From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id F257029BDAB for ; Mon, 11 Aug 2025 17:26:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754933172; cv=none; b=gokR0hdAWgaJfrPUxEIyy+NgJ2WSqHeVIJxWUPpriKLNY0jurGQGb92lxlt21iHjgABuK9uWHEqATyzVHTTQKsrK5YWt47qrbEnQUK1o+KTwQ/xPlEataLin+aJ0RtGfvee3MIZH8T6tgiOt0hFWgNCp2EyYTIup3+NAoDF0g6c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754933172; c=relaxed/simple; bh=uICC0HmUS6u193dRdy5ircuYP9/0Oy60iDOHPl7W5Z4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=J35ZiI0q1WZGiwkxIJr1lLhJQIWnkJfrtAb1K5/AuUCSmb4dCoX0ZhbDPtGY0tBxY3nwOw/joQEK7Dv+CcM1SsdogeJkLBGcvkwxBvNm3lPVGoD2km0tz7DdWt8vwYROsuAxlkHwE7lfW3QLUZjVU+/WPcAHki6FV35XbVKr2TM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 111EB1A32; Mon, 11 Aug 2025 10:26:02 -0700 (PDT) Received: from arm.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CFE693F63F; Mon, 11 Aug 2025 10:26:07 -0700 (PDT) Date: Mon, 11 Aug 2025 18:26:05 +0100 From: Catalin Marinas To: Shanker Donthineni Cc: Will Deacon , Marek Szyprowski , Suzuki K Poulose , Steven Price , linux-arm-kernel@lists.infradead.org, Robin Murphy , Gavin Shan , Mike Rapoport , Vikram Sethi , Jason Sequeira , Dev Jain , David Rientjes , linux-kernel@vger.kernel.org, iommu@lists.linux.dev Subject: Re: [RESEND PATCH 1/2] dma/pool: Use vmap() address for memory encryption helpers on ARM64 Message-ID: References: <20250811005036.714274-1-sdonthineni@nvidia.com> <20250811005036.714274-2-sdonthineni@nvidia.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250811005036.714274-2-sdonthineni@nvidia.com> On Sun, Aug 10, 2025 at 07:50:34PM -0500, Shanker Donthineni wrote: > In atomic_pool_expand(), set_memory_encrypted()/set_memory_decrypted() > are currently called with page_to_virt(page). On ARM64 with > CONFIG_DMA_DIRECT_REMAP=y, the atomic pool is mapped via vmap(), so > page_to_virt(page) does not reference the actual mapped region. > > Using this incorrect address can cause encryption attribute updates to > be applied to the wrong memory region. On ARM64 systems with memory > encryption enabled (e.g. CCA), this can lead to data corruption or > crashes. > > Fix this by using the vmap() address ('addr') on ARM64 when invoking > the memory encryption helpers, while retaining the existing > page_to_virt(page) usage for other architectures. > > Fixes: 76a19940bd62 ("dma-direct: atomic allocations must come from atomic coherent pools") > Signed-off-by: Shanker Donthineni > --- > kernel/dma/pool.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c > index 7b04f7575796b..ba08a301590fd 100644 > --- a/kernel/dma/pool.c > +++ b/kernel/dma/pool.c > @@ -81,6 +81,7 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size, > { > unsigned int order; > struct page *page = NULL; > + void *vaddr; > void *addr; > int ret = -ENOMEM; > > @@ -113,8 +114,8 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size, > * Memory in the atomic DMA pools must be unencrypted, the pools do not > * shrink so no re-encryption occurs in dma_direct_free(). > */ > - ret = set_memory_decrypted((unsigned long)page_to_virt(page), > - 1 << order); > + vaddr = IS_ENABLED(CONFIG_ARM64) ? addr : page_to_virt(page); > + ret = set_memory_decrypted((unsigned long)vaddr, 1 << order); At least with arm CCA, there are two aspects to setting the memory encrypted/decrypted: an RMM (realm management monitor) call and setting of the attributes of the stage 1 mapping. The RMM call doesn't care about the virtual address, only the (intermediate) physical address, so having page_to_virt(page) here is fine. The second part is setting the (fake) attribute for this mapping (top bit of the IPA space). Can we not instead just call: addr = dma_common_contiguous_remap(page, pool_size, pgprot_decrypted(pgprot_dmacoherent(PAGE_KERNEL)), __builtin_return_address(0)); in the atomic pool code? The advantage is that we keep the set_memory_decrypted() call on the linear map so that we change its attributes as well. I want avoid walking the page tables for vmap regions if possible in the arm64 set_memory_* implementation. At some point I was proposing a GFP_DECRYPTED flag for allocations but never got around to post a patch (and implement vmalloc() support): https://lore.kernel.org/linux-arm-kernel/ZmNJdSxSz-sYpVgI@arm.com/ -- Catalin