From: Petr Tesarik <ptesarik@suse•com>
To: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel•org>
Cc: iommu@lists•linux.dev, linux-arm-kernel@lists•infradead.org,
linux-kernel@vger•kernel.org, linux-coco@lists•linux.dev,
Robin Murphy <robin.murphy@arm•com>,
Marek Szyprowski <m.szyprowski@samsung•com>,
Will Deacon <will@kernel•org>, Marc Zyngier <maz@kernel•org>,
Steven Price <steven.price@arm•com>,
Suzuki K Poulose <Suzuki.Poulose@arm•com>,
Catalin Marinas <catalin.marinas@arm•com>,
Jiri Pirko <jiri@resnulli•us>, Jason Gunthorpe <jgg@ziepe•ca>,
Mostafa Saleh <smostafa@google•com>,
Alexey Kardashevskiy <aik@amd•com>,
Dan Williams <dan.j.williams@intel•com>,
Xu Yilun <yilun.xu@linux•intel.com>,
linuxppc-dev@lists•ozlabs.org, linux-s390@vger•kernel.org,
Madhavan Srinivasan <maddy@linux•ibm.com>,
Michael Ellerman <mpe@ellerman•id.au>,
Nicholas Piggin <npiggin@gmail•com>,
"Christophe Leroy (CS GROUP)" <chleroy@kernel•org>,
Alexander Gordeev <agordeev@linux•ibm.com>,
Gerald Schaefer <gerald.schaefer@linux•ibm.com>,
Heiko Carstens <hca@linux•ibm.com>,
Vasily Gorbik <gor@linux•ibm.com>,
Christian Borntraeger <borntraeger@linux•ibm.com>,
Sven Schnelle <svens@linux•ibm.com>,
x86@kernel•org, Michael Kelley <mhklinux@outlook•com>
Subject: Re: [PATCH v6 19/20] swiotlb: Preserve allocation virtual address for dynamic pools
Date: Tue, 9 Jun 2026 15:40:18 +0200 [thread overview]
Message-ID: <20260609154018.554e5448@mordecai> (raw)
In-Reply-To: <20260604083959.1265923-20-aneesh.kumar@kernel.org>
On Thu, 4 Jun 2026 14:09:58 +0530
"Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel•org> wrote:
> swiotlb_alloc_tlb() can allocate from the DMA atomic pool when a decrypted
> pool is needed from atomic context. With CONFIG_DMA_DIRECT_REMAP, the
> atomic pool is backed by remapped virtual addresses, which are not the same
> as the direct-map addresses returned by phys_to_virt().
>
> swiotlb_init_io_tlb_pool() currently reconstructs the pool virtual address
> from the physical start address. For atomic-pool backed allocations this
> stores the wrong address in pool->vaddr. Later, swiotlb_free_tlb() passes
> that address to dma_free_from_pool(), which will fail to recognize the
> chunk
>
> Pass the virtual address returned by the allocation path into
> swiotlb_init_io_tlb_pool(), and store that address in pool->vaddr. This
> keeps the pool free path using the same virtual address as the allocator.
>
> Tested-by: Michael Kelley <mhklinux@outlook•com>
> Tested-by: Mostafa Saleh <smostafa@google•com>
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel•org>
Hm, so the old code was broken; you may want to add:
Fixes: 79636caad361 ("swiotlb: if swiotlb is full, fall back to a transient memory pool")
And of course:
Reviewed-by: Petr Tesarik <ptesarik@suse•com>
Thank you!
Petr T
> ---
> kernel/dma/swiotlb.c | 32 +++++++++++++++++++-------------
> 1 file changed, 19 insertions(+), 13 deletions(-)
>
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 14d834ca298b..e4bd8c9eaeda 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -302,9 +302,9 @@ void __init swiotlb_update_mem_attributes(void)
> }
>
> static void swiotlb_init_io_tlb_pool(struct io_tlb_pool *mem, phys_addr_t start,
> - unsigned long nslabs, bool late_alloc, unsigned int nareas)
> + void *vaddr, unsigned long nslabs, bool late_alloc,
> + unsigned int nareas)
> {
> - void *vaddr = phys_to_virt(start);
> unsigned long bytes = nslabs << IO_TLB_SHIFT, i;
>
> mem->nslabs = nslabs;
> @@ -445,7 +445,7 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags,
> return;
> }
>
> - swiotlb_init_io_tlb_pool(mem, __pa(tlb), nslabs, false, nareas);
> + swiotlb_init_io_tlb_pool(mem, __pa(tlb), tlb, nslabs, false, nareas);
> add_mem_pool(&io_tlb_default_mem, mem);
>
> if (flags & SWIOTLB_VERBOSE)
> @@ -553,7 +553,7 @@ int swiotlb_init_late(size_t size, gfp_t gfp_mask,
> }
> }
>
> - swiotlb_init_io_tlb_pool(mem, virt_to_phys(vstart), nslabs, true,
> + swiotlb_init_io_tlb_pool(mem, virt_to_phys(vstart), vstart, nslabs, true,
> nareas);
> add_mem_pool(&io_tlb_default_mem, mem);
>
> @@ -664,25 +664,26 @@ static struct page *alloc_dma_pages(gfp_t gfp, size_t bytes,
> * @phys_limit: Maximum allowed physical address of the buffer.
> * @attrs: DMA attributes for the allocation.
> * @gfp: GFP flags for the allocation.
> + * @vaddr: Receives the virtual address for the allocated buffer.
> *
> * Return: Allocated pages, or %NULL on allocation failure.
> */
> static struct page *swiotlb_alloc_tlb(struct device *dev, size_t bytes,
> - u64 phys_limit, unsigned long attrs, gfp_t gfp)
> + u64 phys_limit, unsigned long attrs, gfp_t gfp, void **vaddr)
> {
> struct page *page;
>
> + *vaddr = NULL;
> +
> /*
> * Allocate from the atomic pools if memory is encrypted and
> * the allocation is atomic, because decrypting may block.
> */
> if (!gfpflags_allow_blocking(gfp) && (attrs & DMA_ATTR_CC_SHARED)) {
> - void *vaddr;
> -
> if (!IS_ENABLED(CONFIG_DMA_COHERENT_POOL))
> return NULL;
>
> - return dma_alloc_from_pool(dev, bytes, &vaddr, gfp,
> + return dma_alloc_from_pool(dev, bytes, vaddr, gfp,
> attrs, dma_coherent_ok);
> }
>
> @@ -705,6 +706,8 @@ static struct page *swiotlb_alloc_tlb(struct device *dev, size_t bytes,
> return NULL;
> }
>
> + if (page)
> + *vaddr = phys_to_virt(page_to_phys(page));
> return page;
> }
>
> @@ -750,6 +753,7 @@ static struct io_tlb_pool *swiotlb_alloc_pool(struct device *dev,
> {
> struct io_tlb_pool *pool;
> unsigned int slot_order;
> + void *tlb_vaddr;
> struct page *tlb;
> size_t pool_size;
> size_t tlb_size;
> @@ -767,7 +771,8 @@ static struct io_tlb_pool *swiotlb_alloc_pool(struct device *dev,
> pool->unencrypted = !!(attrs & DMA_ATTR_CC_SHARED);
>
> tlb_size = nslabs << IO_TLB_SHIFT;
> - while (!(tlb = swiotlb_alloc_tlb(dev, tlb_size, phys_limit, attrs, gfp))) {
> + while (!(tlb = swiotlb_alloc_tlb(dev, tlb_size, phys_limit, attrs, gfp,
> + &tlb_vaddr))) {
> if (nslabs <= minslabs)
> goto error_tlb;
> nslabs = ALIGN(nslabs >> 1, IO_TLB_SEGSIZE);
> @@ -781,12 +786,12 @@ static struct io_tlb_pool *swiotlb_alloc_pool(struct device *dev,
> if (!pool->slots)
> goto error_slots;
>
> - swiotlb_init_io_tlb_pool(pool, page_to_phys(tlb), nslabs, true, nareas);
> + swiotlb_init_io_tlb_pool(pool, page_to_phys(tlb), tlb_vaddr, nslabs,
> + true, nareas);
> return pool;
>
> error_slots:
> - swiotlb_free_tlb(page_address(tlb), tlb_size,
> - !!(attrs & DMA_ATTR_CC_SHARED));
> + swiotlb_free_tlb(tlb_vaddr, tlb_size, !!(attrs & DMA_ATTR_CC_SHARED));
> error_tlb:
> kfree(pool);
> error:
> @@ -1995,7 +2000,8 @@ static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
> mem->unencrypted = false;
> }
>
> - swiotlb_init_io_tlb_pool(pool, rmem->base, nslabs,
> + swiotlb_init_io_tlb_pool(pool, rmem->base, phys_to_virt(rmem->base),
> + nslabs,
> false, nareas);
> mem->force_bounce = true;
> mem->for_alloc = true;
next prev parent reply other threads:[~2026-06-09 13:40 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-04 8:39 [PATCH v6 00/20] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Aneesh Kumar K.V (Arm)
2026-06-04 8:39 ` [PATCH v6 01/20] s390: Expose protected virtualization through cc_platform_has() Aneesh Kumar K.V (Arm)
2026-06-06 0:34 ` JAEHOON KIM
2026-06-09 13:44 ` Catalin Marinas
2026-06-04 8:39 ` [PATCH v6 02/20] dma-direct: swiotlb: handle swiotlb alloc/free outside __dma_direct_alloc_pages Aneesh Kumar K.V (Arm)
2026-06-09 12:15 ` Petr Tesarik
2026-06-04 8:39 ` [PATCH v6 03/20] dma-direct: use DMA_ATTR_CC_SHARED in alloc/free paths Aneesh Kumar K.V (Arm)
2026-06-09 12:18 ` Petr Tesarik
2026-06-04 8:39 ` [PATCH v6 04/20] dma-pool: track decrypted atomic pools and select them via attrs Aneesh Kumar K.V (Arm)
2026-06-09 12:23 ` Petr Tesarik
2026-06-09 14:32 ` Jason Gunthorpe
2026-06-04 8:39 ` [PATCH v6 05/20] dma: swiotlb: pass mapping attributes by reference Aneesh Kumar K.V (Arm)
2026-06-09 12:21 ` Petr Tesarik
2026-06-04 8:39 ` [PATCH v6 06/20] dma: swiotlb: track pool encryption state and honor DMA_ATTR_CC_SHARED Aneesh Kumar K.V (Arm)
2026-06-09 12:48 ` Petr Tesarik
2026-06-04 8:39 ` [PATCH v6 07/20] dma-mapping: make dma_pgprot() " Aneesh Kumar K.V (Arm)
2026-06-04 8:39 ` [PATCH v6 08/20] dma-direct: pass attrs to dma_capable() for DMA_ATTR_CC_SHARED checks Aneesh Kumar K.V (Arm)
2026-06-09 12:50 ` Petr Tesarik
2026-06-04 8:39 ` [PATCH v6 09/20] dma-direct: make dma_direct_map_phys() honor DMA_ATTR_CC_SHARED Aneesh Kumar K.V (Arm)
2026-06-04 8:39 ` [PATCH v6 10/20] dma-direct: set decrypted flag for remapped DMA allocations Aneesh Kumar K.V (Arm)
2026-06-04 8:39 ` [PATCH v6 11/20] dma-direct: select DMA address encoding from DMA_ATTR_CC_SHARED Aneesh Kumar K.V (Arm)
2026-06-04 8:39 ` [PATCH v6 12/20] dma-pool: fix page leak in atomic_pool_expand() cleanup Aneesh Kumar K.V (Arm)
2026-06-04 8:39 ` [PATCH v6 13/20] dma-direct: rename ret to cpu_addr in alloc helpers Aneesh Kumar K.V (Arm)
2026-06-09 12:54 ` Petr Tesarik
2026-06-04 8:39 ` [PATCH v6 14/20] dma-direct: return struct page from dma_direct_alloc_from_pool() Aneesh Kumar K.V (Arm)
2026-06-09 13:12 ` Petr Tesarik
2026-06-09 13:45 ` Catalin Marinas
2026-06-09 14:15 ` Jason Gunthorpe
2026-06-04 8:39 ` [PATCH v6 15/20] iommu/dma: Check atomic pool allocation result directly Aneesh Kumar K.V (Arm)
2026-06-09 13:13 ` Petr Tesarik
2026-06-04 8:39 ` [PATCH v6 16/20] dma: swiotlb: free dynamic pools from process context Aneesh Kumar K.V (Arm)
2026-06-09 13:23 ` Petr Tesarik
2026-06-04 8:39 ` [PATCH v6 17/20] dma: swiotlb: handle set_memory_decrypted() failures Aneesh Kumar K.V (Arm)
2026-06-09 13:32 ` Petr Tesarik
2026-06-04 8:39 ` [PATCH v6 18/20] dma: free atomic pool pages by physical address Aneesh Kumar K.V (Arm)
2026-06-04 8:39 ` [PATCH v6 19/20] swiotlb: Preserve allocation virtual address for dynamic pools Aneesh Kumar K.V (Arm)
2026-06-09 13:40 ` Petr Tesarik [this message]
2026-06-04 8:39 ` [PATCH v6 20/20] swiotlb: remove unused SWIOTLB_FORCE flag Aneesh Kumar K.V (Arm)
2026-06-09 13:44 ` Petr Tesarik
2026-06-09 13:43 ` [PATCH v6 00/20] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Catalin Marinas
2026-06-09 14:47 ` Jason Gunthorpe
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