pptx704
a1bd439c75
Implement full snapshot lifecycle: pause (snapshot + free resources), resume (UFFD-based lazy restore), and named snapshot templates that can spawn new sandboxes from frozen VM state. Key changes: - Snapshot header system with generational diff mapping (inspired by e2b) - UFFD server for lazy page fault handling during snapshot restore - Stable rootfs symlink path (/tmp/fc-vm/) for snapshot compatibility - Templates DB table and CRUD API endpoints (POST/GET/DELETE /v1/snapshots) - CreateSnapshot/DeleteSnapshot RPCs in hostagent proto - Reconciler excludes paused sandboxes (expected absent from host agent) - Snapshot templates lock vcpus/memory to baked-in values - Proper cleanup of uffd sockets and pause snapshot files on destroy
36 lines
1.2 KiB
Go
36 lines
1.2 KiB
Go
package uffd
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import "fmt"
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// Region is a mapping of guest memory to host virtual address space.
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// Firecracker sends these as JSON when connecting to the UFFD socket.
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// The JSON field names match Firecracker's UFFD protocol.
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type Region struct {
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BaseHostVirtAddr uintptr `json:"base_host_virt_addr"`
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Size uintptr `json:"size"`
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Offset uintptr `json:"offset"`
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PageSize uintptr `json:"page_size_kib"` // Actually in bytes despite the name.
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}
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// Mapping translates between host virtual addresses and logical memory offsets.
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type Mapping struct {
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Regions []Region
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}
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// NewMapping creates a Mapping from a list of regions.
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func NewMapping(regions []Region) *Mapping {
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return &Mapping{Regions: regions}
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}
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// GetOffset converts a host virtual address to a logical memory file offset
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// and returns the page size. This is called on every UFFD page fault.
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func (m *Mapping) GetOffset(hostVirtAddr uintptr) (int64, uintptr, error) {
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for _, r := range m.Regions {
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if hostVirtAddr >= r.BaseHostVirtAddr && hostVirtAddr < r.BaseHostVirtAddr+r.Size {
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offset := int64(hostVirtAddr-r.BaseHostVirtAddr) + int64(r.Offset)
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return offset, r.PageSize, nil
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}
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}
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return 0, 0, fmt.Errorf("address %#x not found in any memory region", hostVirtAddr)
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}
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