OvmfPkg/PvScsiDxe: Introduce DMA communication buffer

In case device is constrained by IOMMU or guest is running under AMD SEV,
input/output buffers provided to device (DataBuffer and SenseData) needs
to be explicitly mapped to device by PciIo->Map().

To avoid the overhead of mapping/unmapping the DataBuffer and SenseData
to the device for every SCSI requst (and to simplify code), introduce a
single DMA communication buffer that will be mapped to device on
initialization. When a SCSI request needs to be sent to device, the
DataBuffer and SenseData will be copied from/to the DMA communication
buffer as required. This will be done by the following commits.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2567
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Message-Id: <20200328200100.60786-15-liran.alon@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/OvmfPkg/PvScsiDxe/PvScsi.h b/OvmfPkg/PvScsiDxe/PvScsi.h
index 6d23b6e1ec..fff12146dc 100644
--- a/OvmfPkg/PvScsiDxe/PvScsi.h
+++ b/OvmfPkg/PvScsiDxe/PvScsi.h
@@ -31,6 +31,21 @@ typedef struct {
   PVSCSI_DMA_DESC      RingCmpsDmaDesc;

 } PVSCSI_RING_DESC;

 

+typedef struct {

+  //

+  // As EFI_EXT_SCSI_PASS_THRU_SCSI_REQUEST_PACKET.SenseDataLength is defined

+  // as UINT8, defining here SenseData size to MAX_UINT8 will guarantee it

+  // cannot overflow when passed to device.

+  //

+  UINT8     SenseData[MAX_UINT8];

+  //

+  // This size of the data is arbitrarily chosen.

+  // It seems to be sufficient for all I/O requests sent through

+  // EFI_SCSI_PASS_THRU_PROTOCOL.PassThru() for common boot scenarios.

+  //

+  UINT8     Data[0x2000];

+} PVSCSI_DMA_BUFFER;

+

 #define PVSCSI_SIG SIGNATURE_32 ('P', 'S', 'C', 'S')

 

 typedef struct {

@@ -38,6 +53,8 @@ typedef struct {
   EFI_PCI_IO_PROTOCOL             *PciIo;

   UINT64                          OriginalPciAttributes;

   PVSCSI_RING_DESC                RingDesc;

+  PVSCSI_DMA_BUFFER               *DmaBuf;

+  PVSCSI_DMA_DESC                 DmaBufDmaDesc;

   UINT8                           MaxTarget;

   UINT8                           MaxLun;

   EFI_EXT_SCSI_PASS_THRU_PROTOCOL PassThru;

@@ -47,4 +64,7 @@ typedef struct {
 #define PVSCSI_FROM_PASS_THRU(PassThruPointer) \

   CR (PassThruPointer, PVSCSI_DEV, PassThru, PVSCSI_SIG)

 

+#define PVSCSI_DMA_BUF_DEV_ADDR(Dev, MemberName) \

+  (Dev->DmaBufDmaDesc.DeviceAddress + OFFSET_OF(PVSCSI_DMA_BUFFER, MemberName))

+

 #endif // __PVSCSI_DXE_H_