From: Tyler Hicks <firstname.lastname@example.org> To: Jens Wiklander <email@example.com>, Allen Pais <firstname.lastname@example.org>, Sumit Garg <email@example.com>, Peter Huewe <firstname.lastname@example.org>, Jarkko Sakkinen <email@example.com>, Jason Gunthorpe <firstname.lastname@example.org>, Vikas Gupta <email@example.com> Cc: "Thirupathaiah Annapureddy" <firstname.lastname@example.org>, "Pavel Tatashin" <email@example.com>, "Rafał Miłecki" <firstname.lastname@example.org>, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com Subject: [PATCH v3 0/7] tee: Improve support for kexec and kdump Date: Tue, 8 Jun 2021 19:23:19 -0500 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) v3: - Tyler inherited the original series from Allen Pais - New patch to fix memory leaks in OP-TEE's pool_op_alloc() + Unrelated to kexec/kdump - New patch to refuse to load the OP-TEE driver when booting the kdump kernel - Minor comment typo cleanups (s/alter/alert/) in the "optee: fix tee out of memory failure seen during kexec reboot" patch, as mentioned in v2 feedback - New patch to clear stale cache entries during initialization to avoid crashes when kexec'ing from a buggy kernel, that didn't disable the shm cache, to a fixed kernel - Three new patches to allow drivers to allocate a multi-page dynamic shm that's not dma-buf backed but is still fully registered with the TEE, ensuring that all driver private shms are unregistered during kexec v2: https://email@example.com/ v1: https://firstname.lastname@example.org/ This series fixes several bugs uncovered while exercising the OP-TEE (Open Portable Trusted Execution Environment), ftpm (firmware TPM), and tee_bnxt_fw (Broadcom BNXT firmware manager) drivers with kexec and kdump (emergency kexec) based workflows. The majority of the problems are caused by missing .shutdown hooks in the drivers. The .shutdown hooks are used by the normal kexec code path to let the drivers clean up prior to executing the target kernel. The .remove hooks, which are already implemented in these drivers, are not called as part of the kexec code path. This resulted in shared memory regions, that were cached and/or registered with OP-TEE, not being cleared/unregistered prior to kexec. The new kernel would then run into problems when handling the previously cached virtual addresses or trying to register newly allocated shared memory objects that overlapped with the previously registered virtual addresses. The TEE didn't receive notification that the old virtual addresses were no longer meaningful and that a new kernel, with a new address space, would soon be running. However, implementing .shutdown hooks was not enough for supporting kexec. There was an additional problem caused by the TEE driver's reliance on the dma-buf subsystem for multi-page shared memory objects that were registered with the TEE. Shared memory objects backed by a dma-buf use a different mechanism for reference counting. When the final reference is released, work is scheduled to be executed to unregister the shared memory with the TEE but that work is only completed prior to the current task returning the userspace. In the case of a kexec operation, the current task that's calling the driver .shutdown hooks never returns to userspace prior to the kexec operation so the shared memory was never unregistered. This eventually caused problems from overlapping shared memory regions that were registered with the TEE after several kexec operations. The large 4M contiguous region allocated by the tee_bnxt_fw driver reliably ran into this issue on the fourth kexec on a system with 8G of RAM. The use of dma-buf makes sense for shared memory that's in use by userspace but dma-buf's aren't needed for shared memory that will only used by the driver. This series separates dma-buf backed shared memory allocated by the kernel from multi-page shared memory that the kernel simply needs registered with the TEE for private use. One other noteworthy change in this series is to completely refuse to load the OP-TEE driver in the kdump kernel. This is needed because the secure world may have had all of its threads in suspended state when the regular kernel crashed. The kdump kernel would then hang during boot because the OP-TEE driver's .probe function would attempt to use a secure world thread when they're all in suspended state. Another problem is that shared memory allocations could fail under the kdump kernel because the previously registered were not unregistered (the .shutdown hook is not called when kexec'ing into the kdump kernel). The first patch in the series fixes potential memory leaks that are not directly related to kexec or kdump but were noticed during the development of this series. Tyler Allen Pais (2): optee: fix tee out of memory failure seen during kexec reboot firmware: tee_bnxt: Release shm, session, and context during kexec Tyler Hicks (5): optee: Fix memory leak when failing to register shm pages optee: Refuse to load the driver under the kdump kernel optee: Clear stale cache entries during initialization tee: Support shm registration without dma-buf backing tpm_ftpm_tee: Free and unregister dynamic shared memory during kexec drivers/char/tpm/tpm_ftpm_tee.c | 2 +- drivers/firmware/broadcom/tee_bnxt_fw.c | 11 ++++++- drivers/tee/optee/call.c | 11 ++++++- drivers/tee/optee/core.c | 42 ++++++++++++++++++++++++- drivers/tee/optee/optee_private.h | 2 +- drivers/tee/optee/shm_pool.c | 17 +++++++--- drivers/tee/tee_shm.c | 11 ++++++- 7 files changed, 85 insertions(+), 11 deletions(-) -- 2.25.1
next reply other threads:[~2021-06-09 0:25 UTC|newest] Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-09 0:23 Tyler Hicks [this message] 2021-06-09 0:23 ` [PATCH v3 1/7] optee: Fix memory leak when failing to register shm pages Tyler Hicks 2021-06-09 0:23 ` [PATCH v3 2/7] optee: Refuse to load the driver under the kdump kernel Tyler Hicks 2021-06-09 0:23 ` [PATCH v3 3/7] optee: fix tee out of memory failure seen during kexec reboot Tyler Hicks 2021-06-09 0:23 ` [PATCH v3 4/7] optee: Clear stale cache entries during initialization Tyler Hicks 2021-06-09 0:23 ` [PATCH v3 5/7] tee: Support shm registration without dma-buf backing Tyler Hicks 2021-06-09 4:29 ` Sumit Garg 2021-06-09 5:46 ` Tyler Hicks 2021-06-09 10:52 ` Sumit Garg 2021-06-09 12:15 ` Jens Wiklander 2021-06-09 13:42 ` Tyler Hicks 2021-06-09 13:51 ` Tyler Hicks 2021-06-10 7:34 ` Jens Wiklander 2021-06-10 21:00 ` Tyler Hicks 2021-06-10 7:49 ` Jens Wiklander 2021-06-10 21:05 ` Tyler Hicks 2021-06-10 7:40 ` Allen Pais 2021-06-10 7:18 ` Jens Wiklander 2021-06-10 12:14 ` Sumit Garg 2021-06-09 0:23 ` [PATCH v3 6/7] tpm_ftpm_tee: Free and unregister dynamic shared memory during kexec Tyler Hicks 2021-06-09 0:23 ` [PATCH v3 7/7] firmware: tee_bnxt: Release shm, session, and context " Tyler Hicks
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