OvmfPkg/XenBusDxe: Add Grant Table functions.

There are used to grant access of pages to other Xen domains.

This code originaly comes from the Xen Project, and more precisely from
MiniOS.

Change in V4:
- Add license to GrantTable.h

Change in V3:
- Add a comment about the use of the BAR of the device.

Change in V2:
- Adding locks
- Redo the file header
- Add functions comment
- Add license

Signed-off-by: Steven Smith <sos22@cam.ac.uk>
Signed-off-by: Grzegorz Milos <gm281@cam.ac.uk>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16264 6f19259b-4bc3-4df7-8a09-765794883524

OvmfPkg/XenBusDxe/GrantTable.c

@@ -0,0 +1,217 @@
+/** @file
+  Grant Table function implementation.
+
+  Grant Table are used to grant access to certain page of the current
+  VM to an other VM.
+
+  Author: Steven Smith (sos22@cam.ac.uk)
+  Changes: Grzegorz Milos (gm281@cam.ac.uk)
+  Copyright (C) 2006, Cambridge University
+  Copyright (C) 2014, Citrix Ltd.
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions
+  are met:
+  1. Redistributions of source code must retain the above copyright
+     notice, this list of conditions and the following disclaimer.
+  2. Redistributions in binary form must reproduce the above copyright
+     notice, this list of conditions and the following disclaimer in the
+     documentation and/or other materials provided with the distribution.
+
+  THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+  ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
+  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+  OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+  SUCH DAMAGE.
+**/
+#include "XenBusDxe.h"
+
+#include <IndustryStandard/Xen/memory.h>
+
+#include "XenHypercall.h"
+
+#include "GrantTable.h"
+#include "InterlockedCompareExchange16.h"
+
+#define NR_RESERVED_ENTRIES 8
+
+/* NR_GRANT_FRAMES must be less than or equal to that configured in Xen */
+#define NR_GRANT_FRAMES 4
+#define NR_GRANT_ENTRIES (NR_GRANT_FRAMES * EFI_PAGE_SIZE / sizeof(grant_entry_v1_t))
+
+STATIC grant_entry_v1_t *GrantTable = NULL;
+STATIC grant_ref_t GrantList[NR_GRANT_ENTRIES];
+STATIC EFI_LOCK mGrantListLock;
+#ifdef GNT_DEBUG
+STATIC BOOLEAN GrantInUseList[NR_GRANT_ENTRIES];
+#endif
+
+STATIC
+VOID
+XenGrantTablePutFreeEntry (
+  grant_ref_t Ref
+  )
+{
+  EfiAcquireLock (&mGrantListLock);
+#ifdef GNT_DEBUG
+  ASSERT (GrantInUseList[Ref]);
+  GrantInUseList[Ref] = FALSE;
+#endif
+  GrantList[Ref] = GrantList[0];
+  GrantList[0] = Ref;
+  EfiReleaseLock (&mGrantListLock);
+}
+
+STATIC
+grant_ref_t
+XenGrantTableGetFreeEntry (
+  VOID
+  )
+{
+  UINTN Ref;
+
+  EfiAcquireLock (&mGrantListLock);
+  Ref = GrantList[0];
+  ASSERT (Ref >= NR_RESERVED_ENTRIES && Ref < NR_GRANT_ENTRIES);
+  GrantList[0] = GrantList[Ref];
+#ifdef GNT_DEBUG
+  ASSERT (!GrantInUseList[Ref]);
+  GrantInUseList[Ref] = TRUE;
+#endif
+  EfiReleaseLock (&mGrantListLock);
+  return Ref;
+}
+
+STATIC
+grant_ref_t
+XenGrantTableGrantAccess (
+  IN domid_t  DomainId,
+  IN UINTN    Frame,
+  IN BOOLEAN  ReadOnly
+  )
+{
+  grant_ref_t Ref;
+  UINT32 Flags;
+
+  ASSERT (GrantTable != NULL);
+  Ref = XenGrantTableGetFreeEntry ();
+  GrantTable[Ref].frame = Frame;
+  GrantTable[Ref].domid = DomainId;
+  MemoryFence ();
+  Flags = GTF_permit_access;
+  if (ReadOnly) {
+    Flags |= GTF_readonly;
+  }
+  GrantTable[Ref].flags = Flags;
+
+  return Ref;
+}
+
+STATIC
+EFI_STATUS
+XenGrantTableEndAccess (
+  grant_ref_t Ref
+  )
+{
+  UINT16 Flags, OldFlags;
+
+  ASSERT (GrantTable != NULL);
+  ASSERT (Ref >= NR_RESERVED_ENTRIES && Ref < NR_GRANT_ENTRIES);
+
+  OldFlags = GrantTable[Ref].flags;
+  do {
+    if ((Flags = OldFlags) & (GTF_reading | GTF_writing)) {
+      DEBUG ((EFI_D_WARN, "WARNING: g.e. still in use! (%x)\n", Flags));
+      return EFI_NOT_READY;
+    }
+    OldFlags = InterlockedCompareExchange16 (&GrantTable[Ref].flags, Flags, 0);
+  } while (OldFlags != Flags);
+
+  XenGrantTablePutFreeEntry (Ref);
+  return EFI_SUCCESS;
+}
+
+VOID
+XenGrantTableInit (
+  IN XENBUS_DEVICE  *Dev,
+  IN UINT64         MmioAddr
+  )
+{
+  xen_add_to_physmap_t Parameters;
+  INTN Index;
+  INTN ReturnCode;
+
+#ifdef GNT_DEBUG
+  SetMem(GrantInUseList, sizeof (GrantInUseList), 1);
+#endif
+  EfiInitializeLock (&mGrantListLock, TPL_NOTIFY);
+  for (Index = NR_RESERVED_ENTRIES; Index < NR_GRANT_ENTRIES; Index++) {
+    XenGrantTablePutFreeEntry (Index);
+  }
+
+  GrantTable = (VOID*)(UINTN) MmioAddr;
+  for (Index = 0; Index < NR_GRANT_FRAMES; Index++) {
+    Parameters.domid = DOMID_SELF;
+    Parameters.idx = Index;
+    Parameters.space = XENMAPSPACE_grant_table;
+    Parameters.gpfn = (((xen_pfn_t) GrantTable) >> EFI_PAGE_SHIFT) + Index;
+    ReturnCode = XenHypercallMemoryOp (Dev, XENMEM_add_to_physmap, &Parameters);
+    if (ReturnCode != 0) {
+      DEBUG ((EFI_D_ERROR, "Xen GrantTable, add_to_physmap hypercall error: %d\n", ReturnCode));
+    }
+  }
+}
+
+VOID
+XenGrantTableDeinit (
+  XENBUS_DEVICE *Dev
+  )
+{
+  INTN ReturnCode, Index;
+  xen_remove_from_physmap_t Parameters;
+
+  if (GrantTable == NULL) {
+    return;
+  }
+
+  for (Index = NR_GRANT_FRAMES - 1; Index >= 0; Index--) {
+    Parameters.domid = DOMID_SELF;
+    Parameters.gpfn = (((xen_pfn_t) GrantTable) >> EFI_PAGE_SHIFT) + Index;
+    DEBUG ((EFI_D_INFO, "Xen GrantTable, removing %X\n", Parameters.gpfn));
+    ReturnCode = XenHypercallMemoryOp (Dev, XENMEM_remove_from_physmap, &Parameters);
+    if (ReturnCode != 0) {
+      DEBUG ((EFI_D_ERROR, "Xen GrantTable, remove_from_physmap hypercall error: %d\n", ReturnCode));
+    }
+  }
+  GrantTable = NULL;
+}
+
+EFI_STATUS
+EFIAPI
+XenBusGrantAccess (
+  IN  XENBUS_PROTOCOL *This,
+  IN  domid_t         DomainId,
+  IN  UINTN           Frame, // MFN
+  IN  BOOLEAN         ReadOnly,
+  OUT grant_ref_t     *RefPtr
+  )
+{
+  *RefPtr = XenGrantTableGrantAccess (DomainId, Frame, ReadOnly);
+  return EFI_SUCCESS;
+}
+
+EFI_STATUS
+EFIAPI
+XenBusGrantEndAccess (
+  IN XENBUS_PROTOCOL  *This,
+  IN grant_ref_t      Ref
+  )
+{
+  return XenGrantTableEndAccess (Ref);
+}

OvmfPkg/XenBusDxe/GrantTable.h

@@ -0,0 +1,77 @@
+/** @file
+  Grant Table function declaration.
+
+  Grant Table are used to grant access to certain page of the current
+  VM to an other VM.
+
+  Copyright (C) 2014, Citrix Ltd.
+
+  This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD License
+  which accompanies this distribution.  The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+#ifndef __GNTTAB_H__
+#define __GNTTAB_H__
+
+#include <IndustryStandard/Xen/grant_table.h>
+
+/**
+  Initialize the Grant Table at the address MmioAddr.
+
+  @param Dev      A pointer to XENBUS_DEVICE.
+  @param MmioAddr An address where the grant table can be mapped into
+                  the guest.
+**/
+VOID
+XenGrantTableInit (
+  IN XENBUS_DEVICE  *Dev,
+  IN UINT64         MmioAddr
+  );
+
+/**
+  Desinitilize the Grant Table.
+**/
+VOID
+XenGrantTableDeinit (
+  IN XENBUS_DEVICE  *Dev
+  );
+
+/**
+  Grant access to the page Frame to the domain DomainId.
+
+  @param This       A pointer to XENBUS_PROTOCOL instance.
+  @param DomainId   ID of the domain to grant acces to.
+  @param Frame      Frame Number of the page to grant access to.
+  @param ReadOnly   Provide read-only or read-write access.
+  @param RefPtr     Reference number of the grant will be writen to this pointer.
+**/
+EFI_STATUS
+EFIAPI
+XenBusGrantAccess (
+  IN  XENBUS_PROTOCOL *This,
+  IN  domid_t         DomainId,
+  IN  UINTN           Frame, // MFN
+  IN  BOOLEAN         ReadOnly,
+  OUT grant_ref_t     *RefPtr
+  );
+
+/**
+  End access to grant Ref, previously return by XenBusGrantAccess.
+
+  @param This       A pointer to XENBUS_PROTOCOL instance.
+  @param Ref        Reference numeber of a grant previously returned by
+                    XenBusGrantAccess.
+**/
+EFI_STATUS
+EFIAPI
+XenBusGrantEndAccess (
+  IN XENBUS_PROTOCOL  *This,
+  IN grant_ref_t      Ref
+  );
+
+#endif /* !__GNTTAB_H__ */

OvmfPkg/XenBusDxe/XenBusDxe.c

@@ -30,6 +30,7 @@
 #include "XenBusDxe.h"
 
 #include "XenHypercall.h"
+#include "GrantTable.h"
 
 
 ///
@@ -282,6 +283,8 @@ XenBusDxeDriverBindingStart (
   EFI_STATUS Status;
   XENBUS_DEVICE *Dev;
   EFI_PCI_IO_PROTOCOL *PciIo;
+  EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR *BarDesc;
+  UINT64 MmioAddr;
 
   Status = gBS->OpenProtocol (
                      ControllerHandle,
@@ -313,6 +316,20 @@ XenBusDxeDriverBindingStart (
   mMyDevice = Dev;
   EfiReleaseLock (&mMyDeviceLock);
 
+  //
+  // The BAR1 of this PCI device is used for shared memory and is supposed to
+  // look like MMIO. The address space of the BAR1 will be used to map the
+  // Grant Table.
+  //
+  Status = PciIo->GetBarAttributes (PciIo, PCI_BAR_IDX1, NULL, (VOID**) &BarDesc);
+  ASSERT_EFI_ERROR (Status);
+  ASSERT (BarDesc->ResType == ACPI_ADDRESS_SPACE_TYPE_MEM);
+
+  /* Get a Memory address for mapping the Grant Table. */
+  DEBUG ((EFI_D_INFO, "XenBus: BAR at %LX\n", BarDesc->AddrRangeMin));
+  MmioAddr = BarDesc->AddrRangeMin;
+  FreePool (BarDesc);
+
   Status = XenHyperpageInit (Dev);
   if (EFI_ERROR (Status)) {
     DEBUG ((EFI_D_ERROR, "XenBus: Unable to retrieve the hyperpage.\n"));
@@ -327,6 +344,8 @@ XenBusDxeDriverBindingStart (
     goto ErrorAllocated;
   }
 
+  XenGrantTableInit (Dev, MmioAddr);
+
   Status = gBS->CreateEvent (EVT_SIGNAL_EXIT_BOOT_SERVICES, TPL_CALLBACK,
                              NotifyExitBoot,
                              (VOID*) Dev,
@@ -380,6 +399,7 @@ XenBusDxeDriverBindingStop (
   XENBUS_DEVICE *Dev = mMyDevice;
 
   gBS->CloseEvent (Dev->ExitBootEvent);
+  XenGrantTableDeinit (Dev);
 
   gBS->CloseProtocol (ControllerHandle, &gEfiPciIoProtocolGuid,
          This->DriverBindingHandle, ControllerHandle);

OvmfPkg/XenBusDxe/XenBusDxe.inf

@@ -38,6 +38,8 @@
   XenHypercall.h
   InterlockedCompareExchange16.c
   InterlockedCompareExchange16.h
+  GrantTable.c
+  GrantTable.h
 
 [Sources.IA32]
   Ia32/hypercall.S