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Re: [Qemu-devel] [PATCH v8 4/7] s390x/cpu: Tolerate max_cpus
From: |
Matthew Rosato |
Subject: |
Re: [Qemu-devel] [PATCH v8 4/7] s390x/cpu: Tolerate max_cpus |
Date: |
Fri, 4 Mar 2016 09:09:17 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 |
On 03/04/2016 03:05 AM, David Hildenbrand wrote:
>> Once hotplug is enabled, interrupts may come in for CPUs
>> with an address > smp_cpus. Allocate for this and allow
>> search routines to look beyond smp_cpus.
>>
>> Signed-off-by: Matthew Rosato <address@hidden>
>> ---
>> hw/s390x/s390-virtio.c | 13 +++++++------
>> 1 file changed, 7 insertions(+), 6 deletions(-)
>>
>> diff --git a/hw/s390x/s390-virtio.c b/hw/s390x/s390-virtio.c
>> index c501a48..90bc58a 100644
>> --- a/hw/s390x/s390-virtio.c
>> +++ b/hw/s390x/s390-virtio.c
>> @@ -58,15 +58,16 @@
>> #define S390_TOD_CLOCK_VALUE_MISSING 0x00
>> #define S390_TOD_CLOCK_VALUE_PRESENT 0x01
>>
>> -static S390CPU **ipi_states;
>> +static S390CPU **cpu_states;
>>
>> S390CPU *s390_cpu_addr2state(uint16_t cpu_addr)
>> {
>> - if (cpu_addr >= smp_cpus) {
>> + if (cpu_addr >= max_cpus) {
>> return NULL;
>> }
>>
>> - return ipi_states[cpu_addr];
>> + /* Fast lookup via CPU ID */
>> + return cpu_states[cpu_addr];
>> }
>>
>> void s390_init_ipl_dev(const char *kernel_filename,
>> @@ -101,14 +102,14 @@ void s390_init_cpus(MachineState *machine)
>> machine->cpu_model = "host";
>> }
>>
>> - ipi_states = g_malloc(sizeof(S390CPU *) * smp_cpus);
>> + cpu_states = g_malloc0(sizeof(S390CPU *) * max_cpus);
>>
>> - for (i = 0; i < smp_cpus; i++) {
>> + for (i = 0; i < max_cpus; i++) {
>> S390CPU *cpu;
>>
>> cpu = cpu_s390x_init(machine->cpu_model);
>>
>> - ipi_states[i] = cpu;
>> + cpu_states[i] = cpu;
>
> This looks wrong (creating all cpus). But the net patch fixes it again.
>
Ouch. Definitely wrong, error introduced during patch split. We
allocate for max_cpus, but should only create smp_cpus cpus during init.
> Can you make this patch a simple rename patch and move the max_cpu stuff into
> the next patch if this makes sense?
>
> Or simply set the cpu_state for everything above smp_cpus to zero in this
> patch.
This is done via the gmalloc0. If I hadn't messed up this loop, the net
result would be the ability to handle > smp_cpus, but nobody will ever
create one (yet).
Matt
- [Qemu-devel] [PATCH v8 0/7] Allow hotplug of s390 CPUs, Matthew Rosato, 2016/03/03
- [Qemu-devel] [PATCH v8 1/7] s390x/cpu: Cleanup init in preparation for hotplug, Matthew Rosato, 2016/03/03
- [Qemu-devel] [PATCH v8 2/7] s390x/cpu: Set initial CPU state in common routine, Matthew Rosato, 2016/03/03
- [Qemu-devel] [PATCH v8 3/7] s390x/cpu: Get rid of side effects when creating a vcpu, Matthew Rosato, 2016/03/03
- [Qemu-devel] [PATCH v8 4/7] s390x/cpu: Tolerate max_cpus, Matthew Rosato, 2016/03/03
- [Qemu-devel] [PATCH v8 5/7] s390x/cpu: Add CPU property links, Matthew Rosato, 2016/03/03
- [Qemu-devel] [PATCH v8 7/7] s390x/cpu: Allow hotplug of CPUs, Matthew Rosato, 2016/03/03
- [Qemu-devel] [PATCH v8 6/7] s390x/cpu: Add error handling to cpu creation, Matthew Rosato, 2016/03/03