Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-04-27 Thread Purcareata Bogdan
On 24.04.2015 00:26, Scott Wood wrote: On Thu, 2015-04-23 at 15:31 +0300, Purcareata Bogdan wrote: On 23.04.2015 03:30, Scott Wood wrote: On Wed, 2015-04-22 at 15:06 +0300, Purcareata Bogdan wrote: On 21.04.2015 03:52, Scott Wood wrote: On Mon, 2015-04-20 at 13:53 +0300, Purcareata Bogdan

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-04-23 Thread Scott Wood
On Thu, 2015-04-23 at 15:31 +0300, Purcareata Bogdan wrote: On 23.04.2015 03:30, Scott Wood wrote: On Wed, 2015-04-22 at 15:06 +0300, Purcareata Bogdan wrote: On 21.04.2015 03:52, Scott Wood wrote: On Mon, 2015-04-20 at 13:53 +0300, Purcareata Bogdan wrote: There was a weird situation for

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-04-23 Thread Purcareata Bogdan
On 23.04.2015 03:30, Scott Wood wrote: On Wed, 2015-04-22 at 15:06 +0300, Purcareata Bogdan wrote: On 21.04.2015 03:52, Scott Wood wrote: On Mon, 2015-04-20 at 13:53 +0300, Purcareata Bogdan wrote: There was a weird situation for .kvmppc_mpic_set_epr - its corresponding inner function is

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-04-22 Thread Scott Wood
On Wed, 2015-04-22 at 15:06 +0300, Purcareata Bogdan wrote: On 21.04.2015 03:52, Scott Wood wrote: On Mon, 2015-04-20 at 13:53 +0300, Purcareata Bogdan wrote: There was a weird situation for .kvmppc_mpic_set_epr - its corresponding inner function is kvmppc_set_epr, which is a static

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-04-22 Thread Purcareata Bogdan
On 21.04.2015 03:52, Scott Wood wrote: On Mon, 2015-04-20 at 13:53 +0300, Purcareata Bogdan wrote: There was a weird situation for .kvmppc_mpic_set_epr - its corresponding inner function is kvmppc_set_epr, which is a static inline. Removing the static inline yields a compiler crash

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-04-20 Thread Scott Wood
On Mon, 2015-04-20 at 13:53 +0300, Purcareata Bogdan wrote: On 10.04.2015 02:53, Scott Wood wrote: On Thu, 2015-04-09 at 10:44 +0300, Purcareata Bogdan wrote: So at this point I was getting kinda frustrated so I decided to measure the time spend in kvm_mpic_write and kvm_mpic_read. I

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-04-20 Thread Purcareata Bogdan
On 10.04.2015 02:53, Scott Wood wrote: On Thu, 2015-04-09 at 10:44 +0300, Purcareata Bogdan wrote: So at this point I was getting kinda frustrated so I decided to measure the time spend in kvm_mpic_write and kvm_mpic_read. I assumed these were the main entry points in the in-kernel MPIC and

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-04-09 Thread Purcareata Bogdan
On 04.04.2015 00:26, Scott Wood wrote: On Fri, 2015-04-03 at 11:07 +0300, Purcareata Bogdan wrote: On 03.04.2015 02:11, Scott Wood wrote: On Fri, 2015-03-27 at 19:07 +0200, Purcareata Bogdan wrote: On 27.02.2015 03:05, Scott Wood wrote: On Thu, 2015-02-26 at 14:31 +0100, Sebastian Andrzej

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-04-03 Thread Purcareata Bogdan
On 03.04.2015 02:11, Scott Wood wrote: On Fri, 2015-03-27 at 19:07 +0200, Purcareata Bogdan wrote: On 27.02.2015 03:05, Scott Wood wrote: On Thu, 2015-02-26 at 14:31 +0100, Sebastian Andrzej Siewior wrote: On 02/26/2015 02:02 PM, Paolo Bonzini wrote: On 24/02/2015 00:27, Scott Wood wrote:

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-04-03 Thread Scott Wood
On Fri, 2015-04-03 at 11:07 +0300, Purcareata Bogdan wrote: On 03.04.2015 02:11, Scott Wood wrote: On Fri, 2015-03-27 at 19:07 +0200, Purcareata Bogdan wrote: On 27.02.2015 03:05, Scott Wood wrote: On Thu, 2015-02-26 at 14:31 +0100, Sebastian Andrzej Siewior wrote: On 02/26/2015 02:02 PM,

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-04-02 Thread Scott Wood
On Fri, 2015-03-27 at 19:07 +0200, Purcareata Bogdan wrote: On 27.02.2015 03:05, Scott Wood wrote: On Thu, 2015-02-26 at 14:31 +0100, Sebastian Andrzej Siewior wrote: On 02/26/2015 02:02 PM, Paolo Bonzini wrote: On 24/02/2015 00:27, Scott Wood wrote: This isn't a host PIC driver.

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-03-27 Thread Purcareata Bogdan
On 27.02.2015 03:05, Scott Wood wrote: On Thu, 2015-02-26 at 14:31 +0100, Sebastian Andrzej Siewior wrote: On 02/26/2015 02:02 PM, Paolo Bonzini wrote: On 24/02/2015 00:27, Scott Wood wrote: This isn't a host PIC driver. It's guest PIC emulation, some of which is indeed not suitable for a

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-27 Thread Paolo Bonzini
On 27/02/2015 02:05, Scott Wood wrote: Obviously leaving it in a buggy state is not what we want -- but I lean towards a short term fix of putting depends on !PREEMPT_RT on the in-kernel MPIC emulation (which is itself just an optimization -- you can still use KVM without it). This way

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-26 Thread Sebastian Andrzej Siewior
On 02/26/2015 02:02 PM, Paolo Bonzini wrote: On 24/02/2015 00:27, Scott Wood wrote: This isn't a host PIC driver. It's guest PIC emulation, some of which is indeed not suitable for a rawlock (in particular, openpic_update_irq which loops on the number of vcpus, with a loop body that calls

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-26 Thread Paolo Bonzini
On 24/02/2015 00:27, Scott Wood wrote: This isn't a host PIC driver. It's guest PIC emulation, some of which is indeed not suitable for a rawlock (in particular, openpic_update_irq which loops on the number of vcpus, with a loop body that calls IRQ_check() which loops over all pending

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-26 Thread Scott Wood
On Thu, 2015-02-26 at 14:31 +0100, Sebastian Andrzej Siewior wrote: On 02/26/2015 02:02 PM, Paolo Bonzini wrote: On 24/02/2015 00:27, Scott Wood wrote: This isn't a host PIC driver. It's guest PIC emulation, some of which is indeed not suitable for a rawlock (in particular,

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-25 Thread Sebastian Andrzej Siewior
* Scott Wood | 2015-02-23 17:27:31 [-0600]: This isn't a host PIC driver. It's guest PIC emulation, some of which is indeed not suitable for a rawlock (in particular, openpic_update_irq which loops on the number of vcpus, with a loop body that calls IRQ_check() which loops over all pending

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-23 Thread Purcareata Bogdan
On 20.02.2015 17:17, Sebastian Andrzej Siewior wrote: On 02/20/2015 04:10 PM, Paolo Bonzini wrote: On 20/02/2015 16:06, Sebastian Andrzej Siewior wrote: On 02/20/2015 03:57 PM, Paolo Bonzini wrote: Yes, but large latencies just mean the code has to be rewritten (x86 doesn't anymore do event

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-23 Thread Scott Wood
On Fri, 2015-02-20 at 15:54 +0100, Sebastian Andrzej Siewior wrote: On 02/20/2015 03:12 PM, Paolo Bonzini wrote: Thomas, what is the usual approach for patches like this? Do you take them into your rt tree or should they get integrated to upstream? Patch 1 is definitely suitable for

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-22 Thread Purcareata Bogdan
On 20.02.2015 17:06, Sebastian Andrzej Siewior wrote: On 02/20/2015 03:57 PM, Paolo Bonzini wrote: On 20/02/2015 15:54, Sebastian Andrzej Siewior wrote: Usually you see scheduling while atomic on -RT and convert them to raw locks if it is appropriate. Bogdan wrote in 2/2 that he needs to

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-22 Thread Purcareata Bogdan
On 20.02.2015 16:54, Sebastian Andrzej Siewior wrote: On 02/20/2015 03:12 PM, Paolo Bonzini wrote: Thomas, what is the usual approach for patches like this? Do you take them into your rt tree or should they get integrated to upstream? Patch 1 is definitely suitable for upstream, that's the

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-20 Thread Paolo Bonzini
On 20/02/2015 14:45, Alexander Graf wrote: On 18.02.15 10:32, Bogdan Purcareata wrote: This patchset enables running KVM SMP guests with external interrupts on an underlying RT-enabled Linux. Previous to this patch, a guest with in-kernel MPIC emulation could easily panic the kernel

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-20 Thread Alexander Graf
On 18.02.15 10:32, Bogdan Purcareata wrote: This patchset enables running KVM SMP guests with external interrupts on an underlying RT-enabled Linux. Previous to this patch, a guest with in-kernel MPIC emulation could easily panic the kernel due to preemption when delivering IPIs and

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-20 Thread Alexander Graf
On 20.02.15 15:12, Paolo Bonzini wrote: On 20/02/2015 14:45, Alexander Graf wrote: On 18.02.15 10:32, Bogdan Purcareata wrote: This patchset enables running KVM SMP guests with external interrupts on an underlying RT-enabled Linux. Previous to this patch, a guest with in-kernel MPIC

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-20 Thread Sebastian Andrzej Siewior
On 02/20/2015 03:12 PM, Paolo Bonzini wrote: Thomas, what is the usual approach for patches like this? Do you take them into your rt tree or should they get integrated to upstream? Patch 1 is definitely suitable for upstream, that's the reason why we have raw_spin_lock vs. raw_spin_unlock.

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-20 Thread Paolo Bonzini
On 20/02/2015 15:54, Sebastian Andrzej Siewior wrote: Usually you see scheduling while atomic on -RT and convert them to raw locks if it is appropriate. Bogdan wrote in 2/2 that he needs to limit the number of CPUs in oder not cause a DoS and large latencies in the host. I haven't seen an

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-20 Thread Sebastian Andrzej Siewior
On 02/20/2015 03:57 PM, Paolo Bonzini wrote: On 20/02/2015 15:54, Sebastian Andrzej Siewior wrote: Usually you see scheduling while atomic on -RT and convert them to raw locks if it is appropriate. Bogdan wrote in 2/2 that he needs to limit the number of CPUs in oder not cause a DoS and

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-20 Thread Sebastian Andrzej Siewior
On 02/20/2015 04:10 PM, Paolo Bonzini wrote: On 20/02/2015 16:06, Sebastian Andrzej Siewior wrote: On 02/20/2015 03:57 PM, Paolo Bonzini wrote: Yes, but large latencies just mean the code has to be rewritten (x86 doesn't anymore do event injection in an atomic regions for example). Until it

Re: [PATCH 0/2] powerpc/kvm: Enable running guests on RT Linux

2015-02-20 Thread Paolo Bonzini
On 20/02/2015 16:06, Sebastian Andrzej Siewior wrote: On 02/20/2015 03:57 PM, Paolo Bonzini wrote: Yes, but large latencies just mean the code has to be rewritten (x86 doesn't anymore do event injection in an atomic regions for example). Until it is, using raw_spin_lock is correct. It