From: Christoph Hellwig <hch@lst.de>
To: Claire Chang <tientzu@chromium.org>
Cc: Rob Herring <robh+dt@kernel.org>,
mpe@ellerman.id.au, Joerg Roedel <joro@8bytes.org>,
Will Deacon <will@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
boris.ostrovsky@oracle.com, jgross@suse.com,
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Subject: Re: [PATCH v9 07/14] swiotlb: Bounce data from/to restricted DMA pool if available
Date: Mon, 14 Jun 2021 08:25:30 +0200 [thread overview]
Message-ID: <20210614062530.GG28343@lst.de> (raw)
In-Reply-To: <20210611152659.2142983-8-tientzu@chromium.org>
On Fri, Jun 11, 2021 at 11:26:52PM +0800, Claire Chang wrote:
> Regardless of swiotlb setting, the restricted DMA pool is preferred if
> available.
>
> The restricted DMA pools provide a basic level of protection against the
> DMA overwriting buffer contents at unexpected times. However, to protect
> against general data leakage and system memory corruption, the system
> needs to provide a way to lock down the memory access, e.g., MPU.
>
> Note that is_dev_swiotlb_force doesn't check if
> swiotlb_force == SWIOTLB_FORCE. Otherwise the memory allocation behavior
> with default swiotlb will be changed by the following patche
> ("dma-direct: Allocate memory from restricted DMA pool if available").
>
> Signed-off-by: Claire Chang <tientzu@chromium.org>
> ---
> include/linux/swiotlb.h | 10 +++++++++-
> kernel/dma/direct.c | 3 ++-
> kernel/dma/direct.h | 3 ++-
> kernel/dma/swiotlb.c | 1 +
> 4 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> index 06cf17a80f5c..8200c100fe10 100644
> --- a/include/linux/swiotlb.h
> +++ b/include/linux/swiotlb.h
> @@ -85,6 +85,7 @@ extern enum swiotlb_force swiotlb_force;
> * unmap calls.
> * @debugfs: The dentry to debugfs.
> * @late_alloc: %true if allocated using the page allocator
> + * @force_swiotlb: %true if swiotlb is forced
> */
> struct io_tlb_mem {
> phys_addr_t start;
> @@ -95,6 +96,7 @@ struct io_tlb_mem {
> spinlock_t lock;
> struct dentry *debugfs;
> bool late_alloc;
> + bool force_swiotlb;
> struct io_tlb_slot {
> phys_addr_t orig_addr;
> size_t alloc_size;
> @@ -115,6 +117,11 @@ static inline void swiotlb_set_io_tlb_default_mem(struct device *dev)
> dev->dma_io_tlb_mem = io_tlb_default_mem;
> }
>
> +static inline bool is_dev_swiotlb_force(struct device *dev)
> +{
> + return dev->dma_io_tlb_mem->force_swiotlb;
> +}
> +
> void __init swiotlb_exit(void);
> unsigned int swiotlb_max_segment(void);
> size_t swiotlb_max_mapping_size(struct device *dev);
> @@ -126,8 +133,9 @@ static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr)
> {
> return false;
> }
> -static inline void swiotlb_set_io_tlb_default_mem(struct device *dev)
> +static inline bool is_dev_swiotlb_force(struct device *dev)
> {
> + return false;
> }
> static inline void swiotlb_exit(void)
> {
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index 7a88c34d0867..078f7087e466 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -496,7 +496,8 @@ size_t dma_direct_max_mapping_size(struct device *dev)
> {
> /* If SWIOTLB is active, use its maximum mapping size */
> if (is_swiotlb_active(dev) &&
> - (dma_addressing_limited(dev) || swiotlb_force == SWIOTLB_FORCE))
> + (dma_addressing_limited(dev) || swiotlb_force == SWIOTLB_FORCE ||
> + is_dev_swiotlb_force(dev)))
I think we can remove the extra swiotlb_force check here if the
swiotlb_force setting is propagated into io_tlb_default_mem->force
when that is initialized. This avoids an extra check in the fast path.
> - if (unlikely(swiotlb_force == SWIOTLB_FORCE))
> + if (unlikely(swiotlb_force == SWIOTLB_FORCE) ||
> + is_dev_swiotlb_force(dev))
Same here.
next prev parent reply other threads:[~2021-06-14 6:25 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-11 15:26 [PATCH v9 00/14] Restricted DMA Claire Chang
2021-06-11 15:26 ` [PATCH v9 01/14] swiotlb: Refactor swiotlb init functions Claire Chang
2021-06-14 6:16 ` Christoph Hellwig
2021-06-15 4:06 ` Claire Chang
2021-06-11 15:26 ` [PATCH v9 02/14] swiotlb: Refactor swiotlb_create_debugfs Claire Chang
2021-06-14 6:17 ` Christoph Hellwig
2021-06-11 15:26 ` [PATCH v9 03/14] swiotlb: Set dev->dma_io_tlb_mem to the swiotlb pool used Claire Chang
2021-06-11 15:33 ` Claire Chang
2021-06-14 6:20 ` Christoph Hellwig
2021-06-11 15:26 ` [PATCH v9 04/14] swiotlb: Add restricted DMA pool initialization Claire Chang
2021-06-14 6:21 ` Christoph Hellwig
2021-06-11 15:26 ` [PATCH v9 05/14] swiotlb: Update is_swiotlb_buffer to add a struct device argument Claire Chang
2021-06-14 6:21 ` Christoph Hellwig
2021-06-11 15:26 ` [PATCH v9 06/14] swiotlb: Update is_swiotlb_active " Claire Chang
2021-06-11 15:34 ` Claire Chang
2021-06-14 6:23 ` Christoph Hellwig
2021-06-11 15:26 ` [PATCH v9 07/14] swiotlb: Bounce data from/to restricted DMA pool if available Claire Chang
2021-06-14 6:25 ` Christoph Hellwig [this message]
2021-06-11 15:26 ` [PATCH v9 08/14] swiotlb: Move alloc_size to find_slots Claire Chang
2021-06-14 6:25 ` Christoph Hellwig
2021-06-11 15:26 ` [PATCH v9 09/14] swiotlb: Refactor swiotlb_tbl_unmap_single Claire Chang
2021-06-14 6:26 ` Christoph Hellwig
2021-06-11 15:26 ` [PATCH v9 10/14] dma-direct: Add a new wrapper __dma_direct_free_pages() Claire Chang
2021-06-11 15:26 ` [PATCH v9 11/14] swiotlb: Add restricted DMA alloc/free support Claire Chang
2021-06-14 6:28 ` Christoph Hellwig
2021-06-14 6:28 ` Christoph Hellwig
2021-06-11 15:26 ` [PATCH v9 12/14] dma-direct: Allocate memory from restricted DMA pool if available Claire Chang
2021-06-11 15:26 ` [PATCH v9 13/14] dt-bindings: of: Add restricted DMA pool Claire Chang
2021-06-11 15:26 ` [PATCH v9 14/14] of: Add plumbing for " Claire Chang
2021-06-15 13:30 ` [PATCH v9 00/14] Restricted DMA Claire Chang
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