Re: [Xen-devel] [PATCH] xen/arm: Switch OMAP5 secondary cores into hyp mode

[Andrew Cooper <andrew.cooper3@citrix.com>]

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On 24/06/2019 12:09, Julien Grall wrote:
> (+ GSOC mentors and Andre)
>
> Hi Denis,
>
> Thank you for the patch.
>
> First of all, may I ask to CC the other mentors?
>
> On 6/21/19 9:02 PM, Denis Obrezkov wrote:
>> This function allows xen to bring secondary CPU cores into non-secure
>> HYP mode. This is done by using a Secure Monitor call.
>>
>> Signed-off-by: Denis Obrezkov <denisobrezkov@gmail.com>
>> ---
>>   xen/arch/arm/arm32/head.S             | 11 ++++++++++-
>>   xen/arch/arm/platforms/omap5.c        |  5 +++--
>>   xen/include/asm-arm/platforms/omap5.h |  3 +++
>>   3 files changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S
>> index 5f817d473e..120e034934 100644
>> --- a/xen/arch/arm/arm32/head.S
>> +++ b/xen/arch/arm/arm32/head.S
>> @@ -36,6 +36,10 @@
>>   #include EARLY_PRINTK_INC
>>   #endif
>>   +
>> +#define API_HYP_ENTRY 0x102
>> +#define AUX_CORE_BOOT0_PA           0x48281800
>> +
>
> I have thought a bit more about the placement of the code. I think it
> would be best if it lives in a separate file (maybe
> platforms/omap5-head.S).

For something this trivial, it is easy to put straight into omap5.c

Completely untested, but this ought to work:

diff --git a/xen/arch/arm/platforms/omap5.c b/xen/arch/arm/platforms/omap5.c
index 6b5cc15af3..1dcc92d3a4 100644
--- a/xen/arch/arm/platforms/omap5.c
+++ b/xen/arch/arm/platforms/omap5.c
@@ -23,6 +23,16 @@
 #include <xen/vmap.h>
 #include <asm/io.h>
 
+void omap5_init_secondary(void);
+asm (
+".text                            \n\t"
+"omap5_init_secondary:            \n\t"
+"        ldr   r12, =0x102        \n\t" /* API_HYP_ENTRY */
+"        adr   r0, init_secondary \n\t"
+"        smc   #0                 \n\t"
+"        b     init_secondary     \n\t"
+);
+
 static uint16_t num_den[8][2] = {
     {         0,          0 },  /* not used */
     {  26 *  64,  26 *  125 },  /* 12.0 Mhz */


I personally find this favourable to introducing new stub files.

Ultimately it is Julien/Stefano's decision, but I'd like to point it out
as an option for anyone who is unaware.

~Andrew

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