iofd is a mechanism to register PIO/MMIO regions to trigger an eventfd signal when written to. Userspace can register any arbitrary address with a corresponding eventfd.
Signed-off-by: Gregory Haskins <[email protected]> --- include/linux/kvm.h | 12 +++++ include/linux/kvm_host.h | 2 + virt/kvm/eventfd.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++ virt/kvm/kvm_main.c | 13 ++++++ 4 files changed, 134 insertions(+), 0 deletions(-) diff --git a/include/linux/kvm.h b/include/linux/kvm.h index dfc4bcc..99b6e45 100644 --- a/include/linux/kvm.h +++ b/include/linux/kvm.h @@ -292,6 +292,17 @@ struct kvm_guest_debug { struct kvm_guest_debug_arch arch; }; +#define KVM_IOFD_FLAG_DEASSIGN (1 << 0) +#define KVM_IOFD_FLAG_PIO (1 << 1) + +struct kvm_iofd { + __u64 addr; + __u32 len; + __u32 fd; + __u32 flags; + __u8 pad[12]; +}; + #define KVM_TRC_SHIFT 16 /* * kvm trace categories @@ -508,6 +519,7 @@ struct kvm_irqfd { #define KVM_DEASSIGN_DEV_IRQ _IOW(KVMIO, 0x75, struct kvm_assigned_irq) #define KVM_ASSIGN_IRQFD _IOW(KVMIO, 0x76, struct kvm_irqfd) #define KVM_DEASSIGN_IRQFD _IOW(KVMIO, 0x77, __u32) +#define KVM_IOFD _IOW(KVMIO, 0x78, struct kvm_iofd) /* * ioctls for vcpu fds diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 1acc528..d53cb70 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -529,5 +529,7 @@ static inline void kvm_free_irq_routing(struct kvm *kvm) {} int kvm_assign_irqfd(struct kvm *kvm, int fd, int gsi, int flags); int kvm_deassign_irqfd(struct kvm *kvm, int fd); void kvm_irqfd_release(struct kvm *kvm); +int kvm_iofd(struct kvm *kvm, unsigned long addr, size_t len, + int fd, int flags); #endif diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 71afd62..8b23317 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -21,12 +21,16 @@ */ #include <linux/kvm_host.h> +#include <linux/kvm.h> #include <linux/workqueue.h> #include <linux/syscalls.h> #include <linux/wait.h> #include <linux/poll.h> #include <linux/file.h> #include <linux/list.h> +#include <linux/eventfd.h> + +#include "iodev.h" /* * -------------------------------------------------------------------- @@ -185,3 +189,106 @@ kvm_irqfd_release(struct kvm *kvm) list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds, list) irqfd_release(irqfd); } + +/* + * -------------------------------------------------------------------- + * iofd: translate a PIO/MMIO memory write to an eventfd signal. + * + * userspace can register a PIO/MMIO address with an eventfd for recieving + * notification when the memory has been touched. + * -------------------------------------------------------------------- + */ + +struct _iofd { + u64 addr; + size_t length; + struct file *file; + struct kvm_io_device dev; +}; + +static int +iofd_in_range(struct kvm_io_device *this, gpa_t addr, int len, int is_write) +{ + struct _iofd *iofd = (struct _iofd *)this->private; + + return ((addr >= iofd->addr && (addr < iofd->addr + iofd->length))); +} + +/* writes trigger an event */ +static void +iofd_write(struct kvm_io_device *this, gpa_t addr, int len, const void *val) +{ + struct _iofd *iofd = (struct _iofd *)this->private; + + eventfd_signal(iofd->file, 1); +} + +/* reads return all zeros */ +static void +iofd_read(struct kvm_io_device *this, gpa_t addr, int len, void *val) +{ + memset(val, 0, len); +} + +static void +iofd_destructor(struct kvm_io_device *this) +{ + struct _iofd *iofd = (struct _iofd *)this->private; + + fput(iofd->file); + kfree(iofd); +} + +static int +kvm_assign_iofd(struct kvm *kvm, unsigned long addr, size_t len, + int fd, int flags) +{ + int pio = flags & KVM_IOFD_FLAG_PIO; + struct kvm_io_bus *bus = pio ? &kvm->pio_bus : &kvm->mmio_bus; + struct _iofd *iofd; + struct file *file; + + file = eventfd_fget(fd); + if (IS_ERR(file)) + return PTR_ERR(file); + + iofd = kzalloc(sizeof(*iofd), GFP_KERNEL); + if (!iofd) { + fput(file); + return -ENOMEM; + } + + iofd->dev.read = iofd_read; + iofd->dev.write = iofd_write; + iofd->dev.in_range = iofd_in_range; + iofd->dev.destructor = iofd_destructor; + iofd->dev.private = iofd; + + iofd->addr = addr; + iofd->length = len; + iofd->file = file; + + kvm_io_bus_register_dev(bus, &iofd->dev); + + printk(KERN_DEBUG "registering %s iofd at %lx of size %d\n", + pio ? "PIO" : "MMIO", addr, (int)len); + + return 0; +} + +static int +kvm_deassign_iofd(struct kvm *kvm, unsigned long addr, size_t len, + int fd, int flags) +{ + /* FIXME: We need an io_bus_unregister() function */ + return -EINVAL; +} + +int +kvm_iofd(struct kvm *kvm, unsigned long addr, size_t len, int fd, int flags) +{ + if (flags & KVM_IOFD_FLAG_DEASSIGN) + return kvm_deassign_iofd(kvm, addr, len, fd, flags); + + return kvm_assign_iofd(kvm, addr, len, fd, flags); +} diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 7aa9f0a..a443974 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2228,6 +2228,19 @@ static long kvm_vm_ioctl(struct file *filp, r = kvm_deassign_irqfd(kvm, data); break; } + case KVM_IOFD: { + struct kvm_iofd entry; + + r = -EFAULT; + if (copy_from_user(&entry, argp, sizeof entry)) + goto out; + + r = kvm_iofd(kvm, entry.addr, entry.len, entry.fd, + entry.flags); + if (r) + goto out; + break; + } default: r = kvm_arch_vm_ioctl(filp, ioctl, arg); } -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
