/** @file Utility functions used by virtio device drivers. Copyright (C) 2012-2016, Red Hat, Inc. Portion of Copyright (C) 2013, ARM Ltd. This program and the accompanying materials are licensed and made available under the terms and conditions of the BSD License which accompanies this distribution. The full text of the license may be found at http://opensource.org/licenses/bsd-license.php THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. **/ #include #include #include #include #include #include /** Configure a virtio ring. This function sets up internal storage (the guest-host communication area) and lays out several "navigation" (ie. no-ownership) pointers to parts of that storage. Relevant sections from the virtio-0.9.5 spec: - 1.1 Virtqueues, - 2.3 Virtqueue Configuration. @param[in] The number of descriptors to allocate for the virtio ring, as requested by the host. @param[out] Ring The virtio ring to set up. @retval EFI_OUT_OF_RESOURCES AllocatePages() failed to allocate contiguous pages for the requested QueueSize. Fields of Ring have indeterminate value. @retval EFI_SUCCESS Allocation and setup successful. Ring->Base (and nothing else) is responsible for deallocation. **/ EFI_STATUS EFIAPI VirtioRingInit ( IN UINT16 QueueSize, OUT VRING *Ring ) { UINTN RingSize; volatile UINT8 *RingPagesPtr; RingSize = ALIGN_VALUE ( sizeof *Ring->Desc * QueueSize + sizeof *Ring->Avail.Flags + sizeof *Ring->Avail.Idx + sizeof *Ring->Avail.Ring * QueueSize + sizeof *Ring->Avail.UsedEvent, EFI_PAGE_SIZE); RingSize += ALIGN_VALUE ( sizeof *Ring->Used.Flags + sizeof *Ring->Used.Idx + sizeof *Ring->Used.UsedElem * QueueSize + sizeof *Ring->Used.AvailEvent, EFI_PAGE_SIZE); Ring->NumPages = EFI_SIZE_TO_PAGES (RingSize); Ring->Base = AllocatePages (Ring->NumPages); if (Ring->Base == NULL) { return EFI_OUT_OF_RESOURCES; } SetMem (Ring->Base, RingSize, 0x00); RingPagesPtr = Ring->Base; Ring->Desc = (volatile VOID *) RingPagesPtr; RingPagesPtr += sizeof *Ring->Desc * QueueSize; Ring->Avail.Flags = (volatile VOID *) RingPagesPtr; RingPagesPtr += sizeof *Ring->Avail.Flags; Ring->Avail.Idx = (volatile VOID *) RingPagesPtr; RingPagesPtr += sizeof *Ring->Avail.Idx; Ring->Avail.Ring = (volatile VOID *) RingPagesPtr; RingPagesPtr += sizeof *Ring->Avail.Ring * QueueSize; Ring->Avail.UsedEvent = (volatile VOID *) RingPagesPtr; RingPagesPtr += sizeof *Ring->Avail.UsedEvent; RingPagesPtr = (volatile UINT8 *) Ring->Base + ALIGN_VALUE (RingPagesPtr - (volatile UINT8 *) Ring->Base, EFI_PAGE_SIZE); Ring->Used.Flags = (volatile VOID *) RingPagesPtr; RingPagesPtr += sizeof *Ring->Used.Flags; Ring->Used.Idx = (volatile VOID *) RingPagesPtr; RingPagesPtr += sizeof *Ring->Used.Idx; Ring->Used.UsedElem = (volatile VOID *) RingPagesPtr; RingPagesPtr += sizeof *Ring->Used.UsedElem * QueueSize; Ring->Used.AvailEvent = (volatile VOID *) RingPagesPtr; RingPagesPtr += sizeof *Ring->Used.AvailEvent; Ring->QueueSize = QueueSize; return EFI_SUCCESS; } /** Tear down the internal resources of a configured virtio ring. The caller is responsible to stop the host from using this ring before invoking this function: the VSTAT_DRIVER_OK bit must be clear in VhdrDeviceStatus. @param[out] Ring The virtio ring to clean up. **/ VOID EFIAPI VirtioRingUninit ( IN OUT VRING *Ring ) { FreePages (Ring->Base, Ring->NumPages); SetMem (Ring, sizeof *Ring, 0x00); } /** Turn off interrupt notifications from the host, and prepare for appending multiple descriptors to the virtio ring. The calling driver must be in VSTAT_DRIVER_OK state. @param[in,out] Ring The virtio ring we intend to append descriptors to. @param[out] Indices The DESC_INDICES structure to initialize. **/ VOID EFIAPI VirtioPrepare ( IN OUT VRING *Ring, OUT DESC_INDICES *Indices ) { // // Prepare for virtio-0.9.5, 2.4.2 Receiving Used Buffers From the Device. // We're going to poll the answer, the host should not send an interrupt. // *Ring->Avail.Flags = (UINT16) VRING_AVAIL_F_NO_INTERRUPT; // // Prepare for virtio-0.9.5, 2.4.1 Supplying Buffers to the Device. // // Since we support only one in-flight descriptor chain, we can always build // that chain starting at entry #0 of the descriptor table. // Indices->HeadDescIdx = 0; Indices->NextDescIdx = Indices->HeadDescIdx; } /** Append a contiguous buffer for transmission / reception via the virtio ring. This function implements the following section from virtio-0.9.5: - 2.4.1.1 Placing Buffers into the Descriptor Table Free space is taken as granted, since the individual drivers support only synchronous requests and host side status is processed in lock-step with request submission. It is the calling driver's responsibility to verify the ring size in advance. The caller is responsible for initializing *Indices with VirtioPrepare() first. @param[in,out] Ring The virtio ring to append the buffer to, as a descriptor. @param[in] BufferPhysAddr (Guest pseudo-physical) start address of the transmit / receive buffer. @param[in] BufferSize Number of bytes to transmit or receive. @param[in] Flags A bitmask of VRING_DESC_F_* flags. The caller computes this mask dependent on further buffers to append and transfer direction. VRING_DESC_F_INDIRECT is unsupported. The VRING_DESC.Next field is always set, but the host only interprets it dependent on VRING_DESC_F_NEXT. @param[in,out] Indices Indices->HeadDescIdx is not accessed. On input, Indices->NextDescIdx identifies the next descriptor to carry the buffer. On output, Indices->NextDescIdx is incremented by one, modulo 2^16. **/ VOID EFIAPI VirtioAppendDesc ( IN OUT VRING *Ring, IN UINTN BufferPhysAddr, IN UINT32 BufferSize, IN UINT16 Flags, IN OUT DESC_INDICES *Indices ) { volatile VRING_DESC *Desc; Desc = &Ring->Desc[Indices->NextDescIdx++ % Ring->QueueSize]; Desc->Addr = BufferPhysAddr; Desc->Len = BufferSize; Desc->Flags = Flags; Desc->Next = Indices->NextDescIdx % Ring->QueueSize; } /** Notify the host about the descriptor chain just built, and wait until the host processes it. @param[in] VirtIo The target virtio device to notify. @param[in] VirtQueueId Identifies the queue for the target device. @param[in,out] Ring The virtio ring with descriptors to submit. @param[in] Indices Indices->NextDescIdx is not accessed. Indices->HeadDescIdx identifies the head descriptor of the descriptor chain. @param[out] UsedLen On success, the total number of bytes, consecutively across the buffers linked by the descriptor chain, that the host wrote. May be NULL if the caller doesn't care, or can compute the same information from device-specific request structures linked by the descriptor chain. @return Error code from VirtIo->SetQueueNotify() if it fails. @retval EFI_SUCCESS Otherwise, the host processed all descriptors. **/ EFI_STATUS EFIAPI VirtioFlush ( IN VIRTIO_DEVICE_PROTOCOL *VirtIo, IN UINT16 VirtQueueId, IN OUT VRING *Ring, IN DESC_INDICES *Indices, OUT UINT32 *UsedLen OPTIONAL ) { UINT16 NextAvailIdx; UINT16 LastUsedIdx; EFI_STATUS Status; UINTN PollPeriodUsecs; // // virtio-0.9.5, 2.4.1.2 Updating the Available Ring // // It is not exactly clear from the wording of the virtio-0.9.5 // specification, but each entry in the Available Ring references only the // head descriptor of any given descriptor chain. // NextAvailIdx = *Ring->Avail.Idx; // // (Due to our lock-step progress, this is where the host will produce the // used element with the head descriptor's index in it.) // LastUsedIdx = NextAvailIdx; Ring->Avail.Ring[NextAvailIdx++ % Ring->QueueSize] = Indices->HeadDescIdx % Ring->QueueSize; // // virtio-0.9.5, 2.4.1.3 Updating the Index Field // MemoryFence(); *Ring->Avail.Idx = NextAvailIdx; // // virtio-0.9.5, 2.4.1.4 Notifying the Device -- gratuitous notifications are // OK. // MemoryFence(); Status = VirtIo->SetQueueNotify (VirtIo, VirtQueueId); if (EFI_ERROR (Status)) { return Status; } // // virtio-0.9.5, 2.4.2 Receiving Used Buffers From the Device // Wait until the host processes and acknowledges our descriptor chain. The // condition we use for polling is greatly simplified and relies on the // synchronous, lock-step progress. // // Keep slowing down until we reach a poll period of slightly above 1 ms. // PollPeriodUsecs = 1; MemoryFence(); while (*Ring->Used.Idx != NextAvailIdx) { gBS->Stall (PollPeriodUsecs); // calls AcpiTimerLib::MicroSecondDelay if (PollPeriodUsecs < 1024) { PollPeriodUsecs *= 2; } MemoryFence(); } MemoryFence(); if (UsedLen != NULL) { volatile CONST VRING_USED_ELEM *UsedElem; UsedElem = &Ring->Used.UsedElem[LastUsedIdx % Ring->QueueSize]; ASSERT (UsedElem->Id == Indices->HeadDescIdx); *UsedLen = UsedElem->Len; } return EFI_SUCCESS; } /** Report the feature bits to the VirtIo 1.0 device that the VirtIo 1.0 driver understands. In VirtIo 1.0, a device can reject a self-inconsistent feature bitmap through the new VSTAT_FEATURES_OK status bit. (For example if the driver requests a higher level feature but clears a prerequisite feature.) This function is a small wrapper around VIRTIO_DEVICE_PROTOCOL.SetGuestFeatures() that also verifies if the VirtIo 1.0 device accepts the feature bitmap. @param[in] VirtIo Report feature bits to this device. @param[in] Features The set of feature bits that the driver wishes to report. The caller is responsible to perform any masking before calling this function; the value is directly written with VIRTIO_DEVICE_PROTOCOL.SetGuestFeatures(). @param[in,out] DeviceStatus On input, the status byte most recently written to the device's status register. On output (even on error), DeviceStatus will be updated so that it is suitable for further status bit manipulation and writing to the device's status register. @retval EFI_SUCCESS The device accepted the configuration in Features. @return EFI_UNSUPPORTED The device rejected the configuration in Features. @retval EFI_UNSUPPORTED VirtIo->Revision is smaller than 1.0.0. @return Error codes from the SetGuestFeatures(), SetDeviceStatus(), GetDeviceStatus() member functions. **/ EFI_STATUS EFIAPI Virtio10WriteFeatures ( IN VIRTIO_DEVICE_PROTOCOL *VirtIo, IN UINT64 Features, IN OUT UINT8 *DeviceStatus ) { EFI_STATUS Status; if (VirtIo->Revision < VIRTIO_SPEC_REVISION (1, 0, 0)) { return EFI_UNSUPPORTED; } Status = VirtIo->SetGuestFeatures (VirtIo, Features); if (EFI_ERROR (Status)) { return Status; } *DeviceStatus |= VSTAT_FEATURES_OK; Status = VirtIo->SetDeviceStatus (VirtIo, *DeviceStatus); if (EFI_ERROR (Status)) { return Status; } Status = VirtIo->GetDeviceStatus (VirtIo, DeviceStatus); if (EFI_ERROR (Status)) { return Status; } if ((*DeviceStatus & VSTAT_FEATURES_OK) == 0) { Status = EFI_UNSUPPORTED; } return Status; }