On 6/21/19 10:38 AM, Marc Zyngier wrote: > We need to allow a guest hypervisor to virtualize the virtual timer. > FOr that, let's propagate CNTVOFF_EL2 to the guest's view of that > timer. > > Signed-off-by: Marc Zyngier <[email protected]> > --- > arch/arm64/include/asm/kvm_host.h | 1 - > arch/arm64/kvm/sys_regs.c | 8 ++++++-- > include/kvm/arm_arch_timer.h | 1 + > virt/kvm/arm/arch_timer.c | 12 ++++++++++++ > 4 files changed, 19 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_host.h > b/arch/arm64/include/asm/kvm_host.h > index b7c44adcdbf3..e0fe9acb46bf 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -252,7 +252,6 @@ enum vcpu_sysreg { > RMR_EL2, /* Reset Management Register */ > CONTEXTIDR_EL2, /* Context ID Register (EL2) */ > TPIDR_EL2, /* EL2 Software Thread ID Register */ > - CNTVOFF_EL2, /* Counter-timer Virtual Offset register */ > CNTHCTL_EL2, /* Counter-timer Hypervisor Control register */ > SP_EL2, /* EL2 Stack Pointer */ > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 1b8016330a19..2031a59fcf49 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -150,7 +150,6 @@ struct el2_sysreg_map { > PURE_EL2_SYSREG( RVBAR_EL2 ), > PURE_EL2_SYSREG( RMR_EL2 ), > PURE_EL2_SYSREG( TPIDR_EL2 ), > - PURE_EL2_SYSREG( CNTVOFF_EL2 ), > PURE_EL2_SYSREG( CNTHCTL_EL2 ), > PURE_EL2_SYSREG( HPFAR_EL2 ), > EL2_SYSREG( SCTLR_EL2, SCTLR_EL1, translate_sctlr ), > @@ -1351,6 +1350,11 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu, > tmr = TIMER_PTIMER; > treg = TIMER_REG_CVAL; > break; > + case SYS_CNTVOFF_EL2: > + tmr = TIMER_VTIMER; > + treg = TIMER_REG_VOFF; > + break; > + > default: > BUG(); > } > @@ -2122,7 +2126,7 @@ static const struct sys_reg_desc sys_reg_descs[] = { > { SYS_DESC(SYS_CONTEXTIDR_EL2), access_rw, reset_val, CONTEXTIDR_EL2, 0 > }, > { SYS_DESC(SYS_TPIDR_EL2), access_rw, reset_val, TPIDR_EL2, 0 }, > > - { SYS_DESC(SYS_CNTVOFF_EL2), access_rw, reset_val, CNTVOFF_EL2, 0 }, > + { SYS_DESC(SYS_CNTVOFF_EL2), access_arch_timer }, > { SYS_DESC(SYS_CNTHCTL_EL2), access_rw, reset_val, CNTHCTL_EL2, 0 }, > > { SYS_DESC(SYS_CNTHP_TVAL_EL2), access_arch_timer }, > diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h > index 3a5d9255120e..3389606f3029 100644 > --- a/include/kvm/arm_arch_timer.h > +++ b/include/kvm/arm_arch_timer.h > @@ -23,6 +23,7 @@ enum kvm_arch_timer_regs { > TIMER_REG_CVAL, > TIMER_REG_TVAL, > TIMER_REG_CTL, > + TIMER_REG_VOFF, > }; > > struct arch_timer_context { > diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c > index 3d84c240071d..1d53352c7d97 100644 > --- a/virt/kvm/arm/arch_timer.c > +++ b/virt/kvm/arm/arch_timer.c > @@ -913,6 +913,10 @@ static u64 kvm_arm_timer_read(struct kvm_vcpu *vcpu, > val = kvm_phys_timer_read() - timer->cntvoff; > break; > > + case TIMER_REG_VOFF: > + val = timer->cntvoff; > + break; > + > default: > BUG(); > } > @@ -955,6 +959,10 @@ static void kvm_arm_timer_write(struct kvm_vcpu *vcpu, > timer->cnt_cval = val; > break; > > + case TIMER_REG_VOFF: > + timer->cntvoff = val; > + break; > + > default: > BUG(); > } > @@ -1166,6 +1174,10 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu) > return -EINVAL; > } > > + /* Nested virtualization requires zero offset for virtual EL2 */ > + if (nested_virt_in_use(vcpu)) > + vcpu_vtimer(vcpu)->cntvoff = 0;
I think this is related to the fact that the virtual offset is treated as 0 when reading CNTVCT_EL0 from EL2, or from from EL2 and EL0 if E2H, TGE are set (please correct me if I'm wrong). However, when the guest runs in virtual EL2, the direct_vtimer is the hvtimer, so the value that ends up in CNTVOFF_EL2 is vcpu_hvtimer(vcpu)->cntvoff. Thanks, Alex > + > get_timer_map(vcpu, &map); > > ret = kvm_vgic_map_phys_irq(vcpu, _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
