From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- drivers/iommu/io-pgtable.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+) create mode 100644 drivers/iommu/io-pgtable.c (limited to 'drivers/iommu/io-pgtable.c') diff --git a/drivers/iommu/io-pgtable.c b/drivers/iommu/io-pgtable.c new file mode 100644 index 000000000..843fec8e8 --- /dev/null +++ b/drivers/iommu/io-pgtable.c @@ -0,0 +1,97 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Generic page table allocator for IOMMUs. + * + * Copyright (C) 2014 ARM Limited + * + * Author: Will Deacon + */ + +#include +#include +#include +#include + +static const struct io_pgtable_init_fns * +io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] = { +#ifdef CONFIG_IOMMU_IO_PGTABLE_LPAE + [ARM_32_LPAE_S1] = &io_pgtable_arm_32_lpae_s1_init_fns, + [ARM_32_LPAE_S2] = &io_pgtable_arm_32_lpae_s2_init_fns, + [ARM_64_LPAE_S1] = &io_pgtable_arm_64_lpae_s1_init_fns, + [ARM_64_LPAE_S2] = &io_pgtable_arm_64_lpae_s2_init_fns, + [ARM_MALI_LPAE] = &io_pgtable_arm_mali_lpae_init_fns, +#endif +#ifdef CONFIG_IOMMU_IO_PGTABLE_DART + [APPLE_DART] = &io_pgtable_apple_dart_init_fns, + [APPLE_DART2] = &io_pgtable_apple_dart_init_fns, +#endif +#ifdef CONFIG_IOMMU_IO_PGTABLE_ARMV7S + [ARM_V7S] = &io_pgtable_arm_v7s_init_fns, +#endif +}; + +static int check_custom_allocator(enum io_pgtable_fmt fmt, + struct io_pgtable_cfg *cfg) +{ + /* No custom allocator, no need to check the format. */ + if (!cfg->alloc && !cfg->free) + return 0; + + /* When passing a custom allocator, both the alloc and free + * functions should be provided. + */ + if (!cfg->alloc || !cfg->free) + return -EINVAL; + + /* Make sure the format supports custom allocators. */ + if (io_pgtable_init_table[fmt]->caps & IO_PGTABLE_CAP_CUSTOM_ALLOCATOR) + return 0; + + return -EINVAL; +} + +struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt, + struct io_pgtable_cfg *cfg, + void *cookie) +{ + struct io_pgtable *iop; + const struct io_pgtable_init_fns *fns; + + if (fmt >= IO_PGTABLE_NUM_FMTS) + return NULL; + + if (check_custom_allocator(fmt, cfg)) + return NULL; + + fns = io_pgtable_init_table[fmt]; + if (!fns) + return NULL; + + iop = fns->alloc(cfg, cookie); + if (!iop) + return NULL; + + iop->fmt = fmt; + iop->cookie = cookie; + iop->cfg = *cfg; + + return &iop->ops; +} +EXPORT_SYMBOL_GPL(alloc_io_pgtable_ops); + +/* + * It is the IOMMU driver's responsibility to ensure that the page table + * is no longer accessible to the walker by this point. + */ +void free_io_pgtable_ops(struct io_pgtable_ops *ops) +{ + struct io_pgtable *iop; + + if (!ops) + return; + + iop = io_pgtable_ops_to_pgtable(ops); + io_pgtable_tlb_flush_all(iop); + io_pgtable_init_table[iop->fmt]->free(iop); +} +EXPORT_SYMBOL_GPL(free_io_pgtable_ops); -- cgit v1.3.1