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 3F7AC17578 for ; Mon, 11 Aug 2025 12:31:29 +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=1754915492; cv=none; b=bE+y3s4z3KiCXY/IscxkjvOd9mnqFCcR4aoVPdavL2h1EQ9oItCFpB2RXj1JcW7H9WOk1Knb/gjDqy4db7q6SZcWY17twDzr0mzkzles8x1FTmYN2LsCv0npU1kUwow5sJ5WuP+mk/X6VRrJxS0d+iJ4yKLfz/5XD0BcVOre7/8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754915492; c=relaxed/simple; bh=crSbkX5wZCnAYf+xoVb8D9BZ0tyCYd1uy4y9JGpiV64=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=BeRN8LKOTjd3zVkWp+71oe6a4vU+xyeoKQIeaDqgDrigLNJJWIhH8p5WGkA7FawUHhMXcQ0jA5G7d0UKIvjsgo1zOLDBOhzyAosHFsM+q4BVfNDKqFJmvOnih8ayjWV/V2hBdaT9bWGySsxCGeIitb03N9lOabsEFzZZcz13i+w= 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 800DF1D13; Mon, 11 Aug 2025 05:31:20 -0700 (PDT) Received: from [10.57.5.137] (unknown [10.57.5.137]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0EC983F738; Mon, 11 Aug 2025 05:31:24 -0700 (PDT) Message-ID: Date: Mon, 11 Aug 2025 13:31:28 +0100 Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RESEND PATCH 2/2] arm64: Add encrypt/decrypt support for vmalloc regions To: Shanker Donthineni , Catalin Marinas , Will Deacon , Marek Szyprowski , Suzuki K Poulose , Steven Price , linux-arm-kernel@lists.infradead.org Cc: Gavin Shan , Mike Rapoport , Vikram Sethi , Jason Sequeira , Dev Jain , David Rientjes , linux-kernel@vger.kernel.org, iommu@lists.linux.dev References: <20250811005036.714274-1-sdonthineni@nvidia.com> <20250811005036.714274-3-sdonthineni@nvidia.com> From: Robin Murphy Content-Language: en-GB X-Mozilla-Draft-Info: internal/draft; vcard=0; receipt=0; DSN=0; uuencode=0; attachmentreminder=0; deliveryformat=0 X-Identity-Key: id1 Fcc: imap://robin.murphy%40arm.com@outlook.office365.com/Sent Items In-Reply-To: <20250811005036.714274-3-sdonthineni@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2025-08-11 1:50 am, Shanker Donthineni wrote: > On ARM64 systems with CCA (Confidential Compute Architecture) enabled, > the kernel may need to change the encryption attributes of memory > regions. The existing implementation of set_memory_encrypted() and > set_memory_decrypted() assumes that the input address is part of the > linear mapping region '__is_lm_address()', and fails with -EINVAL > otherwise. > > This breaks use cases where the memory region resides in the vmalloc > area, which is mapped in non-linear mapping region. > > This patch introduces a new helper, realm_set_memory(), which detects > whether the given address is from a non-linear mapping. If so, it uses > vmalloc_to_page() to resolve each page’s physical address and applies > attribute changes one page at a time. For the linear address regions, > it maintains the existing fast-path. > > This change ensures that encrypted/decrypted memory attribute updates > correctly for all memory regions, including those allocated via vmap(), > module allocations, or other vmalloc-backed paths. > > Call stack of Realm crash, QEMU hypervisor + NVME device (emulated): > ... > Freeing unused kernel memory: 6336K > Run /sbin/init as init process > Internal error: synchronous external abort: 0000000096000250 [#1] SMP > Modules linked in: > CPU: 0 UID: 0 PID: 64 Comm: lsblk Not tainted 6.15.5 #2 PREEMPT(undef) > Hardware name: linux,dummy-virt (DT) > pstate: 43400005 (nZcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) > pc : __pi_memset_generic+0x16c/0x188 > lr : dma_alloc_from_pool+0xd0/0x1b8 > sp : ffff80008335b350 > x29: ffff80008335b350 x28: ffff800083162000 x27: ffff80008335b3c0 > x26: ffff80008144f000 x25: ffff8000801a27e8 x24: ffff800081e14000 > x23: ffffc1ffc0000000 x22: 0000000000001000 x21: ffff800081458310 > x20: 0000000042a40000 x19: ffff00000232fcc0 x18: 0000000000200000 > x17: 00000000000120c0 x16: ffff0000795520c0 x15: 0000000000000000 > x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 > x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 > x8 : ffff800083162000 x7 : 0000000000000000 x6 : 000000000000003f > x5 : 0000000000000040 x4 : 0000000000000000 x3 : 0000000000000004 > x2 : 0000000000000fc0 x1 : 0000000000000000 x0 : ffff800083162000 > Call trace: > __pi_memset_generic+0x16c/0x188 (P) > dma_direct_alloc_from_pool+0xc4/0x230 But isn't that exactly the case that patch #1 is supposed to have fixed? From a quick scan of set_memory_decrypted() callers I don't see anything obvious jumping out - can you clarify who you think needs this for reasons other than papering over bugs in the DMA layer? Thanks, Robin. > dma_direct_alloc+0x80/0x4a0 > dma_alloc_attrs+0x94/0x238 > dma_pool_alloc+0x128/0x258 > nvme_prep_rq.part.0+0x5f0/0x950 > nvme_queue_rq+0x78/0x1e8 > blk_mq_dispatch_rq_list+0x10c/0x6f0 > __blk_mq_sched_dispatch_requests+0x4a0/0x580 > blk_mq_sched_dispatch_requests+0x38/0xa0 > blk_mq_run_hw_queue+0x288/0x2f8 > blk_mq_flush_plug_list+0x134/0x630 > __blk_flush_plug+0x100/0x168 > blk_finish_plug+0x40/0x60 > read_pages+0x1a0/0x2b0 > page_cache_ra_unbounded+0x1f8/0x268 > force_page_cache_ra+0xa4/0xe0 > page_cache_sync_ra+0x48/0x268 > filemap_get_pages+0xf4/0x7a0 > filemap_read+0xf0/0x448 > blkdev_read_iter+0x8c/0x1a8 > vfs_read+0x288/0x330 > ksys_read+0x78/0x118 > __arm64_sys_read+0x24/0x40 > invoke_syscall+0x50/0x120 > el0_svc_common.constprop.0+0x48/0xf0 > do_el0_svc+0x24/0x38 > el0_svc+0x34/0xf8 > el0t_64_sync_handler+0x10c/0x138 > el0t_64_sync+0x1ac/0x1b0 > > Signed-off-by: Shanker Donthineni > --- > arch/arm64/mm/pageattr.c | 55 +++++++++++++++++++++++++++++++++++----- > 1 file changed, 48 insertions(+), 7 deletions(-) > > diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c > index 04d4a8f676db4..65c3322a86b49 100644 > --- a/arch/arm64/mm/pageattr.c > +++ b/arch/arm64/mm/pageattr.c > @@ -202,21 +202,26 @@ int set_direct_map_default_noflush(struct page *page) > PAGE_SIZE, change_page_range, &data); > } > > +/* > + * Common function for setting memory encryption or decryption attributes. > + * > + * @addr: Virtual start address of the memory region > + * @start: Corresponding physical start address > + * @numpages: Number of pages to update > + * @encrypt: If true, set memory as encrypted; if false, decrypt > + */ > static int __set_memory_enc_dec(unsigned long addr, > + phys_addr_t start, > int numpages, > bool encrypt) > { > unsigned long set_prot = 0, clear_prot = 0; > - phys_addr_t start, end; > + phys_addr_t end; > int ret; > > if (!is_realm_world()) > return 0; > > - if (!__is_lm_address(addr)) > - return -EINVAL; > - > - start = __virt_to_phys(addr); > end = start + numpages * PAGE_SIZE; > > if (encrypt) > @@ -248,9 +253,45 @@ static int __set_memory_enc_dec(unsigned long addr, > __pgprot(0)); > } > > +/* > + * Wrapper for __set_memory_enc_dec() that handles both linear-mapped > + * and vmalloc/module memory regions. > + * > + * If the address is in the linear map, we can directly compute the > + * physical address. If not (e.g. vmalloc memory), we walk each page > + * and call the attribute update individually. > + */ > +static int realm_set_memory(unsigned long addr, int numpages, bool encrypt) > +{ > + phys_addr_t start; > + struct page *page; > + int ret, i; > + > + if (__is_lm_address(addr)) { > + start = __virt_to_phys(addr); > + return __set_memory_enc_dec(addr, start, numpages, encrypt); > + } > + > + for (i = 0; i < numpages; i++) { > + page = vmalloc_to_page((void *)addr); > + if (!page) > + return -EINVAL; > + > + start = page_to_phys(page); > + ret = __set_memory_enc_dec(addr, start, 1, encrypt); > + if (ret) > + return ret; > + > + addr += PAGE_SIZE; > + } > + > + return 0; > +} > + > static int realm_set_memory_encrypted(unsigned long addr, int numpages) > { > - int ret = __set_memory_enc_dec(addr, numpages, true); > + int ret = realm_set_memory(addr, numpages, true); > + > > /* > * If the request to change state fails, then the only sensible cause > @@ -264,7 +305,7 @@ static int realm_set_memory_encrypted(unsigned long addr, int numpages) > > static int realm_set_memory_decrypted(unsigned long addr, int numpages) > { > - int ret = __set_memory_enc_dec(addr, numpages, false); > + int ret = realm_set_memory(addr, numpages, false); > > WARN(ret, "Failed to decrypt memory, %d pages will be leaked", > numpages);