On 2020-08-19 11:18, Jianyong Wu wrote:
-----Original Message-----
From: Marc Zyngier <maz@xxxxxxxxxx>
Sent: Wednesday, August 19, 2020 6:00 PM
To: Jianyong Wu <Jianyong.Wu@xxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>; Peng Hao
<richard.peng@xxxxxxxx>; kernel-team@xxxxxxxxxxx;
kvm@xxxxxxxxxxxxxxx; Will Deacon <will@xxxxxxxxxx>; Catalin Marinas
<Catalin.Marinas@xxxxxxx>; Alexander Graf <graf@xxxxxxxxxx>;
kvmarm@xxxxxxxxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [PATCH 47/56] KVM: arm64: timers: Move timer registers to
the
sys_regs file
On 2020-08-19 10:24, Jianyong Wu wrote:
> Hi Marc,
>
> -----Original Message-----
> From: kvmarm-bounces@xxxxxxxxxxxxxxxxxxxxx
> <kvmarm-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of Marc Zyngier
> Sent: Thursday, August 6, 2020 1:57 AM
> To: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Peng Hao <richard.peng@xxxxxxxx>; kernel-team@xxxxxxxxxxx;
> kvm@xxxxxxxxxxxxxxx; Will Deacon <will@xxxxxxxxxx>; Catalin Marinas
> <Catalin.Marinas@xxxxxxx>; Alexander Graf <graf@xxxxxxxxxx>;
> kvmarm@xxxxxxxxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Subject: [PATCH 47/56] KVM: arm64: timers: Move timer registers to the
> sys_regs file
>
> Move the timer gsisters to the sysreg file. This will further help
> when they are directly changed by a nesting hypervisor in the VNCR
> page.
>
> This requires moving the initialisation of the timer struct so that
> some of the helpers (such as arch_timer_ctx_index) can work correctly
> at an early stage.
>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/kvm_host.h | 6 ++
> arch/arm64/kvm/arch_timer.c | 155 +++++++++++++++++++++++-------
> arch/arm64/kvm/trace_arm.h | 8 +-
> include/kvm/arm_arch_timer.h | 11 +--
> 4 files changed, 136 insertions(+), 44 deletions(-)
>
> +static u64 timer_get_offset(struct arch_timer_context *ctxt) {
> + struct kvm_vcpu *vcpu = ctxt->vcpu;
> +
> + switch(arch_timer_ctx_index(ctxt)) {
> + case TIMER_VTIMER:
> + return __vcpu_sys_reg(vcpu, CNTVOFF_EL2);
> + default:
> + return 0;
> + }
> +}
> +
> Can I export this helper? As in my ptp_kvm implementation I need get
> VCNT offset value separately not just give me a result of VCNT.
Sorry, you need to give me a bit more context. What do you need the
offset
for exactly?
Yeah,
In my ptp_kvm implementation, I need acquire wall time and counter
cycle in the same time in host. After get host counter cycle, I need
subtract it by VCNT offset to obtain VCNT. See
https://lkml.org/lkml/2020/6/19/441
https://lkml.org/lkml/2020/6/19/441
But now I can't get the VCNT offset easily like before using "
vcpu_vtimer(vcpu)->cntvoff" and I can't use the helper like
"kvm_arm_timer_read" as I need acquire the counter cycle in the same
time with the host wall time.
I must be missing something. CNTVOFF_EL2 is now implemented as
a standard system register, and has the same visibility as any
other vcpu sysreg.
Why doesn't vcpu_read_sys_reg(vcpu, CNTVOFF_EL2) work for you?
M.
--
Jazz is not dead. It just smells funny...
