This patch is functionally correct. I'd like to request three stylistic improvements:
On 08/25/17 23:43, Brijesh Singh wrote: > When device is behind the IOMMU, driver is require to pass the device > address of virtio request, response and any memory referenced by those > request/response to the bus master. > > The patch uses IOMMU-like member functions from VIRTIO_DEVICE_PROTOCOL to > map request and response buffers system physical address to the device > address. > > - If the buffer need to be accessed by both the processor and a bus > master then map with BusMasterCommonBuffer. > > - If the buffer need to be accessed for a write operation by a bus master > then map with BusMasterWrite. > > - If the buffer need to be accessed for a read operation by a bus master > then map with BusMasterRead. > > Cc: Ard Biesheuvel <[email protected]> > Cc: Jordan Justen <[email protected]> > Cc: Tom Lendacky <[email protected]> > Cc: Laszlo Ersek <[email protected]> > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Brijesh Singh <[email protected]> > --- > OvmfPkg/VirtioBlkDxe/VirtioBlk.c | 157 ++++++++++++++++++-- > 1 file changed, 143 insertions(+), 14 deletions(-) > > diff --git a/OvmfPkg/VirtioBlkDxe/VirtioBlk.c > b/OvmfPkg/VirtioBlkDxe/VirtioBlk.c > index 663ba281ab73..ab69cb08a625 100644 > --- a/OvmfPkg/VirtioBlkDxe/VirtioBlk.c > +++ b/OvmfPkg/VirtioBlkDxe/VirtioBlk.c > @@ -232,7 +232,8 @@ VerifyReadWriteRequest ( > > @retval EFI_DEVICE_ERROR Failed to notify host side via VirtIo write, > or > unable to parse host response, or host > response > - is not VIRTIO_BLK_S_OK. > + is not VIRTIO_BLK_S_OK or failed to map Buffer > + for a bus master operation. > > **/ > > @@ -249,8 +250,16 @@ SynchronousRequest ( > { > UINT32 BlockSize; > volatile VIRTIO_BLK_REQ Request; > - volatile UINT8 HostStatus; > + 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, Ret; (1) Please rename the "Ret" variable to "UnmapStatus", and define it separately. > > BlockSize = Dev->BlockIoMedia.BlockSize; > > @@ -278,9 +287,89 @@ SynchronousRequest ( > VirtioPrepare (&Dev->Ring, &Indices); > > // > + // 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; > + } > + > + // > + // 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) { > + if (RequestIsWrite) { > + Status = VirtioMapAllBytesInSharedBuffer ( > + Dev->VirtIo, > + VirtioOperationBusMasterRead, > + (VOID *) Buffer, > + BufferSize, > + &BufferDeviceAddress, > + &BufferMapping > + ); > + } else { > + Status = VirtioMapAllBytesInSharedBuffer ( > + Dev->VirtIo, > + VirtioOperationBusMasterWrite, > + (VOID *) Buffer, > + BufferSize, > + &BufferDeviceAddress, > + &BufferMapping > + ); > + } (2) Please squash these two branches into one, and determine the Operation argument like this: (RequestIsWrite ? VirtioOperationBusMasterRead : VirtioOperationBusMasterWrite), (The conditional operator (? :) should be used sparingly, but when it improves readability, it should be used.) > + > + if (EFI_ERROR (Status)) { > + Status = EFI_DEVICE_ERROR; > + goto UnmapRequestBuffer; > + } > + } > + > + // > + // 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; > + } > + > + HostStatus = HostStatusBuffer; > + > + // > // preset a host status for ourselves that we do not accept as success > // > - HostStatus = VIRTIO_BLK_S_IOERR; > + *HostStatus = VIRTIO_BLK_S_IOERR; > > // > // ensured by VirtioBlkInit() -- this predicate, in combination with the > @@ -291,8 +380,13 @@ SynchronousRequest ( > // > // virtio-blk header in first desc > // > - VirtioAppendDesc (&Dev->Ring, (UINTN) &Request, sizeof Request, > - VRING_DESC_F_NEXT, &Indices); > + VirtioAppendDesc ( > + &Dev->Ring, > + RequestDeviceAddress, > + sizeof Request, > + VRING_DESC_F_NEXT, > + &Indices > + ); > > // > // data buffer for read/write in second desc > @@ -311,27 +405,62 @@ SynchronousRequest ( > // > // VRING_DESC_F_WRITE is interpreted from the host's point of view. > // > - VirtioAppendDesc (&Dev->Ring, (UINTN) Buffer, (UINT32) BufferSize, > + VirtioAppendDesc ( > + &Dev->Ring, > + BufferDeviceAddress, > + (UINT32) BufferSize, > VRING_DESC_F_NEXT | (RequestIsWrite ? 0 : VRING_DESC_F_WRITE), > - &Indices); > + &Indices > + ); > } > > // > // host status in last (second or third) desc > // > - VirtioAppendDesc (&Dev->Ring, (UINTN) &HostStatus, sizeof HostStatus, > - VRING_DESC_F_WRITE, &Indices); > + 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) { > - return EFI_SUCCESS; > + Status = VirtioFlush (Dev->VirtIo, 0, &Dev->Ring, &Indices, NULL); > + > + // > + // Unmap the HostStatus buffer before accessing it > + // > + Ret = Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, StatusMapping); (3) Okay, so here you will assign UnmapStatus. And then, the rest: > + if (EFI_ERROR (Ret)) { > + Status = EFI_DEVICE_ERROR; > + } > + > + if (!EFI_ERROR (Status) && > + *HostStatus == VIRTIO_BLK_S_OK) { > + Status = EFI_SUCCESS; > + } else { > + Status = EFI_DEVICE_ERROR; > } should be written like this: if (EFI_ERROR (Status) || EFI_ERROR (UnmapStatus) || *HostStatus != VIRTIO_BLK_S_OK) { Status = EFI_DEVICE_ERROR; } Namely, - this block will ensure that we only look at *HostStatus when we're allowed to (i.e., after both VirtioFlush() and Unmap succeeded), - If VirtioFlush() fails and sets Status to some error code, then we coerce Status to EFI_DEVICE_ERROR, - If the entire condition evaluates to FALSE, then Status is already EFI_SUCCESS, so no need to touch it. Regarding the VirtioScsiDxe driver... in this patch, we get away with the above shortcut (without making a mess of the code), but in the VirtioScsiDxe driver, we won't. In that driver, the bus master device can produce *two* output buffers, so you will have to unmap at least one of those under an error-handling label -- when you mapped the first successfully, and failed to map the second. (In this patch you managed to unmap StatusMapping in shared code, but that only worked because you had only one output buffer, and you could put its mapping last.) And once you unmap an output buffer on both the success path and the failure path, things get more complex. I think that's OK, we should just be consistent about it. So, for VirtioScsiDxe, I suggest the pattern I laid out in <[email protected]">http://mid.mail-archive.com/[email protected]>. Thank you, Laszlo > > - return EFI_DEVICE_ERROR; > +UnmapDataBuffer: > + if (BufferSize > 0) { > + Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, BufferMapping); > + } > + > +UnmapRequestBuffer: > + Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, RequestMapping); > + > +FreeHostStatusBuffer: > + Dev->VirtIo->FreeSharedPages ( > + Dev->VirtIo, > + EFI_SIZE_TO_PAGES (sizeof *HostStatus), > + HostStatusBuffer > + ); > + > + return Status; > } > > > _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
