[PATCH v6 0/8] dma: swiotlb: Centralize default pool policy and sizing

["Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>]

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 v5:
https://lore.kernel.org/all/20260921063628.362078-1-aneesh.kumar@kernel.org
* Collect Reviewed-by tags.
* Drop the x86 crash changes
* Add two new patches:
  "dma: swiotlb: Consolidate slab rounding"
  "dma: swiotlb: Rename swiotlb_size_or_default()"
* Drop the swiotlb_default_size_changed() helper.
* Simplify swiotlb_adjust_pool_size().

Changes from v4:
https://lore.kernel.org/all/20260914070135.313337-1-aneesh.kumar@kernel.org
* Collect Reviewed-by tags.
* Add a new patch, "dma: swiotlb: Track whether the pool size was explicitly set".
* Retain SWIOTLB_ANY usage for RISC-V until patch 6.
* Rename SWIOTLB_INIT_FORCE_DISABLE to SWIOTLB_INIT_DEFAULT_OFF.

Changes from v3:
https://lore.kernel.org/all/20260904101810.1193505-1-aneesh.kumar@kernel.org
* Add a new patch, "dma: swiotlb: Add an overridable architecture pool opt-out".
* Clarify the change in default behavior with the removal of SWIOTLB_ANY.

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@arm.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suzuki K Poulose <Suzuki.Poulose@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Mostafa Saleh <smostafa@google.com>
Cc: Petr Tesarik <ptesarik@suse.com>
Cc: Alexey Kardashevskiy <aik@amd.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Xu Yilun <yilun.xu@linux.intel.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: "Christophe Leroy (CS GROUP)" <chleroy@kernel.org>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: loongarch@lists.linux.dev
Cc: linux-mips@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: x86@kernel.org

Aneesh Kumar K.V (Arm) (8):
  dma: swiotlb: Rename swiotlb_size_or_default()
  dma: swiotlb: Consolidate slab rounding
  dma: swiotlb: Track whether the pool size was explicitly set
  dma: swiotlb: Centralize default pool policy selection
  dma: swiotlb: Centralize minimal pool sizing
  dma: swiotlb: Centralize memory-encryption pool sizing
  dma: swiotlb: Add an overridable architecture pool opt-out
  dma: swiotlb: Remove SWIOTLB_ANY

 Documentation/core-api/swiotlb.rst   |   8 +-
 arch/arm/mm/init.c                   |   6 +-
 arch/arm/xen/mm.c                    |   2 +-
 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/kernel/pci-dma.c            |  23 +++-
 arch/x86/mm/mem_encrypt.c            |  24 ----
 include/linux/swiotlb.h              |  17 ++-
 kernel/dma/swiotlb.c                 | 193 +++++++++++++++++++--------
 19 files changed, 210 insertions(+), 147 deletions(-)


base-commit: 704340f1cd0dcef829eb62f5b48ae95a2ce17bdf
-- 
2.43.0