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KVM: Document KVM_SET_USER_MEMORY_REGION

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Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Avi Kivity <avi@redhat.com>
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Avi Kivity 2010-03-25 12:16:48 +02:00
parent 84b0c8c6a6
commit 0f2d8f4dd0
1 changed files with 45 additions and 0 deletions
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Documentation/kvm/api.txt
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@ -749,6 +749,51 @@ Writes debug registers into the vcpu.
See KVM_GET_DEBUGREGS for the data structure. The flags field is unused
yet and must be cleared on entry.
4.34 KVM_SET_USER_MEMORY_REGION
Capability: KVM_CAP_USER_MEM
Architectures: all
Type: vm ioctl
Parameters: struct kvm_userspace_memory_region (in)
Returns: 0 on success, -1 on error
struct kvm_userspace_memory_region {
__u32 slot;
__u32 flags;
__u64 guest_phys_addr;
__u64 memory_size; /* bytes */
__u64 userspace_addr; /* start of the userspace allocated memory */
};
/* for kvm_memory_region::flags */
#define KVM_MEM_LOG_DIRTY_PAGES 1UL
This ioctl allows the user to create or modify a guest physical memory
slot. When changing an existing slot, it may be moved in the guest
physical memory space, or its flags may be modified. It may not be
resized. Slots may not overlap in guest physical address space.
Memory for the region is taken starting at the address denoted by the
field userspace_addr, which must point at user addressable memory for
the entire memory slot size. Any object may back this memory, including
anonymous memory, ordinary files, and hugetlbfs.
It is recommended that the lower 21 bits of guest_phys_addr and userspace_addr
be identical. This allows large pages in the guest to be backed by large
pages in the host.
The flags field supports just one flag, KVM_MEM_LOG_DIRTY_PAGES, which
instructs kvm to keep track of writes to memory within the slot. See
the KVM_GET_DIRTY_LOG ioctl.
When the KVM_CAP_SYNC_MMU capability, changes in the backing of the memory
region are automatically reflected into the guest. For example, an mmap()
that affects the region will be made visible immediately. Another example
is madvise(MADV_DROP).
It is recommended to use this API instead of the KVM_SET_MEMORY_REGION ioctl.
The KVM_SET_MEMORY_REGION does not allow fine grained control over memory
allocation and is deprecated.
5. The kvm_run structure