From e130229c0aea069f44fc942e585733b435680a35 Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Wed, 2 Aug 2017 15:13:15 +0200 Subject: [PATCH] OvmfPkg/IoMmuDxe: rework setup of "MapInfo->PlainTextAddress" in Map() There are three issues with the current calculations: - The initial logic that sets up "DmaMemoryTop" and "AllocateType" checks for the BusMasterCommonBuffer64 operation in two places. The inner check for BusMasterCommonBuffer64 will never evaluate to TRUE however, because the outer check excludes BusMasterCommonBuffer64. - In order to lower "DmaMemoryTop" to (SIZE_4GB - 1), the outer check requires that the encrypted (original) buffer cross the 4GB mark. This is wrong: for BusMasterRead[64] and BusMasterWrite[64] operations, we unconditionally need a bounce buffer (a decrypted memory area), and for the 32-bit variants, "DmaMemoryTop" should be lowered regardless of the location of the original (encrypted) buffer. - The current logic would be hard to extend for the in-place decryption that we'll implement in the next patch. Therefore rework the "MapInfo->PlainTextAddress" setup. No functional changes beyond said bugfixes. Cc: Ard Biesheuvel Cc: Brijesh Singh Cc: Jordan Justen Cc: Tom Lendacky Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek Tested-by: Brijesh Singh Reviewed-by: Brijesh Singh --- OvmfPkg/IoMmuDxe/AmdSevIoMmu.c | 156 ++++++++++++++++++--------------- 1 file changed, 87 insertions(+), 69 deletions(-) diff --git a/OvmfPkg/IoMmuDxe/AmdSevIoMmu.c b/OvmfPkg/IoMmuDxe/AmdSevIoMmu.c index d899b0ab9e..0a85ee6559 100644 --- a/OvmfPkg/IoMmuDxe/AmdSevIoMmu.c +++ b/OvmfPkg/IoMmuDxe/AmdSevIoMmu.c @@ -72,9 +72,7 @@ IoMmuMap ( ) { EFI_STATUS Status; - EFI_PHYSICAL_ADDRESS PhysicalAddress; MAP_INFO *MapInfo; - EFI_PHYSICAL_ADDRESS DmaMemoryTop; EFI_ALLOCATE_TYPE AllocateType; if (HostAddress == NULL || NumberOfBytes == NULL || DeviceAddress == NULL || @@ -82,88 +80,105 @@ IoMmuMap ( return EFI_INVALID_PARAMETER; } - // - // Make sure that Operation is valid - // - if ((UINT32) Operation >= EdkiiIoMmuOperationMaximum) { - return EFI_INVALID_PARAMETER; - } - PhysicalAddress = (EFI_PHYSICAL_ADDRESS) (UINTN) HostAddress; - - DmaMemoryTop = (UINTN)-1; - AllocateType = AllocateAnyPages; - - if (((Operation != EdkiiIoMmuOperationBusMasterRead64 && - Operation != EdkiiIoMmuOperationBusMasterWrite64 && - Operation != EdkiiIoMmuOperationBusMasterCommonBuffer64)) && - ((PhysicalAddress + *NumberOfBytes) > SIZE_4GB)) { - // - // If the root bridge or the device cannot handle performing DMA above - // 4GB but any part of the DMA transfer being mapped is above 4GB, then - // map the DMA transfer to a buffer below 4GB. - // - DmaMemoryTop = SIZE_4GB - 1; - AllocateType = AllocateMaxAddress; - - if (Operation == EdkiiIoMmuOperationBusMasterCommonBuffer || - Operation == EdkiiIoMmuOperationBusMasterCommonBuffer64) { - // - // Common Buffer operations can not be remapped. If the common buffer - // if above 4GB, then it is not possible to generate a mapping, so - // return an error. - // - return EFI_UNSUPPORTED; - } - } - - // - // CommandBuffer was allocated by us (AllocateBuffer) and is already in - // unencryted buffer so no need to create bounce buffer - // - if (Operation == EdkiiIoMmuOperationBusMasterCommonBuffer || - Operation == EdkiiIoMmuOperationBusMasterCommonBuffer64) { - *Mapping = NO_MAPPING; - *DeviceAddress = PhysicalAddress; - - return EFI_SUCCESS; - } - // // Allocate a MAP_INFO structure to remember the mapping when Unmap() is // called later. // MapInfo = AllocatePool (sizeof (MAP_INFO)); if (MapInfo == NULL) { - *NumberOfBytes = 0; - return EFI_OUT_OF_RESOURCES; + Status = EFI_OUT_OF_RESOURCES; + goto Failed; } // - // Initialize the MAP_INFO structure + // Initialize the MAP_INFO structure, except the PlainTextAddress field // MapInfo->Operation = Operation; MapInfo->NumberOfBytes = *NumberOfBytes; MapInfo->NumberOfPages = EFI_SIZE_TO_PAGES (MapInfo->NumberOfBytes); - MapInfo->CryptedAddress = PhysicalAddress; - MapInfo->PlainTextAddress = DmaMemoryTop; + MapInfo->CryptedAddress = (UINTN)HostAddress; // - // Allocate a buffer to map the transfer to. + // In the switch statement below, we point "MapInfo->PlainTextAddress" to the + // plaintext buffer, according to Operation. // - Status = gBS->AllocatePages ( - AllocateType, - EfiBootServicesData, - MapInfo->NumberOfPages, - &MapInfo->PlainTextAddress - ); - if (EFI_ERROR (Status)) { + MapInfo->PlainTextAddress = MAX_ADDRESS; + AllocateType = AllocateAnyPages; + switch (Operation) { + // + // For BusMasterRead[64] and BusMasterWrite[64] operations, a bounce buffer + // is necessary regardless of whether the original (crypted) buffer crosses + // the 4GB limit or not -- we have to allocate a separate plaintext buffer. + // The only variable is whether the plaintext buffer should be under 4GB. + // + case EdkiiIoMmuOperationBusMasterRead: + case EdkiiIoMmuOperationBusMasterWrite: + MapInfo->PlainTextAddress = BASE_4GB - 1; + AllocateType = AllocateMaxAddress; + // + // fall through + // + case EdkiiIoMmuOperationBusMasterRead64: + case EdkiiIoMmuOperationBusMasterWrite64: + // + // Allocate the implicit plaintext bounce buffer. + // + Status = gBS->AllocatePages ( + AllocateType, + EfiBootServicesData, + MapInfo->NumberOfPages, + &MapInfo->PlainTextAddress + ); + if (EFI_ERROR (Status)) { + goto FreeMapInfo; + } + break; + + // + // For BusMasterCommonBuffer[64] operations, a plaintext buffer has been + // allocated already, with AllocateBuffer(). We only check whether the + // address is low enough for the requested operation. + // + case EdkiiIoMmuOperationBusMasterCommonBuffer: + if ((MapInfo->CryptedAddress > BASE_4GB) || + (EFI_PAGES_TO_SIZE (MapInfo->NumberOfPages) > + BASE_4GB - MapInfo->CryptedAddress)) { + // + // CommonBuffer operations cannot be remapped. If the common buffer is + // above 4GB, then it is not possible to generate a mapping, so return an + // error. + // + Status = EFI_UNSUPPORTED; + goto FreeMapInfo; + } + // + // fall through + // + case EdkiiIoMmuOperationBusMasterCommonBuffer64: + // + // The buffer at MapInfo->CryptedAddress comes from AllocateBuffer(), + // and it is already decrypted. + // + MapInfo->PlainTextAddress = MapInfo->CryptedAddress; + + // + // Therefore no mapping is necessary. + // + *DeviceAddress = MapInfo->PlainTextAddress; + *Mapping = NO_MAPPING; FreePool (MapInfo); - *NumberOfBytes = 0; - return Status; + return EFI_SUCCESS; + + default: + // + // Operation is invalid + // + Status = EFI_INVALID_PARAMETER; + goto FreeMapInfo; } // - // Clear the memory encryption mask from the device buffer + // Clear the memory encryption mask on the plaintext buffer. // Status = MemEncryptSevClearPageEncMask ( 0, @@ -188,13 +203,9 @@ IoMmuMap ( } // - // The DeviceAddress is the address of the maped buffer below 4GB + // Populate output parameters. // *DeviceAddress = MapInfo->PlainTextAddress; - - // - // Return a pointer to the MAP_INFO structure in Mapping - // *Mapping = MapInfo; DEBUG (( @@ -208,6 +219,13 @@ IoMmuMap ( )); return EFI_SUCCESS; + +FreeMapInfo: + FreePool (MapInfo); + +Failed: + *NumberOfBytes = 0; + return Status; } /**