diff options
| author | David Woodhouse <dwmw@amazon.co.uk> | 2020-10-24 22:35:01 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-10-28 20:26:23 +0100 |
| commit | 26573a97746c7a99f394f9d398ce91a8853b3b89 (patch) | |
| tree | 1976a1d6ffcd6ffd621b526d082cb1e8ee8c6a42 /arch/x86/kernel/apic/x2apic_phys.c | |
| parent | 5a169bf04cd2bfdbac967d12eb5b70915b29d7ee (diff) | |
x86/apic: Fix x2apic enablement without interrupt remapping
Currently, Linux as a hypervisor guest will enable x2apic only if there are
no CPUs present at boot time with an APIC ID above 255.
Hotplugging a CPU later with a higher APIC ID would result in a CPU which
cannot be targeted by external interrupts.
Add a filter in x2apic_apic_id_valid() which can be used to prevent such
CPUs from coming online, and allow x2apic to be enabled even if they are
present at boot time.
Fixes: ce69a784504 ("x86/apic: Enable x2APIC without interrupt remapping under KVM")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201024213535.443185-2-dwmw2@infradead.org
Diffstat (limited to 'arch/x86/kernel/apic/x2apic_phys.c')
| -rw-r--r-- | arch/x86/kernel/apic/x2apic_phys.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c index bc9693841353..e14eae6d6ea7 100644 --- a/arch/x86/kernel/apic/x2apic_phys.c +++ b/arch/x86/kernel/apic/x2apic_phys.c @@ -8,6 +8,12 @@ int x2apic_phys; static struct apic apic_x2apic_phys; +static u32 x2apic_max_apicid __ro_after_init; + +void __init x2apic_set_max_apicid(u32 apicid) +{ + x2apic_max_apicid = apicid; +} static int __init set_x2apic_phys_mode(char *arg) { @@ -98,6 +104,9 @@ static int x2apic_phys_probe(void) /* Common x2apic functions, also used by x2apic_cluster */ int x2apic_apic_id_valid(u32 apicid) { + if (x2apic_max_apicid && apicid > x2apic_max_apicid) + return 0; + return 1; } |