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    Subject[PATCH v19 014/130] KVM: Add KVM vcpu ioctl to pre-populate guest memory
    Date
    From: Isaku Yamahata <isaku.yamahata@intel.com>

    Add new ioctl KVM_MEMORY_MAPPING in the kvm common code. It iterates on the
    memory range and call arch specific function. Add stub function as weak
    symbol.

    Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
    ---
    v19:
    - newly added
    ---
    include/linux/kvm_host.h | 4 +++
    include/uapi/linux/kvm.h | 10 ++++++
    virt/kvm/kvm_main.c | 67 ++++++++++++++++++++++++++++++++++++++++
    3 files changed, 81 insertions(+)

    diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
    index 0520cd8d03cc..eeaf4e73317c 100644
    --- a/include/linux/kvm_host.h
    +++ b/include/linux/kvm_host.h
    @@ -2389,4 +2389,8 @@ static inline int kvm_gmem_get_pfn(struct kvm *kvm,
    }
    #endif /* CONFIG_KVM_PRIVATE_MEM */

    +void kvm_arch_vcpu_pre_memory_mapping(struct kvm_vcpu *vcpu);
    +int kvm_arch_vcpu_memory_mapping(struct kvm_vcpu *vcpu,
    + struct kvm_memory_mapping *mapping);
    +
    #endif
    diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
    index c3308536482b..5e2b28934aa9 100644
    --- a/include/uapi/linux/kvm.h
    +++ b/include/uapi/linux/kvm.h
    @@ -1155,6 +1155,7 @@ struct kvm_ppc_resize_hpt {
    #define KVM_CAP_MEMORY_ATTRIBUTES 233
    #define KVM_CAP_GUEST_MEMFD 234
    #define KVM_CAP_VM_TYPES 235
    +#define KVM_CAP_MEMORY_MAPPING 236

    #ifdef KVM_CAP_IRQ_ROUTING

    @@ -2227,4 +2228,13 @@ struct kvm_create_guest_memfd {
    __u64 reserved[6];
    };

    +#define KVM_MEMORY_MAPPING _IOWR(KVMIO, 0xd5, struct kvm_memory_mapping)
    +
    +struct kvm_memory_mapping {
    + __u64 base_gfn;
    + __u64 nr_pages;
    + __u64 flags;
    + __u64 source;
    +};
    +
    #endif /* __LINUX_KVM_H */
    diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
    index 0349e1f241d1..2f0a8e28795e 100644
    --- a/virt/kvm/kvm_main.c
    +++ b/virt/kvm/kvm_main.c
    @@ -4409,6 +4409,62 @@ static int kvm_vcpu_ioctl_get_stats_fd(struct kvm_vcpu *vcpu)
    return fd;
    }

    +__weak void kvm_arch_vcpu_pre_memory_mapping(struct kvm_vcpu *vcpu)
    +{
    +}
    +
    +__weak int kvm_arch_vcpu_memory_mapping(struct kvm_vcpu *vcpu,
    + struct kvm_memory_mapping *mapping)
    +{
    + return -EOPNOTSUPP;
    +}
    +
    +static int kvm_vcpu_memory_mapping(struct kvm_vcpu *vcpu,
    + struct kvm_memory_mapping *mapping)
    +{
    + bool added = false;
    + int idx, r = 0;
    +
    + /* flags isn't used yet. */
    + if (mapping->flags)
    + return -EINVAL;
    +
    + /* Sanity check */
    + if (!IS_ALIGNED(mapping->source, PAGE_SIZE) ||
    + !mapping->nr_pages ||
    + mapping->nr_pages & GENMASK_ULL(63, 63 - PAGE_SHIFT) ||
    + mapping->base_gfn + mapping->nr_pages <= mapping->base_gfn)
    + return -EINVAL;
    +
    + vcpu_load(vcpu);
    + idx = srcu_read_lock(&vcpu->kvm->srcu);
    + kvm_arch_vcpu_pre_memory_mapping(vcpu);
    +
    + while (mapping->nr_pages) {
    + if (signal_pending(current)) {
    + r = -ERESTARTSYS;
    + break;
    + }
    +
    + if (need_resched())
    + cond_resched();
    +
    + r = kvm_arch_vcpu_memory_mapping(vcpu, mapping);
    + if (r)
    + break;
    +
    + added = true;
    + }
    +
    + srcu_read_unlock(&vcpu->kvm->srcu, idx);
    + vcpu_put(vcpu);
    +
    + if (added && mapping->nr_pages > 0)
    + r = -EAGAIN;
    +
    + return r;
    +}
    +
    static long kvm_vcpu_ioctl(struct file *filp,
    unsigned int ioctl, unsigned long arg)
    {
    @@ -4610,6 +4666,17 @@ static long kvm_vcpu_ioctl(struct file *filp,
    r = kvm_vcpu_ioctl_get_stats_fd(vcpu);
    break;
    }
    + case KVM_MEMORY_MAPPING: {
    + struct kvm_memory_mapping mapping;
    +
    + r = -EFAULT;
    + if (copy_from_user(&mapping, argp, sizeof(mapping)))
    + break;
    + r = kvm_vcpu_memory_mapping(vcpu, &mapping);
    + if (copy_to_user(argp, &mapping, sizeof(mapping)))
    + r = -EFAULT;
    + break;
    + }
    default:
    r = kvm_arch_vcpu_ioctl(filp, ioctl, arg);
    }
    --
    2.25.1

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