[PATCH v3 0/4] dma: swiotlb: Centralize default pool policy and sizing

[Aneesh Kumar K.V (Arm)]

Hi,

This series centralizes swiotlb default-pool selection and sizing, and
simplifies the initialization flags used to describe pool placement.

The first patch replaces the addressing-limit argument with initialization
flags and introduces explicit policies for the different reasons a default
pool may be needed. Architectures now report DMA addressing constraints with
SWIOTLB_INIT_ADDRESSING_LIMIT, while the core selects the corresponding pool
policy.

The second patch moves the reduced sizing used when the pool is needed only
for unaligned kmalloc bouncing from arm64 and RISC-V into the swiotlb core.

The third patch centralizes swiotlb sizing for memory-encrypted systems. It
moves the existing x86 guest-sizing policy into the core. Host memory
encryption retains the normal pool size, and a shared default pool is not
selected solely for guest memory encryption when a restricted DMA pool is
present.

The fourth patch removes SWIOTLB_ANY. Pool placement is derived directly from
SWIOTLB_INIT_ADDRESSING_LIMIT: pools required for limited DMA addressing are
allocated below the architecture's low address limit, while other pools may
be allocated anywhere in directly mapped memory. Xen continues to request a
pool explicitly with SWIOTLB_INIT_REMAP without imposing a low-address
constraint.

Changes from v2:
https://lore.kernel.org/all/20260813102521.1367737-1-aneesh.kumar@kernel.org
* Rebase to latest tree.
* Drop SWIOTLB_ANY and derive that based on SWIOTLB_INIT_ADDRESSING_LIMIT
* Add SWIOTLB_INIT_REMAP.

v1:
https://lore.kernel.org/all/20260811134056.756015-1-aneesh.kumar@kernel.org

Cc: Robin Murphy <robin.murphy at arm.com>
Cc: Marek Szyprowski <m.szyprowski at samsung.com>
Cc: Will Deacon <will at kernel.org>
Cc: Marc Zyngier <maz at kernel.org>
Cc: Steven Price <steven.price at arm.com>
Cc: Suzuki K Poulose <Suzuki.Poulose at arm.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Jiri Pirko <jiri at resnulli.us>
Cc: Jason Gunthorpe <jgg at ziepe.ca>
Cc: Mostafa Saleh <smostafa at google.com>
Cc: Petr Tesarik <ptesarik at suse.com>
Cc: Alexey Kardashevskiy <aik at amd.com>
Cc: Dan Williams <dan.j.williams at intel.com>
Cc: Xu Yilun <yilun.xu at linux.intel.com>
Cc: Madhavan Srinivasan <maddy at linux.ibm.com>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Nicholas Piggin <npiggin at gmail.com>
Cc: "Christophe Leroy (CS GROUP)" <chleroy at kernel.org>
Cc: Alexander Gordeev <agordeev at linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer at linux.ibm.com>
Cc: Heiko Carstens <hca at linux.ibm.com>
Cc: Vasily Gorbik <gor at linux.ibm.com>
Cc: Christian Borntraeger <borntraeger at linux.ibm.com>
Cc: Sven Schnelle <svens at linux.ibm.com>
Cc: Russell King <linux at armlinux.org.uk>
Cc: Huacai Chen <chenhuacai at kernel.org>
Cc: Thomas Bogendoerfer <tsbogend at alpha.franken.de>
Cc: Jiaxun Yang <jiaxun.yang at flygoat.com>
Cc: Paul Walmsley <pjw at kernel.org>
Cc: Palmer Dabbelt <palmer at dabbelt.com>
Cc: Albert Ou <aou at eecs.berkeley.edu>
Cc: Thomas Gleixner <tglx at kernel.org>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: Borislav Petkov <bp at alien8.de>
Cc: Dave Hansen <dave.hansen at linux.intel.com>
Cc: linux-arm-kernel at lists.infradead.org
Cc: linux-kernel at vger.kernel.org
Cc: loongarch at lists.linux.dev
Cc: linux-mips at vger.kernel.org
Cc: linuxppc-dev at lists.ozlabs.org
Cc: linux-riscv at lists.infradead.org
Cc: linux-s390 at vger.kernel.org
Cc: x86 at kernel.org

Aneesh Kumar K.V (Arm) (4):
  dma: swiotlb: Centralize default pool policy selection
  dma: swiotlb: Centralize minimal pool sizing
  dma: swiotlb: Centralize memory-encryption pool sizing
  dma: swiotlb: Remove SWIOTLB_ANY

 Documentation/core-api/swiotlb.rst   |   8 +-
 arch/arm/mm/init.c                   |   6 +-
 arch/arm64/mm/init.c                 |  14 +-
 arch/loongarch/kernel/setup.c        |   2 +-
 arch/mips/cavium-octeon/dma-octeon.c |   2 +-
 arch/mips/loongson64/dma.c           |   2 +-
 arch/mips/sibyte/common/dma.c        |   2 +-
 arch/powerpc/kernel/dma-swiotlb.c    |   4 +-
 arch/powerpc/mm/mem.c                |  17 ++-
 arch/powerpc/platforms/pseries/svm.c |  10 --
 arch/powerpc/sysdev/fsl_pci.c        |   1 +
 arch/riscv/mm/init.c                 |  24 +--
 arch/s390/mm/init.c                  |   2 +-
 arch/x86/include/asm/crash_reserve.h |   4 +-
 arch/x86/include/asm/iommu.h         |   2 +
 arch/x86/kernel/amd_gart_64.c        |   1 +
 arch/x86/kernel/pci-dma.c            |  19 ++-
 arch/x86/mm/mem_encrypt.c            |  24 ---
 include/linux/swiotlb.h              |  19 ++-
 kernel/dma/swiotlb.c                 | 214 ++++++++++++++++++++-------
 20 files changed, 236 insertions(+), 141 deletions(-)


base-commit: 89a312991dc6e638a36adc43ccb91dbc25504c04
-- 
2.43.0