KVM: Move architecture capability Kconfigs to header defines

With s390 hosting multiple independent KVM implementations within the
same kernel build (native s390 KVM and arm64 on s390), global Kconfig
selections force both implementations to inherit options that only apply
to one of them.

Replace global Kconfig options which only apply to one KVM
implementation with architecture-specific opt-in defines in the
respective <asm/kvm_host.h>. Only remove Kconfig symbols that would be
different on both s390 KVM implementations

  - __KVM_HAVE_INVALID_WAKEUPS		(formerly HAVE_KVM_INVALID_WAKEUPS)
  - __KVM_HAVE_MSI			(formerly HAVE_KVM_MSI)
  - __KVM_HAVE_NO_POLL			(formerly HAVE_KVM_NO_POLL)
  - __KVM_HAVE_READONLY_MEM		(formerly HAVE_KVM_READONLY_MEM)
  - __KVM_HAVE_VCPU_RUN_PID_CHANGE	(formerly HAVE_KVM_VCPU_RUN_PID_CHANGE)

This allows each architecture and guest implementation to configure its
supported capabilities independently in its kvm_host header and eliminates
adding unnecessary fallback stubs across different KVM targets.

Acked-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
Link: https://patch.msgid.link/20261013121343.1997112-1-seiden@linux.ibm.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 11 insertions, 7 deletions

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 5624b572cb85..e4ae201a1707 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -750,7 +750,11 @@ static inline u64 kvm_gmem_get_supported_flags(struct kvm *kvm)
 #ifndef kvm_arch_has_readonly_mem
 static inline bool kvm_arch_has_readonly_mem(struct kvm *kvm)
 {
-	return IS_ENABLED(CONFIG_HAVE_KVM_READONLY_MEM);
+#ifdef __KVM_HAVE_READONLY_MEM
+	return true;
+#else
+	return false;
+#endif
 }
 #endif
 
@@ -2483,7 +2487,7 @@ void kvm_arch_update_irqfd_routing(struct kvm_kernel_irqfd *irqfd,
 				   struct kvm_kernel_irq_routing_entry *new);
 #endif /* CONFIG_HAVE_KVM_IRQ_BYPASS */
 
-#ifdef CONFIG_HAVE_KVM_INVALID_WAKEUPS
+#ifdef __KVM_HAVE_INVALID_WAKEUPS
 /* If we wakeup during the poll time, was it a sucessful poll? */
 static inline bool vcpu_valid_wakeup(struct kvm_vcpu *vcpu)
 {
@@ -2495,9 +2499,9 @@ static inline bool vcpu_valid_wakeup(struct kvm_vcpu *vcpu)
 {
 	return true;
 }
-#endif /* CONFIG_HAVE_KVM_INVALID_WAKEUPS */
+#endif /* __KVM_HAVE_INVALID_WAKEUPS */
 
-#ifdef CONFIG_HAVE_KVM_NO_POLL
+#ifdef __KVM_HAVE_NO_POLL
 /* Callback that tells if we must not poll */
 bool kvm_arch_no_poll(struct kvm_vcpu *vcpu);
 #else
@@ -2505,18 +2509,18 @@ static inline bool kvm_arch_no_poll(struct kvm_vcpu *vcpu)
 {
 	return false;
 }
-#endif /* CONFIG_HAVE_KVM_NO_POLL */
+#endif /* __KVM_HAVE_NO_POLL */
 
 void kvm_arch_guest_memory_reclaimed(struct kvm *kvm);
 
-#ifdef CONFIG_HAVE_KVM_VCPU_RUN_PID_CHANGE
+#ifdef __KVM_HAVE_VCPU_RUN_PID_CHANGE
 int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu);
 #else
 static inline int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
 {
 	return 0;
 }
-#endif /* CONFIG_HAVE_KVM_VCPU_RUN_PID_CHANGE */
+#endif /* __KVM_HAVE_VCPU_RUN_PID_CHANGE */
 
 #ifdef CONFIG_VIRT_XFER_TO_GUEST_WORK
 static inline void kvm_handle_signal_exit(struct kvm_vcpu *vcpu)