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ARM: qcom: scm: Flush the command buffer only instead of the entire cache
scm_call flushes the entire cache before calling into the secure world. This is both a performance penalty as well as insufficient on SMP systems where the CPUs possess a write-back L1 cache. Flush only the command and response buffers instead, moving the responsibility of flushing any other cached buffer (being passed to the secure world) to callers. Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Kumar Gala <galak@codeaurora.org>
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@ -196,12 +196,12 @@ static int __scm_call(const struct scm_command *cmd)
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u32 cmd_addr = virt_to_phys(cmd);
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/*
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* Flush the entire cache here so callers don't have to remember
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* to flush the cache when passing physical addresses to the secure
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* side in the buffer.
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* Flush the command buffer so that the secure world sees
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* the correct data.
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*/
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flush_cache_all();
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outer_flush_all();
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__cpuc_flush_dcache_area((void *)cmd, cmd->len);
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outer_flush_range(cmd_addr, cmd_addr + cmd->len);
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ret = smc(cmd_addr);
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if (ret < 0)
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ret = scm_remap_error(ret);
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@ -238,6 +238,13 @@ static void scm_inv_range(unsigned long start, unsigned long end)
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* @resp_len: length of the response buffer
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*
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* Sends a command to the SCM and waits for the command to finish processing.
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*
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* A note on cache maintenance:
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* Note that any buffers that are expected to be accessed by the secure world
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* must be flushed before invoking scm_call and invalidated in the cache
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* immediately after scm_call returns. Cache maintenance on the command and
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* response buffers is taken care of by scm_call; however, callers are
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* responsible for any other cached buffers passed over to the secure world.
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*/
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int scm_call(u32 svc_id, u32 cmd_id, const void *cmd_buf, size_t cmd_len,
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void *resp_buf, size_t resp_len)
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