/**
Produces and returns an RNG value using either the default or specified RNG
algorithm.
@param[in] This A pointer to the EFI_RNG_PROTOCOL
instance.
@param[in] RNGAlgorithm A pointer to the EFI_RNG_ALGORITHM that
identifies the RNG algorithm to use. May
be NULL in which case the function will
use its default RNG algorithm.
@param[in] RNGValueLength The length in bytes of the memory buffer
pointed to by RNGValue. The driver shall
return exactly this numbers of bytes.
@param[out] RNGValue A caller-allocated memory buffer filled
by the driver with the resulting RNG
value.
@retval EFI_SUCCESS The RNG value was returned successfully.
@retval EFI_UNSUPPORTED The algorithm specified by RNGAlgorithm
is not supported by this driver.
@retval EFI_DEVICE_ERROR An RNG value could not be retrieved due
to a hardware or firmware error.
@retval EFI_NOT_READY There is not enough random data available
to satisfy the length requested by
RNGValueLength.
@retval EFI_INVALID_PARAMETER RNGValue is NULL or RNGValueLength is
zero.
**/
STATIC
EFI_STATUS
EFIAPI
VirtioRngGetRNG (
IN EFI_RNG_PROTOCOL *This,
IN EFI_RNG_ALGORITHM *RNGAlgorithm, OPTIONAL
IN UINTN RNGValueLength,
OUT UINT8 *RNGValue
)
{
VIRTIO_RNG_DEV *Dev;
DESC_INDICES Indices;
volatile UINT8 *Buffer;
UINTN Index;
UINT32 Len;
UINT32 BufferSize;
EFI_STATUS Status;
EFI_PHYSICAL_ADDRESS DeviceAddress;
VOID *Mapping;
if (This == NULL || RNGValueLength == 0 || RNGValue == NULL) {
return EFI_INVALID_PARAMETER;
}
//
// We only support the raw algorithm, so reject requests for anything else
//
if (RNGAlgorithm != NULL &&
!CompareGuid (RNGAlgorithm, &gEfiRngAlgorithmRaw)) {
return EFI_UNSUPPORTED;
}
Buffer = (volatile UINT8 *)AllocatePool (RNGValueLength);
if (Buffer == NULL) {
return EFI_DEVICE_ERROR;
}
Dev = VIRTIO_ENTROPY_SOURCE_FROM_RNG (This);
//
// Map Buffer's system phyiscal address to device address
//
Status = VirtioMapAllBytesInSharedBuffer (
Dev->VirtIo,
VirtioOperationBusMasterWrite,
(VOID *)Buffer,
RNGValueLength,
&DeviceAddress,
&Mapping
);
if (EFI_ERROR (Status)) {
Status = EFI_DEVICE_ERROR;
goto FreeBuffer;
}
//
// The Virtio RNG device may return less data than we asked it to, and can
// only return MAX_UINT32 bytes per invocation. So loop as long as needed to
// get all the entropy we were asked for.
//
for (Index = 0; Index < RNGValueLength; Index += Len) {
BufferSize = (UINT32)MIN (RNGValueLength - Index, (UINTN)MAX_UINT32);
VirtioPrepare (&Dev->Ring, &Indices);
VirtioAppendDesc (&Dev->Ring,
DeviceAddress + Index,
BufferSize,
VRING_DESC_F_WRITE,
&Indices);
if (VirtioFlush (Dev->VirtIo, 0, &Dev->Ring, &Indices, &Len) !=
EFI_SUCCESS) {
Status = EFI_DEVICE_ERROR;
goto UnmapBuffer;
}
ASSERT (Len > 0);
ASSERT (Len <= BufferSize);
}
//
// Unmap the device buffer before accessing it.
//
Status = Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Mapping);
if (EFI_ERROR (Status)) {
Status = EFI_DEVICE_ERROR;
goto FreeBuffer;
}
for (Index = 0; Index < RNGValueLength; Index++) {
RNGValue[Index] = Buffer[Index];
}
Status = EFI_SUCCESS;
UnmapBuffer:
//
// If we are reached here due to the error then unmap the buffer otherwise
// the buffer is already unmapped after VirtioFlush().
//
if (EFI_ERROR (Status)) {
Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Mapping);
}
FreeBuffer:
FreePool ((VOID *)Buffer);
return Status;
}
STATIC
EFI_STATUS
EFIAPI
SynchronousRequest (
IN VBLK_DEV *Dev,
IN EFI_LBA Lba,
IN UINTN BufferSize,
IN OUT volatile VOID *Buffer,
IN BOOLEAN RequestIsWrite
)
{
UINT32 BlockSize;
volatile VIRTIO_BLK_REQ Request;
volatile UINT8 *HostStatus;
VOID *HostStatusBuffer;
DESC_INDICES Indices;
VOID *RequestMapping;
VOID *StatusMapping;
VOID *BufferMapping;
EFI_PHYSICAL_ADDRESS BufferDeviceAddress;
EFI_PHYSICAL_ADDRESS HostStatusDeviceAddress;
EFI_PHYSICAL_ADDRESS RequestDeviceAddress;
EFI_STATUS Status;
EFI_STATUS UnmapStatus;
BlockSize = Dev->BlockIoMedia.BlockSize;
//
// Set BufferMapping and BufferDeviceAddress to suppress incorrect
// compiler/analyzer warnings.
//
BufferMapping = NULL;
BufferDeviceAddress = 0;
//
// ensured by VirtioBlkInit()
//
ASSERT (BlockSize > 0);
ASSERT (BlockSize % 512 == 0);
//
// ensured by contract above, plus VerifyReadWriteRequest()
//
ASSERT (BufferSize % BlockSize == 0);
//
// Prepare virtio-blk request header, setting zero size for flush.
// IO Priority is homogeneously 0.
//
Request.Type = RequestIsWrite ?
(BufferSize == 0 ? VIRTIO_BLK_T_FLUSH : VIRTIO_BLK_T_OUT) :
VIRTIO_BLK_T_IN;
Request.IoPrio = 0;
Request.Sector = MultU64x32(Lba, BlockSize / 512);
//
// Host status is bi-directional (we preset with a value and expect the
// device to update it). Allocate a host status buffer which can be mapped
// to access equally by both processor and the device.
//
Status = Dev->VirtIo->AllocateSharedPages (
Dev->VirtIo,
EFI_SIZE_TO_PAGES (sizeof *HostStatus),
&HostStatusBuffer
);
if (EFI_ERROR (Status)) {
return EFI_DEVICE_ERROR;
}
HostStatus = HostStatusBuffer;
//
// Map virtio-blk request header (must be done after request header is
// populated)
//
Status = VirtioMapAllBytesInSharedBuffer (
Dev->VirtIo,
VirtioOperationBusMasterRead,
(VOID *) &Request,
sizeof Request,
&RequestDeviceAddress,
&RequestMapping
);
if (EFI_ERROR (Status)) {
Status = EFI_DEVICE_ERROR;
goto FreeHostStatusBuffer;
}
//
// Map data buffer
//
if (BufferSize > 0) {
Status = VirtioMapAllBytesInSharedBuffer (
Dev->VirtIo,
(RequestIsWrite ?
VirtioOperationBusMasterRead :
VirtioOperationBusMasterWrite),
(VOID *) Buffer,
BufferSize,
&BufferDeviceAddress,
&BufferMapping
);
if (EFI_ERROR (Status)) {
Status = EFI_DEVICE_ERROR;
goto UnmapRequestBuffer;
}
}
//
// preset a host status for ourselves that we do not accept as success
//
*HostStatus = VIRTIO_BLK_S_IOERR;
//
// Map the Status Buffer with VirtioOperationBusMasterCommonBuffer so that
// both processor and device can access it.
//
Status = VirtioMapAllBytesInSharedBuffer (
Dev->VirtIo,
VirtioOperationBusMasterCommonBuffer,
HostStatusBuffer,
sizeof *HostStatus,
&HostStatusDeviceAddress,
&StatusMapping
);
if (EFI_ERROR (Status)) {
Status = EFI_DEVICE_ERROR;
goto UnmapDataBuffer;
}
VirtioPrepare (&Dev->Ring, &Indices);
//
// ensured by VirtioBlkInit() -- this predicate, in combination with the
// lock-step progress, ensures we don't have to track free descriptors.
//
ASSERT (Dev->Ring.QueueSize >= 3);
//
// virtio-blk header in first desc
//
VirtioAppendDesc (
&Dev->Ring,
RequestDeviceAddress,
sizeof Request,
VRING_DESC_F_NEXT,
&Indices
);
//
// data buffer for read/write in second desc
//
if (BufferSize > 0) {
//
// From virtio-0.9.5, 2.3.2 Descriptor Table:
// "no descriptor chain may be more than 2^32 bytes long in total".
//
// The predicate is ensured by the call contract above (for flush), or
// VerifyReadWriteRequest() (for read/write). It also implies that
// converting BufferSize to UINT32 will not truncate it.
//
ASSERT (BufferSize <= SIZE_1GB);
//
// VRING_DESC_F_WRITE is interpreted from the host's point of view.
//
VirtioAppendDesc (
&Dev->Ring,
BufferDeviceAddress,
(UINT32) BufferSize,
VRING_DESC_F_NEXT | (RequestIsWrite ? 0 : VRING_DESC_F_WRITE),
&Indices
);
}
//
// host status in last (second or third) desc
//
VirtioAppendDesc (
&Dev->Ring,
HostStatusDeviceAddress,
sizeof *HostStatus,
VRING_DESC_F_WRITE,
&Indices
);
//
// virtio-blk's only virtqueue is #0, called "requestq" (see Appendix D).
//
if (VirtioFlush (Dev->VirtIo, 0, &Dev->Ring, &Indices,
NULL) == EFI_SUCCESS &&
*HostStatus == VIRTIO_BLK_S_OK) {
Status = EFI_SUCCESS;
} else {
Status = EFI_DEVICE_ERROR;
}
Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, StatusMapping);
UnmapDataBuffer:
if (BufferSize > 0) {
UnmapStatus = Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, BufferMapping);
if (EFI_ERROR (UnmapStatus) && !RequestIsWrite && !EFI_ERROR (Status)) {
//
// Data from the bus master may not reach the caller; fail the request.
//
Status = EFI_DEVICE_ERROR;
}
}
UnmapRequestBuffer:
Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, RequestMapping);
FreeHostStatusBuffer:
Dev->VirtIo->FreeSharedPages (
Dev->VirtIo,
EFI_SIZE_TO_PAGES (sizeof *HostStatus),
HostStatusBuffer
);
return Status;
}