On Thu, May 09, 2013 at 08:12:51AM +0000, Bhushan Bharat-R65777 wrote: > > > > -----Original Message----- > > From: Kevin Hao [mailto:haokexin@xxxxxxxxx] > > Sent: Thursday, May 09, 2013 1:38 PM > > To: Bhushan Bharat-R65777 > > Cc: tiejun.chen; Caraman Mihai Claudiu-B02008; kvm@xxxxxxxxxxxxxxx; Wood Scott- > > B07421; agraf@xxxxxxx; kvm-ppc@xxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx > > Subject: Re: [RFC][KVM][PATCH 1/1] kvm:ppc:booke-64: soft-disable interrupts > > > > On Thu, May 09, 2013 at 07:51:09AM +0000, Bhushan Bharat-R65777 wrote: > > > > > > > > > > -----Original Message----- > > > > From: tiejun.chen [mailto:tiejun.chen@xxxxxxxxxxxxx] > > > > Sent: Thursday, May 09, 2013 1:18 PM > > > > To: Bhushan Bharat-R65777 > > > > Cc: Caraman Mihai Claudiu-B02008; Wood Scott-B07421; linuxppc- > > > > dev@xxxxxxxxxxxxxxxx; agraf@xxxxxxx; kvm-ppc@xxxxxxxxxxxxxxx; > > > > kvm@xxxxxxxxxxxxxxx > > > > Subject: Re: [RFC][KVM][PATCH 1/1] kvm:ppc:booke-64: soft-disable > > > > interrupts > > > > > > > > On 05/09/2013 03:33 PM, Bhushan Bharat-R65777 wrote: > > > > > > > > > > > > > > >> -----Original Message----- > > > > >> From: Linuxppc-dev [mailto:linuxppc-dev- > > > > >> bounces+bharat.bhushan=freescale.com@xxxxxxxxxxxxxxxx] On Behalf > > > > >> bounces+Of Caraman > > > > >> Mihai Claudiu-B02008 > > > > >> Sent: Wednesday, May 08, 2013 6:44 PM > > > > >> To: Wood Scott-B07421; tiejun.chen > > > > >> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx; agraf@xxxxxxx; > > > > >> kvm-ppc@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx > > > > >> Subject: RE: [RFC][KVM][PATCH 1/1] kvm:ppc:booke-64: soft-disable > > > > >> interrupts > > > > >> > > > > >>>> This only disable soft interrupt for kvmppc_restart_interrupt() > > > > >>>> that restarts interrupts if they were meant for the host: > > > > >>>> > > > > >>>> a. SOFT_DISABLE_INTS() only for BOOKE_INTERRUPT_EXTERNAL | > > > > >>>> BOOKE_INTERRUPT_DECREMENTER | BOOKE_INTERRUPT_DOORBELL > > > > >>> > > > > >>> Those aren't the only exceptions that can end up going to the host. > > > > >>> We could get a TLB miss that results in a heavyweight MMIO exit, etc. > > > > >>> > > > > >>>> And shouldn't we handle kvmppc_restart_interrupt() like the > > > > >>>> original HOST flow? > > > > >>>> > > > > >>>> #define MASKABLE_EXCEPTION(trapnum, intnum, label, hdlr, > > > > >>>> ack) \ > > > > >>>> > > > > >>>> START_EXCEPTION(label); \ > > > > >>>> NORMAL_EXCEPTION_PROLOG(trapnum, intnum, > > > > >>>> PROLOG_ADDITION_MASKABLE)\ > > > > >>>> EXCEPTION_COMMON(trapnum, PACA_EXGEN, > > > > >>>> *INTS_DISABLE*) \ > > > > >>>> ... > > > > >>> > > > > >>> Could you elaborate on what you mean? > > > > >> > > > > >> I think Tiejun was saying that host has flags and replays only > > > > >> EE/DEC/DBELL interrupts. There is special macro > > > > >> masked_interrupt_book3e in those exception handlers that sets > > > > >> paca- > > > > >irq_happened. > > > > >> > > > > >> The list of replied interrupts is limited to asynchronous > > > > >> noncritical interrupts which can be masked by MSR[EE] (therefore no TLB > > miss). > > > > > > > > > > Embedded Perfmon interrupt is also asynchronous, Why that is not > > > > > in the list > > > > of masked interruts. > > > > > > > > Are you saying perfmon? If so, its also in that list: > > > > > > > > START_EXCEPTION(perfmon); > > > > NORMAL_EXCEPTION_PROLOG(0x260, BOOKE_INTERRUPT_PERFORMANCE_MONITOR, > > > > PROLOG_ADDITION_NONE) > > > > EXCEPTION_COMMON(0x260, PACA_EXGEN, INTS_DISABLE) > > > > > > Where it is recorded in paca->irq_happned to be replayed later ? > > > > Actually we don't want replay the perfmon interrupt later. We would run it even > > soft irq is disabled and just treat it as NMI. Please see the following function > > quoted from arch/powerpc/perf/core-fsl-emb.c: > > /* > > * If interrupts were soft-disabled when a PMU interrupt occurs, treat > > * it as an NMI. > > */ > > static inline int perf_intr_is_nmi(struct pt_regs *regs) > > { > > #ifdef __powerpc64__ > > return !regs->softe; > > #else > > return 0; > > #endif > > } > > Is it because that we cannot afford to lose perfmon interrupt for more accurate capturing of data ? Yes, I think this will definitely improve the perf sample quality. Thanks, Kevin > > -Bharat > > > > > Thanks, > > Kevin > > > > > > > > > > > > > Tiejun > > > > > > > > > > > > > > -Bharat > > > > > > > > > >> Now on KVM book3e we > > > > >> don't want to put them in the irq_happened lazy state but rather > > > > >> to execute them directly, so there is no reason for exception > > > > >> handling symmetry between host and guest. > > > > >> > > > > >> -Mike > > > > > > > > > > _______________________________________________ > > > Linuxppc-dev mailing list > > > Linuxppc-dev@xxxxxxxxxxxxxxxx > > > https://lists.ozlabs.org/listinfo/linuxppc-dev >
Attachment:
pgpRx5Z6lDH7y.pgp
Description: PGP signature
