 #define kvm_pfn_pmd(pfn, prot)		pfn_pmd(pfn, prot)
+#define kvm_pfn_pud(pfn, prot)		pfn_pud(pfn, prot)
 
 #define kvm_pmd_mkhuge(pmd)		pmd_mkhuge(pmd)
+#define kvm_pud_mkhuge(pud)		pud_mkhuge(pud)
 
 static inline pte_t kvm_s2pte_mkwrite(pte_t pte)
 {
@@ -190,6 +193,12 @@ static inline pmd_t kvm_s2pmd_mkwrite(pmd_t pmd)
 	return pmd;
 }
 
+static inline pud_t kvm_s2pud_mkwrite(pud_t pud)
+{
+	pud_val(pud) |= PUD_S2_RDWR;
+	return pud;
+}
+
 static inline pte_t kvm_s2pte_mkexec(pte_t pte)
 {
 	pte_val(pte) &= ~PTE_S2_XN;
@@ -202,6 +211,12 @@ static inline pmd_t kvm_s2pmd_mkexec(pmd_t pmd)
 	return pmd;
 }
 
+static inline pud_t kvm_s2pud_mkexec(pud_t pud)
+{
+	pud_val(pud) &= ~PUD_S2_XN;
+	return pud;
+}
+
 static inline void kvm_set_s2pte_readonly(pte_t *ptep)
 {
 	pteval_t old_pteval, pteval;
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index fd208eac9f2a..e327665e94d1 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -193,6 +193,10 @@
 #define PMD_S2_RDWR		(_AT(pmdval_t, 3) << 6)   /* HAP[2:1] */
 #define PMD_S2_XN		(_AT(pmdval_t, 2) << 53)  /* XN[1:0] */
 
+#define PUD_S2_RDONLY		(_AT(pudval_t, 1) << 6)   /* HAP[2:1] */
+#define PUD_S2_RDWR		(_AT(pudval_t, 3) << 6)   /* HAP[2:1] */
+#define PUD_S2_XN		(_AT(pudval_t, 2) << 53)  /* XN[1:0] */
+
 /*
  * Memory Attribute override for Stage-2 (MemAttr[3:0])
  */
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 7c4c8f318ba9..31ea9fda07e3 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -386,6 +386,8 @@ static inline int pmd_protnone(pmd_t pmd)
 
 #define pud_write(pud)		pte_write(pud_pte(pud))
 
+#define pud_mkhuge(pud)		(__pud(pud_val(pud) & ~PUD_TABLE_BIT))
+
 #define __pud_to_phys(pud)	__pte_to_phys(pud_pte(pud))
 #define __phys_to_pud_val(phys)	__phys_to_pte_val(phys)
 #define pud_pfn(pud)		((__pud_to_phys(pud) & PUD_MASK) >> PAGE_SHIFT)
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 671d3c0825f2..b0931fa2d64e 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1036,6 +1036,26 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
 	return 0;
 }
 
+static int stage2_set_pud_huge(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
+			       phys_addr_t addr, const pud_t *new_pud)
+{
+	pud_t *pud, old_pud;
+
+	pud = stage2_get_pud(kvm, cache, addr);
+	VM_BUG_ON(!pud);
+
+	old_pud = *pud;
+	if (pud_present(old_pud)) {
+		pud_clear(pud);
+		kvm_tlb_flush_vmid_ipa(kvm, addr);
+	} else {
+		get_page(virt_to_page(pud));
+	}
+
+	kvm_set_pud(pud, *new_pud);
+	return 0;
+}
+
 static bool stage2_is_exec(struct kvm *kvm, phys_addr_t addr)
 {
 	pmd_t *pmdp;
@@ -1467,9 +1487,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	}
 
 	vma_pagesize = vma_kernel_pagesize(vma);
-	if (vma_pagesize == PMD_SIZE && !logging_active) {
+	if ((vma_pagesize == PMD_SIZE || vma_pagesize == PUD_SIZE) &&
+	    !logging_active) {
+		struct hstate *h = hstate_vma(vma);
+
 		hugetlb = true;
-		gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT;
+		gfn = (fault_ipa & huge_page_mask(h)) >> PAGE_SHIFT;
 	} else {
 		/*
 		 * Pages belonging to memslots that don't have the same
@@ -1555,7 +1578,18 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	if (exec_fault)
 		invalidate_icache_guest_page(pfn, vma_pagesize);
 
-	if (vma_pagesize == PMD_SIZE) {
+	if (vma_pagesize == PUD_SIZE) {
+		pud_t new_pud = kvm_pfn_pud(pfn, mem_type);
+
+		new_pud = kvm_pud_mkhuge(new_pud);
+		if (writable)
+			new_pud = kvm_s2pud_mkwrite(new_pud);
+
+		if (stage2_should_exec(kvm, fault_ipa, exec_fault, fault_status))
+			new_pud = kvm_s2pud_mkexec(new_pud);
+
+		ret = stage2_set_pud_huge(kvm, memcache, fault_ipa, &new_pud);
+	} else if (vma_pagesize == PMD_SIZE) {
 		pmd_t new_pmd = kvm_pfn_pmd(pfn, mem_type);
 
 		new_pmd = kvm_pmd_mkhuge(new_pmd);
-- 
2.17.0

Re: [PATCH v3 4/4] KVM: arm64: Add support for PUD hugepages at stage 2

[Catalin Marinas]

On Mon, May 14, 2018 at 03:43:04PM +0100, Punit Agrawal wrote:
> KVM only supports PMD hugepages at stage 2. Extend the stage 2 fault
> handling to add support for PUD hugepages.
> 
> Addition of pud hugepage support enables additional hugepage
> sizes (e.g., 1G with 4K granule) which can be useful on cores that
> support mapping larger block sizes in the TLB entries.
> 
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> ---
>  arch/arm/include/asm/kvm_mmu.h         | 19 ++++++++++++
>  arch/arm64/include/asm/kvm_mmu.h       | 15 ++++++++++
>  arch/arm64/include/asm/pgtable-hwdef.h |  4 +++
>  arch/arm64/include/asm/pgtable.h       |  2 ++
>  virt/kvm/arm/mmu.c                     | 40 ++++++++++++++++++++++++--
>  5 files changed, 77 insertions(+), 3 deletions(-)

It looks like I acked an earlier version. I'll ack it again here:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Re: [PATCH v3 4/4] KVM: arm64: Add support for PUD hugepages at stage 2

[Suzuki K Poulose]

On 05/14/2018 03:43 PM, Punit Agrawal wrote:
> KVM only supports PMD hugepages at stage 2. Extend the stage 2 fault
> handling to add support for PUD hugepages.
> 
> Addition of pud hugepage support enables additional hugepage
> sizes (e.g., 1G with 4K granule) which can be useful on cores that
> support mapping larger block sizes in the TLB entries.
> 
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> ---
>   arch/arm/include/asm/kvm_mmu.h         | 19 ++++++++++++
>   arch/arm64/include/asm/kvm_mmu.h       | 15 ++++++++++
>   arch/arm64/include/asm/pgtable-hwdef.h |  4 +++
>   arch/arm64/include/asm/pgtable.h       |  2 ++
>   virt/kvm/arm/mmu.c                     | 40 ++++++++++++++++++++++++--
>   5 files changed, 77 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> index 224c22c0a69c..155916dbdd7e 100644
> --- a/arch/arm/include/asm/kvm_mmu.h
> +++ b/arch/arm/include/asm/kvm_mmu.h
> @@ -77,8 +77,11 @@ void kvm_clear_hyp_idmap(void);
>   
>   #define kvm_pfn_pte(pfn, prot)	pfn_pte(pfn, prot)
>   #define kvm_pfn_pmd(pfn, prot)	pfn_pmd(pfn, prot)
> +#define kvm_pfn_pud(pfn, prot)	(__pud(0))
>   
>   #define kvm_pmd_mkhuge(pmd)	pmd_mkhuge(pmd)
> +/* No support for pud hugepages */
> +#define kvm_pud_mkhuge(pud)	(pud)
>   
>   /*
>    * The following kvm_*pud*() functionas are provided strictly to allow
> @@ -95,6 +98,22 @@ static inline bool kvm_s2pud_readonly(pud_t *pud)
>   	return false;
>   }
>   
> +static inline void kvm_set_pud(pud_t *pud, pud_t new_pud)
> +{
> +	BUG();
> +}
> +
> +static inline pud_t kvm_s2pud_mkwrite(pud_t pud)
> +{
> +	BUG();
> +	return pud;
> +}
> +
> +static inline pud_t kvm_s2pud_mkexec(pud_t pud)
> +{
> +	BUG();
> +	return pud;
> +}
>   
>   static inline void kvm_set_pmd(pmd_t *pmd, pmd_t new_pmd)
>   {
> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> index f440cf216a23..f49a68fcbf26 100644
> --- a/arch/arm64/include/asm/kvm_mmu.h
> +++ b/arch/arm64/include/asm/kvm_mmu.h
> @@ -172,11 +172,14 @@ void kvm_clear_hyp_idmap(void);
>   
>   #define	kvm_set_pte(ptep, pte)		set_pte(ptep, pte)
>   #define	kvm_set_pmd(pmdp, pmd)		set_pmd(pmdp, pmd)
> +#define kvm_set_pud(pudp, pud)		set_pud(pudp, pud)
>   
>   #define kvm_pfn_pte(pfn, prot)		pfn_pte(pfn, prot)
>   #define kvm_pfn_pmd(pfn, prot)		pfn_pmd(pfn, prot)
> +#define kvm_pfn_pud(pfn, prot)		pfn_pud(pfn, prot)
>   
>   #define kvm_pmd_mkhuge(pmd)		pmd_mkhuge(pmd)
> +#define kvm_pud_mkhuge(pud)		pud_mkhuge(pud)
>   
>   static inline pte_t kvm_s2pte_mkwrite(pte_t pte)
>   {
> @@ -190,6 +193,12 @@ static inline pmd_t kvm_s2pmd_mkwrite(pmd_t pmd)
>   	return pmd;
>   }
>   
> +static inline pud_t kvm_s2pud_mkwrite(pud_t pud)
> +{
> +	pud_val(pud) |= PUD_S2_RDWR;
> +	return pud;
> +}
> +
>   static inline pte_t kvm_s2pte_mkexec(pte_t pte)
>   {
>   	pte_val(pte) &= ~PTE_S2_XN;
> @@ -202,6 +211,12 @@ static inline pmd_t kvm_s2pmd_mkexec(pmd_t pmd)
>   	return pmd;
>   }
>   
> +static inline pud_t kvm_s2pud_mkexec(pud_t pud)
> +{
> +	pud_val(pud) &= ~PUD_S2_XN;
> +	return pud;
> +}
> +
>   static inline void kvm_set_s2pte_readonly(pte_t *ptep)
>   {
>   	pteval_t old_pteval, pteval;
> diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
> index fd208eac9f2a..e327665e94d1 100644
> --- a/arch/arm64/include/asm/pgtable-hwdef.h
> +++ b/arch/arm64/include/asm/pgtable-hwdef.h
> @@ -193,6 +193,10 @@
>   #define PMD_S2_RDWR		(_AT(pmdval_t, 3) << 6)   /* HAP[2:1] */
>   #define PMD_S2_XN		(_AT(pmdval_t, 2) << 53)  /* XN[1:0] */
>   
> +#define PUD_S2_RDONLY		(_AT(pudval_t, 1) << 6)   /* HAP[2:1] */
> +#define PUD_S2_RDWR		(_AT(pudval_t, 3) << 6)   /* HAP[2:1] */
> +#define PUD_S2_XN		(_AT(pudval_t, 2) << 53)  /* XN[1:0] */
> +
>   /*
>    * Memory Attribute override for Stage-2 (MemAttr[3:0])
>    */
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 7c4c8f318ba9..31ea9fda07e3 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -386,6 +386,8 @@ static inline int pmd_protnone(pmd_t pmd)
>   
>   #define pud_write(pud)		pte_write(pud_pte(pud))
>   
> +#define pud_mkhuge(pud)		(__pud(pud_val(pud) & ~PUD_TABLE_BIT))
> +
>   #define __pud_to_phys(pud)	__pte_to_phys(pud_pte(pud))
>   #define __phys_to_pud_val(phys)	__phys_to_pte_val(phys)
>   #define pud_pfn(pud)		((__pud_to_phys(pud) & PUD_MASK) >> PAGE_SHIFT)
> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
> index 671d3c0825f2..b0931fa2d64e 100644
> --- a/virt/kvm/arm/mmu.c
> +++ b/virt/kvm/arm/mmu.c
> @@ -1036,6 +1036,26 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
>   	return 0;
>   }
>   
> +static int stage2_set_pud_huge(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
> +			       phys_addr_t addr, const pud_t *new_pud)
> +{
> +	pud_t *pud, old_pud;
> +
> +	pud = stage2_get_pud(kvm, cache, addr);
> +	VM_BUG_ON(!pud);
> +
> +	old_pud = *pud;
> +	if (pud_present(old_pud)) {
> +		pud_clear(pud);
> +		kvm_tlb_flush_vmid_ipa(kvm, addr);
> +	} else {
> +		get_page(virt_to_page(pud));
> +	}
> +
> +	kvm_set_pud(pud, *new_pud);
> +	return 0;
> +}
> +
>   static bool stage2_is_exec(struct kvm *kvm, phys_addr_t addr)
>   {
>   	pmd_t *pmdp;
> @@ -1467,9 +1487,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>   	}
>   
>   	vma_pagesize = vma_kernel_pagesize(vma);
> -	if (vma_pagesize == PMD_SIZE && !logging_active) {
> +	if ((vma_pagesize == PMD_SIZE || vma_pagesize == PUD_SIZE) &&
> +	    !logging_active) {
> +		struct hstate *h = hstate_vma(vma);
> +
>   		hugetlb = true;
> -		gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT;
> +		gfn = (fault_ipa & huge_page_mask(h)) >> PAGE_SHIFT;
>   	} else {
>   		/*
>   		 * Pages belonging to memslots that don't have the same
> @@ -1555,7 +1578,18 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>   	if (exec_fault)
>   		invalidate_icache_guest_page(pfn, vma_pagesize);
>   
> -	if (vma_pagesize == PMD_SIZE) {
> +	if (vma_pagesize == PUD_SIZE) {
> +		pud_t new_pud = kvm_pfn_pud(pfn, mem_type);
> +
> +		new_pud = kvm_pud_mkhuge(new_pud);
> +		if (writable)
> +			new_pud = kvm_s2pud_mkwrite(new_pud);
> +
> +		if (stage2_should_exec(kvm, fault_ipa, exec_fault, fault_status))
> +			new_pud = kvm_s2pud_mkexec(new_pud);
> +
> +		ret = stage2_set_pud_huge(kvm, memcache, fault_ipa, &new_pud);
> +	} else if (vma_pagesize == PMD_SIZE) {
>   		pmd_t new_pmd = kvm_pfn_pmd(pfn, mem_type);
>   
>   		new_pmd = kvm_pmd_mkhuge(new_pmd);
> 


Punit,

Sorry for the late notice. I was looking deeply in to the stage2 table
code to rework the same for dynamic IPA and thus found this.

I am wondering if these changes are sufficient enough to add the PUD 
hugepage support. There are lots places where we simply get the
stage2_pmd of a given address and then go about doing something at the
PMD level or drill down to PTE if the PMD is not huge. (e.g 
stage2_is_exec, handle_access_fault etc). We simply do a pmd_offset()
on a PUD entry, without even checking if the PUD is huge or not.

With the PUD huge support, I think we need to go a level up in all these 
cases and drill down from PUD level, down to the PMD level and then 
further down, depending on whether we have huge page support at either 
of these levels.


Cheers
Suzuki

Re: [PATCH v3 4/4] KVM: arm64: Add support for PUD hugepages at stage 2

[Punit Agrawal]

Suzuki K Poulose <suzuki.poulose@arm.com> writes:

> On 05/14/2018 03:43 PM, Punit Agrawal wrote:
>> KVM only supports PMD hugepages at stage 2. Extend the stage 2 fault
>> handling to add support for PUD hugepages.
>>
>> Addition of pud hugepage support enables additional hugepage
>> sizes (e.g., 1G with 4K granule) which can be useful on cores that
>> support mapping larger block sizes in the TLB entries.
>>
>> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
>> Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
>> Cc: Marc Zyngier <marc.zyngier@arm.com>
>> Cc: Russell King <linux@armlinux.org.uk>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will.deacon@arm.com>
>> ---
>>   arch/arm/include/asm/kvm_mmu.h         | 19 ++++++++++++
>>   arch/arm64/include/asm/kvm_mmu.h       | 15 ++++++++++
>>   arch/arm64/include/asm/pgtable-hwdef.h |  4 +++
>>   arch/arm64/include/asm/pgtable.h       |  2 ++
>>   virt/kvm/arm/mmu.c                     | 40 ++++++++++++++++++++++++--
>>   5 files changed, 77 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
>> index 224c22c0a69c..155916dbdd7e 100644
>> --- a/arch/arm/include/asm/kvm_mmu.h
>> +++ b/arch/arm/include/asm/kvm_mmu.h
>> @@ -77,8 +77,11 @@ void kvm_clear_hyp_idmap(void);
>>     #define kvm_pfn_pte(pfn, prot)	pfn_pte(pfn, prot)
>>   #define kvm_pfn_pmd(pfn, prot)	pfn_pmd(pfn, prot)
>> +#define kvm_pfn_pud(pfn, prot)	(__pud(0))
>>     #define kvm_pmd_mkhuge(pmd)	pmd_mkhuge(pmd)
>> +/* No support for pud hugepages */
>> +#define kvm_pud_mkhuge(pud)	(pud)
>>     /*
>>    * The following kvm_*pud*() functionas are provided strictly to allow
>> @@ -95,6 +98,22 @@ static inline bool kvm_s2pud_readonly(pud_t *pud)
>>   	return false;
>>   }
>>   +static inline void kvm_set_pud(pud_t *pud, pud_t new_pud)
>> +{
>> +	BUG();
>> +}
>> +
>> +static inline pud_t kvm_s2pud_mkwrite(pud_t pud)
>> +{
>> +	BUG();
>> +	return pud;
>> +}
>> +
>> +static inline pud_t kvm_s2pud_mkexec(pud_t pud)
>> +{
>> +	BUG();
>> +	return pud;
>> +}
>>     static inline void kvm_set_pmd(pmd_t *pmd, pmd_t new_pmd)
>>   {
>> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
>> index f440cf216a23..f49a68fcbf26 100644
>> --- a/arch/arm64/include/asm/kvm_mmu.h
>> +++ b/arch/arm64/include/asm/kvm_mmu.h
>> @@ -172,11 +172,14 @@ void kvm_clear_hyp_idmap(void);
>>     #define	kvm_set_pte(ptep, pte)		set_pte(ptep, pte)
>>   #define	kvm_set_pmd(pmdp, pmd)		set_pmd(pmdp, pmd)
>> +#define kvm_set_pud(pudp, pud)		set_pud(pudp, pud)
>>     #define kvm_pfn_pte(pfn, prot)		pfn_pte(pfn, prot)
>>   #define kvm_pfn_pmd(pfn, prot)		pfn_pmd(pfn, prot)
>> +#define kvm_pfn_pud(pfn, prot)		pfn_pud(pfn, prot)
>>     #define kvm_pmd_mkhuge(pmd)		pmd_mkhuge(pmd)
>> +#define kvm_pud_mkhuge(pud)		pud_mkhuge(pud)
>>     static inline pte_t kvm_s2pte_mkwrite(pte_t pte)
>>   {
>> @@ -190,6 +193,12 @@ static inline pmd_t kvm_s2pmd_mkwrite(pmd_t pmd)
>>   	return pmd;
>>   }
>>   +static inline pud_t kvm_s2pud_mkwrite(pud_t pud)
>> +{
>> +	pud_val(pud) |= PUD_S2_RDWR;
>> +	return pud;
>> +}
>> +
>>   static inline pte_t kvm_s2pte_mkexec(pte_t pte)
>>   {
>>   	pte_val(pte) &= ~PTE_S2_XN;
>> @@ -202,6 +211,12 @@ static inline pmd_t kvm_s2pmd_mkexec(pmd_t pmd)
>>   	return pmd;
>>   }
>>   +static inline pud_t kvm_s2pud_mkexec(pud_t pud)
>> +{
>> +	pud_val(pud) &= ~PUD_S2_XN;
>> +	return pud;
>> +}
>> +
>>   static inline void kvm_set_s2pte_readonly(pte_t *ptep)
>>   {
>>   	pteval_t old_pteval, pteval;
>> diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
>> index fd208eac9f2a..e327665e94d1 100644
>> --- a/arch/arm64/include/asm/pgtable-hwdef.h
>> +++ b/arch/arm64/include/asm/pgtable-hwdef.h
>> @@ -193,6 +193,10 @@
>>   #define PMD_S2_RDWR		(_AT(pmdval_t, 3) << 6)   /* HAP[2:1] */
>>   #define PMD_S2_XN		(_AT(pmdval_t, 2) << 53)  /* XN[1:0] */
>>   +#define PUD_S2_RDONLY		(_AT(pudval_t, 1) << 6)   /*
>> HAP[2:1] */
>> +#define PUD_S2_RDWR		(_AT(pudval_t, 3) << 6)   /* HAP[2:1] */
>> +#define PUD_S2_XN		(_AT(pudval_t, 2) << 53)  /* XN[1:0] */
>> +
>>   /*
>>    * Memory Attribute override for Stage-2 (MemAttr[3:0])
>>    */
>> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
>> index 7c4c8f318ba9..31ea9fda07e3 100644
>> --- a/arch/arm64/include/asm/pgtable.h
>> +++ b/arch/arm64/include/asm/pgtable.h
>> @@ -386,6 +386,8 @@ static inline int pmd_protnone(pmd_t pmd)
>>     #define pud_write(pud)		pte_write(pud_pte(pud))
>>   +#define pud_mkhuge(pud)		(__pud(pud_val(pud) &
>> ~PUD_TABLE_BIT))
>> +
>>   #define __pud_to_phys(pud)	__pte_to_phys(pud_pte(pud))
>>   #define __phys_to_pud_val(phys)	__phys_to_pte_val(phys)
>>   #define pud_pfn(pud)		((__pud_to_phys(pud) & PUD_MASK) >> PAGE_SHIFT)
>> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
>> index 671d3c0825f2..b0931fa2d64e 100644
>> --- a/virt/kvm/arm/mmu.c
>> +++ b/virt/kvm/arm/mmu.c
>> @@ -1036,6 +1036,26 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
>>   	return 0;
>>   }
>>   +static int stage2_set_pud_huge(struct kvm *kvm, struct
>> kvm_mmu_memory_cache *cache,
>> +			       phys_addr_t addr, const pud_t *new_pud)
>> +{
>> +	pud_t *pud, old_pud;
>> +
>> +	pud = stage2_get_pud(kvm, cache, addr);
>> +	VM_BUG_ON(!pud);
>> +
>> +	old_pud = *pud;
>> +	if (pud_present(old_pud)) {
>> +		pud_clear(pud);
>> +		kvm_tlb_flush_vmid_ipa(kvm, addr);
>> +	} else {
>> +		get_page(virt_to_page(pud));
>> +	}
>> +
>> +	kvm_set_pud(pud, *new_pud);
>> +	return 0;
>> +}
>> +
>>   static bool stage2_is_exec(struct kvm *kvm, phys_addr_t addr)
>>   {
>>   	pmd_t *pmdp;
>> @@ -1467,9 +1487,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>>   	}
>>     	vma_pagesize = vma_kernel_pagesize(vma);
>> -	if (vma_pagesize == PMD_SIZE && !logging_active) {
>> +	if ((vma_pagesize == PMD_SIZE || vma_pagesize == PUD_SIZE) &&
>> +	    !logging_active) {
>> +		struct hstate *h = hstate_vma(vma);
>> +
>>   		hugetlb = true;
>> -		gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT;
>> +		gfn = (fault_ipa & huge_page_mask(h)) >> PAGE_SHIFT;
>>   	} else {
>>   		/*
>>   		 * Pages belonging to memslots that don't have the same
>> @@ -1555,7 +1578,18 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>>   	if (exec_fault)
>>   		invalidate_icache_guest_page(pfn, vma_pagesize);
>>   -	if (vma_pagesize == PMD_SIZE) {
>> +	if (vma_pagesize == PUD_SIZE) {
>> +		pud_t new_pud = kvm_pfn_pud(pfn, mem_type);
>> +
>> +		new_pud = kvm_pud_mkhuge(new_pud);
>> +		if (writable)
>> +			new_pud = kvm_s2pud_mkwrite(new_pud);
>> +
>> +		if (stage2_should_exec(kvm, fault_ipa, exec_fault, fault_status))
>> +			new_pud = kvm_s2pud_mkexec(new_pud);
>> +
>> +		ret = stage2_set_pud_huge(kvm, memcache, fault_ipa, &new_pud);
>> +	} else if (vma_pagesize == PMD_SIZE) {
>>   		pmd_t new_pmd = kvm_pfn_pmd(pfn, mem_type);
>>     		new_pmd = kvm_pmd_mkhuge(new_pmd);
>>
>
>
> Punit,
>
> Sorry for the late notice. I was looking deeply in to the stage2 table
> code to rework the same for dynamic IPA and thus found this.
>
> I am wondering if these changes are sufficient enough to add the PUD
> hugepage support. There are lots places where we simply get the
> stage2_pmd of a given address and then go about doing something at the
> PMD level or drill down to PTE if the PMD is not huge. (e.g
> stage2_is_exec, handle_access_fault etc). We simply do a pmd_offset()
> on a PUD entry, without even checking if the PUD is huge or not.

Having stared at the relevant code, I agree that more bits in the stage2
mmu logic needs to be made huge PUD aware.

I've been running guests with huge PUD on hardware and didn't hit any
issues. But this seems to be due to the affected code running only in
certain scenarios such as when save-restoring and possibly under memory
pressure.

I'll make sure to add this to my testing for the next version.

>
> With the PUD huge support, I think we need to go a level up in all
> these cases and drill down from PUD level, down to the PMD level and
> then further down, depending on whether we have huge page support at
> either of these levels.

>From a quick check I've identified the following functions (in addition
to stage2_is_exec and handle_access_fault) which need to looked into -

* stage2_get_pmd
* stage2_set_pte
* kvm_age_hva_handler
* kvm_test_age_hva_handler

I'll address PUD huegpage awareness throughout stage2 in the next
version.

Thanks,
Punit


>
>
> Cheers
> Suzuki
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