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268 lines
9.9 KiB
268 lines
9.9 KiB
/****************************************************************************** |
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* netif.h |
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* |
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* Unified network-device I/O interface for Xen guest OSes. |
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* |
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* Copyright (c) 2003-2004, Keir Fraser |
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*/ |
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#ifndef __XEN_PUBLIC_IO_NETIF_H__ |
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#define __XEN_PUBLIC_IO_NETIF_H__ |
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#include <xen/interface/io/ring.h> |
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#include <xen/interface/grant_table.h> |
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/* |
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* Older implementation of Xen network frontend / backend has an |
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* implicit dependency on the MAX_SKB_FRAGS as the maximum number of |
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* ring slots a skb can use. Netfront / netback may not work as |
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* expected when frontend and backend have different MAX_SKB_FRAGS. |
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* |
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* A better approach is to add mechanism for netfront / netback to |
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* negotiate this value. However we cannot fix all possible |
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* frontends, so we need to define a value which states the minimum |
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* slots backend must support. |
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* |
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* The minimum value derives from older Linux kernel's MAX_SKB_FRAGS |
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* (18), which is proved to work with most frontends. Any new backend |
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* which doesn't negotiate with frontend should expect frontend to |
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* send a valid packet using slots up to this value. |
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*/ |
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#define XEN_NETIF_NR_SLOTS_MIN 18 |
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/* |
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* Notifications after enqueuing any type of message should be conditional on |
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* the appropriate req_event or rsp_event field in the shared ring. |
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* If the client sends notification for rx requests then it should specify |
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* feature 'feature-rx-notify' via xenbus. Otherwise the backend will assume |
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* that it cannot safely queue packets (as it may not be kicked to send them). |
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*/ |
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/* |
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* "feature-split-event-channels" is introduced to separate guest TX |
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* and RX notificaion. Backend either doesn't support this feature or |
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* advertise it via xenstore as 0 (disabled) or 1 (enabled). |
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* |
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* To make use of this feature, frontend should allocate two event |
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* channels for TX and RX, advertise them to backend as |
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* "event-channel-tx" and "event-channel-rx" respectively. If frontend |
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* doesn't want to use this feature, it just writes "event-channel" |
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* node as before. |
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*/ |
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/* |
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* Multiple transmit and receive queues: |
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* If supported, the backend will write the key "multi-queue-max-queues" to |
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* the directory for that vif, and set its value to the maximum supported |
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* number of queues. |
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* Frontends that are aware of this feature and wish to use it can write the |
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* key "multi-queue-num-queues", set to the number they wish to use, which |
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* must be greater than zero, and no more than the value reported by the backend |
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* in "multi-queue-max-queues". |
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* |
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* Queues replicate the shared rings and event channels. |
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* "feature-split-event-channels" may optionally be used when using |
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* multiple queues, but is not mandatory. |
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* |
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* Each queue consists of one shared ring pair, i.e. there must be the same |
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* number of tx and rx rings. |
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* |
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* For frontends requesting just one queue, the usual event-channel and |
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* ring-ref keys are written as before, simplifying the backend processing |
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* to avoid distinguishing between a frontend that doesn't understand the |
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* multi-queue feature, and one that does, but requested only one queue. |
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* |
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* Frontends requesting two or more queues must not write the toplevel |
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* event-channel (or event-channel-{tx,rx}) and {tx,rx}-ring-ref keys, |
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* instead writing those keys under sub-keys having the name "queue-N" where |
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* N is the integer ID of the queue for which those keys belong. Queues |
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* are indexed from zero. For example, a frontend with two queues and split |
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* event channels must write the following set of queue-related keys: |
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* |
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* /local/domain/1/device/vif/0/multi-queue-num-queues = "2" |
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* /local/domain/1/device/vif/0/queue-0 = "" |
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* /local/domain/1/device/vif/0/queue-0/tx-ring-ref = "<ring-ref-tx0>" |
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* /local/domain/1/device/vif/0/queue-0/rx-ring-ref = "<ring-ref-rx0>" |
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* /local/domain/1/device/vif/0/queue-0/event-channel-tx = "<evtchn-tx0>" |
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* /local/domain/1/device/vif/0/queue-0/event-channel-rx = "<evtchn-rx0>" |
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* /local/domain/1/device/vif/0/queue-1 = "" |
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* /local/domain/1/device/vif/0/queue-1/tx-ring-ref = "<ring-ref-tx1>" |
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* /local/domain/1/device/vif/0/queue-1/rx-ring-ref = "<ring-ref-rx1" |
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* /local/domain/1/device/vif/0/queue-1/event-channel-tx = "<evtchn-tx1>" |
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* /local/domain/1/device/vif/0/queue-1/event-channel-rx = "<evtchn-rx1>" |
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* |
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* If there is any inconsistency in the XenStore data, the backend may |
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* choose not to connect any queues, instead treating the request as an |
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* error. This includes scenarios where more (or fewer) queues were |
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* requested than the frontend provided details for. |
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* |
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* Mapping of packets to queues is considered to be a function of the |
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* transmitting system (backend or frontend) and is not negotiated |
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* between the two. Guests are free to transmit packets on any queue |
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* they choose, provided it has been set up correctly. Guests must be |
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* prepared to receive packets on any queue they have requested be set up. |
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*/ |
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/* |
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* "feature-no-csum-offload" should be used to turn IPv4 TCP/UDP checksum |
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* offload off or on. If it is missing then the feature is assumed to be on. |
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* "feature-ipv6-csum-offload" should be used to turn IPv6 TCP/UDP checksum |
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* offload on or off. If it is missing then the feature is assumed to be off. |
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*/ |
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/* |
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* "feature-gso-tcpv4" and "feature-gso-tcpv6" advertise the capability to |
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* handle large TCP packets (in IPv4 or IPv6 form respectively). Neither |
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* frontends nor backends are assumed to be capable unless the flags are |
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* present. |
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*/ |
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/* |
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* This is the 'wire' format for packets: |
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* Request 1: xen_netif_tx_request -- XEN_NETTXF_* (any flags) |
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* [Request 2: xen_netif_extra_info] (only if request 1 has XEN_NETTXF_extra_info) |
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* [Request 3: xen_netif_extra_info] (only if request 2 has XEN_NETIF_EXTRA_MORE) |
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* Request 4: xen_netif_tx_request -- XEN_NETTXF_more_data |
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* Request 5: xen_netif_tx_request -- XEN_NETTXF_more_data |
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* ... |
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* Request N: xen_netif_tx_request -- 0 |
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*/ |
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/* Protocol checksum field is blank in the packet (hardware offload)? */ |
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#define _XEN_NETTXF_csum_blank (0) |
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#define XEN_NETTXF_csum_blank (1U<<_XEN_NETTXF_csum_blank) |
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/* Packet data has been validated against protocol checksum. */ |
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#define _XEN_NETTXF_data_validated (1) |
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#define XEN_NETTXF_data_validated (1U<<_XEN_NETTXF_data_validated) |
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/* Packet continues in the next request descriptor. */ |
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#define _XEN_NETTXF_more_data (2) |
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#define XEN_NETTXF_more_data (1U<<_XEN_NETTXF_more_data) |
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/* Packet to be followed by extra descriptor(s). */ |
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#define _XEN_NETTXF_extra_info (3) |
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#define XEN_NETTXF_extra_info (1U<<_XEN_NETTXF_extra_info) |
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#define XEN_NETIF_MAX_TX_SIZE 0xFFFF |
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struct xen_netif_tx_request { |
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grant_ref_t gref; /* Reference to buffer page */ |
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uint16_t offset; /* Offset within buffer page */ |
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uint16_t flags; /* XEN_NETTXF_* */ |
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uint16_t id; /* Echoed in response message. */ |
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uint16_t size; /* Packet size in bytes. */ |
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}; |
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/* Types of xen_netif_extra_info descriptors. */ |
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#define XEN_NETIF_EXTRA_TYPE_NONE (0) /* Never used - invalid */ |
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#define XEN_NETIF_EXTRA_TYPE_GSO (1) /* u.gso */ |
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#define XEN_NETIF_EXTRA_TYPE_MCAST_ADD (2) /* u.mcast */ |
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#define XEN_NETIF_EXTRA_TYPE_MCAST_DEL (3) /* u.mcast */ |
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#define XEN_NETIF_EXTRA_TYPE_MAX (4) |
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/* xen_netif_extra_info flags. */ |
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#define _XEN_NETIF_EXTRA_FLAG_MORE (0) |
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#define XEN_NETIF_EXTRA_FLAG_MORE (1U<<_XEN_NETIF_EXTRA_FLAG_MORE) |
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/* GSO types */ |
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#define XEN_NETIF_GSO_TYPE_NONE (0) |
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#define XEN_NETIF_GSO_TYPE_TCPV4 (1) |
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#define XEN_NETIF_GSO_TYPE_TCPV6 (2) |
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/* |
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* This structure needs to fit within both netif_tx_request and |
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* netif_rx_response for compatibility. |
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*/ |
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struct xen_netif_extra_info { |
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uint8_t type; /* XEN_NETIF_EXTRA_TYPE_* */ |
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uint8_t flags; /* XEN_NETIF_EXTRA_FLAG_* */ |
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union { |
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struct { |
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/* |
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* Maximum payload size of each segment. For |
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* example, for TCP this is just the path MSS. |
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*/ |
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uint16_t size; |
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/* |
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* GSO type. This determines the protocol of |
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* the packet and any extra features required |
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* to segment the packet properly. |
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*/ |
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uint8_t type; /* XEN_NETIF_GSO_TYPE_* */ |
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/* Future expansion. */ |
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uint8_t pad; |
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/* |
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* GSO features. This specifies any extra GSO |
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* features required to process this packet, |
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* such as ECN support for TCPv4. |
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*/ |
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uint16_t features; /* XEN_NETIF_GSO_FEAT_* */ |
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} gso; |
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struct { |
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uint8_t addr[6]; /* Address to add/remove. */ |
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} mcast; |
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uint16_t pad[3]; |
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} u; |
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}; |
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struct xen_netif_tx_response { |
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uint16_t id; |
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int16_t status; /* XEN_NETIF_RSP_* */ |
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}; |
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struct xen_netif_rx_request { |
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uint16_t id; /* Echoed in response message. */ |
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grant_ref_t gref; /* Reference to incoming granted frame */ |
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}; |
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/* Packet data has been validated against protocol checksum. */ |
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#define _XEN_NETRXF_data_validated (0) |
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#define XEN_NETRXF_data_validated (1U<<_XEN_NETRXF_data_validated) |
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/* Protocol checksum field is blank in the packet (hardware offload)? */ |
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#define _XEN_NETRXF_csum_blank (1) |
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#define XEN_NETRXF_csum_blank (1U<<_XEN_NETRXF_csum_blank) |
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/* Packet continues in the next request descriptor. */ |
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#define _XEN_NETRXF_more_data (2) |
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#define XEN_NETRXF_more_data (1U<<_XEN_NETRXF_more_data) |
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/* Packet to be followed by extra descriptor(s). */ |
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#define _XEN_NETRXF_extra_info (3) |
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#define XEN_NETRXF_extra_info (1U<<_XEN_NETRXF_extra_info) |
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/* GSO Prefix descriptor. */ |
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#define _XEN_NETRXF_gso_prefix (4) |
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#define XEN_NETRXF_gso_prefix (1U<<_XEN_NETRXF_gso_prefix) |
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struct xen_netif_rx_response { |
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uint16_t id; |
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uint16_t offset; /* Offset in page of start of received packet */ |
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uint16_t flags; /* XEN_NETRXF_* */ |
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int16_t status; /* -ve: BLKIF_RSP_* ; +ve: Rx'ed pkt size. */ |
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}; |
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/* |
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* Generate netif ring structures and types. |
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*/ |
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DEFINE_RING_TYPES(xen_netif_tx, |
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struct xen_netif_tx_request, |
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struct xen_netif_tx_response); |
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DEFINE_RING_TYPES(xen_netif_rx, |
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struct xen_netif_rx_request, |
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struct xen_netif_rx_response); |
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#define XEN_NETIF_RSP_DROPPED -2 |
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#define XEN_NETIF_RSP_ERROR -1 |
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#define XEN_NETIF_RSP_OKAY 0 |
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/* No response: used for auxiliary requests (e.g., xen_netif_extra_info). */ |
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#define XEN_NETIF_RSP_NULL 1 |
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#endif
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