On Fri, Jul 17, 2015 at 04:25:06PM +0800, Shannon Zhao wrote: > > > On 2015/7/17 2:45, Christoffer Dall wrote: > > On Mon, Jul 06, 2015 at 10:17:33AM +0800, [email protected] wrote: > >> From: Shannon Zhao <[email protected]> > >> > >> We are about to trap and emulate acccesses to each PMU register > >> individually. This adds the context offsets for the AArch64 PMU > >> registers and their AArch32 counterparts. > >> > >> Signed-off-by: Shannon Zhao <[email protected]> > >> --- > >> arch/arm64/include/asm/kvm_asm.h | 59 > >> +++++++++++++++++++++++++++++++++++----- > >> 1 file changed, 52 insertions(+), 7 deletions(-) > >> > >> diff --git a/arch/arm64/include/asm/kvm_asm.h > >> b/arch/arm64/include/asm/kvm_asm.h > >> index 3c5fe68..21b5d3b 100644 > >> --- a/arch/arm64/include/asm/kvm_asm.h > >> +++ b/arch/arm64/include/asm/kvm_asm.h > >> @@ -56,14 +56,36 @@ > >> #define DBGWVR15_EL1 86 > >> #define MDCCINT_EL1 87 /* Monitor Debug Comms Channel > >> Interrupt Enable Reg */ > >> > >> +/* Performance Monitors Registers */ > >> +#define PMCR_EL0 88 /* Control Register */ > >> +#define PMOVSSET_EL0 89 /* Overflow Flag Status Set Register */ > >> +#define PMOVSCLR_EL0 90 /* Overflow Flag Status Clear Register > >> */ > >> +#define PMCCNTR_EL0 91 /* Cycle Counter Register */ > >> +#define PMSELR_EL0 92 /* Event Counter Selection Register */ > >> +#define PMCEID0_EL0 93 /* Common Event Identification Register > >> 0 */ > >> +#define PMCEID1_EL0 94 /* Common Event Identification Register > >> 1 */ > >> +#define PMEVCNTR0_EL0 95 /* Event Counter Register (0-30) */ > > > > why do we need these when we trap-and-emulate and we have the kvm_pmc > > structs? > This just makes the guest work when accessing these registers. > > > Is that because the kvm_pmc structs are only used when we > > actually have an active counter running and registered with perf? > > > > Right, the kvm_pmc structs are used to store the status of perf evnets, > like the event type, count number of this perf event. > > On the other hand, the kernel perf codes will not directly access to the > PMEVCNTRx_EL0 and PMEVTYPERx_EL0 registers. It will firstly write the > index of select counter to PMSELR_EL0 and access to PMXEVCNTR_EL0 or > PMXEVTYPER_EL0. Then this is architecturally mapped to PMEVCNTRx_EL0 and > PMEVTYPERx_EL0. >
I'm just wondering if it makes sense to keep virtual state around for all these registers, since we don't emulate the counter values, so why do we need to preserve any virtual cpu state for all of them? -Christoffer -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
