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 <[email protected]> Cc: Laszlo Ersek <[email protected]> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Brijesh Singh <[email protected]> --- OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf | 7 ++ OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxe.c | 108 ++++++++++++++++++++ 2 files changed, 115 insertions(+) diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf index d7e368e5435d..ec128f82c702 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 gIoMmuDetectedProtocolGuid diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxe.c b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxe.c index ac05f4c347f3..bda1a80b5eb9 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 +102,22 @@ 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, "QemuwCfgSevDma: failed to locate IOMMU protocol\n")); + ASSERT (FALSE); + CpuDeadLoop (); + } + } + return RETURN_SUCCESS; } @@ -114,3 +153,72 @@ 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 _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
