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Re: [Xen-devel] [RFC] arm: Handle SiP Service Calls



Hello,

On 07/12/17 06:48, Peng Fan wrote:
Support ARM SiP (Silicon Provider) services.
  - Import arm-smccc.h from Linux Kernel
    ca122fe376fc ("Merge tag 'arc-4.15-rc1' of
    git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc")
  - Introudce a new callback function in platform_desc
  - Add do_trap_hvccc to handle non xen specific hypercalls

  Platforms that want to use SiP service could use platform
  specific sip implementation.

It looks like to me that this patch is based on an older version of Xen. 3 months ago, a framework to support SMC Calling Convention for guest was added.

In general, patch sent upstream should be based on latest Xen. So please rebase your code.


Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
---

In my Dom0 kernel, there is SiP smccc call. Without xen, the call
will trap to ATF. With xen, I use hvccc to replace smccc, but
xen still report error, because xen does not handle SiP calls.
Not sure this is the best way. Since SiP is silicon provider
service, so I put it into platform code.

When I see a new callback added, I would expect to see a user in the series. So what is the expected behavior of this callback? Who is going to be allowed to access to the SiP services?

Guessing from your description, the callback would just be implemented as "forward SiP call". In that case, I don't see a reason to have a callback implemented.

However, you would need to know whether the platform support SMCCC. How do you recognize that on yours?

Now the next question, is it safe to let the hardware domain to access all SiP service? Can you explain the kind of service present in SiP for your platform?

Cheers,

--
Julien Grall

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