From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f201.google.com (mail-pf1-f201.google.com [209.85.210.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F0E7839EF33 for ; Wed, 8 Jul 2026 23:48:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783554541; cv=none; b=sSBP1Mwao1rm9/mtl8FHhC1nevfcCRkxJNGyK3takWl5zuuGscuCKmVQ+gsYRKjRAcImxHDIVk+573o/QPYychsquw8nmY6pv8BdcvNIeptgJuEL1fI2cdYXuuEWhuXxmHnwTOb0/eY1ugdcuFjLJG4iZPkBoUxi9trjwKq5ir0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783554541; c=relaxed/simple; bh=flV+QBf/yjrsblh7126q3g6Yp2R55A3g6V9+p+TNh5E=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=LnRtzErj1hYjwM58HPSzslM1rwgINoffjBA2I1HSXADX1W7cVq4DF9LDKt0EGW4s1tHeA44pE1yBwuqcS8KBaKK1mZr1PQbCSfFKbF9HI93jAQGfMOsWWiVJOlNoFsfU0cQBgtvLkWs/bj3Qz58ZuPCdfCR5pYKWcF9gkmprPvQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--skhawaja.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=TNey1Y4Y; arc=none smtp.client-ip=209.85.210.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--skhawaja.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="TNey1Y4Y" Received: by mail-pf1-f201.google.com with SMTP id d2e1a72fcca58-8484f26852dso745210b3a.1 for ; Wed, 08 Jul 2026 16:48:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1783554539; x=1784159339; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=jKjGm5vgqAcCxqxTVhSOTHzJTWIKM6FvnNwlshe3+A8=; b=TNey1Y4YwiG0DJS1sNkwmNDIF4V+gIVlOOuVMv8TXOLBq0sRR93BHO+HLMLOnOe0PC sk925ugJHLNtEVnkSDmJ3A0Hm75Jmw6mHtta0YYDHrl/ObX03bM/97+xtV3vqbNOETOd BUu8mtsdejiFftr6oUBAag4vBwTQlbQ3L7nthR/HSbwP/LrUXiNIA4Bs+U7o3rx97VSm ZO/a3jeH/pAITz0E+xgg2KLzztAYbCLXyJJKnjuzbbxEdiV3Yb0YFVqTOLoP5SFmTeeB brfjaRMDApopEJdeitYD/PxYn3i7yjy4JkcbMaFnpwoAyJO9pp39Cu8qHhBQtjUlQ0xH D4uA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1783554539; x=1784159339; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=jKjGm5vgqAcCxqxTVhSOTHzJTWIKM6FvnNwlshe3+A8=; b=FTY+qnaxh9aOoSJbIiSSI2ndrUXDKMEdfvgHwt+id2lZdeSe/+04dOHnaT9deFR9MG eNecZPfvYy3PRWao/YPB/0LlIhkn5VUaYzqywAJ2CnuMUvhRZQTm1H/N1FqDg5pkOvLM rc4FIo2gHTSjgqgNjMdpqU6qMMXKg6OH4chAX44NhNiAYl3Ijw7E1bE2vpZK35OT671x 6uHJNEhIgwfBQnYOBZEkSXo9vHIWtc5q+suIZZsVW0koCHOWGkZS/EPAdvZ7QA+UjbJY mrlS/p4/2XPluJKsGw5iowKJjBYIi+38ExPoCgWeLoTI5ZhoMP5yLODCH7V5erW8fqTB Sgfw== X-Forwarded-Encrypted: i=1; AHgh+Rr8fY/P1+HA/tbpH1z09BPflgfuBLSt591AjtmyycJXBmT9JfjHVOkyYWGOq8DfiHIvXoyMh3SbBT+NVfI=@vger.kernel.org X-Gm-Message-State: AOJu0Yw6ekhCySHBZB/TN6y0Z5ozKCj9cUb0sBHN25PyobvPh0f3wPR/ yEM4GbLWiBrbKyyZVRMbSqmH94RZ/eAcI3T9t6DpV10lZN2z2PwwWApGQ0OJHSg/4/frZ7gEqyN 2xJ/m6cr++IbV9A== X-Received: from pfx25.prod.google.com ([2002:a05:6a00:a459:b0:847:878f:44f0]) (user=skhawaja job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:4191:b0:845:d274:c021 with SMTP id d2e1a72fcca58-84843682779mr4464782b3a.58.1783554539065; Wed, 08 Jul 2026 16:48:59 -0700 (PDT) Date: Wed, 8 Jul 2026 23:48:49 +0000 In-Reply-To: <20260708234854.4044652-1-skhawaja@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260708234854.4044652-1-skhawaja@google.com> X-Mailer: git-send-email 2.55.0.795.g602f6c329a-goog Message-ID: <20260708234854.4044652-6-skhawaja@google.com> Subject: [RFC PATCH v2 05/10] dma-direct: Add API to preserve/restore allocations From: Samiullah Khawaja To: Marek Szyprowski , Will Deacon , Jason Gunthorpe Cc: Samiullah Khawaja , Pasha Tatashin , Mike Rapoport , Pratyush Yadav , Alexander Graf , Robin Murphy , Kevin Tian , iommu@lists.linux.dev, kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Matlack , Andrew Morton , Pranjal Shrivastava , Vipin Sharma Content-Type: text/plain; charset="UTF-8" Add an API to preserve/restore the DMA direct allocation for liveupdate. The underlying memory is preserved/restored using KHO. During restore the memory is setup based on the device configuration, gfp flags and allocation attributes. Once restored, the driver can use the usual dma_free* API to deallocate the restored DMA allocation. This API will be used to add support in dma_alloc* APIs to preserve/restore the DMA allocations. Signed-off-by: Samiullah Khawaja --- include/linux/dma-direct.h | 29 ++++++ kernel/dma/Kconfig | 4 + kernel/dma/direct.c | 189 +++++++++++++++++++++++++++++++++++++ 3 files changed, 222 insertions(+) diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h index c249912456f9..0efe2bc1a815 100644 --- a/include/linux/dma-direct.h +++ b/include/linux/dma-direct.h @@ -141,6 +141,35 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size, u64 dma_direct_get_required_mask(struct device *dev); void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs); + +#ifdef CONFIG_DMA_LIVEUPDATE +int dma_direct_preserve_allocation(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, + unsigned long attrs, u64 *state); +void dma_direct_unpreserve_allocation(struct device *dev, u64 state); +void *dma_direct_restore_allocation(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp, + unsigned long attrs, u64 state); +#else +static inline int dma_direct_preserve_allocation(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, + unsigned long attrs, u64 *state) +{ + return -EOPNOTSUPP; +} + +static inline void dma_direct_unpreserve_allocation(struct device *dev, u64 state) +{ +} + +static inline void *dma_direct_restore_allocation(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp, + unsigned long attrs, u64 state) +{ + return NULL; +} +#endif + void dma_direct_free(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs); struct page *dma_direct_alloc_pages(struct device *dev, size_t size, diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig index bfef21b4a9ae..d93958931303 100644 --- a/kernel/dma/Kconfig +++ b/kernel/dma/Kconfig @@ -265,3 +265,7 @@ config DMA_MAP_BENCHMARK performance of dma_(un)map_page. See tools/testing/selftests/dma/dma_map_benchmark.c + +config DMA_LIVEUPDATE + bool "Enable preservation of DMA direct allocations" + depends on LIVEUPDATE diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index ec887f443741..117ebae8a81f 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -6,6 +6,8 @@ */ #include /* for max_pfn */ #include +#include +#include #include #include #include @@ -307,6 +309,193 @@ void *dma_direct_alloc(struct device *dev, size_t size, return NULL; } +#ifdef CONFIG_DMA_LIVEUPDATE +int dma_direct_preserve_allocation(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, + unsigned long attrs, u64 *state) +{ + struct dma_alloc_ser *ser; + int ret; + + if (!kho_is_enabled()) + return -EOPNOTSUPP; + + size = PAGE_ALIGN(size); + if (dma_is_from_cma(dma_to_phys(dev, dma_handle), size)) + return -EOPNOTSUPP; + + if (is_swiotlb_for_alloc(dev)) + return -EOPNOTSUPP; + + if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) && + !force_dma_unencrypted(dev)) + return -EOPNOTSUPP; + + if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_ALLOC) && + !dev_is_dma_coherent(dev)) + return -EOPNOTSUPP; + + if (IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) && + !dev_is_dma_coherent(dev)) + return -EOPNOTSUPP; + + if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) && + dma_is_from_pool(cpu_addr, size)) + return -EOPNOTSUPP; + + ser = kho_alloc_preserve(sizeof(*ser)); + if (IS_ERR(ser)) + return PTR_ERR(ser); + + ser->page_phys = dma_to_phys(dev, dma_handle); + ser->force_decrypted = force_dma_unencrypted(dev); + ser->size = size; + ser->attrs = (attrs & ~DMA_ATTR_NO_WARN); + + ret = kho_preserve_pages(phys_to_page(ser->page_phys), + 1 << get_order(size)); + if (ret) { + kho_unpreserve_free(ser); + return ret; + } + + *state = virt_to_phys(ser); + return 0; +} + +void dma_direct_unpreserve_allocation(struct device *dev, u64 state) +{ + struct dma_alloc_ser *ser; + + if (!kho_is_enabled()) + return; + + ser = phys_to_virt(state); + kho_unpreserve_pages(phys_to_page(ser->page_phys), + 1 << get_order(ser->size)); + kho_unpreserve_free(ser); +} + +void *dma_direct_restore_allocation(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp, + unsigned long attrs, u64 state) +{ + bool remap = false, set_uncached = false; + struct dma_alloc_ser *ser = NULL; + struct page *page; + void *cpu_addr = NULL; + int i; + + if (!kho_is_enabled()) + return NULL; + + ser = phys_to_virt(state); + page = phys_to_page(ser->page_phys); + + size = PAGE_ALIGN(size); + if (size != ser->size) + return NULL; + + WARN_ON_ONCE((attrs & ~DMA_ATTR_NO_WARN) != ser->attrs); + + /* + * Cannot free the restored pages on error here as these might be in use + * by a device with direct allocation in the previous kernel. + */ + if (is_swiotlb_for_alloc(dev)) + goto err; + + if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) && + !force_dma_unencrypted(dev)) + goto err; + + if (!dev_is_dma_coherent(dev)) { + if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_ALLOC)) + goto err; + + if (IS_ENABLED(CONFIG_DMA_GLOBAL_POOL)) + goto err; + + set_uncached = IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED); + remap = IS_ENABLED(CONFIG_DMA_DIRECT_REMAP); + if (!set_uncached && !remap) + goto err; + } + + if (PageHighMem(page)) { + remap = true; + set_uncached = false; + } + + /* + * Remapping will be blocking so return error. The preserved memory + * might be already decrypted in the previous kernel, but the decryption + * call is not guaranteed to be non-blocking so return error always if + * decryption is required. + */ + if ((remap || force_dma_unencrypted(dev)) && + dma_direct_use_pool(dev, gfp)) + goto err; + + /* + * Encryption scheme changed between two kernels and this might cause + * issues if device/driver is not handling it properly. + */ + WARN_ON_ONCE(ser->force_decrypted != force_dma_unencrypted(dev)); + + /* + * arch_dma_prep_coherent() should make sure that any cache lines from + * the previous kernel, if the device was coherent previously or cached + * mapping in this kernel during init are not problematic for + * non-coherent allocations. + */ + if (remap) { + pgprot_t prot = dma_pgprot(dev, PAGE_KERNEL, attrs); + + if (force_dma_unencrypted(dev)) + prot = pgprot_decrypted(prot); + + arch_dma_prep_coherent(page, size); + + cpu_addr = dma_common_contiguous_remap(page, size, prot, + __builtin_return_address(0)); + if (!cpu_addr) + goto err; + } else { + cpu_addr = page_address(page); + if (dma_set_decrypted(dev, cpu_addr, size)) { + cpu_addr = NULL; + goto err; + } + } + + if (set_uncached) { + arch_dma_prep_coherent(page, size); + cpu_addr = arch_dma_set_uncached(cpu_addr, size); + if (IS_ERR(cpu_addr)) { + cpu_addr = NULL; + goto err; + } + } + + *dma_handle = phys_to_dma_direct(dev, ser->page_phys); + +err: + WARN_ON(!kho_restore_pages(ser->page_phys, + 1 << get_order(ser->size))); + kho_restore_free(ser); + + /* + * DMA direct API expects high-order allocations, so set refcount of + * tail pages to zero. + */ + for (i = (1 << get_order(size)) - 1; i > 0; --i) + set_page_count(page + i, 0); + + return cpu_addr; +} +#endif + void dma_direct_free(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs) { -- 2.55.0.795.g602f6c329a-goog