[Xen-devel] [PATCH v5 13/18] xen/arm: vpsci: Remove parameter 'ver' from do_common_cpu

[Julien Grall <julien.grall@xxxxxxx>]

Currently, the behavior of do_common_cpu will slightly change depending
on the PSCI version passed in parameter. Looking at the code, more the
specific 0.2 behavior could move out of the function or adapted for 0.1:

    - x0/r0 can be updated on PSCI 0.1 because general purpose registers
    are undefined upon CPU on. This was deduced from the spec not
    mentioning the state of general purpose registers on CPU on.
    - PSCI 0.1 does not defined PSCI_ALREADY_ON. However, it would be
    safer to bail out if the CPU is already on.

Based on this, the parameter 'ver' is removed and do_psci_cpu_on
(implementation for PSCI 0.1) is adapted to avoid returning
PSCI_ALREADY_ON.

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
Reviewed-by: Volodymyr Babchuk <volodymyr.babchuk@xxxxxxxx>
Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>

---
    The reviewed-by was kept despite move this patch towards the end
    of the series because there was no clash with the rest of the series.

    Changes in v4:
        - Slightly update the comment to mention the spec
        - Add Stefano's acked-by
        - Add Andre's reviewed-by

    Changes in v2:
        - Move the patch towards the end of the series as not strictly
        necessary for SP2.
        - Add Volodymyr's reviewed-by
---
 xen/arch/arm/vpsci.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/xen/arch/arm/vpsci.c b/xen/arch/arm/vpsci.c
index 19ee7caeb4..7ea3ea58e3 100644
--- a/xen/arch/arm/vpsci.c
+++ b/xen/arch/arm/vpsci.c
@@ -22,7 +22,7 @@
 #include <public/sched.h>
 
 static int do_common_cpu_on(register_t target_cpu, register_t entry_point,
-                       register_t context_id,int ver)
+                            register_t context_id)
 {
     struct vcpu *v;
     struct domain *d = current->domain;
@@ -40,8 +40,7 @@ static int do_common_cpu_on(register_t target_cpu, register_t 
entry_point,
     if ( is_64bit_domain(d) && is_thumb )
         return PSCI_INVALID_PARAMETERS;
 
-    if ( (ver == PSCI_VERSION(0, 2)) &&
-            !test_bit(_VPF_down, &v->pause_flags) )
+    if ( !test_bit(_VPF_down, &v->pause_flags) )
         return PSCI_ALREADY_ON;
 
     if ( (ctxt = alloc_vcpu_guest_context()) == NULL )
@@ -55,18 +54,21 @@ static int do_common_cpu_on(register_t target_cpu, 
register_t entry_point,
     ctxt->ttbr0 = 0;
     ctxt->ttbr1 = 0;
     ctxt->ttbcr = 0; /* Defined Reset Value */
+
+    /*
+     * x0/r0_usr are always updated because for PSCI 0.1 the general
+     * purpose registers are undefined upon CPU_on.
+     */
     if ( is_32bit_domain(d) )
     {
         ctxt->user_regs.cpsr = PSR_GUEST32_INIT;
-        if ( ver == PSCI_VERSION(0, 2) )
-            ctxt->user_regs.r0_usr = context_id;
+        ctxt->user_regs.r0_usr = context_id;
     }
 #ifdef CONFIG_ARM_64
     else
     {
         ctxt->user_regs.cpsr = PSR_GUEST64_INIT;
-        if ( ver == PSCI_VERSION(0, 2) )
-            ctxt->user_regs.x0 = context_id;
+        ctxt->user_regs.x0 = context_id;
     }
 #endif
 
@@ -93,7 +95,14 @@ static int do_common_cpu_on(register_t target_cpu, 
register_t entry_point,
 
 static int32_t do_psci_cpu_on(uint32_t vcpuid, register_t entry_point)
 {
-    return do_common_cpu_on(vcpuid, entry_point, 0 , PSCI_VERSION(0, 1));
+    int32_t ret;
+
+    ret = do_common_cpu_on(vcpuid, entry_point, 0);
+    /*
+     * PSCI 0.1 does not define the return code PSCI_ALREADY_ON.
+     * Instead, return PSCI_INVALID_PARAMETERS.
+     */
+    return (ret == PSCI_ALREADY_ON) ? PSCI_INVALID_PARAMETERS : ret;
 }
 
 static int32_t do_psci_cpu_off(uint32_t power_state)
@@ -137,8 +146,7 @@ static int32_t do_psci_0_2_cpu_on(register_t target_cpu,
                                   register_t entry_point,
                                   register_t context_id)
 {
-    return do_common_cpu_on(target_cpu, entry_point, context_id,
-                            PSCI_VERSION(0, 2));
+    return do_common_cpu_on(target_cpu, entry_point, context_id);
 }
 
 static const unsigned long target_affinity_mask[] = {
-- 
2.11.0


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel