[PATCH v12 08/45] KVM: Provide generic interface for checking memory private/shared status
From: Ackerley Tng via B4 Relay <devnull+ackerleytng.google.com@kernel.org>
Date: 2026-08-31 00:25:20
Also in:
b4-sent, kvm, linux-coco, linux-doc, linux-kselftest, linux-mm, lkml
Subsystem:
kernel virtual machine (kvm), the rest · Maintainers:
Paolo Bonzini, Linus Torvalds
From: Sean Christopherson <seanjc@google.com> Introduce a generic kvm_is_private_gfn() interface using a static call to determine if a GFN is private. This allows the implementation for checking a GFN's private/shared status to be set at runtime. In preparation for choosing implementations between a guest_memfd lookup and the existing VM attribute lookup, rename the existing VM-attribute-based check to kvm_vm_is_private_gfn() to emphasize that it looks up VM attributes. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Xiaoyao Li <redacted> Reviewed-by: Fuad Tabba <redacted> Tested-by: Shivank Garg <redacted> Reviewed-by: Binbin Wu <redacted> Signed-off-by: Ackerley Tng <redacted> --- include/linux/kvm_host.h | 14 ++++++++++++-- virt/kvm/kvm_main.c | 15 +++++++++++++++ 2 files changed, 27 insertions(+), 2 deletions(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 9b97266f61ec8..3579feb631775 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h@@ -2573,16 +2573,26 @@ bool kvm_arch_pre_set_vm_memory_attributes(struct kvm *kvm, bool kvm_arch_post_set_vm_memory_attributes(struct kvm *kvm, struct kvm_gfn_range *range); -static inline bool kvm_is_private_gfn(struct kvm *kvm, gfn_t gfn) +static inline bool kvm_vm_is_private_gfn(struct kvm *kvm, gfn_t gfn) { return kvm_get_vm_memory_attributes(kvm, gfn) & KVM_MEMORY_ATTRIBUTE_PRIVATE; } +#endif /* CONFIG_KVM_VM_MEMORY_ATTRIBUTES */ + +#ifdef kvm_arch_has_private_mem +typedef bool (kvm_is_private_gfn_t)(struct kvm *kvm, gfn_t gfn); +DECLARE_STATIC_CALL(__kvm_is_private_gfn, kvm_is_private_gfn_t); + +static inline bool kvm_is_private_gfn(struct kvm *kvm, gfn_t gfn) +{ + return static_call(__kvm_is_private_gfn)(kvm, gfn); +} #else static inline bool kvm_is_private_gfn(struct kvm *kvm, gfn_t gfn) { return false; } -#endif /* CONFIG_KVM_VM_MEMORY_ATTRIBUTES */ +#endif /* kvm_arch_has_private_mem */ #ifdef CONFIG_KVM_GUEST_MEMFD int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 91d5af7d60d0f..78278730b2ae4 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c@@ -2628,6 +2628,20 @@ static int kvm_vm_ioctl_set_mem_attributes(struct kvm *kvm, } #endif /* CONFIG_KVM_VM_MEMORY_ATTRIBUTES */ +#ifdef kvm_arch_has_private_mem +DEFINE_STATIC_CALL_RET0(__kvm_is_private_gfn, kvm_is_private_gfn_t); +EXPORT_STATIC_CALL_GPL(__kvm_is_private_gfn); + +static void kvm_init_memory_attributes(void) +{ +#ifdef CONFIG_KVM_VM_MEMORY_ATTRIBUTES + static_call_update(__kvm_is_private_gfn, kvm_vm_is_private_gfn); +#endif +} +#else +static void kvm_init_memory_attributes(void) { } +#endif + struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn) { return __gfn_to_memslot(kvm_memslots(kvm), gfn);
@@ -6541,6 +6555,7 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module) kvm_preempt_ops.sched_in = kvm_sched_in; kvm_preempt_ops.sched_out = kvm_sched_out; + kvm_init_memory_attributes(); kvm_init_debug(); r = kvm_vfio_ops_init();
--
2.55.0.897.gb25b4bd76c-goog