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/** @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.
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "XenBusDxe.h"
#include <IndustryStandard/Xen/memory.h>
#include <Library/XenHypercallLib.h>
#include <Library/SynchronizationLib.h>
#include "GrantTable.h"
#define NR_RESERVED_ENTRIES 8
#define NR_GRANT_FRAMES (FixedPcdGet32 (PcdXenGrantFrames))
#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
)
{
grant_ref_t 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;
UINT16 Flags;
ASSERT (GrantTable != NULL);
Ref = XenGrantTableGetFreeEntry ();
GrantTable[Ref].frame = (UINT32)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 ((DEBUG_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
)
{
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 ((grant_ref_t)Index);
}
GrantTable = (VOID*)(UINTN) Dev->XenIo->GrantTableAddress;
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) ((UINTN) GrantTable >> EFI_PAGE_SHIFT) + Index;
ReturnCode = XenHypercallMemoryOp (XENMEM_add_to_physmap, &Parameters);
if (ReturnCode != 0) {
DEBUG ((DEBUG_ERROR,
"Xen GrantTable, add_to_physmap hypercall error: %Ld\n",
(INT64)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) ((UINTN) GrantTable >> EFI_PAGE_SHIFT) + Index;
DEBUG ((DEBUG_INFO, "Xen GrantTable, removing %Lx\n",
(UINT64)Parameters.gpfn));
ReturnCode = XenHypercallMemoryOp (XENMEM_remove_from_physmap, &Parameters);
if (ReturnCode != 0) {
DEBUG ((DEBUG_ERROR,
"Xen GrantTable, remove_from_physmap hypercall error: %Ld\n",
(INT64)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);
}
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