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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>
This commit is contained in:
Liran Alon 2020-03-28 23:00:57 +03:00 committed by mergify[bot]
parent b654edec03
commit 6510e19794
2 changed files with 58 additions and 2 deletions
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40
OvmfPkg/PvScsiDxe/PvScsi.c
View File

@ -677,6 +677,19 @@ PvScsiInit (
goto RestorePciAttributes;
}
//
// Allocate DMA communication buffer
//
Status = PvScsiAllocateSharedPages (
Dev,
EFI_SIZE_TO_PAGES (sizeof (*Dev->DmaBuf)),
(VOID **)&Dev->DmaBuf,
&Dev->DmaBufDmaDesc
);
if (EFI_ERROR (Status)) {
goto FreeRings;
}
//
// Populate the exported interface's attributes
//
@ -708,6 +721,15 @@ PvScsiInit (
return EFI_SUCCESS;
FreeRings:
//
// Reset device to stop device usage of the rings.
// This is required to safely free the rings.
//
PvScsiResetAdapter (Dev);
PvScsiFreeRings (Dev);
RestorePciAttributes:
PvScsiRestorePciAttributes (Dev);
@ -721,11 +743,25 @@ PvScsiUninit (
)
{
//
// Reset device to stop device usage of the rings.
// This is required to safely free the rings.
// Reset device to:
// - Make device stop processing all requests.
// - Stop device usage of the rings.
//
// This is required to safely free the DMA communication buffer
// and the rings.
//
PvScsiResetAdapter (Dev);
//
// Free DMA communication buffer
//
PvScsiFreeSharedPages (
Dev,
EFI_SIZE_TO_PAGES (sizeof (*Dev->DmaBuf)),
Dev->DmaBuf,
&Dev->DmaBufDmaDesc
);
PvScsiFreeRings (Dev);
PvScsiRestorePciAttributes (Dev);

20
OvmfPkg/PvScsiDxe/PvScsi.h
View File

@ -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_