| Message ID | 1444844997-27314-3-git-send-email-stefano.stabellini@eu.citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Stefano, On 14/10/2015 18:49, Stefano Stabellini wrote: > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > --- > arch/arm/xen/enlighten.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c > index 6c09cc4..59f5421 100644 > --- a/arch/arm/xen/enlighten.c > +++ b/arch/arm/xen/enlighten.c > @@ -93,6 +93,12 @@ static void xen_percpu_init(void) > int err; > int cpu = get_cpu(); > > + /* vcpu_info already registered, can happen with cpu-hotplug */ Can you please add more comment and explain in the commit message why this is necessary for cpu-hotplug? I had to look at the x86 code to fully understand that it's not possible to call VCPUOP_register_vcpu_info twice because there is no hypercall to remove the vcpu shared page. > + if (per_cpu(xen_vcpu, cpu) != NULL) { > + put_cpu(); > + return; > + } > + > pr_info("Xen: initializing cpu%d\n", cpu); > vcpup = per_cpu_ptr(xen_vcpu_info, cpu); > > Regards,
On Wed, 14 Oct 2015, Julien Grall wrote: > Hi Stefano, > > On 14/10/2015 18:49, Stefano Stabellini wrote: > > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > > --- > > arch/arm/xen/enlighten.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c > > index 6c09cc4..59f5421 100644 > > --- a/arch/arm/xen/enlighten.c > > +++ b/arch/arm/xen/enlighten.c > > @@ -93,6 +93,12 @@ static void xen_percpu_init(void) > > int err; > > int cpu = get_cpu(); > > > > + /* vcpu_info already registered, can happen with cpu-hotplug */ > > Can you please add more comment and explain in the commit message why this is > necessary for cpu-hotplug? > > I had to look at the x86 code to fully understand that it's not possible to > call VCPUOP_register_vcpu_info twice because there is no hypercall to remove > the vcpu shared page. Sure > > > + if (per_cpu(xen_vcpu, cpu) != NULL) { > > + put_cpu(); > > + return; > > + } > > + > > pr_info("Xen: initializing cpu%d\n", cpu); > > vcpup = per_cpu_ptr(xen_vcpu_info, cpu); > > > > > > Regards, > > -- > Julien Grall >
diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c index 6c09cc4..59f5421 100644 --- a/arch/arm/xen/enlighten.c +++ b/arch/arm/xen/enlighten.c @@ -93,6 +93,12 @@ static void xen_percpu_init(void) int err; int cpu = get_cpu(); + /* vcpu_info already registered, can happen with cpu-hotplug */ + if (per_cpu(xen_vcpu, cpu) != NULL) { + put_cpu(); + return; + } + pr_info("Xen: initializing cpu%d\n", cpu); vcpup = per_cpu_ptr(xen_vcpu_info, cpu);
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> --- arch/arm/xen/enlighten.c | 6 ++++++ 1 file changed, 6 insertions(+)