Re: [PATCH v10 07/41] KVM: guest_memfd: Stub in ability to enable in-place shared<=>private conversion

From: Sean Christopherson <seanjc@google.com>

Stub in global variable to enable in-place guest_memfd private<=>shared
memory conversion, which will eventually be exposed to userspace via a
module param, and wire up the __kvm_mem_is_private() static call to the
guest_memfd version when in-place conversion is enabled, i.e. when gmem is
the sole authority on private vs. shared memory.

Cc: Fuad Tabba <redacted>
Cc: Xiaoyao Li <redacted>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Co-developed-by: Ackerley Tng <redacted>
Signed-off-by: Ackerley Tng <redacted>
---
 include/linux/kvm_host.h |  6 ++++++
 virt/kvm/guest_memfd.c   | 26 ++++++++++++++++++++++++++
 virt/kvm/kvm_main.c      | 12 +++++++++++-
 3 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 65fbce46b63f4..9477ecebbbced 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h

@@ -2580,6 +2580,8 @@ static inline bool kvm_vm_mem_is_private(struct kvm *kvm, gfn_t gfn)
 #endif  /* CONFIG_KVM_VM_MEMORY_ATTRIBUTES */
 
 #ifdef kvm_arch_has_private_mem
+extern bool gmem_in_place_conversion;

+
 typedef bool (kvm_mem_is_private_t)(struct kvm *kvm, gfn_t gfn);
 DECLARE_STATIC_CALL(__kvm_mem_is_private, kvm_mem_is_private_t);
 

@@ -2588,6 +2590,8 @@ static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn)
 	return static_call(__kvm_mem_is_private)(kvm, gfn);
 }
 #else
+#define gmem_in_place_conversion false
+
 static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn)
 {
 	return false;

@@ -2595,6 +2599,8 @@ static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn)
 #endif /* kvm_arch_has_private_mem */
 
 #ifdef CONFIG_KVM_GUEST_MEMFD
+bool kvm_gmem_is_private(struct kvm *kvm, gfn_t gfn);