[PATCH v14 04/21] KVM: x86: Introduce kvm->arch.supports_gmem

[Fuad Tabba <tabba@google.com>]

Introduce a new boolean member, supports_gmem, to kvm->arch.

Previously, the has_private_mem boolean within kvm->arch was implicitly
used to indicate whether guest_memfd was supported for a KVM instance.
However, with the broader support for guest_memfd, it's not exclusively
for private or confidential memory. Therefore, it's necessary to
distinguish between a VM's general guest_memfd capabilities and its
support for private memory.

This new supports_gmem member will now explicitly indicate guest_memfd
support for a given VM, allowing has_private_mem to represent only
support for private memory.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Shivank Garg <shivankg@amd.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Co-developed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
---
 arch/x86/include/asm/kvm_host.h | 3 ++-
 arch/x86/kvm/svm/svm.c          | 1 +
 arch/x86/kvm/vmx/tdx.c          | 1 +
 arch/x86/kvm/x86.c              | 4 ++--
 4 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index bde811b2d303..938b5be03d33 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1348,6 +1348,7 @@ struct kvm_arch {
 	u8 mmu_valid_gen;
 	u8 vm_type;
 	bool has_private_mem;
+	bool supports_gmem;
 	bool has_protected_state;
 	bool pre_fault_allowed;
 	struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES];
@@ -2277,7 +2278,7 @@ void kvm_configure_mmu(bool enable_tdp, int tdp_forced_root_level,
 
 #ifdef CONFIG_KVM_GMEM
 #define kvm_arch_has_private_mem(kvm) ((kvm)->arch.has_private_mem)
-#define kvm_arch_supports_gmem(kvm) kvm_arch_has_private_mem(kvm)
+#define kvm_arch_supports_gmem(kvm)  ((kvm)->arch.supports_gmem)
 #else
 #define kvm_arch_has_private_mem(kvm) false
 #define kvm_arch_supports_gmem(kvm) false
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index ab9b947dbf4f..d1c484eaa8ad 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -5181,6 +5181,7 @@ static int svm_vm_init(struct kvm *kvm)
 		to_kvm_sev_info(kvm)->need_init = true;
 
 		kvm->arch.has_private_mem = (type == KVM_X86_SNP_VM);
+		kvm->arch.supports_gmem = (type == KVM_X86_SNP_VM);
 		kvm->arch.pre_fault_allowed = !kvm->arch.has_private_mem;
 	}
 
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index f31ccdeb905b..a3db6df245ee 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -632,6 +632,7 @@ int tdx_vm_init(struct kvm *kvm)
 
 	kvm->arch.has_protected_state = true;
 	kvm->arch.has_private_mem = true;
+	kvm->arch.supports_gmem = true;
 	kvm->arch.disabled_quirks |= KVM_X86_QUIRK_IGNORE_GUEST_PAT;
 
 	/*
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 357b9e3a6cef..adbdc2cc97d4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12780,8 +12780,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 		return -EINVAL;
 
 	kvm->arch.vm_type = type;
-	kvm->arch.has_private_mem =
-		(type == KVM_X86_SW_PROTECTED_VM);
+	kvm->arch.has_private_mem = (type == KVM_X86_SW_PROTECTED_VM);
+	kvm->arch.supports_gmem = (type == KVM_X86_SW_PROTECTED_VM);
 	/* Decided by the vendor code for other VM types.  */
 	kvm->arch.pre_fault_allowed =
 		type == KVM_X86_DEFAULT_VM || type == KVM_X86_SW_PROTECTED_VM;
-- 
2.50.0.727.gbf7dc18ff4-goog