[PATCH v8 09/29] KVM: Replace CONFIG_KVM_MMIO with KVM_NO_MMIO

[Steffen Eiden <seiden@linux.ibm.com>]

Defining KVM_MMIO is not flexible enough for multi-KVM systems where one
KVM implements MMIO but others do not. Therefore, remove KVM_MMIO from
the config space and use the macro KVM_NO_MMIO instead.
Define KVM_NO_MMIO for KVM/s390 and for selected KVM/powerpc
configurations.

coalesced_mmio.c is now always compiled&linked. However, for
architectures/configurations defining KVM_NO_MMIO this effectively
collapses to an empty object with no mmio code.

No functional changes.

Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/arm64/kvm/Kconfig                | 1 -
 arch/loongarch/kvm/Kconfig            | 1 -
 arch/mips/kvm/Kconfig                 | 1 -
 arch/powerpc/include/asm/kvm_host.h   | 7 +++++++
 arch/powerpc/kvm/Kconfig              | 4 ----
 arch/riscv/kvm/Kconfig                | 1 -
 arch/s390/include/asm/kvm_host_s390.h | 2 ++
 arch/x86/kvm/Kconfig                  | 1 -
 include/linux/kvm_host.h              | 2 +-
 virt/kvm/Kconfig                      | 3 ---
 virt/kvm/Makefile.kvm                 | 4 ++--
 virt/kvm/coalesced_mmio.c             | 4 ++++
 virt/kvm/coalesced_mmio.h             | 2 +-
 virt/kvm/kvm_main.c                   | 8 ++++----
 14 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 7329124deb2f..8475f32ad9e6 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -22,7 +22,6 @@ menuconfig KVM
 	select KVM_COMMON
 	select KVM_GENERIC_HARDWARE_ENABLING
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
-	select KVM_MMIO
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select VIRT_XFER_TO_GUEST_WORK
 	select KVM_VFIO
diff --git a/arch/loongarch/kvm/Kconfig b/arch/loongarch/kvm/Kconfig
index a427429a2b05..fd387326d2f2 100644
--- a/arch/loongarch/kvm/Kconfig
+++ b/arch/loongarch/kvm/Kconfig
@@ -26,7 +26,6 @@ config KVM
 	select KVM_COMMON
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select KVM_GENERIC_HARDWARE_ENABLING
-	select KVM_MMIO
 	select VIRT_XFER_TO_GUEST_WORK
 	select SCHED_INFO
 	select GUEST_PERF_EVENTS if PERF_EVENTS
diff --git a/arch/mips/kvm/Kconfig b/arch/mips/kvm/Kconfig
index c24b872afbcb..849ce7c7c4df 100644
--- a/arch/mips/kvm/Kconfig
+++ b/arch/mips/kvm/Kconfig
@@ -22,7 +22,6 @@ config KVM
 	select EXPORT_UASM
 	select KVM_COMMON
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
-	select KVM_MMIO
 	select KVM_GENERIC_HARDWARE_ENABLING
 	help
 	  Support for hosting Guest kernels.
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index ad7c34e9b227..620f163d65a9 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -29,6 +29,13 @@
 
 #define __KVM_HAVE_ARCH_VCPU_DEBUGFS
 
+#if !defined(CONFIG_KVM_BOOK3S_32_HANDLER) && \
+	!defined(CONFIG_KVM_BOOK3S_PR_POSSIBLE) && \
+	!defined(CONFIG_KVM_E500V2) && \
+	!defined(CONFIG_KVM_E500MC)
+#define KVM_NO_MMIO
+#endif
+
 #define KVM_MAX_VCPUS		NR_CPUS
 #define KVM_MAX_VCORES		NR_CPUS
 
diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
index 1fae2de8fa68..cacc22e34afd 100644
--- a/arch/powerpc/kvm/Kconfig
+++ b/arch/powerpc/kvm/Kconfig
@@ -30,7 +30,6 @@ config KVM_BOOK3S_HANDLER
 config KVM_BOOK3S_32_HANDLER
 	bool
 	select KVM_BOOK3S_HANDLER
-	select KVM_MMIO
 
 config KVM_BOOK3S_64_HANDLER
 	bool
@@ -38,7 +37,6 @@ config KVM_BOOK3S_64_HANDLER
 
 config KVM_BOOK3S_PR_POSSIBLE
 	bool
-	select KVM_MMIO
 
 config KVM_BOOK3S_HV_POSSIBLE
 	bool
@@ -201,7 +199,6 @@ config KVM_E500V2
 	depends on PPC_E500 && !PPC_E500MC
 	depends on !CONTEXT_TRACKING_USER
 	select KVM
-	select KVM_MMIO
 	help
 	  Support running unmodified E500 guest kernels in virtual machines on
 	  E500v2 host processors.
@@ -216,7 +213,6 @@ config KVM_E500MC
 	depends on PPC_E500MC
 	depends on !CONTEXT_TRACKING_USER
 	select KVM
-	select KVM_MMIO
 	select KVM_BOOKE_HV
 	help
 	  Support running unmodified E500MC/E5500/E6500 guest kernels in
diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
index 3cb4f8037300..2e3c4e6c1cd7 100644
--- a/arch/riscv/kvm/Kconfig
+++ b/arch/riscv/kvm/Kconfig
@@ -26,7 +26,6 @@ config KVM
 	select KVM_COMMON
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select KVM_GENERIC_HARDWARE_ENABLING
-	select KVM_MMIO
 	select VIRT_XFER_TO_GUEST_WORK
 	select SCHED_INFO
 	select GUEST_PERF_EVENTS if PERF_EVENTS
diff --git a/arch/s390/include/asm/kvm_host_s390.h b/arch/s390/include/asm/kvm_host_s390.h
index 5fd7f49d7c0d..451346f32008 100644
--- a/arch/s390/include/asm/kvm_host_s390.h
+++ b/arch/s390/include/asm/kvm_host_s390.h
@@ -40,6 +40,8 @@
 
 #define KVM_S390_MANAGES_S390_GUEST 1
 
+#define KVM_NO_MMIO
+
 /*
  * These seem to be used for allocating ->chip in the routing table, which we
  * don't use. 1 is as small as we can get to reduce the needed memory. If we
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index fa20f64d6a2f..82b6c91e763b 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -31,7 +31,6 @@ config KVM_X86
 	select VHOST_TASK
 	select KVM_ASYNC_PF
 	select USER_RETURN_NOTIFIER
-	select KVM_MMIO
 	select SCHED_INFO
 	select PERF_EVENTS
 	select GUEST_PERF_EVENTS
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index b7bd20fc9e34..7ebc9aaaec2d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -846,7 +846,7 @@ struct kvm {
 	struct kvm_vm_stat stat;
 	struct kvm_arch arch;
 	refcount_t users_count;
-#ifdef CONFIG_KVM_MMIO
+#ifndef KVM_NO_MMIO
 	struct kvm_coalesced_mmio_ring *coalesced_mmio_ring;
 	spinlock_t ring_lock;
 	struct list_head coalesced_zones;
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index 008b110ebdb7..69b47cb6526c 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -40,9 +40,6 @@ config NEED_KVM_DIRTY_RING_WITH_BITMAP
 	bool
 	depends on HAVE_KVM_DIRTY_RING
 
-config KVM_MMIO
-       bool
-
 config KVM_ASYNC_PF
        bool
 
diff --git a/virt/kvm/Makefile.kvm b/virt/kvm/Makefile.kvm
index ee66d460c494..9a3b05a01c62 100644
--- a/virt/kvm/Makefile.kvm
+++ b/virt/kvm/Makefile.kvm
@@ -10,9 +10,9 @@ KVM_DEV_MINOR ?= KVM_MINOR
 
 ccflags-y +=-DKVM_DEV_NAME=$(KVM_DEV_NAME) -DKVM_DEV_MINOR=$(KVM_DEV_MINOR)
 
-kvm-y := $(KVM)/kvm_main.o $(KVM)/eventfd.o $(KVM)/binary_stats.o
+kvm-y := $(KVM)/kvm_main.o $(KVM)/eventfd.o $(KVM)/binary_stats.o \
+	 $(KVM)/coalesced_mmio.o
 kvm-$(CONFIG_KVM_VFIO) += $(KVM)/vfio.o
-kvm-$(CONFIG_KVM_MMIO) += $(KVM)/coalesced_mmio.o
 kvm-$(CONFIG_KVM_ASYNC_PF) += $(KVM)/async_pf.o
 kvm-$(CONFIG_HAVE_KVM_IRQ_ROUTING) += $(KVM)/irqchip.o
 kvm-$(CONFIG_HAVE_KVM_DIRTY_RING) += $(KVM)/dirty_ring.o
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index 6b1d90161099..d6cae6855237 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -15,6 +15,8 @@
 #include <linux/slab.h>
 #include <linux/kvm.h>
 
+#ifndef KVM_NO_MMIO
+
 #include "coalesced_mmio.h"
 
 static inline struct kvm_coalesced_mmio_dev *to_mmio(struct kvm_io_device *dev)
@@ -188,3 +190,5 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
 	 */
 	return 0;
 }
+
+#endif /* !KVM_NO_MMIO */
diff --git a/virt/kvm/coalesced_mmio.h b/virt/kvm/coalesced_mmio.h
index 36f84264ed25..bcaa34fce1e8 100644
--- a/virt/kvm/coalesced_mmio.h
+++ b/virt/kvm/coalesced_mmio.h
@@ -11,7 +11,7 @@
  *
  */
 
-#ifdef CONFIG_KVM_MMIO
+#ifndef KVM_NO_MMIO
 
 #include <linux/list.h>
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a7ce1f22b3de..32b8aad8fa2b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4061,7 +4061,7 @@ static vm_fault_t kvm_vcpu_fault(struct vm_fault *vmf)
 	else if (vmf->pgoff == KVM_PIO_PAGE_OFFSET)
 		page = virt_to_page(vcpu->arch.pio_data);
 #endif
-#ifdef CONFIG_KVM_MMIO
+#ifndef KVM_NO_MMIO
 	else if (vmf->pgoff == KVM_COALESCED_MMIO_PAGE_OFFSET)
 		page = virt_to_page(vcpu->kvm->coalesced_mmio_ring);
 #endif
@@ -4902,7 +4902,7 @@ static int kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
 	case KVM_CAP_ENABLE_CAP_VM:
 	case KVM_CAP_HALT_POLL:
 		return 1;
-#ifdef CONFIG_KVM_MMIO
+#ifndef KVM_NO_MMIO
 	case KVM_CAP_COALESCED_MMIO:
 		return KVM_COALESCED_MMIO_PAGE_OFFSET;
 	case KVM_CAP_COALESCED_PIO:
@@ -5243,7 +5243,7 @@ static long kvm_vm_ioctl(struct file *filp,
 		break;
 	}
 #endif
-#ifdef CONFIG_KVM_MMIO
+#ifndef KVM_NO_MMIO
 	case KVM_REGISTER_COALESCED_MMIO: {
 		struct kvm_coalesced_mmio_zone zone;
 
@@ -5578,7 +5578,7 @@ static long kvm_dev_ioctl(struct file *filp,
 #ifdef CONFIG_X86
 		r += PAGE_SIZE;    /* pio data page */
 #endif
-#ifdef CONFIG_KVM_MMIO
+#ifndef KVM_NO_MMIO
 		r += PAGE_SIZE;    /* coalesced mmio ring page */
 #endif
 		break;
-- 
2.53.0