In order for Unmap() to be callable from ExitBootServices() event handler
context (for cleaning up a BusMasterCommonBuffer[64] operation), we have
to completely liberate the affected path in Unmap() from dynamic memory
management.
The last remaining piece is the release of the MAP_INFO structure. Rather
than freeing it with FreePool(), recycle it to an internal list. Elements
of this "free list" can be reused for any kind of Map() operation, and can
be freed later, or recycled again.
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>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
Upon a MemEncryptSevClearPageEncMask() failure in Map(), it wouldn't be
difficult to release the bounce buffer that was implicitly allocated for
BusMasterRead[64] and BusMasterWrite[64] operations. However, undoing any
partial memory encryption mask changes -- partial page splitting and PTE
modifications -- is practically impossible. (For example, restoring the
encryption mask on the entire range has no reason to fare any better than
the MemEncryptSevClearPageEncMask() call itself.)
For this reason, keep ASSERT_EFI_ERROR(), but hang in RELEASE builds too,
if MemEncryptSevClearPageEncMask() or MemEncryptSevSetPageEncMask() fails.
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>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
At the moment, we have the following distribution of actions between the
IOMMU protocol member functions:
- AllocateBuffer() allocates pages and clears the memory encryption mask.
- FreeBuffer() re-sets the memory encryption mask, and deallocates pages.
- Map() does nothing at all when BusMasterCommonBuffer[64] is requested
(and AllocateBuffer() was called previously). Otherwise, Map() allocates
pages, and clears the memory encryption mask.
- Unmap() does nothing when cleaning up a BusMasterCommonBuffer[64]
operation. Otherwise, Unmap() clears the encryption mask, and frees the
pages.
This is wrong: the AllocateBuffer() protocol member is not expected to
produce a buffer that is immediately usable, and client code is required
to call Map() unconditionally, even if BusMasterCommonBuffer[64] is the
desired operation. Implement the right distribution of actions as follows:
- AllocateBuffer() allocates pages and does not touch the encryption mask.
- FreeBuffer() deallocates pages and does not touch the encryption mask.
- Map() does not allocate pages when BusMasterCommonBuffer[64] is
requested, and it allocates pages (bounce buffer) otherwise. Regardless
of the BusMaster operation, Map() (and Map() only) clears the memory
encryption mask.
- Unmap() restores the encryption mask unconditionally. If the operation
was BusMasterCommonBuffer[64], then Unmap() does not release the pages.
Otherwise, the pages (bounce buffer) are released.
This approach also ensures that Unmap() can be called from
ExitBootServices() event handlers, for cleaning up
BusMasterCommonBuffer[64] operations. (More specifically, for restoring
the SEV encryption mask on any in-flight buffers, after resetting any
referring devices.) ExitBootServices() event handlers must not change the
UEFI memory map, thus any memory allocation or freeing in Unmap() would
disqualify Unmap() from being called in such a context.
Map()-ing and Unmap()-ing memory for a BusMasterCommonBuffer[64] operation
effectively means in-place decryption and encryption in a SEV context. As
an additional hurdle, section "7.10.8 Encrypt-in-Place" of AMD publication
Nr.24593 implies that we need a separate temporary buffer for decryption
and encryption that will eventually land in-place. Allocating said
temporary buffer in the straightforward way would violate the above
allocation/freeing restrictions on Map()/Unmap(), therefore pre-allocate
this "stash buffer" too in AllocateBuffer(), and free it in FreeBuffer().
To completely rid Unmap() of dynamic memory impact, for
BusMasterCommonBuffer[64] operations, we're going to rework the lifecycle of
the MAP_INFO structures in a later patch.
(The MemEncryptSevSetPageEncMask() call in Unmap() could theoretically
allocate memory internally for page splitting, however this won't happen
in practice: in Unmap() we only restore the memory encryption mask, and
don't genuinely set it. Any page splitting will have occurred in Map()'s
MemEncryptSevClearPageEncMask() call first.)
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>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
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 <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>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
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>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
If we cannot install the IOMMU protocol for whatever reason, exit the
driver with an error. The same is already done for the IOMMU Absent
protocol.
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>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
The portable way to print UINTN values is to use the %Lx format specifier,
and to convert the values to UINT64. The second step is currently missing,
add it.
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>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
As a continuation of the last patch, clarify that the area pointed-to by
"HostAddress" is encrypted and hidden from the hypervisor.
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>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
In this particular IOMMU driver, "DeviceAddress" is just as accessible to
the CPU as "HostAddress", the difference is that the area pointed-to by
the former is plain-text and accessible to the hypervisor. Rename
"DeviceAddress" to "PlainTextAddress" in MAP_INFO.
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>
Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
The IOMMU protocol driver provides capabilities to set a DMA access
attribute and methods to allocate, free, map and unmap the DMA memory
for the PCI Bus devices.
Due to security reasons all DMA operations inside the SEV guest must
be performed on shared (i.e unencrypted) pages. The IOMMU protocol
driver for the SEV guest uses a bounce buffer to map guest DMA buffer
to shared pages inorder to provide the support for DMA operations inside
SEV guest.
IoMmuDxe driver looks for SEV capabilities, if present then it installs
the real IOMMU protocol otherwise it installs placeholder protocol.
Currently, PciHostBridgeDxe and QemuFWCfgLib need to know the existance
of IOMMU protocol. The modules needing to know the existance of IOMMU
support should add
gEdkiiIoMmuProtocolGuid OR gIoMmuAbsentProtocolGuid
in their depex to ensure that platform IOMMU detection has been performed.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Leo Duran <leo.duran@amd.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Suggested-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>
Laszlo Ersek
Brijesh Singh