KVM: guest_memfd: Rename prepare() hook and Kconfig to make_private() / CONVERT

Rework guest_memfd's prepare() hook into a more accurate make_private(),
and rework its Kconfig from PREPARE to a more generic CONVERT.  This will
allow x86 to share (pun intended) a kvm_x86_ops.gmem_make_shared() hook
between the "convert to shared" and "reclaim" flows, which are one and the
same for SNP.

No functional change intended.

Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Reviewed-by: Fuad Tabba <fuad.tabba@linux.dev>
Link: https://patch.msgid.link/20260723210811.72720-8-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

arch/x86/include/asm/kvm-x86-ops.h

@@ -146,8 +146,8 @@ KVM_X86_OP(vcpu_deliver_sipi_vector)
 KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons);
 KVM_X86_OP_OPTIONAL(get_untagged_addr)
 KVM_X86_OP_OPTIONAL(alloc_apic_backing_page)
-#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_PREPARE
-KVM_X86_OP_OPTIONAL_RET0(gmem_prepare)
+#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_CONVERT
+KVM_X86_OP_OPTIONAL_RET0(gmem_make_private)
 #endif
 #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_RECLAIM
 KVM_X86_OP_OPTIONAL(gmem_make_shared)

arch/x86/include/asm/kvm_host.h

@@ -1903,8 +1903,8 @@ struct kvm_x86_ops {
 
 	gva_t (*get_untagged_addr)(struct kvm_vcpu *vcpu, gva_t gva, unsigned int flags);
 	void *(*alloc_apic_backing_page)(struct kvm_vcpu *vcpu);
-#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_PREPARE
-	int (*gmem_prepare)(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order);
+#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_CONVERT
+	int (*gmem_make_private)(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order);
 #endif
 #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_RECLAIM
 	void (*gmem_make_shared)(kvm_pfn_t pfn, kvm_pfn_t nr_pages);

arch/x86/kvm/Kconfig

@@ -160,7 +160,7 @@ config KVM_AMD_SEV
 	depends on CRYPTO_DEV_SP_PSP && !(KVM_AMD=y && CRYPTO_DEV_CCP_DD=m)
 	select ARCH_HAS_CC_PLATFORM
 	select KVM_GENERIC_MEMORY_ATTRIBUTES
-	select HAVE_KVM_ARCH_GMEM_PREPARE
+	select HAVE_KVM_ARCH_GMEM_CONVERT
 	select HAVE_KVM_ARCH_GMEM_RECLAIM
 	select HAVE_KVM_ARCH_GMEM_INVALIDATE
 	select HAVE_KVM_ARCH_GMEM_POPULATE

arch/x86/kvm/svm/sev.c

@@ -5112,7 +5112,7 @@ static bool is_large_rmp_possible(struct kvm *kvm, kvm_pfn_t pfn, int order)
 	return false;
 }
 
-int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order)
+int sev_gmem_make_private(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order)
 {
 	struct kvm_sev_info *sev = to_kvm_sev_info(kvm);
 	kvm_pfn_t pfn_aligned;

arch/x86/kvm/svm/svm.c

@@ -5450,7 +5450,7 @@ struct kvm_x86_ops svm_x86_ops __initdata = {
 	.vm_copy_enc_context_from = sev_vm_copy_enc_context_from,
 	.vm_move_enc_context_from = sev_vm_move_enc_context_from,
 
-	.gmem_prepare = sev_gmem_prepare,
+	.gmem_make_private = sev_gmem_make_private,
 	.gmem_make_shared = sev_gmem_make_shared,
 	.gmem_invalidate_range = sev_gmem_invalidate_range,
 	.gmem_max_mapping_level = sev_gmem_max_mapping_level,

arch/x86/kvm/svm/svm.h

@@ -1009,7 +1009,7 @@ int sev_cpu_init(struct svm_cpu_data *sd);
 int sev_dev_get_attr(u32 group, u64 attr, u64 *val);
 extern unsigned int max_sev_asid;
 void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code);
-int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order);
+int sev_gmem_make_private(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order);
 void sev_gmem_make_shared(kvm_pfn_t pfn, kvm_pfn_t nr_pages);
 void sev_gmem_invalidate_range(struct kvm *kvm, struct kvm_gfn_range *range);
 int sev_gmem_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn, bool is_private);

arch/x86/kvm/x86.c

@@ -10589,10 +10589,10 @@ bool kvm_arch_supports_gmem_init_shared(struct kvm *kvm)
 	return !kvm_arch_has_private_mem(kvm);
 }
 
-#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_PREPARE
-int kvm_arch_gmem_prepare(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, int max_order)
+#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_CONVERT
+int kvm_arch_gmem_make_private(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, int max_order)
 {
-	return kvm_x86_call(gmem_prepare)(kvm, pfn, gfn, max_order);
+	return kvm_x86_call(gmem_make_private)(kvm, pfn, gfn, max_order);
 }
 #endif
 

include/linux/kvm_host.h

@@ -2572,8 +2572,9 @@ static inline int kvm_gmem_get_pfn(struct kvm *kvm,
 }
 #endif /* CONFIG_KVM_GUEST_MEMFD */
 
-#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_PREPARE
-int kvm_arch_gmem_prepare(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, int max_order);
+#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_CONVERT
+int kvm_arch_gmem_make_private(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn,
+			       int max_order);
 #endif
 
 #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_POPULATE

virt/kvm/Kconfig

@@ -107,7 +107,7 @@ config KVM_GUEST_MEMFD
        select XARRAY_MULTI
        bool
 
-config HAVE_KVM_ARCH_GMEM_PREPARE
+config HAVE_KVM_ARCH_GMEM_CONVERT
        bool
        depends on KVM_GUEST_MEMFD
 

virt/kvm/guest_memfd.c

@@ -73,11 +73,11 @@ static bool kvm_gmem_is_shared_mem(struct inode *inode, pgoff_t index)
 static int __kvm_gmem_prepare_folio(struct kvm *kvm, struct kvm_memory_slot *slot,
 				    pgoff_t index, struct folio *folio)
 {
-#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_PREPARE
+#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_CONVERT
 	kvm_pfn_t pfn = folio_file_pfn(folio, index);
 	gfn_t gfn = slot->base_gfn + index - slot->gmem.pgoff;
 
-	return kvm_arch_gmem_prepare(kvm, gfn, pfn, folio_order(folio));
+	return kvm_arch_gmem_make_private(kvm, gfn, pfn, folio_order(folio));
 #else
 	return 0;
 #endif