KVM: introduce CONFIG_KVM_COMMON

CONFIG_HAVE_KVM is currently used by some architectures to either
enabled the KVM config proper, or to enable host-side code that is
not part of the KVM module.  However, CONFIG_KVM's "select" statement
in virt/kvm/Kconfig corresponds to a third meaning, namely to
enable common Kconfigs required by all architectures that support
KVM.

These three meanings can be replaced respectively by an
architecture-specific Kconfig, by IS_ENABLED(CONFIG_KVM), or by
a new Kconfig symbol that is in turn selected by the
architecture-specific "config KVM".

Start by introducing such a new Kconfig symbol, CONFIG_KVM_COMMON.
Unlike CONFIG_HAVE_KVM, it is selected by CONFIG_KVM, not by
architecture code, and it brings in all dependencies of common
KVM code.  In particular, INTERVAL_TREE was missing in loongarch
and riscv, so that is another thing that is fixed.

Fixes: 8132d887a7 ("KVM: remove CONFIG_HAVE_KVM_EVENTFD", 2023-12-08)
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Closes: https://lore.kernel.org/all/44907c6b-c5bd-4e4a-a921-e4d3825539d8@infradead.org/
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/arm64/kvm/Kconfig

@@ -21,9 +21,9 @@ if VIRTUALIZATION
 menuconfig KVM
 	bool "Kernel-based Virtual Machine (KVM) support"
 	depends on HAVE_KVM
+	select KVM_COMMON
 	select KVM_GENERIC_HARDWARE_ENABLING
 	select KVM_GENERIC_MMU_NOTIFIER
-	select PREEMPT_NOTIFIERS
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
 	select KVM_MMIO
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
@@ -39,7 +39,6 @@ menuconfig KVM
 	select HAVE_KVM_VCPU_RUN_PID_CHANGE
 	select SCHED_INFO
 	select GUEST_PERF_EVENTS if PERF_EVENTS
-	select INTERVAL_TREE
 	select XARRAY_MULTI
 	help
 	  Support hosting virtualized guest machines.

arch/loongarch/kvm/Kconfig

@@ -23,12 +23,12 @@ config KVM
 	depends on HAVE_KVM
 	select HAVE_KVM_DIRTY_RING_ACQ_REL
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
+	select KVM_COMMON
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select KVM_GENERIC_HARDWARE_ENABLING
 	select KVM_GENERIC_MMU_NOTIFIER
 	select KVM_MMIO
 	select KVM_XFER_TO_GUEST_WORK
-	select PREEMPT_NOTIFIERS
 	help
 	  Support hosting virtualized guest machines using
 	  hardware virtualization extensions. You will need

arch/mips/kvm/Kconfig

@@ -20,12 +20,11 @@ config KVM
 	depends on HAVE_KVM
 	depends on MIPS_FP_SUPPORT
 	select EXPORT_UASM
-	select PREEMPT_NOTIFIERS
+	select KVM_COMMON
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
 	select KVM_MMIO
 	select KVM_GENERIC_MMU_NOTIFIER
-	select INTERVAL_TREE
 	select KVM_GENERIC_HARDWARE_ENABLING
 	help
 	  Support for hosting Guest kernels.

arch/powerpc/kvm/Kconfig

@@ -19,12 +19,11 @@ if VIRTUALIZATION
 
 config KVM
 	bool
-	select PREEMPT_NOTIFIERS
+	select KVM_COMMON
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
 	select KVM_VFIO
 	select IRQ_BYPASS_MANAGER
 	select HAVE_KVM_IRQ_BYPASS
-	select INTERVAL_TREE
 
 config KVM_BOOK3S_HANDLER
 	bool

arch/riscv/kvm/Kconfig

@@ -24,12 +24,12 @@ config KVM
 	select HAVE_KVM_IRQ_ROUTING
 	select HAVE_KVM_MSI
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
+	select KVM_COMMON
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select KVM_GENERIC_HARDWARE_ENABLING
 	select KVM_MMIO
 	select KVM_XFER_TO_GUEST_WORK
 	select KVM_GENERIC_MMU_NOTIFIER
-	select PREEMPT_NOTIFIERS
 	select SCHED_INFO
 	help
 	  Support hosting virtualized guest machines.

arch/s390/kvm/Kconfig

@@ -20,17 +20,16 @@ config KVM
 	def_tristate y
 	prompt "Kernel-based Virtual Machine (KVM) support"
 	depends on HAVE_KVM
-	select PREEMPT_NOTIFIERS
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
 	select KVM_ASYNC_PF
 	select KVM_ASYNC_PF_SYNC
+	select KVM_COMMON
 	select HAVE_KVM_IRQCHIP
 	select HAVE_KVM_IRQ_ROUTING
 	select HAVE_KVM_INVALID_WAKEUPS
 	select HAVE_KVM_NO_POLL
 	select KVM_VFIO
-	select INTERVAL_TREE
 	select MMU_NOTIFIER
 	help
 	  Support hosting paravirtualized guest machines using the SIE

arch/x86/kvm/Kconfig

@@ -23,7 +23,7 @@ config KVM
 	depends on HAVE_KVM
 	depends on HIGH_RES_TIMERS
 	depends on X86_LOCAL_APIC
-	select PREEMPT_NOTIFIERS
+	select KVM_COMMON
 	select KVM_GENERIC_MMU_NOTIFIER
 	select HAVE_KVM_IRQCHIP
 	select HAVE_KVM_PFNCACHE
@@ -44,7 +44,6 @@ config KVM
 	select KVM_XFER_TO_GUEST_WORK
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select KVM_VFIO
-	select INTERVAL_TREE
 	select HAVE_KVM_PM_NOTIFIER if PM
 	select KVM_GENERIC_HARDWARE_ENABLING
 	help

virt/kvm/Kconfig

@@ -3,7 +3,12 @@
 
 config HAVE_KVM
        bool
+
+config KVM_COMMON
+       bool
        select EVENTFD
+       select INTERVAL_TREE
+       select PREEMPT_NOTIFIERS
 
 config HAVE_KVM_PFNCACHE
        bool