f6c909ae5d
Commit 09719a01b11b (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>
70 lines
2.1 KiB
C
70 lines
2.1 KiB
C
/** @file
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Internal interfaces specific to the QemuFwCfgLib instances in OvmfPkg.
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Copyright (C) 2016, Red Hat, Inc.
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Copyright (C) 2017, Advanced Micro Devices. All rights reserved
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This program and the accompanying materials are licensed and made available
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under the terms and conditions of the BSD License which accompanies this
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distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
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WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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#ifndef __QEMU_FW_CFG_LIB_INTERNAL_H__
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#define __QEMU_FW_CFG_LIB_INTERNAL_H__
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/**
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Returns a boolean indicating if the firmware configuration interface is
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available for library-internal purposes.
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This function never changes fw_cfg state.
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@retval TRUE The interface is available internally.
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@retval FALSE The interface is not available internally.
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**/
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BOOLEAN
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InternalQemuFwCfgIsAvailable (
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VOID
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);
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/**
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Returns a boolean indicating whether QEMU provides the DMA-like access method
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for fw_cfg.
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@retval TRUE The DMA-like access method is available.
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@retval FALSE The DMA-like access method is unavailable.
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**/
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BOOLEAN
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InternalQemuFwCfgDmaIsAvailable (
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VOID
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);
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/**
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Transfer an array of bytes, or skip a number of bytes, using the DMA
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interface.
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@param[in] Size Size in bytes to transfer or skip.
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@param[in,out] Buffer Buffer to read data into or write data from. Ignored,
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and may be NULL, if Size is zero, or Control is
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FW_CFG_DMA_CTL_SKIP.
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@param[in] Control One of the following:
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FW_CFG_DMA_CTL_WRITE - write to fw_cfg from Buffer.
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FW_CFG_DMA_CTL_READ - read from fw_cfg into Buffer.
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FW_CFG_DMA_CTL_SKIP - skip bytes in fw_cfg.
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**/
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VOID
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InternalQemuFwCfgDmaBytes (
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IN UINT32 Size,
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IN OUT VOID *Buffer OPTIONAL,
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IN UINT32 Control
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);
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#endif
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