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Commit 721eecbf authored by Gregory Haskins's avatar Gregory Haskins Committed by Avi Kivity
Browse files

KVM: irqfd 



KVM provides a complete virtual system environment for guests, including
support for injecting interrupts modeled after the real exception/interrupt
facilities present on the native platform (such as the IDT on x86).
Virtual interrupts can come from a variety of sources (emulated devices,
pass-through devices, etc) but all must be injected to the guest via
the KVM infrastructure.  This patch adds a new mechanism to inject a specific
interrupt to a guest using a decoupled eventfd mechnanism:  Any legal signal
on the irqfd (using eventfd semantics from either userspace or kernel) will
translate into an injected interrupt in the guest at the next available
interrupt window.

Signed-off-by: default avatarGregory Haskins <ghaskins@novell.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 0ba12d10

arch/x86/kvm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ config KVM 
	select MMU_NOTIFIER

	select ANON_INODES

	select HAVE_KVM_IRQCHIP

	select HAVE_KVM_EVENTFD

	---help---

	  Support hosting fully virtualized guest machines using hardware

	  virtualization extensions.  You will need a fairly recent

arch/x86/kvm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
EXTRA_CFLAGS += -Ivirt/kvm -Iarch/x86/kvm



kvm-y			+= $(addprefix ../../../virt/kvm/, kvm_main.o ioapic.o \

				coalesced_mmio.o irq_comm.o)

				coalesced_mmio.o irq_comm.o eventfd.o)

kvm-$(CONFIG_KVM_TRACE)	+= $(addprefix ../../../virt/kvm/, kvm_trace.o)

kvm-$(CONFIG_IOMMU_API)	+= $(addprefix ../../../virt/kvm/, iommu.o)

arch/x86/kvm/x86.c

+1 −0
Original line number Diff line number Diff line
@@ -1126,6 +1126,7 @@ int kvm_dev_ioctl_check_extension(long ext) 
	case KVM_CAP_REINJECT_CONTROL:

	case KVM_CAP_IRQ_INJECT_STATUS:

	case KVM_CAP_ASSIGN_DEV_IRQ:

	case KVM_CAP_IRQFD:

		r = 1;

		break;

	case KVM_CAP_COALESCED_MMIO:

include/linux/kvm.h

+11 −0
Original line number Diff line number Diff line
@@ -418,6 +418,7 @@ struct kvm_trace_rec { 
#ifdef __KVM_HAVE_MCE

#define KVM_CAP_MCE 31

#endif

#define KVM_CAP_IRQFD 32



#ifdef KVM_CAP_IRQ_ROUTING
@@ -470,6 +471,15 @@ struct kvm_x86_mce { 
};

#endif



#define KVM_IRQFD_FLAG_DEASSIGN (1 << 0)



struct kvm_irqfd {

	__u32 fd;

	__u32 gsi;

	__u32 flags;

	__u8  pad[20];

};



/*

 * ioctls for VM fds

 */
@@ -514,6 +524,7 @@ struct kvm_x86_mce { 
#define KVM_ASSIGN_SET_MSIX_ENTRY \

			_IOW(KVMIO, 0x74, struct kvm_assigned_msix_entry)

#define KVM_DEASSIGN_DEV_IRQ       _IOW(KVMIO, 0x75, struct kvm_assigned_irq)

#define KVM_IRQFD                  _IOW(KVMIO, 0x76, struct kvm_irqfd)



/*

 * ioctls for vcpu fds

include/linux/kvm_host.h

+24 −0
Original line number Diff line number Diff line
@@ -136,6 +136,12 @@ struct kvm { 
	struct list_head vm_list;

	struct kvm_io_bus mmio_bus;

	struct kvm_io_bus pio_bus;

#ifdef CONFIG_HAVE_KVM_EVENTFD

	struct {

		spinlock_t        lock;

		struct list_head  items;

	} irqfds;

#endif

	struct kvm_vm_stat stat;

	struct kvm_arch arch;

	atomic_t users_count;
@@ -525,4 +531,22 @@ static inline void kvm_free_irq_routing(struct kvm *kvm) {} 


#endif



#ifdef CONFIG_HAVE_KVM_EVENTFD



void kvm_irqfd_init(struct kvm *kvm);

int kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags);

void kvm_irqfd_release(struct kvm *kvm);



#else



static inline void kvm_irqfd_init(struct kvm *kvm) {}

static inline int kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags)

{

	return -EINVAL;

}



static inline void kvm_irqfd_release(struct kvm *kvm) {}



#endif /* CONFIG_HAVE_KVM_EVENTFD */



#endif