KVM: arm64: Introduce KVM_PGTABLE_S2_NOFWB stage 2 flag

In order to further configure stage 2 page-tables, pass flags to the
init function using a new enum.

The first of these flags allows to disable FWB even if the hardware
supports it as we will need to do so for the host stage 2.

Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-33-qperret@google.com

1 files changed, 31 insertions, 25 deletions

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index dc6ef2cfe3eb..b22b4860630c 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -508,11 +508,22 @@ u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift)
 	return vtcr;
 }
 
-static int stage2_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep)
+static bool stage2_has_fwb(struct kvm_pgtable *pgt)
+{
+	if (!cpus_have_const_cap(ARM64_HAS_STAGE2_FWB))
+		return false;
+
+	return !(pgt->flags & KVM_PGTABLE_S2_NOFWB);
+}
+
+#define KVM_S2_MEMATTR(pgt, attr) PAGE_S2_MEMATTR(attr, stage2_has_fwb(pgt))
+
+static int stage2_set_prot_attr(struct kvm_pgtable *pgt, enum kvm_pgtable_prot prot,
+				kvm_pte_t *ptep)
 {
 	bool device = prot & KVM_PGTABLE_PROT_DEVICE;
-	kvm_pte_t attr = device ? PAGE_S2_MEMATTR(DEVICE_nGnRE) :
-			    PAGE_S2_MEMATTR(NORMAL);
+	kvm_pte_t attr = device ? KVM_S2_MEMATTR(pgt, DEVICE_nGnRE) :
+			    KVM_S2_MEMATTR(pgt, NORMAL);
 	u32 sh = KVM_PTE_LEAF_ATTR_LO_S2_SH_IS;
 
 	if (!(prot & KVM_PGTABLE_PROT_X))
@@ -749,7 +760,7 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 		.arg		= &map_data,
 	};
 
-	ret = stage2_set_prot_attr(prot, &map_data.attr);
+	ret = stage2_set_prot_attr(pgt, prot, &map_data.attr);
 	if (ret)
 		return ret;
 
@@ -784,18 +795,10 @@ int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
 	return ret;
 }
 
-static void stage2_flush_dcache(void *addr, u64 size)
-{
-	if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB))
-		return;
-
-	__flush_dcache_area(addr, size);
-}
-
-static bool stage2_pte_cacheable(kvm_pte_t pte)
+static bool stage2_pte_cacheable(struct kvm_pgtable *pgt, kvm_pte_t pte)
 {
 	u64 memattr = pte & KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR;
-	return memattr == PAGE_S2_MEMATTR(NORMAL);
+	return memattr == KVM_S2_MEMATTR(pgt, NORMAL);
 }
 
 static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
@@ -821,8 +824,8 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 
 		if (mm_ops->page_count(childp) != 1)
 			return 0;
-	} else if (stage2_pte_cacheable(pte)) {
-		need_flush = true;
+	} else if (stage2_pte_cacheable(pgt, pte)) {
+		need_flush = !stage2_has_fwb(pgt);
 	}
 
 	/*
@@ -833,7 +836,7 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	stage2_put_pte(ptep, mmu, addr, level, mm_ops);
 
 	if (need_flush) {
-		stage2_flush_dcache(kvm_pte_follow(pte, mm_ops),
+		__flush_dcache_area(kvm_pte_follow(pte, mm_ops),
 				    kvm_granule_size(level));
 	}
 
@@ -979,13 +982,14 @@ static int stage2_flush_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 			       enum kvm_pgtable_walk_flags flag,
 			       void * const arg)
 {
-	struct kvm_pgtable_mm_ops *mm_ops = arg;
+	struct kvm_pgtable *pgt = arg;
+	struct kvm_pgtable_mm_ops *mm_ops = pgt->mm_ops;
 	kvm_pte_t pte = *ptep;
 
-	if (!kvm_pte_valid(pte) || !stage2_pte_cacheable(pte))
+	if (!kvm_pte_valid(pte) || !stage2_pte_cacheable(pgt, pte))
 		return 0;
 
-	stage2_flush_dcache(kvm_pte_follow(pte, mm_ops), kvm_granule_size(level));
+	__flush_dcache_area(kvm_pte_follow(pte, mm_ops), kvm_granule_size(level));
 	return 0;
 }
 
@@ -994,17 +998,18 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
 	struct kvm_pgtable_walker walker = {
 		.cb	= stage2_flush_walker,
 		.flags	= KVM_PGTABLE_WALK_LEAF,
-		.arg	= pgt->mm_ops,
+		.arg	= pgt,
 	};
 
-	if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB))
+	if (stage2_has_fwb(pgt))
 		return 0;
 
 	return kvm_pgtable_walk(pgt, addr, size, &walker);
 }
 
-int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_arch *arch,
-			    struct kvm_pgtable_mm_ops *mm_ops)
+int kvm_pgtable_stage2_init_flags(struct kvm_pgtable *pgt, struct kvm_arch *arch,
+				  struct kvm_pgtable_mm_ops *mm_ops,
+				  enum kvm_pgtable_stage2_flags flags)
 {
 	size_t pgd_sz;
 	u64 vtcr = arch->vtcr;
@@ -1021,6 +1026,7 @@ int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_arch *arch,
 	pgt->start_level	= start_level;
 	pgt->mm_ops		= mm_ops;
 	pgt->mmu		= &arch->mmu;
+	pgt->flags		= flags;
 
 	/* Ensure zeroed PGD pages are visible to the hardware walker */
 	dsb(ishst);
@@ -1101,7 +1107,7 @@ int kvm_pgtable_stage2_find_range(struct kvm_pgtable *pgt, u64 addr,
 	u32 level;
 	int ret;
 
-	ret = stage2_set_prot_attr(prot, &attr);
+	ret = stage2_set_prot_attr(pgt, prot, &attr);
 	if (ret)
 		return ret;
 	attr &= KVM_PTE_LEAF_S2_COMPAT_MASK;