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From: Jianyong Wu <Jianyong.Wu@arm.com>
To: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <Mark.Rutland@arm.com>,
	Justin He <Justin.He@arm.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	Suzuki Poulose <Suzuki.Poulose@arm.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"richardcochran@gmail.com" <richardcochran@gmail.com>,
	Steve Capper <Steve.Capper@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"sean.j.christopherson@intel.com"
	<sean.j.christopherson@intel.com>,
	Steven Price <Steven.Price@arm.com>, Kaly Xin <Kaly.Xin@arm.com>,
	"john.stultz@linaro.org" <john.stultz@linaro.org>,
	"yangbo.lu@nxp.com" <yangbo.lu@nxp.com>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>, nd <nd@arm.com>,
	"will@kernel.org" <will@kernel.org>,
	"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: RE: [RFC PATCH v9 6/8] psci: Add hvc call service for ptp_kvm.
Date: Tue, 14 Jan 2020 10:34:51 +0000	[thread overview]
Message-ID: <HE1PR0801MB1676C93AF0AA7980F4A79B3FF4340@HE1PR0801MB1676.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <22ba1283a7b82f018c1fdf85414e5bfe@kernel.org>

Hi Marc,

> -----Original Message-----
> From: Marc Zyngier <maz@kernel.org>
> Sent: Monday, January 13, 2020 7:16 PM
> To: Jianyong Wu <Jianyong.Wu@arm.com>
> Cc: netdev@vger.kernel.org; yangbo.lu@nxp.com; john.stultz@linaro.org;
> tglx@linutronix.de; pbonzini@redhat.com; sean.j.christopherson@intel.com;
> richardcochran@gmail.com; Mark Rutland <Mark.Rutland@arm.com>;
> will@kernel.org; Suzuki Poulose <Suzuki.Poulose@arm.com>; Steven Price
> <Steven.Price@arm.com>; linux-kernel@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; kvmarm@lists.cs.columbia.edu;
> kvm@vger.kernel.org; Steve Capper <Steve.Capper@arm.com>; Kaly Xin
> <Kaly.Xin@arm.com>; Justin He <Justin.He@arm.com>; nd <nd@arm.com>
> Subject: Re: [RFC PATCH v9 6/8] psci: Add hvc call service for ptp_kvm.
> 
> Hi Jianyong,
> 
> On 2020-01-13 10:30, Jianyong Wu wrote:
> > Hi Marc,
> >
> >> -----Original Message-----
> >> From: Marc Zyngier <maz@kernel.org>
> >> Sent: Friday, January 10, 2020 6:56 PM NV breaks that assumtion,
> >> because the guest hypervisor is using the physical counter. Also,
> >> let's not forget that the hypercall isn't Linux specific.
> >> I can write my own non-Linux guest and still use this hypercall.
> >> Nothing in
> >> there says that I can't use the physical counter if I want to.
> >>
> >> So somehow, you need to convey the the hypervisor the notion of
> >> *which*
> >> counter the guest uses.
> >>
> >> Does it make sense? Or am I missing something?
> >>
> > I know what you say. Let me try to solve this problem.
> > 	Step 0, summary out all the conditions we should process, which will
> > sever as branch condition.(now only normal virt and nested virt, I
> > think)
> 
> No. You shouldn't think of the various use cases, but of which time
> references a guest can use. You don't need nested virt to use the physical
> counter, for example.
Ok,

> 
> > 	Step 1, figure out the set of reference counter value used by guest
> > in all condition.
> 
> That should be for the guest to tell you when it calls into the PV service.
> 
Yeah

> > 	Step 2, determine which reference counter value will be used by
> guest
> > in a certain condition in hypercall.
> > In step 1, can we give the set only 2 elements that one is physical
> > counter the other is virtual counter?
> 
> I don't think returning the two values is useful. Just return what the guest
> asks for.
> 
> > For step 2, I have no idea for that now. can you give me some hint
> > about it?
> 
> Just expand your SMC call to take a parameter indicating the reference
> counter, and return the sampled (or computed) value corresponding to that
> counter.
Get it, I'll try it.

Thanks
Jianyong 

> 
>          M.
> --
> Jazz is not dead. It just smells funny...

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  reply	other threads:[~2020-01-14 10:35 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-10  3:40 [RFC PATCH v9 0/8] Enable ptp_kvm for arm64 Jianyong Wu
2019-12-10  3:40 ` [RFC PATCH v9 1/8] arm/arm64: smccc/psci: add arm_smccc_1_1_get_conduit() Jianyong Wu
2019-12-10  3:40 ` [RFC PATCH v9 2/8] psci: let arm_smccc_1_1_invoke available by modules Jianyong Wu
2019-12-10  3:40 ` [RFC PATCH v9 3/8] ptp: Reorganize ptp_kvm modules to make it arch-independent Jianyong Wu
2019-12-10  3:40 ` [RFC PATCH v9 4/8] time: Add mechanism to recognize clocksource in time_get_snapshot Jianyong Wu
2019-12-10  3:40 ` [RFC PATCH v9 5/8] clocksource: Add clocksource id for arm arch counter Jianyong Wu
2019-12-10  3:40 ` [RFC PATCH v9 6/8] psci: Add hvc call service for ptp_kvm Jianyong Wu
2020-01-07  9:16   ` Marc Zyngier
2020-01-09  5:45     ` Jianyong Wu
2020-01-09  9:16       ` Marc Zyngier
2020-01-10  9:51         ` Jianyong Wu
2020-01-10 10:56           ` Marc Zyngier
2020-01-13 10:30             ` Jianyong Wu
2020-01-13 11:16               ` Marc Zyngier
2020-01-14 10:34                 ` Jianyong Wu [this message]
2019-12-10  3:40 ` [RFC PATCH v9 7/8] ptp: arm64: Enable ptp_kvm for arm64 Jianyong Wu
2020-01-07  9:29   ` Marc Zyngier
2020-01-09  5:59     ` Jianyong Wu
2020-01-09  9:24       ` Marc Zyngier
2020-01-09  9:46         ` Marc Zyngier
2020-01-10 10:15           ` Jianyong Wu
2020-01-10 10:15         ` Jianyong Wu
2020-01-10 10:35           ` Marc Zyngier
2020-01-13 10:37             ` Jianyong Wu
2020-01-13 11:21               ` Marc Zyngier
2020-01-14 10:22                 ` Jianyong Wu
2019-12-10  3:40 ` [RFC PATCH v9 8/8] kvm: arm64: Add capability check extension for ptp_kvm Jianyong Wu
2020-01-06  9:38 ` [RFC PATCH v9 0/8] Enable ptp_kvm for arm64 Jianyong Wu
2020-01-07  8:15   ` Paolo Bonzini
2020-01-07  9:33     ` Marc Zyngier

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