5 files changed, 269 insertions, 0 deletions

diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index a281afeddfbb..1c908ac29c6c 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -173,6 +173,30 @@ struct kvm_run {
         };
 };
 
+/* for KVM_REGISTER_COALESCED_MMIO / KVM_UNREGISTER_COALESCED_MMIO */
+
+struct kvm_coalesced_mmio_zone {
+        __u64 addr;
+        __u32 size;
+        __u32 pad;
+};
+
+struct kvm_coalesced_mmio {
+        __u64 phys_addr;
+        __u32 len;
+        __u32 pad;
+        __u8  data[8];
+};
+
+struct kvm_coalesced_mmio_ring {
+        __u32 first, last;
+        struct kvm_coalesced_mmio coalesced_mmio[0];
+};
+
+#define KVM_COALESCED_MMIO_MAX \
+        ((PAGE_SIZE - sizeof(struct kvm_coalesced_mmio_ring)) / \
+         sizeof(struct kvm_coalesced_mmio))
+
 /* for KVM_TRANSLATE */
 struct kvm_translation {
         /* in */
@@ -346,6 +370,7 @@ struct kvm_trace_rec {
 #define KVM_CAP_NOP_IO_DELAY 12
 #define KVM_CAP_PV_MMU 13
 #define KVM_CAP_MP_STATE 14
+#define KVM_CAP_COALESCED_MMIO 15
 
 /*
  * ioctls for VM fds
@@ -371,6 +396,10 @@ struct kvm_trace_rec {
 #define KVM_CREATE_PIT            _IO(KVMIO,  0x64)
 #define KVM_GET_PIT               _IOWR(KVMIO, 0x65, struct kvm_pit_state)
 #define KVM_SET_PIT               _IOR(KVMIO,  0x66, struct kvm_pit_state)
+#define KVM_REGISTER_COALESCED_MMIO \
+                        _IOW(KVMIO,  0x67, struct kvm_coalesced_mmio_zone)
+#define KVM_UNREGISTER_COALESCED_MMIO \
+                        _IOW(KVMIO,  0x68, struct kvm_coalesced_mmio_zone)
 
 /*
  * ioctls for vcpu fds
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 499ff0604234..d220b4926c4a 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -117,6 +117,10 @@ struct kvm {
         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
 };
 
 /* The guest did something we don't support. */
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
new file mode 100644
index 000000000000..5ae620d32fac
--- /dev/null
+++ b/virt/kvm/coalesced_mmio.c
@@ -0,0 +1,156 @@
+/*
+ * KVM coalesced MMIO
+ *
+ * Copyright (c) 2008 Bull S.A.S.
+ *
+ *  Author: Laurent Vivier <Laurent.Vivier@bull.net>
+ *
+ */
+
+#include "iodev.h"
+
+#include <linux/kvm_host.h>
+#include <linux/kvm.h>
+
+#include "coalesced_mmio.h"
+
+static int coalesced_mmio_in_range(struct kvm_io_device *this,
+                                   gpa_t addr, int len, int is_write)
+{
+        struct kvm_coalesced_mmio_dev *dev =
+                                (struct kvm_coalesced_mmio_dev*)this->private;
+        struct kvm_coalesced_mmio_zone *zone;
+        int next;
+        int i;
+
+        if (!is_write)
+                return 0;
+
+        /* kvm->lock is taken by the caller and must be not released before
+         * dev.read/write
+         */
+
+        /* Are we able to batch it ? */
+
+        /* last is the first free entry
+         * check if we don't meet the first used entry
+         * there is always one unused entry in the buffer
+         */
+
+        next = (dev->kvm->coalesced_mmio_ring->last + 1) %
+                                                        KVM_COALESCED_MMIO_MAX;
+        if (next == dev->kvm->coalesced_mmio_ring->first) {
+                /* full */
+                return 0;
+        }
+
+        /* is it in a batchable area ? */
+
+        for (i = 0; i < dev->nb_zones; i++) {
+                zone = &dev->zone[i];
+
+                /* (addr,len) is fully included in
+                 * (zone->addr, zone->size)
+                 */
+
+                if (zone->addr <= addr &&
+                    addr + len <= zone->addr + zone->size)
+                        return 1;
+        }
+        return 0;
+}
+
+static void coalesced_mmio_write(struct kvm_io_device *this,
+                                 gpa_t addr, int len, const void *val)
+{
+        struct kvm_coalesced_mmio_dev *dev =
+                                (struct kvm_coalesced_mmio_dev*)this->private;
+        struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
+
+        /* kvm->lock must be taken by caller before call to in_range()*/
+
+        /* copy data in first free entry of the ring */
+
+        ring->coalesced_mmio[ring->last].phys_addr = addr;
+        ring->coalesced_mmio[ring->last].len = len;
+        memcpy(ring->coalesced_mmio[ring->last].data, val, len);
+        smp_wmb();
+        ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
+}
+
+static void coalesced_mmio_destructor(struct kvm_io_device *this)
+{
+        kfree(this);
+}
+
+int kvm_coalesced_mmio_init(struct kvm *kvm)
+{
+        struct kvm_coalesced_mmio_dev *dev;
+
+        dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
+        if (!dev)
+                return -ENOMEM;
+        dev->dev.write  = coalesced_mmio_write;
+        dev->dev.in_range  = coalesced_mmio_in_range;
+        dev->dev.destructor  = coalesced_mmio_destructor;
+        dev->dev.private  = dev;
+        dev->kvm = kvm;
+        kvm->coalesced_mmio_dev = dev;
+        kvm_io_bus_register_dev(&kvm->mmio_bus, &dev->dev);
+
+        return 0;
+}
+
+int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
+                                         struct kvm_coalesced_mmio_zone *zone)
+{
+        struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
+
+        if (dev == NULL)
+                return -EINVAL;
+
+        mutex_lock(&kvm->lock);
+        if (dev->nb_zones >= KVM_COALESCED_MMIO_ZONE_MAX) {
+                mutex_unlock(&kvm->lock);
+                return -ENOBUFS;
+        }
+
+        dev->zone[dev->nb_zones] = *zone;
+        dev->nb_zones++;
+
+        mutex_unlock(&kvm->lock);
+        return 0;
+}
+
+int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
+                                           struct kvm_coalesced_mmio_zone *zone)
+{
+        int i;
+        struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
+        struct kvm_coalesced_mmio_zone *z;
+
+        if (dev == NULL)
+                return -EINVAL;
+
+        mutex_lock(&kvm->lock);
+
+        i = dev->nb_zones;
+        while(i) {
+                z = &dev->zone[i - 1];
+
+                /* unregister all zones
+                 * included in (zone->addr, zone->size)
+                 */
+
+                if (zone->addr <= z->addr &&
+                    z->addr + z->size <= zone->addr + zone->size) {
+                        dev->nb_zones--;
+                        *z = dev->zone[dev->nb_zones];
+                }
+                i--;
+        }
+
+        mutex_unlock(&kvm->lock);
+
+        return 0;
+}
diff --git a/virt/kvm/coalesced_mmio.h b/virt/kvm/coalesced_mmio.h
new file mode 100644
index 000000000000..5ac0ec628461
--- /dev/null
+++ b/virt/kvm/coalesced_mmio.h
@@ -0,0 +1,23 @@
+/*
+ * KVM coalesced MMIO
+ *
+ * Copyright (c) 2008 Bull S.A.S.
+ *
+ *  Author: Laurent Vivier <Laurent.Vivier@bull.net>
+ *
+ */
+
+#define KVM_COALESCED_MMIO_ZONE_MAX 100
+
+struct kvm_coalesced_mmio_dev {
+        struct kvm_io_device dev;
+        struct kvm *kvm;
+        int nb_zones;
+        struct kvm_coalesced_mmio_zone zone[KVM_COALESCED_MMIO_ZONE_MAX];
+};
+
+int kvm_coalesced_mmio_init(struct kvm *kvm);
+int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
+                                       struct kvm_coalesced_mmio_zone *zone);
+int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
+                                         struct kvm_coalesced_mmio_zone *zone);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9330fad2b918..7d10dfa0d388 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -47,6 +47,10 @@
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 
+#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
+#include "coalesced_mmio.h"
+#endif
+
 MODULE_AUTHOR("Qumranet");
 MODULE_LICENSE("GPL");
 
@@ -185,10 +189,23 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_uninit);
 static struct kvm *kvm_create_vm(void)
 {
         struct kvm *kvm = kvm_arch_create_vm();
+#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
+        struct page *page;
+#endif
 
         if (IS_ERR(kvm))
                 goto out;
 
+#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
+        page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+        if (!page) {
+                kfree(kvm);
+                return ERR_PTR(-ENOMEM);
+        }
+        kvm->coalesced_mmio_ring =
+                        (struct kvm_coalesced_mmio_ring *)page_address(page);
+#endif
+
         kvm->mm = current->mm;
         atomic_inc(&kvm->mm->mm_count);
         spin_lock_init(&kvm->mmu_lock);
@@ -200,6 +217,9 @@ static struct kvm *kvm_create_vm(void)
         spin_lock(&kvm_lock);
         list_add(&kvm->vm_list, &vm_list);
         spin_unlock(&kvm_lock);
+#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
+        kvm_coalesced_mmio_init(kvm);
+#endif
 out:
         return kvm;
 }
@@ -242,6 +262,10 @@ static void kvm_destroy_vm(struct kvm *kvm)
         spin_unlock(&kvm_lock);
         kvm_io_bus_destroy(&kvm->pio_bus);
         kvm_io_bus_destroy(&kvm->mmio_bus);
+#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
+        if (kvm->coalesced_mmio_ring != NULL)
+                free_page((unsigned long)kvm->coalesced_mmio_ring);
+#endif
         kvm_arch_destroy_vm(kvm);
         mmdrop(mm);
 }
@@ -826,6 +850,10 @@ static int kvm_vcpu_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
         else if (vmf->pgoff == KVM_PIO_PAGE_OFFSET)
                 page = virt_to_page(vcpu->arch.pio_data);
 #endif
+#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
+        else if (vmf->pgoff == KVM_COALESCED_MMIO_PAGE_OFFSET)
+                page = virt_to_page(vcpu->kvm->coalesced_mmio_ring);
+#endif
         else
                 return VM_FAULT_SIGBUS;
         get_page(page);
@@ -1148,6 +1176,32 @@ static long kvm_vm_ioctl(struct file *filp,
                         goto out;
                 break;
         }
+#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
+        case KVM_REGISTER_COALESCED_MMIO: {
+                struct kvm_coalesced_mmio_zone zone;
+                r = -EFAULT;
+                if (copy_from_user(&zone, argp, sizeof zone))
+                        goto out;
+                r = -ENXIO;
+                r = kvm_vm_ioctl_register_coalesced_mmio(kvm, &zone);
+                if (r)
+                        goto out;
+                r = 0;
+                break;
+        }
+        case KVM_UNREGISTER_COALESCED_MMIO: {
+                struct kvm_coalesced_mmio_zone zone;
+                r = -EFAULT;
+                if (copy_from_user(&zone, argp, sizeof zone))
+                        goto out;
+                r = -ENXIO;
+                r = kvm_vm_ioctl_unregister_coalesced_mmio(kvm, &zone);
+                if (r)
+                        goto out;
+                r = 0;
+                break;
+        }
+#endif
         default:
                 r = kvm_arch_vm_ioctl(filp, ioctl, arg);
         }
@@ -1232,6 +1286,9 @@ static long kvm_dev_ioctl(struct file *filp,
 #ifdef CONFIG_X86
                 r += PAGE_SIZE;    /* pio data page */
 #endif
+#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
+                r += PAGE_SIZE;    /* coalesced mmio ring page */
+#endif
                 break;
         case KVM_TRACE_ENABLE:
         case KVM_TRACE_PAUSE: