From: Thomas Gleixner <[email protected]>
Now that the core code drops sparse_irq_lock after the idle thread
synchronized, it's pointless to wait for the AP to mark itself online.
Whether the control CPU runs in a wait loop or sleeps in the core code
waiting for the online operation to complete makes no difference.
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Michael Kelley <[email protected]>
---
arch/x86/xen/smp_pv.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -340,11 +340,11 @@ static int xen_pv_cpu_up(unsigned int cp
xen_pmu_init(cpu);
- rc = HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL);
- BUG_ON(rc);
-
- while (cpu_report_state(cpu) != CPU_ONLINE)
- HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
+ /*
+ * Why is this a BUG? If the hypercall fails then everything can be
+ * rolled back, no?
+ */
+ BUG_ON(HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL));
return 0;
}
The following commit has been merged into the smp/core branch of tip:
Commit-ID: 2de7fd26d90729c4e3430f9924b199dea810a9bc
Gitweb: https://git.kernel.org/tip/2de7fd26d90729c4e3430f9924b199dea810a9bc
Author: Thomas Gleixner <[email protected]>
AuthorDate: Fri, 12 May 2023 23:07:24 +02:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Mon, 15 May 2023 13:44:54 +02:00
x86/xen/smp_pv: Remove wait for CPU online
Now that the core code drops sparse_irq_lock after the idle thread
synchronized, it's pointless to wait for the AP to mark itself online.
Whether the control CPU runs in a wait loop or sleeps in the core code
waiting for the online operation to complete makes no difference.
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Tested-by: Michael Kelley <[email protected]>
Tested-by: Oleksandr Natalenko <[email protected]>
Tested-by: Helge Deller <[email protected]> # parisc
Tested-by: Guilherme G. Piccoli <[email protected]> # Steam Deck
Link: https://lore.kernel.org/r/[email protected]
---
arch/x86/xen/smp_pv.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index a6f9128..be40927 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -340,11 +340,11 @@ static int xen_pv_cpu_up(unsigned int cpu, struct task_struct *idle)
xen_pmu_init(cpu);
- rc = HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL);
- BUG_ON(rc);
-
- while (cpu_report_state(cpu) != CPU_ONLINE)
- HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
+ /*
+ * Why is this a BUG? If the hypercall fails then everything can be
+ * rolled back, no?
+ */
+ BUG_ON(HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL));
return 0;
}