kvm: Allow build-time configuration of KVM device assignment

We hope to at some point deprecate KVM legacy device assignment in
favor of VFIO-based assignment.  Towards that end, allow legacy
device assignment to be deconfigured.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

8 files changed, 32 insertions, 15 deletions

diff --git a/arch/ia64/include/uapi/asm/kvm.h b/arch/ia64/include/uapi/asm/kvm.h
index ec6c6b301238..99503c284400 100644
--- a/arch/ia64/include/uapi/asm/kvm.h
+++ b/arch/ia64/include/uapi/asm/kvm.h
@@ -27,7 +27,6 @@
 /* Select x86 specific features in <linux/kvm.h> */
 #define __KVM_HAVE_IOAPIC
 #define __KVM_HAVE_IRQ_LINE
-#define __KVM_HAVE_DEVICE_ASSIGNMENT
 
 /* Architectural interrupt line count. */
 #define KVM_NR_INTERRUPTS 256
diff --git a/arch/ia64/kvm/Kconfig b/arch/ia64/kvm/Kconfig
index 043183a06409..990b86420cc6 100644
--- a/arch/ia64/kvm/Kconfig
+++ b/arch/ia64/kvm/Kconfig
@@ -21,8 +21,6 @@ config KVM
         tristate "Kernel-based Virtual Machine (KVM) support"
         depends on BROKEN
         depends on HAVE_KVM && MODULES
-        # for device assignment:
-        depends on PCI
         depends on BROKEN
         select PREEMPT_NOTIFIERS
         select ANON_INODES
@@ -51,6 +49,17 @@ config KVM_INTEL
           Provides support for KVM on Itanium 2 processors equipped with the VT
           extensions.
 
+config KVM_DEVICE_ASSIGNMENT
+        bool "KVM legacy PCI device assignment support"
+        depends on KVM && PCI && IOMMU_API
+        default y
+        ---help---
+          Provide support for legacy PCI device assignment through KVM.  The
+          kernel now also supports a full featured userspace device driver
+          framework through VFIO, which supersedes much of this support.
+
+          If unsure, say Y.
+
 source drivers/vhost/Kconfig
 
 endif # VIRTUALIZATION
diff --git a/arch/ia64/kvm/Makefile b/arch/ia64/kvm/Makefile
index 511f64a78d56..1a4053789d01 100644
--- a/arch/ia64/kvm/Makefile
+++ b/arch/ia64/kvm/Makefile
@@ -49,10 +49,10 @@ ccflags-y := -Ivirt/kvm -Iarch/ia64/kvm/
 asflags-y := -Ivirt/kvm -Iarch/ia64/kvm/
 
 common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o ioapic.o \
-                coalesced_mmio.o irq_comm.o assigned-dev.o irqchip.o)
+                coalesced_mmio.o irq_comm.o)
 
-ifeq ($(CONFIG_IOMMU_API),y)
-common-objs += $(addprefix ../../../virt/kvm/, iommu.o)
+ifeq ($(CONFIG_KVM_DEVICE_ASSIGNMENT),y)
+common-objs += $(addprefix ../../../virt/kvm/, assigned-dev.o iommu.o)
 endif
 
 kvm-objs := $(common-objs) kvm-ia64.o kvm_fw.o
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 032c54d63c3d..dcc560729c20 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1368,9 +1368,7 @@ void kvm_arch_sync_events(struct kvm *kvm)
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
         kvm_iommu_unmap_guest(kvm);
-#ifdef  KVM_CAP_DEVICE_ASSIGNMENT
         kvm_free_all_assigned_devices(kvm);
-#endif
         kfree(kvm->arch.vioapic);
         kvm_release_vm_pages(kvm);
 }
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index a65ec29e6ffb..5d9a3033b3d7 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -29,7 +29,6 @@
 #define __KVM_HAVE_PIT
 #define __KVM_HAVE_IOAPIC
 #define __KVM_HAVE_IRQ_LINE
-#define __KVM_HAVE_DEVICE_ASSIGNMENT
 #define __KVM_HAVE_MSI
 #define __KVM_HAVE_USER_NMI
 #define __KVM_HAVE_GUEST_DEBUG
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 9d50efdb719d..a47a3e54b964 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -21,8 +21,6 @@ config KVM
         tristate "Kernel-based Virtual Machine (KVM) support"
         depends on HAVE_KVM
         depends on HIGH_RES_TIMERS
-        # for device assignment:
-        depends on PCI
         # for TASKSTATS/TASK_DELAY_ACCT:
         depends on NET
         select PREEMPT_NOTIFIERS
@@ -83,6 +81,17 @@ config KVM_MMU_AUDIT
          This option adds a R/W kVM module parameter 'mmu_audit', which allows
          audit  KVM MMU at runtime.
 
+config KVM_DEVICE_ASSIGNMENT
+        bool "KVM legacy PCI device assignment support"
+        depends on KVM && PCI && IOMMU_API
+        default y
+        ---help---
+          Provide support for legacy PCI device assignment through KVM.  The
+          kernel now also supports a full featured userspace device driver
+          framework through VFIO, which supersedes much of this support.
+
+          If unsure, say Y.
+
 # OK, it's a little counter-intuitive to do this, but it puts it neatly under
 # the virtualization menu.
 source drivers/vhost/Kconfig
diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index a797b8e43ade..d609e1d84048 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -7,8 +7,9 @@ CFLAGS_vmx.o := -I.
 
 kvm-y                   += $(addprefix ../../../virt/kvm/, kvm_main.o ioapic.o \
                                 coalesced_mmio.o irq_comm.o eventfd.o \
-                                assigned-dev.o irqchip.o)
-kvm-$(CONFIG_IOMMU_API) += $(addprefix ../../../virt/kvm/, iommu.o)
+                                irqchip.o)
+kvm-$(CONFIG_KVM_DEVICE_ASSIGNMENT)     += $(addprefix ../../../virt/kvm/, \
+                                assigned-dev.o iommu.o)
 kvm-$(CONFIG_KVM_ASYNC_PF)      += $(addprefix ../../../virt/kvm/, async_pf.o)
 
 kvm-y                   += x86.o mmu.o emulate.o i8259.o irq.o lapic.o \
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 145b1c81011b..8747fef7fd59 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2501,7 +2501,6 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_USER_NMI:
         case KVM_CAP_REINJECT_CONTROL:
         case KVM_CAP_IRQ_INJECT_STATUS:
-        case KVM_CAP_ASSIGN_DEV_IRQ:
         case KVM_CAP_IRQFD:
         case KVM_CAP_IOEVENTFD:
         case KVM_CAP_PIT2:
@@ -2519,9 +2518,12 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_XSAVE:
         case KVM_CAP_ASYNC_PF:
         case KVM_CAP_GET_TSC_KHZ:
-        case KVM_CAP_PCI_2_3:
         case KVM_CAP_KVMCLOCK_CTRL:
         case KVM_CAP_READONLY_MEM:
+#ifdef CONFIG_KVM_DEVICE_ASSIGNMENT
+        case KVM_CAP_ASSIGN_DEV_IRQ:
+        case KVM_CAP_PCI_2_3:
+#endif
                 r = 1;
                 break;
         case KVM_CAP_COALESCED_MMIO: