[xen master] xen/arm: psci: Do not keep a rejected PSCI version in psci_ver

[patchbot@xxxxxxx]

commit 46678752be2d97f61317d793408a59927a429847
Author:     Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
AuthorDate: Wed Oct 21 15:26:40 2026 +0200
Commit:     Michal Orzel <michal.orzel@xxxxxxx>
CommitDate: Mon Oct 26 09:01:40 2026 +0100

    xen/arm: psci: Do not keep a rejected PSCI version in psci_ver
    
    psci_init_0_2() stores the value returned by PSCI_VERSION in the global
    psci_ver before checking that Xen supports it. When the firmware reports
    a version other than 0.2 or 1.x, the function prints "Unrecognized PSCI
    version" and returns -EOPNOTSUPP, but psci_ver keeps the rejected value
    and psci_cpu_on_nr stays 0.
    
    psci_init() then tries the PSCI 0.1 fallback, which overwrites psci_ver
    on success. When the fallback fails as well (the /psci node is not
    compatible with "arm,psci", it has no "cpu_on" property, or Xen boots
    with ACPI), psci_init() returns an error that smp_init_cpus() ignores,
    and psci_ver still holds the rejected version. All the users of
    psci_ver then consider PSCI as available:
     - on arm64, smp_psci_init() installs call_psci_cpu_on() as the method
       to bring up the secondary CPUs;
     - on arm32, platform_cpu_up() calls call_psci_cpu_on() instead of the
       platform specific cpu_up() callback;
     - call_psci_cpu_off(), call_psci_system_off() and
       call_psci_system_reset() issue their PSCI calls.
    
    As a result, Xen brings up each secondary CPU with an SMC using function
    ID 0. An SMCCC compliant firmware refuses it, and Xen reports "Failed to
    bring up CPU<n> (error -1)" for each secondary CPU.
    
    Fix it by setting psci_ver back to 0 before returning the error.
    
    Fixes: 4d3d72c01467 ("xen/arm: Initial support for PSCI-0.2")
    Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
    Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
---
 xen/arch/arm/psci.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/xen/arch/arm/psci.c b/xen/arch/arm/psci.c
index 634d0d7467..967cb4b77d 100644
--- a/xen/arch/arm/psci.c
+++ b/xen/arch/arm/psci.c
@@ -198,6 +198,7 @@ static int __init psci_init_0_2(void)
     {
         printk("Error: Unrecognized PSCI version %u.%u\n",
                PSCI_VERSION_MAJOR(psci_ver), PSCI_VERSION_MINOR(psci_ver));
+        psci_ver = 0;
         return -EOPNOTSUPP;
     }
 
--
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