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[104.155.91.135]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c25d039d796sm138037066b.40.2026.09.02.06.27.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Sep 2026 06:27:32 -0700 (PDT) Date: Wed, 2 Sep 2026 14:27:28 +0100 From: Vincent Donnefort To: catalin.marinas@arm.com, will@kernel.org, rppt@kernel.org, akpm@linux-foundation.org, sudeep.holla@kernel.org, jenswi@kernel.org, robh@kernel.org Cc: mark.rutland@arm.com, sumit.garg@kernel.org, ardb@kernel.org, thierry.reding@kernel.org, david@kernel.org, danielmentz@google.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, op-tee@lists.trustedfirmware.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v9 00/10] arm64: Unmap FF-A lent memory from direct map Message-ID: References: <20260902104712.2399797-1-vdonnefort@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260902104712.2399797-1-vdonnefort@google.com> X-Rspam-User: X-Stat-Signature: jn465scouwwwbiqdb6zd6ixwcpuj8gsn X-Rspamd-Queue-Id: 2BB7CA0007 X-Rspamd-Server: rspam06 X-HE-Tag: 1788355655-534811 X-HE-Meta: U2FsdGVkX199s1QdNWfVH9rbSNooDKc2f8CXz0PmzmUtnVZYl663J1SuoIr7M5nBBNCnsrn2ySRT7a9It7w9aad1n+AThdN0q9RG72QGpuVcJUQ218ItpuGZqimG7taNpY6bmYdF7a5PexcZoadc0iB+jqlQbRtfTYuw5BvUwUpEUidBnypl0TDfeRm11tHoo+ENihC2zjuSw0gs7IjN/8GvfhhvCTwCxmvh53GLfKwo+EnDH1kr5uMRTTq6/l9xk0mzr9+/r+wYWID+cWLqIaR9uh2Ofk5Vrge9GUntt5TMvn9smOLIyPHOVuzYNmMyXoarpDdmrSQTwpw9ZAeoML87Q4EDzsKhWmBl/0fA6Bjw5oQB8dvCrZFJ26CbZEOrsOJn2thCjbS9ISwqyIn4GQNkmMztKe+1tYvfvEMGHVuomSJMddq/TYDwB4eianPFYXkyHO7MzvpHcQDypfPkAvcRu7Y80SghvNq2RfurH7q3+OKaGrT8UxZCY/gN5lnvRmDEQPfY4j+R3oqIY6OXJfWZOFdKbBYUbTNC26feM+fpudoF1ZdbqB1XFO6fs2mePURZd15fPLZFytepD87RE+3hfEx8UrJG334PcOdW8raSCP2mXzOvYHvaMQVaEnPxUdukM747hF54oMRCjgSMtrZXCJ4koMq8edQKcKIWHYQ8iLNDIxZrkOgyYCcHYJ2C/5KhDEWXH0AqZoH5LYzMTlojEhOV1YlYMbbtZEHkqxTskBGzzvItiX5tN3CshjE4Ys2haSScj1hgLvXM0MzKCUEA5ikn4l29cAEjLpMI3MbWkyygEVrP0i3lyEJTBpTbClSUBZRL/IeeSUspKjNyoBUX6NCp+gtsaNChHD7ixf3TwSbyV0kVNFRsh3dDp7VswVfqIO5h9is29F/zmwobdpdbaLPBBlEgTZYmZZzE3RDzofh0kww9tPsplJue9YsayvpzIR//EwGGw8OyBpy r+NnICJx 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: This is of course v1, not v9... On Wed, Sep 02, 2026 at 11:47:02AM +0100, Vincent Donnefort wrote: > This series is a follow-up to the discussion that has started here [1]. > While standalone, it also provides primitives reusable for the VPR DMA > heap. > > When memory is lent to the Secure world via FF-A, CPU speculative > accesses from NS to the lent pages can still occur as long as it retains > a cacheable mapping to it. > > Ideally, lent memory would be "no-map" but that would mean giving up > MiBs of useful memory, so let's try to do better with the help of a CMA > pool. > > On arm64, modifying the direct map at runtime is generally restricted > because the linear map defaults to block mapping and splitting blocks at > runtime may trigger fatal page fault, unless the CPU implements BBML3 > or the entire direct map was mapped at page granularity from boot. > Forcing last-level mappings system-wide incurs a severe penalty we want > to avoid. Instead, this series introduces targeted last-level mappings > for designated memory regions, along with the "arm,ffa-lend-pool" CMA > driver to manage unmapping and remapping on lend/reclaim transitions: > > 1. memblock & OF reserved memory ("ll-map"): > - Introduce MEMBLOCK_LLMAP and the DT "ll-map" property for reserved-memory > nodes to force last-level (PTE) mappings only for a specific region. > > 2. set_memory infrastructure: > - Introduce can_set_direct_map_range() to check if a specific address > range is mapped with last-level entries and can be modified safely. > - Introduce __set_direct_map_*() variants that bypass redundant checks > when the caller has already validated the range. > > 3. "arm,ffa-lend-pool" driver > - Introduce the "arm,ffa-lend-pool" CMA reserved-memory driver, which > unmaps pages prior to lending (ffa_prepare_lend()) and restores them > when reclaimed (ffa_lend_reclaimed()). > > 4. Optee support > - Hook OP-TEE dynamic protected memory pools to "arm,ffa-lend-pool" for > both SMC (via DT memory-region phandle) and FF-A (via > ffa_lend_pool_attach()) transports. > > Testing: > ======== > > Tested with QEMU v8 using OP-TEE OS (built with CFG_CORE_DYN_PROTMEM=y) > under both SMC and FF-A transports [2] > > static void dump_direct_map(const char *label) > { > printf("\n=== %s ===\n", label); > fflush(stdout); > system("sed -n '/Linear Mapping start/,/Linear Mapping end/p' /sys/kernel/debug/kernel_page_tables"); > fflush(stdout); > } > > int main(int argc, char *argv[]) > { > int heap_fd; > int dmabuf_fd; > struct dma_heap_allocation_data data = { 0 }; > size_t size = 1024 * 1024; /* 1MB */ > > if (argc > 1) > size = strtoul(argv[1], NULL, 0); > > dump_direct_map("BEFORE ALLOCATION"); > > heap_fd = open("/dev/dma_heap/protected,secure-video", O_RDWR); > if (heap_fd < 0) { > perror("open /dev/dma_heap/protected,secure-video"); > return 1; > } > > printf("\nOpened /dev/dma_heap/protected,secure-video\n"); > printf("Allocating %zu bytes of protected memory via DMA heap...\n", size); > > data.len = size; > data.fd_flags = O_RDWR | O_CLOEXEC; > if (ioctl(heap_fd, DMA_HEAP_IOCTL_ALLOC, &data) < 0) { > perror("ioctl DMA_HEAP_IOCTL_ALLOC"); > close(heap_fd); > return 1; > } > > dmabuf_fd = data.fd; > printf("Successfully allocated %zu bytes! dmabuf_fd = %d\n", size, dmabuf_fd); > > dump_direct_map("DURING LEND (EXPECT HOLE IN DIRECT MAP)"); > > printf("\nReleasing dmabuf_fd...\n"); > close(dmabuf_fd); > close(heap_fd); > > dump_direct_map("AFTER RECLAIM (RESTORED DIRECT MAP)"); > > return 0; > } > > [1] https://lore.kernel.org/all/20260807-tegra-vpr-v4-7-5510d16af89e@nvidia.com/ > [2] https://optee.readthedocs.io/en/latest/building/gits/build.html#qemu-v8 > > Vincent Donnefort (10): > memblock: Introduce MEMBLOCK_LLMAP > of: reserved_mem: Introduce "ll-map" property > set_memory.h: Introduce can_set_direct_map_range() > set_memory.h: Introduce __set_direct_map*() > arm64: can_set_direct_map() if BBML3 > arm64: Implement can_set_direct_map_range() > arm64: Implement __set_direct_map*() > arm64: Add support for MEMBLOCK_LLMAP > firmware: arm_ffa: Introduce ffa-lend-pool > optee: Add support for arm,ffa-lend-pool > > arch/arm64/include/asm/set_memory.h | 7 + > arch/arm64/mm/mmu.c | 23 ++- > arch/arm64/mm/pageattr.c | 67 +++++++- > drivers/firmware/arm_ffa/Kconfig | 5 + > drivers/firmware/arm_ffa/Makefile | 1 + > drivers/firmware/arm_ffa/lend_pool.c | 223 +++++++++++++++++++++++++++ > drivers/of/of_reserved_mem.c | 104 ++++++++++--- > drivers/tee/optee/ffa_abi.c | 13 +- > drivers/tee/optee/protmem.c | 8 - > drivers/tee/optee/smc_abi.c | 17 +- > drivers/tee/tee_shm.c | 11 +- > include/linux/arm_ffa.h | 21 +++ > include/linux/memblock.h | 9 ++ > include/linux/set_memory.h | 39 +++++ > mm/memblock.c | 50 ++++++ > 15 files changed, 545 insertions(+), 53 deletions(-) > create mode 100644 drivers/firmware/arm_ffa/lend_pool.c > > > base-commit: cee9395acd8043be0644b25c34bfa86623f2b935 > -- > 2.55.0.970.g62bdec98f9-goog > -- Vincent