f6c909ae5d
Commit 09719a01b1 (OvmfPkg/QemuFwCfgLib: Implement SEV internal function
for Dxe phase) uses IOMMU protocol to allocate and free FW_CFG_DMA_ACCESS
buffer when SEV is active. During initial commits we made assumption that
IOMMU.AllocateBuffer() will provide PlainTextAddress (i.e C-bit cleared).
This assumption was wrong, the AllocateBuffer() protocol member is not
expected to produce a buffer that is immediatly usable, and client is
required to call Map() uncondtionally with BusMasterCommonBuffer[64] to
get a mapping which is accessable by both host and device.
The patch refactors code a bit and add the support to Map()
FW_CFG_DMA_ACCESS buffer using BusMasterCommonBuffer operation after
allocation and Unamp() before free.
The complete discussion about this and recommendation from Laszlo can be
found here [1]
[1] https://lists.01.org/pipermail/edk2-devel/2017-July/012652.html
Suggested-by: Laszlo Ersek <lersek@redhat.com>
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>
[lersek@redhat.com: convert pointers to UINTN before converting to UINT64]
[lersek@redhat.com: fix argument indentation in multi-line function call]
[lersek@redhat.com: explicitly compare pointers to NULL]
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
EDK II Project
A modern, feature-rich, cross-platform firmware development environment for the UEFI and PI specifications from www.uefi.org.
Contributions to the EDK II open source project are covered by the TianoCore Contribution Agreement 1.1
The majority of the content in the EDK II open source project uses a BSD 2-Clause License. The EDK II open source project contains the following components that are covered by additional licenses:
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