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WARM1d

Revision v18 of 4 in this series.

Revisions (4)
  1. v17 [diff vs current]
  2. v18 current
  3. v19 [diff vs current]
  4. v20 [diff vs current]

[PATCH v18 09/23] KVM: arm64: Add VM specific callback for S2 MMU operations

From: Suzuki K Poulose <suzuki.poulose@arm.com>
Date: 2026-09-15 16:02:20
Also in: kvm, kvmarm, linux-coco, lkml
Subsystem: arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers: Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds

Add VM type specific S2 MMU operation backends which can be initialized per VM
flavor, to keep the handling cleaner. Realm VM ops will be added gradually.

Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 arch/arm64/include/asm/kvm_host.h |  15 ++++
 arch/arm64/kvm/mmu.c              | 137 +++++++++++++++++++++++++-----
 2 files changed, 131 insertions(+), 21 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 8601103717643..ad3b34ba0b805 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -155,6 +155,19 @@ struct kvm_vcpu_ops {
 	void (*vcpu_put)(struct kvm_vcpu *vcpu);
 };
 
+struct kvm_gfn_range;
+
+struct kvm_vm_s2_ops {
+	bool (*vm_age_gfn)(struct kvm *kvm, struct kvm_gfn_range *range);
+	bool (*vm_test_age_gfn)(struct kvm *kvm, struct kvm_gfn_range *range);
+	int (*vm_flush_remote_tlbs)(struct kvm *kvm);
+	int (*vm_flush_remote_tlbs_range)(struct kvm *kvm, gfn_t gfn,
+					  u64 nr_pages);
+	void (*vm_stage2_unmap_range)(struct kvm_s2_mmu *mmu,
+				      phys_addr_t start, u64 size,
+				      bool may_block);
+};
+
 struct kvm_s2_mmu {
 	struct kvm_vmid vmid;
 
@@ -331,6 +344,8 @@ struct kvm_arch {
 	 */
 	u64 fgu[__NR_FGT_GROUP_IDS__];
 
+	const struct kvm_vm_s2_ops *vm_s2_ops;
+
 	/*
 	 * Stage 2 paging state for VMs with nested S2 using a virtual
 	 * VMID.
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 67852acf7a6f8..3d8b6e5b811ed 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -37,6 +37,8 @@ static unsigned long __ro_after_init io_map_base;
 
 #define KVM_PGT_FN(fn)		(!is_protected_kvm_enabled() ? fn : p ## fn)
 
+static int kvm_vm_init_vm_s2_ops(struct kvm *kvm);
+
 static phys_addr_t __stage2_range_addr_end(phys_addr_t addr, phys_addr_t end,
 					   phys_addr_t size)
 {
@@ -166,6 +168,18 @@ static bool memslot_is_logging(struct kvm_memory_slot *memslot)
 	return memslot->dirty_bitmap && !(memslot->flags & KVM_MEM_READONLY);
 }
 
+static int pkvm_flush_remote_tlbs(struct kvm *kvm)
+{
+	kvm_call_hyp_nvhe(__pkvm_tlb_flush_vmid, kvm->arch.pkvm.handle);
+	return 0;
+}
+
+static int kvm_vm_flush_remote_tlbs(struct kvm *kvm)
+{
+	kvm_call_hyp(__kvm_tlb_flush_vmid, &kvm->arch.mmu);
+	return 0;
+}
+
 /**
  * kvm_arch_flush_remote_tlbs() - flush all VM TLB entries for v7/8
  * @kvm:	pointer to kvm structure.
@@ -174,26 +188,36 @@ static bool memslot_is_logging(struct kvm_memory_slot *memslot)
  */
 int kvm_arch_flush_remote_tlbs(struct kvm *kvm)
 {
-	if (is_protected_kvm_enabled())
-		kvm_call_hyp_nvhe(__pkvm_tlb_flush_vmid, kvm->arch.pkvm.handle);
-	else
-		kvm_call_hyp(__kvm_tlb_flush_vmid, &kvm->arch.mmu);
-	return 0;
+	if (!kvm->arch.vm_s2_ops->vm_flush_remote_tlbs)
+		return 1;
+	return kvm->arch.vm_s2_ops->vm_flush_remote_tlbs(kvm);
 }
 
-int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm,
-				      gfn_t gfn, u64 nr_pages)
+static int pkvm_flush_remote_tlbs_range(struct kvm *kvm,
+					gfn_t gfn, u64 nr_pages)
+{
+	return pkvm_flush_remote_tlbs(kvm);
+}
+
+static int kvm_vm_flush_remote_tlbs_range(struct kvm *kvm,
+					 gfn_t gfn, u64 nr_pages)
 {
 	u64 size = nr_pages << PAGE_SHIFT;
 	u64 addr = gfn << PAGE_SHIFT;
 
-	if (is_protected_kvm_enabled())
-		kvm_call_hyp_nvhe(__pkvm_tlb_flush_vmid, kvm->arch.pkvm.handle);
-	else
-		kvm_tlb_flush_vmid_range(&kvm->arch.mmu, addr, size);
+	kvm_tlb_flush_vmid_range(&kvm->arch.mmu, addr, size);
 	return 0;
 }
 
+int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm,
+				     gfn_t gfn, u64 nr_pages)
+{
+	if (!kvm->arch.vm_s2_ops->vm_flush_remote_tlbs_range)
+		return 1;
+
+	return kvm->arch.vm_s2_ops->vm_flush_remote_tlbs_range(kvm, gfn, nr_pages);
+}
+
 static void *stage2_memcache_zalloc_page(void *arg)
 {
 	struct kvm_mmu_memory_cache *mc = arg;
@@ -337,13 +361,20 @@ static void __unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64
 				   may_block));
 }
 
+static void kvm_vm_stage2_unmap_range(struct kvm_s2_mmu *mmu,
+				      phys_addr_t start,
+				      u64 size, bool may_block)
+{
+	__unmap_stage2_range(mmu, start, size, may_block);
+}
+
 void kvm_stage2_unmap_range(struct kvm_s2_mmu *mmu, phys_addr_t start,
 			    u64 size, bool may_block)
 {
-	if (kvm_vm_is_protected(kvm_s2_mmu_to_kvm(mmu)))
-		return;
+	struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
 
-	__unmap_stage2_range(mmu, start, size, may_block);
+	if (kvm->arch.vm_s2_ops->vm_stage2_unmap_range)
+		kvm->arch.vm_s2_ops->vm_stage2_unmap_range(mmu, start, size, may_block);
 }
 
 void kvm_stage2_flush_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end)
@@ -983,6 +1014,12 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t
 	int cpu, err;
 	struct kvm_pgtable *pgt;
 
+	/* Initialize the VM ops for the VM instance for the first time */
+	if (mmu == &kvm->arch.mmu) {
+		err = kvm_vm_init_vm_s2_ops(kvm);
+		if (err)
+			return err;
+	}
 	/*
 	 * If we already have our page tables in place, and that the
 	 * MMU context is the canonical one, we have a bug somewhere,
@@ -2447,34 +2484,46 @@ bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
 	return false;
 }
 
-bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+static bool kvm_vm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
 	u64 size = (range->end - range->start) << PAGE_SHIFT;
 
-	if (!kvm->arch.mmu.pgt || kvm_vm_is_protected(kvm))
-		return false;
-
 	return KVM_PGT_FN(kvm_pgtable_stage2_test_clear_young)(kvm->arch.mmu.pgt,
 						   range->start << PAGE_SHIFT,
 						   size, true);
+}
+
+bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+	if (!kvm->arch.mmu.pgt || !kvm->arch.vm_s2_ops->vm_age_gfn)
+		return false;
+
+	return kvm->arch.vm_s2_ops->vm_age_gfn(kvm, range);
 	/*
 	 * TODO: Handle nested_mmu structures here using the reverse mapping in
 	 * a later version of patch series.
 	 */
 }
 
-bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+static bool kvm_vm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
 	u64 size = (range->end - range->start) << PAGE_SHIFT;
 
-	if (!kvm->arch.mmu.pgt || kvm_vm_is_protected(kvm))
-		return false;
 
 	return KVM_PGT_FN(kvm_pgtable_stage2_test_clear_young)(kvm->arch.mmu.pgt,
 						   range->start << PAGE_SHIFT,
 						   size, false);
 }
 
+bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+
+	if (!kvm->arch.mmu.pgt || !kvm->arch.vm_s2_ops->vm_test_age_gfn)
+		return false;
+
+	return kvm->arch.vm_s2_ops->vm_test_age_gfn(kvm, range);
+}
+
 phys_addr_t kvm_mmu_get_httbr(void)
 {
 	return __pa(hyp_pgtable->pgd);
@@ -2796,3 +2845,49 @@ void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled)
 
 	trace_kvm_toggle_cache(*vcpu_pc(vcpu), was_enabled, now_enabled);
 }
+
+static const struct kvm_vm_s2_ops protected_pkvm_vm_s2_ops = {
+	.vm_flush_remote_tlbs		= pkvm_flush_remote_tlbs,
+	.vm_flush_remote_tlbs_range	= pkvm_flush_remote_tlbs_range,
+	/*
+	 * Not supported for Protected VMs under pKVM
+	 * .vm_age_gfn
+	 * .vm_test_age_gfn
+	 * .vm_stage2_unmap_range
+	 */
+};
+
+static const struct kvm_vm_s2_ops pkvm_vm_s2_ops = {
+	.vm_flush_remote_tlbs		= pkvm_flush_remote_tlbs,
+	.vm_flush_remote_tlbs_range	= pkvm_flush_remote_tlbs_range,
+	.vm_age_gfn			= kvm_vm_age_gfn,
+	.vm_test_age_gfn		= kvm_vm_test_age_gfn,
+	.vm_stage2_unmap_range		= kvm_vm_stage2_unmap_range,
+};
+
+static const struct kvm_vm_s2_ops kvm_default_vm_s2_ops = {
+	.vm_flush_remote_tlbs		= kvm_vm_flush_remote_tlbs,
+	.vm_flush_remote_tlbs_range	= kvm_vm_flush_remote_tlbs_range,
+	.vm_age_gfn			= kvm_vm_age_gfn,
+	.vm_test_age_gfn		= kvm_vm_test_age_gfn,
+	.vm_stage2_unmap_range		= kvm_vm_stage2_unmap_range,
+};
+
+#define KVM_VM_S2_OPS(flavor, ops)		\
+		[flavor] = ops
+static const struct kvm_vm_s2_ops *arm64_vm_s2_ops[] = {
+	KVM_VM_S2_OPS(VM_VHE, &kvm_default_vm_s2_ops),
+	KVM_VM_S2_OPS(VM_NVHE, &kvm_default_vm_s2_ops),
+	KVM_VM_S2_OPS(VM_PKVM, &pkvm_vm_s2_ops),
+	KVM_VM_S2_OPS(VM_PROTECTED_PKVM, &protected_pkvm_vm_s2_ops),
+};
+
+static int kvm_vm_init_vm_s2_ops(struct kvm *kvm)
+{
+	BUILD_BUG_ON(ARRAY_SIZE(arm64_vm_s2_ops) != VM_FLAVOR_MAX);
+
+	kvm->arch.vm_s2_ops = arm64_vm_s2_ops[kvm->arch.vm_flavor];
+	if (WARN_ON(!kvm->arch.vm_s2_ops))
+		return -EINVAL;
+	return 0;
+}
-- 
2.43.0

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