From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration Manually perform cache maintenance on the source VM during intra-host migration to ensure no stale data is left in CPU caches after the VM is destroyed. Because the source VM is "converted" to a non-SEV VM, KVM's memory reclaim flows won't trigger cache maintenance, e.g. when all guest memory is reclaimed in response to detaching from the mmu_notifier. Note, relying on the destination VM to do cache maintenance isn't an option as KVM doesn't require identical guest memory configurations, i.e. the source VM may have access to memory that the destination VM does not. Enforcing equivalent memory configurations is infeasible, as it would require a *deep* comparison of memslots, e.g. to verify that not only are the memslot identical, but what the memslots point at is also identical. Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration") Cc: stable@vger.kernel.org Reported-by: Stefan Teodorescu Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- 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