lkml.org 
[lkml]   [2020]   [Apr]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [rfc v2 4/6] dma-direct: atomic allocations must come from atomic coherent pools
From
Date
On 4/8/20 4:21 PM, David Rientjes wrote:
> When a device required unencrypted memory and the context does not allow

required => requires

> blocking, memory must be returned from the atomic coherent pools.
>
> This avoids the remap when CONFIG_DMA_DIRECT_REMAP is not enabled and the
> config only requires CONFIG_DMA_COHERENT_POOL. This will be used for
> CONFIG_AMD_MEM_ENCRYPT in a subsequent patch.
>
> Keep all memory in these pools unencrypted.
>
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
> kernel/dma/direct.c | 16 ++++++++++++++++
> kernel/dma/pool.c | 15 +++++++++++++--
> 2 files changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index 70800ca64f13..44165263c185 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -124,6 +124,18 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
> struct page *page;
> void *ret;
>
> + /*
> + * Unencrypted memory must come directly from DMA atomic pools if
> + * blocking is not allowed.
> + */
> + if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
> + force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp)) {
> + ret = dma_alloc_from_pool(dev, PAGE_ALIGN(size), &page, gfp);
> + if (!ret)
> + return NULL;
> + goto done;
> + }
> +
> if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
> dma_alloc_need_uncached(dev, attrs) &&
> !gfpflags_allow_blocking(gfp)) {
> @@ -203,6 +215,10 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
> {
> unsigned int page_order = get_order(size);
>
> + if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
> + dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size)))
> + return;
> +
> if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
> !force_dma_unencrypted(dev)) {
> /* cpu_addr is a struct page cookie, not a kernel address */
> diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
> index e14c5a2da734..6685ab89cfa7 100644
> --- a/kernel/dma/pool.c
> +++ b/kernel/dma/pool.c
> @@ -9,6 +9,7 @@
> #include <linux/dma-contiguous.h>
> #include <linux/init.h>
> #include <linux/genalloc.h>
> +#include <linux/set_memory.h>
> #include <linux/slab.h>
> #include <linux/vmalloc.h>
> #include <linux/workqueue.h>
> @@ -55,12 +56,20 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
>
> arch_dma_prep_coherent(page, pool_size);
>
> +#ifdef CONFIG_DMA_DIRECT_REMAP
> addr = dma_common_contiguous_remap(page, pool_size,
> pgprot_dmacoherent(PAGE_KERNEL),
> __builtin_return_address(0));
> if (!addr)
> goto free_page;
> -
> +#else
> + addr = page_to_virt(page);
> +#endif
> + /*
> + * Memory in the atomic DMA pools must be unencrypted, the pools do not
> + * shrink so no re-encryption occurs in dma_direct_free_pages().
> + */
> + set_memory_decrypted((unsigned long)page_to_virt(page), 1 << order);
> ret = gen_pool_add_virt(pool, (unsigned long)addr, page_to_phys(page),
> pool_size, NUMA_NO_NODE);
> if (ret)
> @@ -69,8 +78,10 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
> return 0;
>
> remove_mapping:
> +#ifdef CONFIG_DMA_DIRECT_REMAP
> dma_common_free_remap(addr, pool_size);

You're about to free the memory, but you've called set_memory_decrypted()
against it, so you need to do a set_memory_encrypted() to bring it back to
a state ready for allocation again.

Thanks,
Tom

> -free_page:
> +#endif
> +free_page: __maybe_unused
> if (!dma_release_from_contiguous(NULL, page, 1 << order))
> __free_pages(page, order);
> out:
>

\
 
 \ /
  Last update: 2020-04-09 23:25    [W:0.121 / U:1.292 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site