Hi,
On 13/11/2018 22:35, Stefano Stabellini wrote:
On Mon, 12 Nov 2018, Mirela Simonovic wrote:
Non-boot CPUs have to be disabled on suspend and enabled on resume
(hotplug-based mechanism). Disabling non-boot CPUs will lead to PSCI
CPU_OFF to be called by each non-boot CPU. Depending on the underlying
platform capabilities, this may lead to the physical powering down of
CPUs. Tested on Xilinx Zynq Ultrascale+ MPSoC (including power down of
each non-boot CPU).
Signed-off-by: Mirela Simonovic <mirela.simono...@aggios.com>
Signed-off-by: Saeed Nowshadi <saeed.nowsh...@xilinx.com>
---
xen/arch/arm/suspend.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/xen/arch/arm/suspend.c b/xen/arch/arm/suspend.c
index 575afd5eb8..dae1b1f7d6 100644
--- a/xen/arch/arm/suspend.c
+++ b/xen/arch/arm/suspend.c
@@ -1,4 +1,5 @@
#include <xen/sched.h>
+#include <xen/cpu.h>
#include <asm/cpufeature.h>
#include <asm/event.h>
#include <asm/psci.h>
@@ -115,17 +116,29 @@ static void vcpu_suspend(register_t epoint, register_t
cid)
/* Xen suspend. Note: data is not used (suspend is the suspend to RAM) */
static long system_suspend(void *data)
{
+ int status;
+
BUG_ON(system_state != SYS_STATE_active);
system_state = SYS_STATE_suspend;
freeze_domains();
+ status = disable_nonboot_cpus();
+ if ( status )
+ {
+ system_state = SYS_STATE_resume;
+ goto resume_nonboot_cpus;
+ }
+
system_state = SYS_STATE_resume;
+resume_nonboot_cpus:
+ enable_nonboot_cpus();
thaw_domains();
system_state = SYS_STATE_active;
+ dsb(sy);
- return -ENOSYS;
+ return status;
}
I think we need a spin_lock to protect system_suspend from concurrent
calls, or (better) we need to make sure that the caller is only allowed
to call system_suspend if there is just one vcpu active in the system,
and that vcpu is blocked on this PSCI system suspend call.
I don't think this is correct. It is valid to have more than on vCPU running
when calling system_suspend. An example would be Dom0 suspending while the other
domain are still running.
This is handled properly via freeze_domains()/thaw_domains().
So a spinlock would be a better solution here. If we can't acquire the lock then
the function would return -EBUSY.
Cheers,
--
Julien Grall
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