fix(armv8/cpu): replace psci_power_down by a WFI call

joaopeixoto13 · joaopeixoto13 · commit bdb870fce0a8 · 2024-09-19T14:43:15.000+01:00
For ARMv8-A physical boards (e.g. ZCU102), when using the Remote I/O
there is a problem already identified when the Frontend VM's
CPU goes to the idle state, as a result of the trap process
and MMIO emulation. In this scenario, currently Bao Hypervisor
is unable to save the state of the registers before powering off.
This commit replaces the psci_power_down call by an explicit WFI
(Wait For Interrupt), similar to ARMv8-R and RISC-V, temporarily
resolving the problem.

Signed-off-by: João Peixoto &lt;joaopeixotooficial@gmail.com&gt;
diff --git a/src/arch/armv8/armv8-a/cpu.c b/src/arch/armv8/armv8-a/cpu.c
@@ -29,7 +29,7 @@ void cpu_arch_profile_init(cpuid_t cpuid, paddr_t load_addr)
 
 void cpu_arch_profile_idle()
 {
-    int64_t err = psci_power_down(PSCI_WAKEUP_IDLE);
+    int64_t err = PSCI_E_NOT_SUPPORTED;
     if (err) {
         switch (err) {
             case PSCI_E_NOT_SUPPORTED:

Original file line number	Diff line number	Diff line change
`@@ -29,7 +29,7 @@ void cpu_arch_profile_init(cpuid_t cpuid, paddr_t load_addr)`
`29`	`29`
`30`	`30`	`void cpu_arch_profile_idle()`
`31`	`31`	`{`
`32`		`- int64_t err = psci_power_down(PSCI_WAKEUP_IDLE);`
	`32`	`+ int64_t err = PSCI_E_NOT_SUPPORTED;`
`33`	`33`	`if (err) {`
`34`	`34`	`switch (err) {`
`35`	`35`	`case PSCI_E_NOT_SUPPORTED:`