Re: [PATCH v5 2/7] xen/arm: zynqmp: Forward plaform specific firmware calls

[Julien Grall <julien.grall@arm.com>]

Hi Stefano,

On 11/12/2018 18:50, Stefano Stabellini wrote:
> On Tue, 11 Dec 2018, Julien Grall wrote:
>> Hi Stefano,
>>
>> On 03/12/2018 21:03, Stefano Stabellini wrote:
>>> From: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>
>>>
>>> From: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
>>>
>>> Introduce zynqmp_eemi: a function responsible for implementing access
>>> controls over the firmware calls. Only calls that are allowed are
>>> forwarded to the firmware.
>>>
>>> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
>>> Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
>>>
>>> ---
>>> Changes in v4:
>>> - fix typo
>>> - add header guard
>>> - add emacs magic
>>> - remove #includes that will only be used later
>>> - add copyright notice to header
>>> - remove SMCCC 1.1 check
>>> ---
>>>    xen/arch/arm/platforms/Makefile                    |  1 +
>>>    xen/arch/arm/platforms/xilinx-zynqmp-eemi.c        | 34
>>> ++++++++++++++++++++++
>>>    xen/arch/arm/platforms/xilinx-zynqmp.c             | 11 +++++++
>>>    xen/include/asm-arm/platforms/xilinx-zynqmp-eemi.h | 30
>>> +++++++++++++++++++
>>>    4 files changed, 76 insertions(+)
>>>    create mode 100644 xen/arch/arm/platforms/xilinx-zynqmp-eemi.c
>>>    create mode 100644 xen/include/asm-arm/platforms/xilinx-zynqmp-eemi.h
>>>
>>> diff --git a/xen/arch/arm/platforms/Makefile
>>> b/xen/arch/arm/platforms/Makefile
>>> index a79bdb9..fe8e0c7 100644
>>> --- a/xen/arch/arm/platforms/Makefile
>>> +++ b/xen/arch/arm/platforms/Makefile
>>> @@ -9,3 +9,4 @@ obj-y += sunxi.o
>>>    obj-$(CONFIG_ARM_64) += thunderx.o
>>>    obj-$(CONFIG_ARM_64) += xgene-storm.o
>>>    obj-$(CONFIG_MPSOC_PLATFORM)  += xilinx-zynqmp.o
>>> +obj-$(CONFIG_MPSOC_PLATFORM)  += xilinx-zynqmp-eemi.o
>>> diff --git a/xen/arch/arm/platforms/xilinx-zynqmp-eemi.c
>>> b/xen/arch/arm/platforms/xilinx-zynqmp-eemi.c
>>> new file mode 100644
>>> index 0000000..369bb3f
>>> --- /dev/null
>>> +++ b/xen/arch/arm/platforms/xilinx-zynqmp-eemi.c
>>> @@ -0,0 +1,34 @@
>>> +/*
>>> + * xen/arch/arm/platforms/xilinx-zynqmp-eemi.c
>>> + *
>>> + * Xilinx ZynqMP EEMI API
>>> + *
>>> + * Copyright (c) 2018 Xilinx Inc.
>>> + * Written by Edgar E. Iglesias <edgar.iglesias@xilinx.com>
>>> + *
>>> + * This program is free software; you can redistribute it and/or
>>> + * modify it under the terms and conditions of the GNU General Public
>>> + * License, version 2, as published by the Free Software Foundation.
>>> + *
>>> + * This program is distributed in the hope that it will be useful,
>>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>>> + * GNU General Public License for more details.
>>> + */
>>> +
>>> +#include <asm/regs.h>
>>> +#include <asm/platforms/xilinx-zynqmp-eemi.h>
>>> +
>>> +bool zynqmp_eemi(struct cpu_user_regs *regs)
>>> +{
>>> +    return false;
>>> +}
>>> +
>>> +/*
>>> + * Local variables:
>>> + * mode: C
>>> + * c-file-style: "BSD"
>>> + * c-basic-offset: 4
>>> + * indent-tabs-mode: nil
>>> + * End:
>>> + */
>>> diff --git a/xen/arch/arm/platforms/xilinx-zynqmp.c
>>> b/xen/arch/arm/platforms/xilinx-zynqmp.c
>>> index d8ceded..9c174d2 100644
>>> --- a/xen/arch/arm/platforms/xilinx-zynqmp.c
>>> +++ b/xen/arch/arm/platforms/xilinx-zynqmp.c
>>> @@ -18,6 +18,8 @@
>>>     */
>>>      #include <asm/platform.h>
>>> +#include <asm/platforms/xilinx-zynqmp-eemi.h>
>>> +#include <asm/smccc.h>
>>>      static const char * const zynqmp_dt_compat[] __initconst =
>>>    {
>>> @@ -32,8 +34,17 @@ static const struct dt_device_match
>>> zynqmp_blacklist_dev[] __initconst =
>>>        { /* sentinel */ },
>>>    };
>>>    +static bool zynqmp_smc(struct cpu_user_regs *regs)
>>> +{
>>> +    if ( !is_64bit_domain(current->domain) )
>>
>> Please document why you only expose eemi to 64-bit domain. What if the user
>> start with 32-bit Dom0?
> 
> I'll add a in-code comment saying that only 64-bit guests are supported
> by the current implementation -- the 32 bit EEMI ABI is not yet covered.

64-bit guests is allowed to use both SMC32 and SMC64. There are actually some 
call that can only be done using SMC32 convention (see patch #6). So why forbid 
32-bit domain when you allow 64-bit using SMC32?

Cheers,

-- 
Julien Grall

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