From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f202.google.com (mail-pf1-f202.google.com [209.85.210.202]) (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 EFDA63AFAE7 for ; Wed, 8 Jul 2026 23:49:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783554543; cv=none; b=WZhdZo51hz6Fi9NeT/3tJAXZ+t+jZn479OQIi4QbJ7tzb/bXKh2Du5fntWTu03LtSkj+XAUAqYi3WPe4CMbDWuLRIO4ztqJU0aSBO1UYV3liTS1TAPS5KVavF0ylbbTR9vT9A4FXblfjrRR7+CW1D8oCpqMaLlfgEYkZMWS7dRc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783554543; c=relaxed/simple; bh=PVTFuMn7F4PLTSzD7pwLWPN9v2JrvWM/BmAGmuEMeYY=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=jHGXRxQ6IGy7IhGygBaE+DbKNFBlbUI9X3De9QZQPMQw+NknIZlxQaY1X6sOvx391uNG9V7SWSAjmMc+ObyMBxR0TqfjCXYL2xiu3bMlY4BVZQPUx1YlE78SC9IODDgaJhKXWp/CxQ8T++7noFmXvXXSvWjYNuVs4jOjJkfolBY= 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=AAxbPEhI; arc=none smtp.client-ip=209.85.210.202 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="AAxbPEhI" Received: by mail-pf1-f202.google.com with SMTP id d2e1a72fcca58-848551b54f5so570779b3a.0 for ; Wed, 08 Jul 2026 16:49:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1783554541; x=1784159341; 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=Mg8HPDVADkikyFkQazKzK0at34W1Wn3VUkaO82xr5dA=; b=AAxbPEhICdvLotLSAwrUdJFmixxXGINf4DSVcLZMlqUqAzR3e9YFCO8uNaYClcOw7I A6ju4cg2Z91hgLtBQYymw8XJ8cFc5z5Yj2Vvp1eyZnp7jXNfZrijmjjZNb3Tk8uJ5jhL vbffPM1FTqaLS4chgjPGZwa8t3J6A+twQ3qrP2B3UsAIwj4ijukoqwXoQqbvunPMZrXC 8PAz37JbEwGuqug8FIxqGteAURmOPGBMOsc/MtgcHmhSrYSZ8AtjHSQfhLyU3ajZ6iOX FFVGMxWc9ULOnfSVGM3Rcrye2m8B+3rQwyF5w0uSp4z1A+DFs0CiwLLlaqSmCdXfIY/O iEXA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1783554541; x=1784159341; 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=Mg8HPDVADkikyFkQazKzK0at34W1Wn3VUkaO82xr5dA=; b=Fbij/89hxjbUjaEQtHj0PK9X+OLBMu7mcyqlXyAVc7KlKP/BSZM/XzJStFePkt6h7L xn39V+W9XpCjeq2Ag+UkpQykWj7O2z4qqCMj5nAKzxCjbwwZPSV133980pb9K6/GyZZ6 Zg70F9makZEgAMSYtFh5XBFdqcRnx1THM6YVl3BDPtM10J419UOC/+pRxk+PjbZ8D1GC Q+R6tk7mwi7u3hiiFwexFRoSdywJuIHXe0NanQjph8DUpKGQihv/b8lnCZOoYB9Vu+aK 3H41ttQQRpwXSpYWlqfXwe71TtPy/sW16ADK41+lW8I5R7h8zBhvfm2aBRgQdu92/Bzp k7UQ== X-Forwarded-Encrypted: i=1; AHgh+RreU0oliQr699v1efXcoJCXCnexKYvLJk37uOTJkaYQFAgQ48s31nibzwNRvr0vzVzdgHWX3sINXwoEn64=@vger.kernel.org X-Gm-Message-State: AOJu0Yzt0t8PxJbzKxQoBPlSLrXPa4/AS7ehKeCSXnbvnTY05wx+Pz2e /nU/IYlyaZ5rWY8V9RPYSBw8WYVzpXxam0NHuTJgT6S8Phfo6pZiQ19IbXlwnFL/vZFTYN5+qm/ ZV4tvmtc6B3MSgQ== X-Received: from pfoc15.prod.google.com ([2002:aa7:880f:0:b0:847:ada8:bf86]) (user=skhawaja job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:1826:b0:842:706e:ad43 with SMTP id d2e1a72fcca58-8484324665bmr4017531b3a.33.1783554541070; Wed, 08 Jul 2026 16:49:01 -0700 (PDT) Date: Wed, 8 Jul 2026 23:48:51 +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: <20260708234854.4044652-8-skhawaja@google.com> Subject: [RFC PATCH v2 07/10] dma-mapping: Add support of preserving dmam 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" Device drivers use dmam_* allocation APIs for managed lifecycle of DMA allocations. Add support of preserving managed DMA allocations so these can be preserved and on restore these are managed again. Signed-off-by: Samiullah Khawaja --- include/linux/dma-mapping.h | 50 ++++++++++++++++++++++ kernel/dma/mapping.c | 83 +++++++++++++++++++++++++++++++++++++ 2 files changed, 133 insertions(+) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 3756fc15467b..4c0c428b6b1c 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -218,6 +218,14 @@ void dma_unpreserve_allocation(struct device *dev, u64 state); void *dma_restore_allocation_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs, u64 state); +int dmam_preserve_allocation_attrs(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, + unsigned long attrs, u64 *state); +void dmam_unpreserve_allocation(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, u64 state); +void *dmam_restore_allocation_attrs(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp, + unsigned long attrs, u64 state); #endif #else /* CONFIG_HAS_DMA */ static inline dma_addr_t dma_map_page_attrs(struct device *dev, @@ -523,6 +531,25 @@ static inline void *dma_restore_allocation_attrs(struct device *dev, size_t size { return NULL; } + +static inline int dmam_preserve_allocation_attrs(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, + unsigned long attrs, u64 *state) +{ + return -EOPNOTSUPP; +} + +static inline void dmam_unpreserve_allocation(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, u64 state) +{ +} + +static inline void *dmam_restore_allocation_attrs(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp, + unsigned long attrs, u64 state) +{ + return NULL; +} #endif struct page *dma_alloc_pages(struct device *dev, size_t size, @@ -797,6 +824,29 @@ static inline void *dmam_alloc_coherent(struct device *dev, size_t size, (gfp & __GFP_NOWARN) ? DMA_ATTR_NO_WARN : 0); } +static inline int dmam_preserve_coherent_allocation(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, u64 *state) +{ + return dmam_preserve_allocation_attrs(dev, cpu_addr, size, + dma_handle, 0, state); +} + +static inline void dmam_unpreserve_coherent_allocation(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, + u64 state) +{ + dmam_unpreserve_allocation(dev, cpu_addr, size, dma_handle, state); +} + +static inline void *dmam_restore_coherent_allocation(struct device *dev, size_t size, + dma_addr_t *dma_handle, + gfp_t gfp, u64 state) +{ + return dmam_restore_allocation_attrs(dev, size, dma_handle, gfp, + (gfp & __GFP_NOWARN) ? DMA_ATTR_NO_WARN : 0, + state); +} + static inline void *dma_alloc_wc(struct device *dev, size_t size, dma_addr_t *dma_addr, gfp_t gfp) { diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 3b07bf30722c..aec1222ab5ae 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -37,12 +37,25 @@ struct dma_devres { void *vaddr; dma_addr_t dma_handle; unsigned long attrs; +#ifdef CONFIG_DMA_LIVEUPDATE + bool is_preserved; +#endif }; static void dmam_release(struct device *dev, void *res) { struct dma_devres *this = res; +#ifdef CONFIG_DMA_LIVEUPDATE + /* + * Freeing the preserved memory is dangerous as it can cause UAF in the + * current or next kernel if the memory is still being used by the + * device. + */ + if (WARN_ON(this->is_preserved)) + return; +#endif + dma_free_attrs(dev, this->size, this->vaddr, this->dma_handle, this->attrs); } @@ -675,6 +688,76 @@ void *dma_restore_allocation_attrs(struct device *dev, size_t size, return cpu_addr; } EXPORT_SYMBOL(dma_restore_allocation_attrs); + +int dmam_preserve_allocation_attrs(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, + unsigned long attrs, u64 *state) +{ + struct dma_devres match_data = { size, cpu_addr, dma_handle }; + struct dma_devres *dr; + int ret; + + dr = devres_find(dev, dmam_release, dmam_match, &match_data); + if (!dr) + return -EINVAL; + + if (dr->is_preserved) + return -EINVAL; + + ret = dma_preserve_allocation_attrs(dev, cpu_addr, size, dma_handle, attrs, state); + if (ret) + return ret; + + dr->is_preserved = true; + return 0; +} +EXPORT_SYMBOL(dmam_preserve_allocation_attrs); + +void dmam_unpreserve_allocation(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, u64 state) +{ + struct dma_devres match_data = { size, cpu_addr, dma_handle }; + struct dma_devres *dr; + + dr = devres_find(dev, dmam_release, dmam_match, &match_data); + if (!dr) + return; + + if (!dr->is_preserved) + return; + + dma_unpreserve_allocation(dev, state); + dr->is_preserved = false; +} +EXPORT_SYMBOL(dmam_unpreserve_allocation); + +void *dmam_restore_allocation_attrs(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp, + unsigned long attrs, u64 state) +{ + struct dma_devres *dr; + void *vaddr; + + dr = devres_alloc(dmam_release, sizeof(*dr), gfp); + if (!dr) + return NULL; + + vaddr = dma_restore_allocation_attrs(dev, size, dma_handle, gfp, attrs, state); + if (!vaddr) { + devres_free(dr); + return NULL; + } + + dr->vaddr = vaddr; + dr->dma_handle = *dma_handle; + dr->size = size; + dr->attrs = attrs; + + devres_add(dev, dr); + + return vaddr; +} +EXPORT_SYMBOL(dmam_restore_allocation_attrs); #endif void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, -- 2.55.0.795.g602f6c329a-goog