On 2016/1/29 4:34, Andrew Jones wrote: > On Wed, Jan 27, 2016 at 11:51:34AM +0800, Shannon Zhao wrote: >> > From: Shannon Zhao <[email protected]> >> > >> > Add access handler which gets host value of PMCEID0 or PMCEID1 when >> > guest access these registers. Writing action to PMCEID0 or PMCEID1 is >> > UNDEFINED. >> > >> > Signed-off-by: Shannon Zhao <[email protected]> >> > --- >> > arch/arm64/kvm/sys_regs.c | 29 +++++++++++++++++++++++++---- >> > 1 file changed, 25 insertions(+), 4 deletions(-) >> > >> > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c >> > index fc60041..06257e2 100644 >> > --- a/arch/arm64/kvm/sys_regs.c >> > +++ b/arch/arm64/kvm/sys_regs.c >> > @@ -492,6 +492,27 @@ static bool access_pmselr(struct kvm_vcpu *vcpu, >> > struct sys_reg_params *p, >> > return true; >> > } >> > >> > +static bool access_pmceid(struct kvm_vcpu *vcpu, struct sys_reg_params *p, >> > + const struct sys_reg_desc *r) >> > +{ >> > + u64 pmceid; >> > + >> > + if (!kvm_arm_pmu_v3_ready(vcpu)) >> > + return trap_raz_wi(vcpu, p, r); >> > + >> > + if (p->is_write) >> > + return false; >> > + >> > + if (!(p->Op2 & 1)) >> > + asm volatile("mrs %0, pmceid0_el0\n" : "=r" (pmceid)); >> > + else >> > + asm volatile("mrs %0, pmceid1_el0\n" : "=r" (pmceid)); > For migratibility concerns we may want to filter some of these events. > With that in mind the answer to my question in 4/21 is 'no'. Instead we > should pick an IMP,IDCODE,N,PMCEID0_EL0,PMCEID1_EL0 that we expect to > represent the least common denominator of all the platforms available > now, and then only expose that view to the guest. If we want to support > more events, and userspace requests it for the guest, then we can relax > the filtering (at the expense of migratibility), when the host has the > support. > As replied at patch 4, I think this could be done by the cross-cpu type support patches.
Thanks, -- Shannon _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
