OvmfPkg: librarize reusable bits from VirtioBlkDxe's SynchronousRequest()

new VirtioLib functions:
- VirtioPrepare(): prepare for appending descriptors
- VirtioFlush(): submit descriptor chain and await host answer

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13844 6f19259b-4bc3-4df7-8a09-765794883524

4 files changed, 205 insertions, 66 deletions

diff --git a/OvmfPkg/Include/Library/VirtioLib.h b/OvmfPkg/Include/Library/VirtioLib.h
index eff66da6b3..07e4add784 100644
--- a/OvmfPkg/Include/Library/VirtioLib.h
+++ b/OvmfPkg/Include/Library/VirtioLib.h
@@ -135,6 +135,36 @@ VirtioRingUninit (
   );

 

 

+//

+// Internal use structure for tracking the submission of a multi-descriptor

+// request.

+//

+typedef struct {

+  UINT16 HeadIdx;

+  UINT16 NextAvailIdx;

+} DESC_INDICES;

+

+

+/**

+

+  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

+  );

+

+

 /**

 

   Append a contiguous buffer for transmission / reception via the virtio ring.

@@ -148,6 +178,9 @@ VirtioRingUninit (
   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.

 

@@ -164,6 +197,8 @@ VirtioRingUninit (
                                 host only interprets it dependent on

                                 VRING_DESC_F_NEXT.

 

+  In *Indices:

+

   @param [in] HeadIdx           The index identifying the head buffer (first

                                 buffer appended) belonging to this same

                                 request.

@@ -176,12 +211,41 @@ VirtioRingUninit (
 VOID

 EFIAPI

 VirtioAppendDesc (

-  IN OUT VRING  *Ring,

-  IN     UINTN  BufferPhysAddr,

-  IN     UINT32 BufferSize,

-  IN     UINT16 Flags,

-  IN     UINT16 HeadIdx,

-  IN OUT UINT16 *NextAvailIdx

+  IN OUT VRING        *Ring,

+  IN     UINTN        BufferPhysAddr,

+  IN     UINT32       BufferSize,

+  IN     UINT16       Flags,

+  IN OUT DESC_INDICES *Indices

+  );

+

+

+/**

+

+  Notify the host about appended descriptors and wait until it processes the

+  last one (ie. all of them).

+

+  @param[in] PciIo        The target virtio PCI 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      The function waits until the host processes

+                          descriptors up to Indices->NextAvailIdx.

+

+

+  @return              Error code from VirtioWrite() if it fails.

+

+  @retval EFI_SUCCESS  Otherwise, the host processed all descriptors.

+

+**/

+EFI_STATUS

+EFIAPI

+VirtioFlush (

+  IN     EFI_PCI_IO_PROTOCOL *PciIo,

+  IN     UINT16              VirtQueueId,

+  IN OUT VRING               *Ring,

+  IN     DESC_INDICES        *Indices

   );

 

 #endif // _VIRTIO_LIB_H_

diff --git a/OvmfPkg/Library/VirtioLib/VirtioLib.c b/OvmfPkg/Library/VirtioLib/VirtioLib.c
index f0328ef4cd..6ed977cd10 100644
--- a/OvmfPkg/Library/VirtioLib/VirtioLib.c
+++ b/OvmfPkg/Library/VirtioLib/VirtioLib.c
@@ -15,9 +15,11 @@
 **/

 

 #include <IndustryStandard/Pci22.h>

+#include <Library/BaseLib.h>

 #include <Library/BaseMemoryLib.h>

 #include <Library/DebugLib.h>

 #include <Library/MemoryAllocationLib.h>

+#include <Library/UefiBootServicesTableLib.h>

 

 #include <Library/VirtioLib.h>

 

@@ -276,6 +278,39 @@ VirtioRingUninit (
 

 /**

 

+  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.

+  //

+  Indices->HeadIdx = *Ring->Avail.Idx;

+  Indices->NextAvailIdx = Indices->HeadIdx;

+}

+

+

+/**

+

   Append a contiguous buffer for transmission / reception via the virtio ring.

 

   This function implements the following sections from virtio-0.9.5:

@@ -287,6 +322,9 @@ VirtioRingUninit (
   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.

 

@@ -303,6 +341,8 @@ VirtioRingUninit (
                                 host only interprets it dependent on

                                 VRING_DESC_F_NEXT.

 

+  In *Indices:

+

   @param [in] HeadIdx           The index identifying the head buffer (first

                                 buffer appended) belonging to this same

                                 request.

@@ -315,21 +355,96 @@ VirtioRingUninit (
 VOID

 EFIAPI

 VirtioAppendDesc (

-  IN OUT VRING  *Ring,

-  IN     UINTN  BufferPhysAddr,

-  IN     UINT32 BufferSize,

-  IN     UINT16 Flags,

-  IN     UINT16 HeadIdx,

-  IN OUT UINT16 *NextAvailIdx

+  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[*NextAvailIdx % Ring->QueueSize];

+  Desc        = &Ring->Desc[Indices->NextAvailIdx % Ring->QueueSize];

   Desc->Addr  = BufferPhysAddr;

   Desc->Len   = BufferSize;

   Desc->Flags = Flags;

-  Ring->Avail.Ring[(*NextAvailIdx)++ % Ring->QueueSize] =

-    HeadIdx % Ring->QueueSize;

-  Desc->Next  = *NextAvailIdx % Ring->QueueSize;

+  Ring->Avail.Ring[Indices->NextAvailIdx++ % Ring->QueueSize] =

+    Indices->HeadIdx % Ring->QueueSize;

+  Desc->Next  = Indices->NextAvailIdx % Ring->QueueSize;

+}

+

+

+/**

+

+  Notify the host about appended descriptors and wait until it processes the

+  last one (ie. all of them).

+

+  @param[in] PciIo        The target virtio PCI 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      The function waits until the host processes

+                          descriptors up to Indices->NextAvailIdx.

+

+

+  @return              Error code from VirtioWrite() if it fails.

+

+  @retval EFI_SUCCESS  Otherwise, the host processed all descriptors.

+

+**/

+EFI_STATUS

+EFIAPI

+VirtioFlush (

+  IN     EFI_PCI_IO_PROTOCOL *PciIo,

+  IN     UINT16              VirtQueueId,

+  IN OUT VRING               *Ring,

+  IN     DESC_INDICES        *Indices

+  )

+{

+  EFI_STATUS Status;

+  UINTN      PollPeriodUsecs;

+

+  //

+  // virtio-0.9.5, 2.4.1.3 Updating the Index Field

+  //

+  MemoryFence();

+  *Ring->Avail.Idx = Indices->NextAvailIdx;

+

+  //

+  // virtio-0.9.5, 2.4.1.4 Notifying the Device -- gratuitous notifications are

+  // OK.

+  //

+  MemoryFence();

+  Status = VirtioWrite (

+             PciIo,

+             OFFSET_OF (VIRTIO_HDR, VhdrQueueNotify),

+             sizeof (UINT16),

+             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 != Indices->NextAvailIdx) {

+    gBS->Stall (PollPeriodUsecs); // calls AcpiTimerLib::MicroSecondDelay

+

+    if (PollPeriodUsecs < 1024) {

+      PollPeriodUsecs *= 2;

+    }

+    MemoryFence();

+  }

+

+  return EFI_SUCCESS;

 }

diff --git a/OvmfPkg/Library/VirtioLib/VirtioLib.inf b/OvmfPkg/Library/VirtioLib/VirtioLib.inf
index cfd93a2c2c..fb5897a88e 100644
--- a/OvmfPkg/Library/VirtioLib/VirtioLib.inf
+++ b/OvmfPkg/Library/VirtioLib/VirtioLib.inf
@@ -29,6 +29,8 @@
   OvmfPkg/OvmfPkg.dec

 

 [LibraryClasses]

+  BaseLib

   BaseMemoryLib

   DebugLib

   MemoryAllocationLib

+  UefiBootServicesTableLib

diff --git a/OvmfPkg/VirtioBlkDxe/VirtioBlk.c b/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
index ce38ff7093..44a05cfb5f 100644
--- a/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
+++ b/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
@@ -248,9 +248,7 @@ SynchronousRequest (
   UINT32                  BlockSize;

   volatile VIRTIO_BLK_REQ Request;

   volatile UINT8          HostStatus;

-  UINT16                  FirstAvailIdx;

-  UINT16                  NextAvailIdx;

-  UINTN                   PollPeriodUsecs;

+  DESC_INDICES            Indices;

 

   BlockSize = Dev->BlockIoMedia.BlockSize;

 

@@ -275,11 +273,7 @@ SynchronousRequest (
   Request.IoPrio = 0;

   Request.Sector = Lba * (BlockSize / 512);

 

-  //

-  // 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.

-  //

-  *Dev->Ring.Avail.Flags = (UINT16) VRING_AVAIL_F_NO_INTERRUPT;

+  VirtioPrepare (&Dev->Ring, &Indices);

 

   //

   // preset a host status for ourselves that we do not accept as success

@@ -293,16 +287,10 @@ SynchronousRequest (
   ASSERT (Dev->Ring.QueueSize >= 3);

 

   //

-  // Implement virtio-0.9.5, 2.4.1 Supplying Buffers to the Device.

-  //

-  FirstAvailIdx = *Dev->Ring.Avail.Idx;

-  NextAvailIdx  = FirstAvailIdx;

-

-  //

   // virtio-blk header in first desc

   //

   VirtioAppendDesc (&Dev->Ring, (UINTN) &Request, sizeof Request,

-    VRING_DESC_F_NEXT, FirstAvailIdx, &NextAvailIdx);

+    VRING_DESC_F_NEXT, &Indices);

 

   //

   // data buffer for read/write in second desc

@@ -323,50 +311,20 @@ SynchronousRequest (
     //

     VirtioAppendDesc (&Dev->Ring, (UINTN) Buffer, (UINT32) BufferSize,

       VRING_DESC_F_NEXT | (RequestIsWrite ? 0 : VRING_DESC_F_WRITE),

-      FirstAvailIdx, &NextAvailIdx);

+      &Indices);

   }

 

   //

   // host status in last (second or third) desc

   //

   VirtioAppendDesc (&Dev->Ring, (UINTN) &HostStatus, sizeof HostStatus,

-    VRING_DESC_F_WRITE, FirstAvailIdx, &NextAvailIdx);

+    VRING_DESC_F_WRITE, &Indices);

 

   //

-  // virtio-0.9.5, 2.4.1.3 Updating the Index Field

+  // virtio-blk's only virtqueue is #0, called "requestq" (see Appendix D).

   //

-  MemoryFence();

-  *Dev->Ring.Avail.Idx = NextAvailIdx;

-

-  //

-  // virtio-0.9.5, 2.4.1.4 Notifying the Device -- gratuitous notifications are

-  // OK. virtio-blk's only virtqueue is #0, called "requestq" (see Appendix D).

-  //

-  MemoryFence();

-  if (EFI_ERROR (VIRTIO_CFG_WRITE (Dev, Generic.VhdrQueueNotify, 0))) {

-    return EFI_DEVICE_ERROR;

-  }

-

-  //

-  // virtio-0.9.5, 2.4.2 Receiving Used Buffers From the Device

-  // Wait until the host processes and acknowledges our 3-part descriptor

-  // chain. The condition we use for polling is greatly simplified and relies

-  // on synchronous, the lock-step progress.

-  //

-  // Keep slowing down until we reach a poll period of slightly above 1 ms.

-  //

-  PollPeriodUsecs = 1;

-  MemoryFence();

-  while (*Dev->Ring.Used.Idx != NextAvailIdx) {

-    gBS->Stall (PollPeriodUsecs); // calls AcpiTimerLib::MicroSecondDelay

-

-    if (PollPeriodUsecs < 1024) {

-      PollPeriodUsecs *= 2;

-    }

-    MemoryFence();

-  }

-

-  if (HostStatus == VIRTIO_BLK_S_OK) {

+  if (VirtioFlush (Dev->PciIo, 0, &Dev->Ring, &Indices) == EFI_SUCCESS &&

+      HostStatus == VIRTIO_BLK_S_OK) {

     return EFI_SUCCESS;

   }