Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 14 Apr 2020 17:04:50 -0700 (PDT)
From:   David Rientjes <rientjes@google.com>
To:     Christoph Hellwig <hch@lst.de>,
        Tom Lendacky <thomas.lendacky@amd.com>
cc:     Brijesh Singh <brijesh.singh@amd.com>,
        Jon Grimm <jon.grimm@amd.com>, Joerg Roedel <joro@8bytes.org>,
        linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org
Subject: [patch 0/7] unencrypted atomic DMA pools with dynamic expansion
Message-ID: <alpine.DEB.2.22.394.2004141700480.68516@chino.kir.corp.google.com>
User-Agent: Alpine 2.22 (DEB 394 2020-01-19)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

set_memory_decrypted() may block so it is not possible to do non-blocking
allocations through the DMA API for devices that required unencrypted
memory.

The solution is to expand the atomic DMA pools for the various possible
gfp requirements as a means to prevent an unnecessary depletion of lowmem.
These atomic pools are separated from the remap code and can be selected
for configurations that need them outside the scope of
CONFIG_DMA_DIRECT_REMAP, such as CONFIG_AMD_MEM_ENCRYPT.

These atomic DMA pools are kept unencrypted so they can immediately be
used for non-blocking allocations.  Since the need for this type of memory
depends on the kernel config and devices being used, these pools are also
dynamically expandable.

The sizes of the various atomic DMA pools is exported through debugfs at
/sys/kernel/debug/dma_pools.

This patchset is based on latest Linus HEAD:

commit 8632e9b5645bbc2331d21d892b0d6961c1a08429
Merge: 6cc9306b8fc0 f3a99e761efa
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Tue Apr 14 11:58:04 2020 -0700

    Merge tag 'hyperv-fixes-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux
---
 arch/x86/Kconfig            |   1 +
 drivers/iommu/dma-iommu.c   |   5 +-
 include/linux/dma-direct.h  |   2 +
 include/linux/dma-mapping.h |   6 +-
 kernel/dma/Kconfig          |   6 +-
 kernel/dma/Makefile         |   1 +
 kernel/dma/direct.c         |  56 ++++++--
 kernel/dma/pool.c           | 275 ++++++++++++++++++++++++++++++++++++
 kernel/dma/remap.c          | 114 ---------------
 9 files changed, 334 insertions(+), 132 deletions(-)
 create mode 100644 kernel/dma/pool.c