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    Subject[RFC PATCH v2 14/19] kvm: add a reset capability
    Date
    We need a way to detect if a VM is reset later in the series, so lets
    add a capability for userspace to signal a VM reset down to the kernel.

    Signed-off-by: Gregory Haskins <ghaskins@novell.com>
    ---

    arch/x86/kvm/x86.c | 1 +
    include/linux/kvm.h | 2 ++
    include/linux/kvm_host.h | 6 ++++++
    virt/kvm/kvm_main.c | 36 ++++++++++++++++++++++++++++++++++++
    4 files changed, 45 insertions(+), 0 deletions(-)

    diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    index 758b7a1..9b0a649 100644
    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -971,6 +971,7 @@ int kvm_dev_ioctl_check_extension(long ext)
    case KVM_CAP_NOP_IO_DELAY:
    case KVM_CAP_MP_STATE:
    case KVM_CAP_SYNC_MMU:
    + case KVM_CAP_RESET:
    r = 1;
    break;
    case KVM_CAP_COALESCED_MMIO:
    diff --git a/include/linux/kvm.h b/include/linux/kvm.h
    index 0424326..7ffd8f5 100644
    --- a/include/linux/kvm.h
    +++ b/include/linux/kvm.h
    @@ -396,6 +396,7 @@ struct kvm_trace_rec {
    #ifdef __KVM_HAVE_USER_NMI
    #define KVM_CAP_USER_NMI 22
    #endif
    +#define KVM_CAP_RESET 23

    /*
    * ioctls for VM fds
    @@ -429,6 +430,7 @@ struct kvm_trace_rec {
    struct kvm_assigned_pci_dev)
    #define KVM_ASSIGN_IRQ _IOR(KVMIO, 0x70, \
    struct kvm_assigned_irq)
    +#define KVM_RESET _IO(KVMIO, 0x67)

    /*
    * ioctls for vcpu fds
    diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
    index bf6f703..506eca1 100644
    --- a/include/linux/kvm_host.h
    +++ b/include/linux/kvm_host.h
    @@ -17,6 +17,7 @@
    #include <linux/preempt.h>
    #include <linux/marker.h>
    #include <linux/msi.h>
    +#include <linux/notifier.h>
    #include <asm/signal.h>

    #include <linux/kvm.h>
    @@ -132,6 +133,8 @@ struct kvm {
    unsigned long mmu_notifier_seq;
    long mmu_notifier_count;
    #endif
    +
    + struct raw_notifier_head reset_notifier; /* triggers when VM reboots */
    };

    /* The guest did something we don't support. */
    @@ -158,6 +161,9 @@ void kvm_exit(void);
    void kvm_get_kvm(struct kvm *kvm);
    void kvm_put_kvm(struct kvm *kvm);

    +int kvm_reset_notifier_register(struct kvm *kvm, struct notifier_block *nb);
    +int kvm_reset_notifier_unregister(struct kvm *kvm, struct notifier_block *nb);
    +
    #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; }
    diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
    index 29a667c..fca2d25 100644
    --- a/virt/kvm/kvm_main.c
    +++ b/virt/kvm/kvm_main.c
    @@ -868,6 +868,8 @@ static struct kvm *kvm_create_vm(void)
    #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
    kvm_coalesced_mmio_init(kvm);
    #endif
    + RAW_INIT_NOTIFIER_HEAD(&kvm->reset_notifier);
    +
    out:
    return kvm;
    }
    @@ -1485,6 +1487,35 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
    }
    }

    +static void kvm_notify_reset(struct kvm *kvm)
    +{
    + mutex_lock(&kvm->lock);
    + raw_notifier_call_chain(&kvm->reset_notifier, 0, kvm);
    + mutex_unlock(&kvm->lock);
    +}
    +
    +int kvm_reset_notifier_register(struct kvm *kvm, struct notifier_block *nb)
    +{
    + int ret;
    +
    + mutex_lock(&kvm->lock);
    + ret = raw_notifier_chain_register(&kvm->reset_notifier, nb);
    + mutex_unlock(&kvm->lock);
    +
    + return ret;
    +}
    +
    +int kvm_reset_notifier_unregister(struct kvm *kvm, struct notifier_block *nb)
    +{
    + int ret;
    +
    + mutex_lock(&kvm->lock);
    + ret = raw_notifier_chain_unregister(&kvm->reset_notifier, nb);
    + mutex_unlock(&kvm->lock);
    +
    + return ret;
    +}
    +
    /*
    * The vCPU has executed a HLT instruction with in-kernel mode enabled.
    */
    @@ -1929,6 +1960,11 @@ static long kvm_vm_ioctl(struct file *filp,
    break;
    }
    #endif
    + case KVM_RESET: {
    + kvm_notify_reset(kvm);
    + r = 0;
    + break;
    + }
    default:
    r = kvm_arch_vm_ioctl(filp, ioctl, arg);
    }


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