From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tyler Hicks To: op-tee@lists.trustedfirmware.org Subject: Re: [PATCH v4 6/8] tee: Support kernel shm registration without dma-buf backing Date: Fri, 11 Jun 2021 08:09:58 -0500 Message-ID: <20210611130958.GR4910@sequoia> In-Reply-To: < > MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="===============7404959035046525914==" List-Id: --===============7404959035046525914== Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On 2021-06-11 10:46:20, Sumit Garg wrote: > On Fri, 11 Jun 2021 at 02:39, Tyler Hicks w= rote: > > > > Uncouple the registration of kernel shared memory buffers from the > > TEE_SHM_DMA_BUF flag. Drivers may wish to allocate multi-page contiguous > > shared memory regions but do not need them to be backed by a dma-buf > > when the memory region is only used by the driver. > > > > If the TEE implementation does not require shared memory to be > > registered, clear the flag prior to calling the corresponding pool alloc > > function. Update the OP-TEE driver to respect TEE_SHM_REGISTER, rather > > than TEE_SHM_DMA_BUF, when deciding whether to (un)register on > > alloc/free operations. >=20 > > The AMD-TEE driver continues to ignore the > > TEE_SHM_REGISTER flag. > > >=20 > That's the main point that no other TEE implementation would honour > TEE_SHM_REGISTER and I think it's just the incorrect usage of > TEE_SHM_REGISTER flag to suffice OP-TEE underlying implementation. >=20 > > Allow callers of tee_shm_alloc_kernel_buf() to allocate and register a > > shared memory region without the backing of dma-buf. > > > > Signed-off-by: Tyler Hicks > > --- > > drivers/tee/optee/shm_pool.c | 5 ++--- > > drivers/tee/tee_shm.c | 13 +++++++++++-- > > 2 files changed, 13 insertions(+), 5 deletions(-) > > >=20 > This patch is just mixing two separate approaches to TEE shared > memory. Have a look at alternative suggestions below. >=20 > > diff --git a/drivers/tee/optee/shm_pool.c b/drivers/tee/optee/shm_pool.c > > index da06ce9b9313..6054343a29fb 100644 > > --- a/drivers/tee/optee/shm_pool.c > > +++ b/drivers/tee/optee/shm_pool.c > > @@ -27,7 +27,7 @@ static int pool_op_alloc(struct tee_shm_pool_mgr *poolm, > > shm->paddr =3D page_to_phys(page); > > shm->size =3D PAGE_SIZE << order; > > > > - if (shm->flags & TEE_SHM_DMA_BUF) { > > + if (shm->flags & TEE_SHM_REGISTER) { >=20 > Here you can just do following check instead: >=20 > if (!(shm->flags & TEE_SHM_PRIV)) { This is a bug fix series that's intended to fix the current and older kernels. tee_shm_alloc_anon_kernel_buf()/TEE_SHM_PRIV is not present in older kernels and isn't required to fix these kexec/kdump bugs. Your suggestion feels like something that should be done in the allocator rewrite that Jens is working on to clean all of this up going forward. Tyler >=20 > And this flag needs to be passed from the call sites here [1] [2]. >=20 > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree= /drivers/tee/optee/core.c#n280 > [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree= /drivers/tee/optee/call.c#n186 >=20 > > unsigned int nr_pages =3D 1 << order, i; > > struct page **pages; > > > > @@ -42,7 +42,6 @@ static int pool_op_alloc(struct tee_shm_pool_mgr *poolm, > > page++; > > } > > > > - shm->flags |=3D TEE_SHM_REGISTER; >=20 > This should remain as it is. >=20 > > rc =3D optee_shm_register(shm->ctx, shm, pages, nr_pages, > > (unsigned long)shm->kaddr); > > kfree(pages); > > @@ -60,7 +59,7 @@ static int pool_op_alloc(struct tee_shm_pool_mgr *poolm, > > static void pool_op_free(struct tee_shm_pool_mgr *poolm, > > struct tee_shm *shm) > > { > > - if (shm->flags & TEE_SHM_DMA_BUF) > > + if (shm->flags & TEE_SHM_REGISTER) >=20 > Same as above. >=20 > > optee_shm_unregister(shm->ctx, shm); > > > > free_pages((unsigned long)shm->kaddr, get_order(shm->size)); > > diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c > > index c65e44707cd6..26a76f817c57 100644 > > --- a/drivers/tee/tee_shm.c > > +++ b/drivers/tee/tee_shm.c > > @@ -117,7 +117,7 @@ struct tee_shm *tee_shm_alloc(struct tee_context *ctx= , size_t size, u32 flags) > > return ERR_PTR(-EINVAL); > > } > > > > - if ((flags & ~(TEE_SHM_MAPPED | TEE_SHM_DMA_BUF))) { > > + if ((flags & ~(TEE_SHM_MAPPED | TEE_SHM_DMA_BUF | TEE_SHM_REGISTE= R))) { >=20 > No need for this change. >=20 > > dev_err(teedev->dev.parent, "invalid shm flags 0x%x", fla= gs); > > return ERR_PTR(-EINVAL); > > } > > @@ -137,6 +137,15 @@ struct tee_shm *tee_shm_alloc(struct tee_context *ct= x, size_t size, u32 flags) > > goto err_dev_put; > > } > > > > + if (!teedev->desc->ops->shm_register || > > + !teedev->desc->ops->shm_unregister) { > > + /* registration is not required by the TEE implementation= */ > > + flags &=3D ~TEE_SHM_REGISTER; > > + } else if (flags & TEE_SHM_DMA_BUF) { > > + /* all dma-buf backed shm allocations are registered */ > > + flags |=3D TEE_SHM_REGISTER; > > + } > > + >=20 > This change isn't required as well as underlying TEE implementation: > OP-TEE in this case knows how to implement shared memory allocation > whether to use reserved shared memory pool or dynamic shared memory > pool. For more details see shared memory pool creation in > optee_probe(). >=20 > > shm->flags =3D flags | TEE_SHM_POOL; > > shm->ctx =3D ctx; > > if (flags & TEE_SHM_DMA_BUF) > > @@ -207,7 +216,7 @@ EXPORT_SYMBOL_GPL(tee_shm_alloc); > > */ > > struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t= size) > > { > > - return tee_shm_alloc(ctx, size, TEE_SHM_MAPPED | TEE_SHM_DMA_BUF); > > + return tee_shm_alloc(ctx, size, TEE_SHM_MAPPED | TEE_SHM_REGISTER= ); >=20 > Here it could just be: >=20 > return tee_shm_alloc(ctx, size, TEE_SHM_MAPPED); >=20 > -Sumit >=20 > > } > > EXPORT_SYMBOL_GPL(tee_shm_alloc_kernel_buf); > > > > -- > > 2.25.1 > > >=20 --===============7404959035046525914==--