Re: kvm-45 problems

Laurent Vivier
2007-10-10T11:23:11Z

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Avi Kivity wrote:
> Zhao, Yunfeng wrote:
>> This fix cannot resolve this issue.
>> Against latest kvm commits, SMP linux with 4 vcpus still cannot boot up.
>> But the issue will not happen , if adding "-smp4 -no-acpi".
>>
>
> Can you try the attached patch?
>
>
>
>
>
>
> ------------------------------------------------------------------------
>
> diff --git a/kernel/kvm_main.c b/kernel/kvm_main.c
> index 0b2894a..61d931e 100644
> --- a/kernel/kvm_main.c
> +++ b/kernel/kvm_main.c
> @@ -235,11 +235,7 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
> * to complete.
> */
> for (cpu = first_cpu(cpus); cpu != NR_CPUS; cpu = next_cpu(cpu, cpus))
> - smp_call_function_single(cpu, ack_flush, &completed, 1, 0);
> - while (atomic_read(&completed) != needed) {
> - cpu_relax();
> - barrier();
> - }
> + smp_call_function_single(cpu, ack_flush, &completed, 1, 1);
> }
>
> int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)

This part will be obsolete as soon as linux will export
smp_call_function_mask(). This is already in mm tree:

ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.23-rc8/2.6.23-rc8-mm2/broken-out/x86_64-mm-export-i386-smp_call_function_mask-to-modules.patch
ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.23-rc8/2.6.23-rc8-mm2/broken-out/x86_64-mm-implement-missing-x86_64-function-smp_call_function_mask.patch

Apply these patches and try the attached patch for KVM.

Laurent
--
---------------- Laurent.Vivier-6ktuUTfB/bM@public.gmane.org -----------------
"Given enough eyeballs, all bugs are shallow" E. S. Raymond

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Index: kvm/drivers/kvm/kvm_main.c
===================================================================
--- kvm.orig/drivers/kvm/kvm_main.c 2007-09-12 17:49:51.000000000 +0200
+++ kvm/drivers/kvm/kvm_main.c 2007-09-12 17:58:18.000000000 +0200
@@ -198,21 +198,15 @@ static void vcpu_put(struct kvm_vcpu *vc

static void ack_flush(void *_completed)
{
- atomic_t *completed = _completed;
-
- atomic_inc(completed);
}

void kvm_flush_remote_tlbs(struct kvm *kvm)
{
- int i, cpu, needed;
+ int i, cpu;
cpumask_t cpus;
struct kvm_vcpu *vcpu;
- atomic_t completed;

- atomic_set(&completed, 0);
cpus_clear(cpus);
- needed = 0;
for (i = 0; i < KVM_MAX_VCPUS; ++i) {
vcpu = kvm->vcpus[i];
if (!vcpu)
@@ -221,23 +215,9 @@ void kvm_flush_remote_tlbs(struct kvm *k
continue;
cpu = vcpu->cpu;
if (cpu != -1 && cpu != raw_smp_processor_id())
- if (!cpu_isset(cpu, cpus)) {
- cpu_set(cpu, cpus);
- ++needed;
- }
- }
-
- /*
- * We really want smp_call_function_mask() here. But that's not
- * available, so ipi all cpus in parallel and wait for them
- * to complete.
- */
- for (cpu = first_cpu(cpus); cpu != NR_CPUS; cpu = next_cpu(cpu, cpus))
- smp_call_function_single(cpu, ack_flush, &completed, 1, 0);
- while (atomic_read(&completed) != needed) {
- cpu_relax();
- barrier();
+ cpu_set(cpu, cpus);
}
+ smp_call_function_mask(cpus, ack_flush, NULL, 1);
}

int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)

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