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linux-next/include/linux/kvm_host.h
Gregory Haskins d34e6b175e KVM: add ioeventfd support
ioeventfd is a mechanism to register PIO/MMIO regions to trigger an eventfd
signal when written to by a guest.  Host userspace can register any
arbitrary IO address with a corresponding eventfd and then pass the eventfd
to a specific end-point of interest for handling.

Normal IO requires a blocking round-trip since the operation may cause
side-effects in the emulated model or may return data to the caller.
Therefore, an IO in KVM traps from the guest to the host, causes a VMX/SVM
"heavy-weight" exit back to userspace, and is ultimately serviced by qemu's
device model synchronously before returning control back to the vcpu.

However, there is a subclass of IO which acts purely as a trigger for
other IO (such as to kick off an out-of-band DMA request, etc).  For these
patterns, the synchronous call is particularly expensive since we really
only want to simply get our notification transmitted asychronously and
return as quickly as possible.  All the sychronous infrastructure to ensure
proper data-dependencies are met in the normal IO case are just unecessary
overhead for signalling.  This adds additional computational load on the
system, as well as latency to the signalling path.

Therefore, we provide a mechanism for registration of an in-kernel trigger
point that allows the VCPU to only require a very brief, lightweight
exit just long enough to signal an eventfd.  This also means that any
clients compatible with the eventfd interface (which includes userspace
and kernelspace equally well) can now register to be notified. The end
result should be a more flexible and higher performance notification API
for the backend KVM hypervisor and perhipheral components.

To test this theory, we built a test-harness called "doorbell".  This
module has a function called "doorbell_ring()" which simply increments a
counter for each time the doorbell is signaled.  It supports signalling
from either an eventfd, or an ioctl().

We then wired up two paths to the doorbell: One via QEMU via a registered
io region and through the doorbell ioctl().  The other is direct via
ioeventfd.

You can download this test harness here:

ftp://ftp.novell.com/dev/ghaskins/doorbell.tar.bz2

The measured results are as follows:

qemu-mmio:       110000 iops, 9.09us rtt
ioeventfd-mmio: 200100 iops, 5.00us rtt
ioeventfd-pio:  367300 iops, 2.72us rtt

I didn't measure qemu-pio, because I have to figure out how to register a
PIO region with qemu's device model, and I got lazy.  However, for now we
can extrapolate based on the data from the NULLIO runs of +2.56us for MMIO,
and -350ns for HC, we get:

qemu-pio:      153139 iops, 6.53us rtt
ioeventfd-hc: 412585 iops, 2.37us rtt

these are just for fun, for now, until I can gather more data.

Here is a graph for your convenience:

http://developer.novell.com/wiki/images/7/76/Iofd-chart.png

The conclusion to draw is that we save about 4us by skipping the userspace
hop.

--------------------

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2009-09-10 08:33:12 +03:00

560 lines
16 KiB
C

#ifndef __KVM_HOST_H
#define __KVM_HOST_H
/*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*/
#include <linux/types.h>
#include <linux/hardirq.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/preempt.h>
#include <linux/marker.h>
#include <linux/msi.h>
#include <asm/signal.h>
#include <linux/kvm.h>
#include <linux/kvm_para.h>
#include <linux/kvm_types.h>
#include <asm/kvm_host.h>
/*
* vcpu->requests bit members
*/
#define KVM_REQ_TLB_FLUSH 0
#define KVM_REQ_MIGRATE_TIMER 1
#define KVM_REQ_REPORT_TPR_ACCESS 2
#define KVM_REQ_MMU_RELOAD 3
#define KVM_REQ_TRIPLE_FAULT 4
#define KVM_REQ_PENDING_TIMER 5
#define KVM_REQ_UNHALT 6
#define KVM_REQ_MMU_SYNC 7
#define KVM_REQ_KVMCLOCK_UPDATE 8
#define KVM_REQ_KICK 9
#define KVM_USERSPACE_IRQ_SOURCE_ID 0
struct kvm;
struct kvm_vcpu;
extern struct kmem_cache *kvm_vcpu_cache;
/*
* It would be nice to use something smarter than a linear search, TBD...
* Thankfully we dont expect many devices to register (famous last words :),
* so until then it will suffice. At least its abstracted so we can change
* in one place.
*/
struct kvm_io_bus {
int dev_count;
#define NR_IOBUS_DEVS 6
struct kvm_io_device *devs[NR_IOBUS_DEVS];
};
void kvm_io_bus_init(struct kvm_io_bus *bus);
void kvm_io_bus_destroy(struct kvm_io_bus *bus);
int kvm_io_bus_write(struct kvm_io_bus *bus, gpa_t addr, int len,
const void *val);
int kvm_io_bus_read(struct kvm_io_bus *bus, gpa_t addr, int len,
void *val);
int __kvm_io_bus_register_dev(struct kvm_io_bus *bus,
struct kvm_io_device *dev);
int kvm_io_bus_register_dev(struct kvm *kvm, struct kvm_io_bus *bus,
struct kvm_io_device *dev);
void __kvm_io_bus_unregister_dev(struct kvm_io_bus *bus,
struct kvm_io_device *dev);
void kvm_io_bus_unregister_dev(struct kvm *kvm, struct kvm_io_bus *bus,
struct kvm_io_device *dev);
struct kvm_vcpu {
struct kvm *kvm;
#ifdef CONFIG_PREEMPT_NOTIFIERS
struct preempt_notifier preempt_notifier;
#endif
int vcpu_id;
struct mutex mutex;
int cpu;
struct kvm_run *run;
unsigned long requests;
unsigned long guest_debug;
int fpu_active;
int guest_fpu_loaded;
wait_queue_head_t wq;
int sigset_active;
sigset_t sigset;
struct kvm_vcpu_stat stat;
#ifdef CONFIG_HAS_IOMEM
int mmio_needed;
int mmio_read_completed;
int mmio_is_write;
int mmio_size;
unsigned char mmio_data[8];
gpa_t mmio_phys_addr;
#endif
struct kvm_vcpu_arch arch;
};
struct kvm_memory_slot {
gfn_t base_gfn;
unsigned long npages;
unsigned long flags;
unsigned long *rmap;
unsigned long *dirty_bitmap;
struct {
unsigned long rmap_pde;
int write_count;
} *lpage_info[KVM_NR_PAGE_SIZES - 1];
unsigned long userspace_addr;
int user_alloc;
};
struct kvm_kernel_irq_routing_entry {
u32 gsi;
u32 type;
int (*set)(struct kvm_kernel_irq_routing_entry *e,
struct kvm *kvm, int level);
union {
struct {
unsigned irqchip;
unsigned pin;
} irqchip;
struct msi_msg msi;
};
struct list_head link;
};
struct kvm {
spinlock_t mmu_lock;
spinlock_t requests_lock;
struct rw_semaphore slots_lock;
struct mm_struct *mm; /* userspace tied to this vm */
int nmemslots;
struct kvm_memory_slot memslots[KVM_MEMORY_SLOTS +
KVM_PRIVATE_MEM_SLOTS];
#ifdef CONFIG_KVM_APIC_ARCHITECTURE
u32 bsp_vcpu_id;
struct kvm_vcpu *bsp_vcpu;
#endif
struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
atomic_t online_vcpus;
struct list_head vm_list;
struct mutex lock;
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;
struct list_head ioeventfds;
#endif
struct kvm_vm_stat stat;
struct kvm_arch arch;
atomic_t users_count;
#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
struct kvm_coalesced_mmio_dev *coalesced_mmio_dev;
struct kvm_coalesced_mmio_ring *coalesced_mmio_ring;
#endif
struct mutex irq_lock;
#ifdef CONFIG_HAVE_KVM_IRQCHIP
struct list_head irq_routing; /* of kvm_kernel_irq_routing_entry */
struct hlist_head mask_notifier_list;
#endif
#ifdef KVM_ARCH_WANT_MMU_NOTIFIER
struct mmu_notifier mmu_notifier;
unsigned long mmu_notifier_seq;
long mmu_notifier_count;
#endif
};
/* The guest did something we don't support. */
#define pr_unimpl(vcpu, fmt, ...) \
do { \
if (printk_ratelimit()) \
printk(KERN_ERR "kvm: %i: cpu%i " fmt, \
current->tgid, (vcpu)->vcpu_id , ## __VA_ARGS__); \
} while (0)
#define kvm_printf(kvm, fmt ...) printk(KERN_DEBUG fmt)
#define vcpu_printf(vcpu, fmt...) kvm_printf(vcpu->kvm, fmt)
static inline struct kvm_vcpu *kvm_get_vcpu(struct kvm *kvm, int i)
{
smp_rmb();
return kvm->vcpus[i];
}
#define kvm_for_each_vcpu(idx, vcpup, kvm) \
for (idx = 0, vcpup = kvm_get_vcpu(kvm, idx); \
idx < atomic_read(&kvm->online_vcpus) && vcpup; \
vcpup = kvm_get_vcpu(kvm, ++idx))
int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id);
void kvm_vcpu_uninit(struct kvm_vcpu *vcpu);
void vcpu_load(struct kvm_vcpu *vcpu);
void vcpu_put(struct kvm_vcpu *vcpu);
int kvm_init(void *opaque, unsigned int vcpu_size,
struct module *module);
void kvm_exit(void);
void kvm_get_kvm(struct kvm *kvm);
void kvm_put_kvm(struct kvm *kvm);
#define HPA_MSB ((sizeof(hpa_t) * 8) - 1)
#define HPA_ERR_MASK ((hpa_t)1 << HPA_MSB)
static inline int is_error_hpa(hpa_t hpa) { return hpa >> HPA_MSB; }
struct page *gva_to_page(struct kvm_vcpu *vcpu, gva_t gva);
extern struct page *bad_page;
extern pfn_t bad_pfn;
int is_error_page(struct page *page);
int is_error_pfn(pfn_t pfn);
int kvm_is_error_hva(unsigned long addr);
int kvm_set_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem,
int user_alloc);
int __kvm_set_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem,
int user_alloc);
int kvm_arch_set_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem,
struct kvm_memory_slot old,
int user_alloc);
void kvm_disable_largepages(void);
void kvm_arch_flush_shadow(struct kvm *kvm);
gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn);
struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn);
unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn);
void kvm_release_page_clean(struct page *page);
void kvm_release_page_dirty(struct page *page);
void kvm_set_page_dirty(struct page *page);
void kvm_set_page_accessed(struct page *page);
pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn);
void kvm_release_pfn_dirty(pfn_t);
void kvm_release_pfn_clean(pfn_t pfn);
void kvm_set_pfn_dirty(pfn_t pfn);
void kvm_set_pfn_accessed(pfn_t pfn);
void kvm_get_pfn(pfn_t pfn);
int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
int len);
int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,
unsigned long len);
int kvm_read_guest(struct kvm *kvm, gpa_t gpa, void *data, unsigned long len);
int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,
int offset, int len);
int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data,
unsigned long len);
int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len);
int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len);
struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);
int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn);
void mark_page_dirty(struct kvm *kvm, gfn_t gfn);
void kvm_vcpu_block(struct kvm_vcpu *vcpu);
void kvm_resched(struct kvm_vcpu *vcpu);
void kvm_load_guest_fpu(struct kvm_vcpu *vcpu);
void kvm_put_guest_fpu(struct kvm_vcpu *vcpu);
void kvm_flush_remote_tlbs(struct kvm *kvm);
void kvm_reload_remote_mmus(struct kvm *kvm);
long kvm_arch_dev_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg);
long kvm_arch_vcpu_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg);
int kvm_dev_ioctl_check_extension(long ext);
int kvm_get_dirty_log(struct kvm *kvm,
struct kvm_dirty_log *log, int *is_dirty);
int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
struct kvm_dirty_log *log);
int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
struct
kvm_userspace_memory_region *mem,
int user_alloc);
long kvm_arch_vm_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg);
int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu);
int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu);
int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
struct kvm_translation *tr);
int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs);
int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs);
int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
struct kvm_sregs *sregs);
int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
struct kvm_sregs *sregs);
int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
struct kvm_mp_state *mp_state);
int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
struct kvm_mp_state *mp_state);
int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
struct kvm_guest_debug *dbg);
int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run);
int kvm_arch_init(void *opaque);
void kvm_arch_exit(void);
int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu);
struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id);
int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu);
int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu);
void kvm_arch_hardware_enable(void *garbage);
void kvm_arch_hardware_disable(void *garbage);
int kvm_arch_hardware_setup(void);
void kvm_arch_hardware_unsetup(void);
void kvm_arch_check_processor_compat(void *rtn);
int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu);
int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu);
void kvm_free_physmem(struct kvm *kvm);
struct kvm *kvm_arch_create_vm(void);
void kvm_arch_destroy_vm(struct kvm *kvm);
void kvm_free_all_assigned_devices(struct kvm *kvm);
void kvm_arch_sync_events(struct kvm *kvm);
int kvm_cpu_get_interrupt(struct kvm_vcpu *v);
int kvm_cpu_has_interrupt(struct kvm_vcpu *v);
int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu);
void kvm_vcpu_kick(struct kvm_vcpu *vcpu);
int kvm_is_mmio_pfn(pfn_t pfn);
struct kvm_irq_ack_notifier {
struct hlist_node link;
unsigned gsi;
void (*irq_acked)(struct kvm_irq_ack_notifier *kian);
};
#define KVM_ASSIGNED_MSIX_PENDING 0x1
struct kvm_guest_msix_entry {
u32 vector;
u16 entry;
u16 flags;
};
struct kvm_assigned_dev_kernel {
struct kvm_irq_ack_notifier ack_notifier;
struct work_struct interrupt_work;
struct list_head list;
int assigned_dev_id;
int host_busnr;
int host_devfn;
unsigned int entries_nr;
int host_irq;
bool host_irq_disabled;
struct msix_entry *host_msix_entries;
int guest_irq;
struct kvm_guest_msix_entry *guest_msix_entries;
unsigned long irq_requested_type;
int irq_source_id;
int flags;
struct pci_dev *dev;
struct kvm *kvm;
spinlock_t assigned_dev_lock;
};
struct kvm_irq_mask_notifier {
void (*func)(struct kvm_irq_mask_notifier *kimn, bool masked);
int irq;
struct hlist_node link;
};
void kvm_register_irq_mask_notifier(struct kvm *kvm, int irq,
struct kvm_irq_mask_notifier *kimn);
void kvm_unregister_irq_mask_notifier(struct kvm *kvm, int irq,
struct kvm_irq_mask_notifier *kimn);
void kvm_fire_mask_notifiers(struct kvm *kvm, int irq, bool mask);
int kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level);
void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin);
void kvm_register_irq_ack_notifier(struct kvm *kvm,
struct kvm_irq_ack_notifier *kian);
void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
struct kvm_irq_ack_notifier *kian);
int kvm_request_irq_source_id(struct kvm *kvm);
void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id);
/* For vcpu->arch.iommu_flags */
#define KVM_IOMMU_CACHE_COHERENCY 0x1
#ifdef CONFIG_IOMMU_API
int kvm_iommu_map_pages(struct kvm *kvm, gfn_t base_gfn,
unsigned long npages);
int kvm_iommu_map_guest(struct kvm *kvm);
int kvm_iommu_unmap_guest(struct kvm *kvm);
int kvm_assign_device(struct kvm *kvm,
struct kvm_assigned_dev_kernel *assigned_dev);
int kvm_deassign_device(struct kvm *kvm,
struct kvm_assigned_dev_kernel *assigned_dev);
#else /* CONFIG_IOMMU_API */
static inline int kvm_iommu_map_pages(struct kvm *kvm,
gfn_t base_gfn,
unsigned long npages)
{
return 0;
}
static inline int kvm_iommu_map_guest(struct kvm *kvm)
{
return -ENODEV;
}
static inline int kvm_iommu_unmap_guest(struct kvm *kvm)
{
return 0;
}
static inline int kvm_assign_device(struct kvm *kvm,
struct kvm_assigned_dev_kernel *assigned_dev)
{
return 0;
}
static inline int kvm_deassign_device(struct kvm *kvm,
struct kvm_assigned_dev_kernel *assigned_dev)
{
return 0;
}
#endif /* CONFIG_IOMMU_API */
static inline void kvm_guest_enter(void)
{
account_system_vtime(current);
current->flags |= PF_VCPU;
}
static inline void kvm_guest_exit(void)
{
account_system_vtime(current);
current->flags &= ~PF_VCPU;
}
static inline int memslot_id(struct kvm *kvm, struct kvm_memory_slot *slot)
{
return slot - kvm->memslots;
}
static inline gpa_t gfn_to_gpa(gfn_t gfn)
{
return (gpa_t)gfn << PAGE_SHIFT;
}
static inline hpa_t pfn_to_hpa(pfn_t pfn)
{
return (hpa_t)pfn << PAGE_SHIFT;
}
static inline void kvm_migrate_timers(struct kvm_vcpu *vcpu)
{
set_bit(KVM_REQ_MIGRATE_TIMER, &vcpu->requests);
}
enum kvm_stat_kind {
KVM_STAT_VM,
KVM_STAT_VCPU,
};
struct kvm_stats_debugfs_item {
const char *name;
int offset;
enum kvm_stat_kind kind;
struct dentry *dentry;
};
extern struct kvm_stats_debugfs_item debugfs_entries[];
extern struct dentry *kvm_debugfs_dir;
#ifdef KVM_ARCH_WANT_MMU_NOTIFIER
static inline int mmu_notifier_retry(struct kvm_vcpu *vcpu, unsigned long mmu_seq)
{
if (unlikely(vcpu->kvm->mmu_notifier_count))
return 1;
/*
* Both reads happen under the mmu_lock and both values are
* modified under mmu_lock, so there's no need of smb_rmb()
* here in between, otherwise mmu_notifier_count should be
* read before mmu_notifier_seq, see
* mmu_notifier_invalidate_range_end write side.
*/
if (vcpu->kvm->mmu_notifier_seq != mmu_seq)
return 1;
return 0;
}
#endif
#ifdef CONFIG_HAVE_KVM_IRQCHIP
#define KVM_MAX_IRQ_ROUTES 1024
int kvm_setup_default_irq_routing(struct kvm *kvm);
int kvm_set_irq_routing(struct kvm *kvm,
const struct kvm_irq_routing_entry *entries,
unsigned nr,
unsigned flags);
void kvm_free_irq_routing(struct kvm *kvm);
#else
static inline void kvm_free_irq_routing(struct kvm *kvm) {}
#endif
#ifdef CONFIG_HAVE_KVM_EVENTFD
void kvm_eventfd_init(struct kvm *kvm);
int kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags);
void kvm_irqfd_release(struct kvm *kvm);
int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args);
#else
static inline void kvm_eventfd_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) {}
static inline int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
{
return -ENOSYS;
}
#endif /* CONFIG_HAVE_KVM_EVENTFD */
#ifdef CONFIG_KVM_APIC_ARCHITECTURE
static inline bool kvm_vcpu_is_bsp(struct kvm_vcpu *vcpu)
{
return vcpu->kvm->bsp_vcpu_id == vcpu->vcpu_id;
}
#endif
#endif