From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (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 C5C3A470E8E for ; Wed, 2 Sep 2026 10:51:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.71 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788346294; cv=none; b=eugfnOprbzV1zFLHBN7WhwLYa08pVAwskr1aF/A3lqNom0i/FqZXiWaX4YWKoqC3kL08RnwLUvTs8XMRodSNsElVPoFMuEfAK2NeTlk3Hequ9NIZqeoQJCoHkWBCX/P+34Xb3f5VlUAyXwr0i26BaHWD5GwbqsJqOgHBZv+Cb6I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788346294; c=relaxed/simple; bh=kTw+a5cGg9fTfwWcDo0uZpH7mwb0/GZmgWLGcOqsPDM=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=CmK+/p4aDMCN3rHXCu6XUamMJhgwe0jj/5f5VbthEUD4QtVdvtyAcYDVFbZMzrZWYdGxLLD8LZccOvH3sRUkDrNbXp0XGGu9My8hwNwu8xqTyBD2+tQkQ9+Q2I0qds0CgmVoRVlTfT021WSzdazPiUsJrfnbHie2HJXPOhca9fM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=UC+bVqb+; arc=none smtp.client-ip=209.85.128.71 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--vdonnefort.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="UC+bVqb+" Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-49cc954a3edso5935685e9.2 for ; Wed, 02 Sep 2026 03:51:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1788346277; x=1788951077; 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=xnnAKTx0rWFGRttv0vRYvbBX3qhJSeyXfYhwCY9t/xQ=; b=UC+bVqb+EofhB5NYpXaXML6PEgtAE8Dndt7tsWfldqIHii9FV6g+Ry3Ns3Su4SR+rU aYy16Nv8puKhdlz9XO/28vxrPJ6ijDvBX7At8LWjV6yUOJSm7MPR6x8n5pDTV0zLyoBE BrOKHCOwXc9hIRLVcygdCLQhyaMFirQv5BQ2yMmXn5bIV/py6TXrunQxEiNxE3eSHIMp S/5kWKge6ziv83eGGMGfRAL32g0sw9tK9p6vlJ8GNcnwFOisAWkp0GnaxA+IGt86f0rz MkZ7536jutQn3tvUfL/XBNnYApjZ0VP40Uf+WcKPLpdQQe8vhX9cMFGUTjwHKI+66JPV 01xA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788346277; x=1788951077; 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=xnnAKTx0rWFGRttv0vRYvbBX3qhJSeyXfYhwCY9t/xQ=; b=Gn/WRwHUBTeBiA/cdPQ4sz5bq3Wm+DG1GfkdrwcAbUrhPrb763GAvwsLROMHdMp9S5 JEa+mT05IukAgus6hPqwrm3GZDtV5r3rJWMnYVQYjmDKkiVgI4kU8ynX+W1ldU5QMXHU LlVbN/5+HwMMwFM/SfnVYC4EBGRTaHDkpYgRxpmKiRwoU9dB6P6EO1aUp7tH2UV5A5TI r+d9HxI0Fu+k2yWoYQzw3WmCpudg4hlfCGebog86NQKQ6MjXE1HPYkXzLFFgmgj5yb1a cYkTThXlq46X6RdtRtbJzo1KZVWhig2RL4XiEeBB+TcbcIxKDACNOOXPQnRx5BqpquoI soTA== X-Forwarded-Encrypted: i=1; AHgh+RqMN8GtBjRmxdpqLqPpyWNxJZqx3ei5x+1JeGJ4sKiUpG1zS3CJ8H4AYzhjSEEddsfoeqxrRGOI5VMp@vger.kernel.org X-Gm-Message-State: AFuF++maZ58Gyn0JrWJxpPAQGjYpL0/PY2CkliovVbAdMA32jc+2Vccw G/jo1hGHe5gfLN48yS9NPvi9+/gRU0zOSe+zoBfYuWGHbaLmMUB9egMGQBhcYRgVETTEY1NK330 GxemgPPoTPhIzyQKIkjGIog== X-Received: from wmqh12.prod.google.com ([2002:a05:600c:350c:b0:496:c04d:501e]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:310f:b0:49b:c8e:a211 with SMTP id 5b1f17b1804b1-49ce57f27e8mr57275175e9.5.1788346277042; Wed, 02 Sep 2026 03:51:17 -0700 (PDT) Date: Wed, 2 Sep 2026 11:47:11 +0100 In-Reply-To: <20260902104712.2399797-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260902104712.2399797-1-vdonnefort@google.com> X-Mailer: git-send-email 2.55.0.970.g62bdec98f9-goog Message-ID: <20260902104712.2399797-10-vdonnefort@google.com> Subject: [PATCH v9 09/10] firmware: arm_ffa: Introduce ffa-lend-pool From: Vincent Donnefort To: catalin.marinas@arm.com, will@kernel.org, rppt@kernel.org, akpm@linux-foundation.org, sudeep.holla@kernel.org, jenswi@kernel.org, robh@kernel.org Cc: mark.rutland@arm.com, sumit.garg@kernel.org, ardb@kernel.org, thierry.reding@kernel.org, david@kernel.org, danielmentz@google.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, op-tee@lists.trustedfirmware.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" When memory is lent to the Secure world via FF-A, fatal CPU speculative reads from Non-Secure can still occur as long as it retains a cacheable mapping to that memory. Introduce the "arm,ffa-lend-pool" reserved-memory CMA driver to unmap pages before lending (ffa_prepare_lend()) and restore them upon reclaim (ffa_lend_reclaimed()). Devices bind to the pool via the "memory-region" DT property or via ffa_lend_pool_attach(). reserved-memory { #address-cells = <0x2>; #size-cells = <0x2>; ranges; ffa_lend: ffa-lend-pool { compatible = "arm,ffa-lend-pool"; reusable; ll-map; size = <0x0 0x4000000>; }; }; Signed-off-by: Vincent Donnefort diff --git a/drivers/firmware/arm_ffa/Kconfig b/drivers/firmware/arm_ffa/Kconfig index 5e3ae5cf82e8..66dbf74c37c3 100644 --- a/drivers/firmware/arm_ffa/Kconfig +++ b/drivers/firmware/arm_ffa/Kconfig @@ -19,3 +19,8 @@ config ARM_FFA_SMCCC bool default ARM_FFA_TRANSPORT depends on ARM64 && HAVE_ARM_SMCCC_DISCOVERY + +config ARM_FFA_LEND_POOL + bool + default y + depends on ARM_FFA_TRANSPORT && CMA && OF_RESERVED_MEM diff --git a/drivers/firmware/arm_ffa/Makefile b/drivers/firmware/arm_ffa/Makefile index 168990a7e792..5ea3019c407b 100644 --- a/drivers/firmware/arm_ffa/Makefile +++ b/drivers/firmware/arm_ffa/Makefile @@ -6,3 +6,4 @@ ffa-core-objs := $(ffa-bus-y) ffa-module-objs := $(ffa-driver-y) $(ffa-transport-y) obj-$(CONFIG_ARM_FFA_TRANSPORT) = ffa-core.o obj-$(CONFIG_ARM_FFA_TRANSPORT) += ffa-module.o +obj-$(CONFIG_ARM_FFA_LEND_POOL) += lend_pool.o diff --git a/drivers/firmware/arm_ffa/lend_pool.c b/drivers/firmware/arm_ffa/lend_pool.c new file mode 100644 index 000000000000..67a36f5d5aa6 --- /dev/null +++ b/drivers/firmware/arm_ffa/lend_pool.c @@ -0,0 +1,223 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Arm FF-A Reserved Memory CMA driver for Memory Lending + * + * Prevents CPU speculative reads to secure memory by unmapping it from the + * kernel direct map. This only works if the reserved-memory is mapped at the + * last-level ("ll-map;" or "rodata=full") or if all CPUs in the system support + * BBML3. + * + * Copyright (C) 2026 Google LLC + * Author: Vincent Donnefort + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static DEFINE_XARRAY(ffa_lend_devices); + +static bool ffa_lend_pool_contains(struct device *dev, phys_addr_t addr, size_t size) +{ + phys_addr_t base, end; + + if (!dev) + return false; + + guard(rcu)(); + + if (xa_load(&ffa_lend_devices, (unsigned long)dev) != dev) + return false; + + if (WARN_ON_ONCE(!dev->cma_area)) + return false; + + base = cma_get_base(dev->cma_area); + end = base + cma_get_size(dev->cma_area); + + return addr >= base && (addr + size) <= end; +} + +/** + * ffa_prepare_lend() - Prepare a memory region to be lent in FF-A + * @dev: Device attached to the lend pool + * @addr: Physical start address of the memory region + * @size: Size in bytes + * + * When memory is lent via FF-A, TrustZone transitions it to the secure state. + * As long as Arm CPUs retain a valid mapping to that now-secure memory, they + * can speculatively read it, which is fatal on some systems. + * + * ffa_prepare_lend() prevents this by unmapping the memory range from the + * kernel's direct map. + * + * Return: 0 on success, negative error code otherwise. + */ +int ffa_prepare_lend(struct device *dev, phys_addr_t addr, size_t size) +{ + unsigned long nr_pages = size >> PAGE_SHIFT; + struct page *page; + unsigned long i; + int ret; + + if (!ffa_lend_pool_contains(dev, addr, size)) + return -ENODEV; + + page = pfn_to_page(PHYS_PFN(addr)); + for (i = 0; i < nr_pages; i++) { + ret = __set_direct_map_invalid_noflush(page + i); + + if (ret) { + while (i--) + __set_direct_map_default_noflush(page + i); + + return ret; + } + } + + return 0; +} +EXPORT_SYMBOL_GPL(ffa_prepare_lend); + +/** + * ffa_lend_reclaimed() - Restore a reclaimed FF-A memory region + * @dev: Device attached to the lend pool + * @addr: Physical start address of the memory region + * @size: Size in bytes + * + * Restores a memory range into the kernel's direct mapping. It must be called + * after a successful FF-A memory reclaim invocation. + */ +void ffa_lend_reclaimed(struct device *dev, phys_addr_t addr, size_t size) +{ + unsigned long nr_pages = size >> PAGE_SHIFT; + struct page *page; + unsigned long i; + + if (!ffa_lend_pool_contains(dev, addr, size)) + return; + + page = pfn_to_page(PHYS_PFN(addr)); + for (i = 0; i < nr_pages; i++) + __set_direct_map_default_noflush(page + i); +} +EXPORT_SYMBOL_GPL(ffa_lend_reclaimed); + +/** + * ffa_lend_pool_attach() - Attach a device to the FF-A lend pool + * @dev: Device to attach + * + * FF-A devices are dynamically discovered and might not have an associated + * device tree node with a "memory-region" phandle. In that case, drivers must + * use this function to attach to the "arm,ffa-lend-pool" reserved memory + * region. + * + * Return: 0 on success, negative error code otherwise. + */ +int ffa_lend_pool_attach(struct device *dev) +{ + struct device_node *np; + struct reserved_mem *rmem; + + np = of_find_compatible_node(NULL, NULL, "arm,ffa-lend-pool"); + if (!np) + return -ENODEV; + + rmem = of_reserved_mem_lookup(np); + of_node_put(np); + if (!rmem || !rmem->ops || !rmem->ops->device_init) + return -EINVAL; + + return rmem->ops->device_init(rmem, dev); +} +EXPORT_SYMBOL_GPL(ffa_lend_pool_attach); + +/** + * ffa_lend_pool_detach() - Detach a device from the FF-A lend pool + * @dev: Device to detach + * + * Releases the device from the "arm,ffa-lend-pool" reserved memory region. + */ +void ffa_lend_pool_detach(struct device *dev) +{ + struct device_node *np; + struct reserved_mem *rmem; + + np = of_find_compatible_node(NULL, NULL, "arm,ffa-lend-pool"); + if (!np) + return; + + rmem = of_reserved_mem_lookup(np); + of_node_put(np); + + if (rmem && rmem->ops && rmem->ops->device_release) + rmem->ops->device_release(rmem, dev); +} +EXPORT_SYMBOL_GPL(ffa_lend_pool_detach); + +static int __init ffa_lend_pool_setup(unsigned long node, struct reserved_mem *rmem) +{ + struct cma *cma; + int ret; + + if (!of_get_flat_dt_prop(node, "reusable", NULL) || + of_get_flat_dt_prop(node, "no-map", NULL)) { + pr_err("FF-A lend pool: node must be 'reusable' and not 'no-map'\n"); + return -EINVAL; + } + + if (!IS_ALIGNED(rmem->base | rmem->size, CMA_MIN_ALIGNMENT_BYTES)) { + pr_err("FF-A lend pool: incorrect alignment of CMA region\n"); + return -EINVAL; + } + + ret = cma_init_reserved_mem(rmem->base, rmem->size, 0, rmem->name, &cma); + if (ret) { + pr_err("FF-A lend pool: unable to setup CMA region (%d)\n", ret); + return ret; + } + + rmem->priv = cma; + + return 0; +} + +static int ffa_lend_pool_device_init(struct reserved_mem *rmem, struct device *dev) +{ + int ret; + + if (!can_set_direct_map_range(pfn_to_page(PHYS_PFN(rmem->base)), rmem->size / PAGE_SIZE)) { + pr_err("FF-A lend pool: reserved memory cannot be unmapped in direct map\n"); + return -EINVAL; + } + + dev->cma_area = rmem->priv; + + ret = xa_err(xa_store(&ffa_lend_devices, (unsigned long)dev, dev, GFP_KERNEL)); + if (ret) + dev->cma_area = NULL; + + return ret; +} + +static void ffa_lend_pool_device_release(struct reserved_mem *rmem, struct device *dev) +{ + xa_erase(&ffa_lend_devices, (unsigned long)dev); + dev->cma_area = NULL; +} + +static const struct reserved_mem_ops ffa_lend_pool_ops = { + .node_init = ffa_lend_pool_setup, + .device_init = ffa_lend_pool_device_init, + .device_release = ffa_lend_pool_device_release, +}; +RESERVEDMEM_OF_DECLARE(ffa_lend_pool, "arm,ffa-lend-pool", &ffa_lend_pool_ops); diff --git a/include/linux/arm_ffa.h b/include/linux/arm_ffa.h index e71d83ee0aef..fa3570f85ff7 100644 --- a/include/linux/arm_ffa.h +++ b/include/linux/arm_ffa.h @@ -519,4 +519,25 @@ struct ffa_ops { const struct ffa_notifier_ops *notifier_ops; }; +#if IS_ENABLED(CONFIG_ARM_FFA_LEND_POOL) +int ffa_lend_pool_attach(struct device *dev); +void ffa_lend_pool_detach(struct device *dev); +int ffa_prepare_lend(struct device *dev, phys_addr_t paddr, size_t size); +void ffa_lend_reclaimed(struct device *dev, phys_addr_t paddr, size_t size); +#else +static inline int ffa_lend_pool_attach(struct device *dev) +{ + return -ENODEV; +} +static inline void ffa_lend_pool_detach(struct device *dev) +{ +} +static inline int ffa_prepare_lend(struct device *dev, phys_addr_t paddr, size_t size) +{ + return -ENODEV; +} +static inline void ffa_lend_reclaimed(struct device *dev, phys_addr_t paddr, size_t size) +{ +} +#endif #endif /* _LINUX_ARM_FFA_H */ -- 2.55.0.970.g62bdec98f9-goog