efi: stmm: Drop unneeded null pointer check

The API documenation of setup_mm_hdr does not mention that dptr can be
NULL, this is a local function, and no caller passes NULL. So drop the
unneeded che

efi: stmm: Drop unneeded null pointer check

The API documenation of setup_mm_hdr does not mention that dptr can be
NULL, this is a local function, and no caller passes NULL. So drop the
unneeded check.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

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efi: stmm: Drop unused EFI error from setup_mm_hdr arguments

No caller ever evaluates what we return in 'ret'. They only use the
return code of the function.

Signed-off-by: Jan Kiszka <jan.kiszka@s

efi: stmm: Drop unused EFI error from setup_mm_hdr arguments

No caller ever evaluates what we return in 'ret'. They only use the
return code of the function.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

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efi: stmm: Do not return EFI_OUT_OF_RESOURCES on internal errors

When we are low on memory or when the internal API is violated, we
cannot return EFI_OUT_OF_RESOURCES. According to the UEFI standard

efi: stmm: Do not return EFI_OUT_OF_RESOURCES on internal errors

When we are low on memory or when the internal API is violated, we
cannot return EFI_OUT_OF_RESOURCES. According to the UEFI standard, that
error code is either related to persistent storage used for the variable
or even not foreseen as possible error (GetVariable e.g.). Use the not
fully accurate but compliant error code EFI_DEVICE_ERROR in those cases.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

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efi: stmm: Fix incorrect buffer allocation method

The communication buffer allocated by setup_mm_hdr() is later on passed
to tee_shm_register_kernel_buf(). The latter expects those buffers to be
con

efi: stmm: Fix incorrect buffer allocation method

The communication buffer allocated by setup_mm_hdr() is later on passed
to tee_shm_register_kernel_buf(). The latter expects those buffers to be
contiguous pages, but setup_mm_hdr() just uses kmalloc(). That can cause
various corruptions or BUGs, specifically since commit 9aec2fb0fd5e
("slab: allocate frozen pages"), though it was broken before as well.

Fix this by using alloc_pages_exact() instead of kmalloc().

Fixes: c44b6be62e8d ("efi: Add tee-based EFI variable driver")
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

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