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

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

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@xxxxxxxxx>
---
  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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