When SEV is enabled, the DMA must be performed on unencrypted pages.
So when get asked to perfom FWCFG DMA read or write, we allocate a
intermediate (bounce buffer) unencrypted buffer and use this buffer
for DMA read or write.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf | 7 ++
OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxe.c | 114 ++++++++++++++++++++
2 files changed, 121 insertions(+)
diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf
index d7e368e5435d..11cbb3c4f393 100644
--- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf
+++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf
@@ -39,6 +39,7 @@ [Sources]
[Packages]
MdePkg/MdePkg.dec
+ MdeModulePkg/MdeModulePkg.dec
OvmfPkg/OvmfPkg.dec
[LibraryClasses]
@@ -47,4 +48,10 @@ [LibraryClasses]
DebugLib
IoLib
MemoryAllocationLib
+ MemEncryptSevLib
+[Protocols]
+ gEdkiiIoMmuProtocolGuid ## SOMETIMES_CONSUMES
+
+[Depex]
+ gEdkiiIoMmuProtocolGuid OR gIoMmuAbsentProtocolGuid
diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxe.c b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxe.c
index ac05f4c347f3..f8eb03bc3a9a 100644
--- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxe.c
+++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxe.c
@@ -4,6 +4,7 @@
Copyright (C) 2013, Red Hat, Inc.
Copyright (c) 2011 - 2013, Intel Corporation. All rights reserved.<BR>
+ Copyright (c) 2017, Advanced Micro Devices. All rights reserved.<BR>
This program and the accompanying materials are licensed and made available
under the terms and conditions of the BSD License which accompanies this
@@ -14,14 +15,36 @@
WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
+#include <Uefi.h>
+
+#include <Protocol/IoMmu.h>
+
+#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/QemuFwCfgLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/MemEncryptSevLib.h>
#include "QemuFwCfgLibInternal.h"
STATIC BOOLEAN mQemuFwCfgSupported = FALSE;
STATIC BOOLEAN mQemuFwCfgDmaSupported;
+STATIC EDKII_IOMMU_PROTOCOL *mIoMmuProtocol;
+/**
+
+ Returns a boolean indicating whether SEV is enabled
+
+ @retval TRUE SEV is enabled
+ @retval FALSE SEV is disabled
+**/
+BOOLEAN
+InternalQemuFwCfgSevIsEnabled (
+ VOID
+ )
+{
+ return MemEncryptSevIsEnabled ();
+}
/**
Returns a boolean indicating if the firmware configuration interface
@@ -79,6 +102,24 @@ QemuFwCfgInitialize (
mQemuFwCfgDmaSupported = TRUE;
DEBUG ((DEBUG_INFO, "QemuFwCfg interface (DMA) is supported.\n"));
}
+
+ if (mQemuFwCfgDmaSupported && MemEncryptSevIsEnabled ()) {
+ EFI_STATUS Status;
+
+ //
+ // IoMmuDxe driver must have installed the IOMMU protocol. If we are not
+ // able to locate the protocol then something must have gone wrong.
+ //
+ Status = gBS->LocateProtocol (&gEdkiiIoMmuProtocolGuid, NULL, (VOID **)&mIoMmuProtocol);
+ if (EFI_ERROR (Status)) {
+ DEBUG ((DEBUG_ERROR,
+ "QemuFwCfgSevDma %a:%a Failed to locate IOMMU protocol.\n",
+ gEfiCallerBaseName, __FUNCTION__));
+ ASSERT (FALSE);
+ CpuDeadLoop ();
+ }
+ }
+
return RETURN_SUCCESS;
}
@@ -114,3 +155,76 @@ InternalQemuFwCfgDmaIsAvailable (
{
return mQemuFwCfgDmaSupported;
}
+
+/**
+ Allocate a bounce buffer for SEV DMA.
+
+ @param[in] NumPage Number of pages.
+ @param[out] Buffer Allocated DMA Buffer pointer
+
+**/
+VOID
+InternalQemuFwCfgSevDmaAllocateBuffer (
+ OUT VOID **Buffer,
+ IN UINT32 NumPages
+ )
+{
+ EFI_STATUS Status;
+
+ ASSERT (mIoMmuProtocol != NULL);
+
+ Status = mIoMmuProtocol->AllocateBuffer (
+ mIoMmuProtocol,
+ 0,
+ EfiBootServicesData,
+ NumPages,
+ Buffer,
+ EDKII_IOMMU_ATTRIBUTE_MEMORY_CACHED
+ );
+ if (EFI_ERROR (Status)) {
+ DEBUG ((DEBUG_ERROR,
+ "%a:%a failed to allocate %u pages\n", gEfiCallerBaseName, __FUNCTION__,
+ NumPages));
+ ASSERT (FALSE);
+ CpuDeadLoop ();
+ }
+
+ DEBUG ((DEBUG_VERBOSE,
+ "%a:%a buffer 0x%Lx Pages %u\n", gEfiCallerBaseName, __FUNCTION__,
+ (UINT64)(UINTN)Buffer, NumPages));
+}
+
+/**
+ Free the DMA buffer allocated using InternalQemuFwCfgSevDmaAllocateBuffer
+
+ @param[in] NumPage Number of pages.
+ @param[in] Buffer DMA Buffer pointer
+
+**/
+VOID
+InternalQemuFwCfgSevDmaFreeBuffer (
+ IN VOID *Buffer,
+ IN UINT32 NumPages
+ )
+{
+ EFI_STATUS Status;
+
+ ASSERT (mIoMmuProtocol != NULL);
+
+ Status = mIoMmuProtocol->FreeBuffer (
+ mIoMmuProtocol,
+ NumPages,
+ Buffer
+ );
+ if (EFI_ERROR (Status)) {
+ DEBUG ((DEBUG_ERROR,
+ "%a:%a failed to free buffer 0x%Lx pages %u\n", gEfiCallerBaseName,
+ __FUNCTION__, (UINT64)(UINTN)Buffer, NumPages));
+ ASSERT (FALSE);
+ CpuDeadLoop ();
+ }
+
+ DEBUG ((DEBUG_VERBOSE,
+ "%a:%a buffer 0x%Lx Pages %u\n", gEfiCallerBaseName,__FUNCTION__,
+ (UINT64)(UINTN)Buffer, NumPages));
+}
--
2.7.4
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