Whenever we release the plaintext bounce buffer pages that were allocated
implicitly in Map() for BusMasterRead[64] and BusMasterWrite[64], we
restore the encryption mask on them. However, we should also rewrite the
area (fill it with zeros) so that the hypervisor is not left with a
plaintext view of the earlier data.
Similarly, whenever we release the plaintext common buffer pages that were
allocated explicitly in AllocateBuffer() for BusMasterCommonBuffer[64], we
restore the encryption mask on them. However, we should also rewrite the
area (fill it with zeros) so that the hypervisor is not left with a
plaintext view of the earlier data.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
OvmfPkg/IoMmuDxe/AmdSevIoMmu.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/OvmfPkg/IoMmuDxe/AmdSevIoMmu.c b/OvmfPkg/IoMmuDxe/AmdSevIoMmu.c
index 8c2c23356a40..d899b0ab9e41 100644
--- a/OvmfPkg/IoMmuDxe/AmdSevIoMmu.c
+++ b/OvmfPkg/IoMmuDxe/AmdSevIoMmu.c
@@ -227,87 +227,91 @@ EFIAPI
IoMmuUnmap (
IN EDKII_IOMMU_PROTOCOL *This,
IN VOID *Mapping
)
{
MAP_INFO *MapInfo;
EFI_STATUS Status;
if (Mapping == NULL) {
return EFI_INVALID_PARAMETER;
}
//
// See if the Map() operation associated with this Unmap() required a mapping
// buffer. If a mapping buffer was not required, then this function simply
// buffer. If a mapping buffer was not required, then this function simply
//
if (Mapping == NO_MAPPING) {
return EFI_SUCCESS;
}
MapInfo = (MAP_INFO *)Mapping;
//
// If this is a write operation from the Bus Master's point of view,
// then copy the contents of the mapped buffer into the real buffer
// so the processor can read the contents of the real buffer.
//
if (MapInfo->Operation == EdkiiIoMmuOperationBusMasterWrite ||
MapInfo->Operation == EdkiiIoMmuOperationBusMasterWrite64) {
CopyMem (
(VOID *) (UINTN) MapInfo->CryptedAddress,
(VOID *) (UINTN) MapInfo->PlainTextAddress,
MapInfo->NumberOfBytes
);
}
DEBUG ((
DEBUG_VERBOSE,
"%a PlainText 0x%Lx Crypted 0x%Lx Pages 0x%Lx Bytes 0x%Lx\n",
__FUNCTION__,
MapInfo->PlainTextAddress,
MapInfo->CryptedAddress,
(UINT64)MapInfo->NumberOfPages,
(UINT64)MapInfo->NumberOfBytes
));
//
// Restore the memory encryption mask
//
Status = MemEncryptSevSetPageEncMask (
0,
MapInfo->PlainTextAddress,
MapInfo->NumberOfPages,
TRUE
);
ASSERT_EFI_ERROR(Status);
+ ZeroMem (
+ (VOID*)(UINTN)MapInfo->PlainTextAddress,
+ EFI_PAGES_TO_SIZE (MapInfo->NumberOfPages)
+ );
//
// Free the mapped buffer and the MAP_INFO structure.
//
gBS->FreePages (MapInfo->PlainTextAddress, MapInfo->NumberOfPages);
FreePool (Mapping);
return EFI_SUCCESS;
}
/**
Allocates pages that are suitable for an OperationBusMasterCommonBuffer or
OperationBusMasterCommonBuffer64 mapping.
@param This The protocol instance pointer.
@param Type This parameter is not used and must be ignored.
@param MemoryType The type of memory to allocate,
EfiBootServicesData or EfiRuntimeServicesData.
@param Pages The number of pages to allocate.
@param HostAddress A pointer to store the base system memory
address of the allocated range.
@param Attributes The requested bit mask of attributes for the
allocated range.
@retval EFI_SUCCESS The requested memory pages were allocated.
@retval EFI_UNSUPPORTED Attributes is unsupported. The only legal
attribute bits are MEMORY_WRITE_COMBINE and
MEMORY_CACHED.
@retval EFI_INVALID_PARAMETER One or more parameters are invalid.
@retval EFI_OUT_OF_RESOURCES The memory pages could not be allocated.
**/
@@ -399,78 +403,79 @@ EFIAPI
IoMmuFreeBuffer (
IN EDKII_IOMMU_PROTOCOL *This,
IN UINTN Pages,
IN VOID *HostAddress
)
{
EFI_STATUS Status;
//
// Set memory encryption mask
//
Status = MemEncryptSevSetPageEncMask (
0,
(EFI_PHYSICAL_ADDRESS)(UINTN)HostAddress,
Pages,
TRUE
);
ASSERT_EFI_ERROR(Status);
+ ZeroMem (HostAddress, EFI_PAGES_TO_SIZE (Pages));
DEBUG ((
DEBUG_VERBOSE,
"%a Address 0x%Lx Pages 0x%Lx\n",
__FUNCTION__,
(UINT64)(UINTN)HostAddress,
(UINT64)Pages
));
return gBS->FreePages ((EFI_PHYSICAL_ADDRESS) (UINTN) HostAddress, Pages);
}
/**
Set IOMMU attribute for a system memory.
If the IOMMU protocol exists, the system memory cannot be used
for DMA by default.
When a device requests a DMA access for a system memory,
the device driver need use SetAttribute() to update the IOMMU
attribute to request DMA access (read and/or write).
The DeviceHandle is used to identify which device submits the request.
The IOMMU implementation need translate the device path to an IOMMU device
ID, and set IOMMU hardware register accordingly.
1) DeviceHandle can be a standard PCI device.
The memory for BusMasterRead need set EDKII_IOMMU_ACCESS_READ.
The memory for BusMasterWrite need set EDKII_IOMMU_ACCESS_WRITE.
The memory for BusMasterCommonBuffer need set
EDKII_IOMMU_ACCESS_READ|EDKII_IOMMU_ACCESS_WRITE.
After the memory is used, the memory need set 0 to keep it being
protected.
2) DeviceHandle can be an ACPI device (ISA, I2C, SPI, etc).
The memory for DMA access need set EDKII_IOMMU_ACCESS_READ and/or
EDKII_IOMMU_ACCESS_WRITE.
@param[in] This The protocol instance pointer.
@param[in] DeviceHandle The device who initiates the DMA access
request.
@param[in] Mapping The mapping value returned from Map().
@param[in] IoMmuAccess The IOMMU access.
@retval EFI_SUCCESS The IoMmuAccess is set for the memory range
specified by DeviceAddress and Length.
@retval EFI_INVALID_PARAMETER DeviceHandle is an invalid handle.
@retval EFI_INVALID_PARAMETER Mapping is not a value that was returned by
Map().
@retval EFI_INVALID_PARAMETER IoMmuAccess specified an illegal combination
of access.
@retval EFI_UNSUPPORTED DeviceHandle is unknown by the IOMMU.
@retval EFI_UNSUPPORTED The bit mask of IoMmuAccess is not supported
by the IOMMU.
@retval EFI_UNSUPPORTED The IOMMU does not support the memory range
specified by Mapping.
@retval EFI_OUT_OF_RESOURCES There are not enough resources available to
modify the IOMMU access.
@retval EFI_DEVICE_ERROR The IOMMU device reported an error while
attempting the operation.
**/
--
2.13.1.3.g8be5a757fa67
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