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From: "Graf (AWS), Alexander" <graf@amazon.de>
To: "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@amd.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"rkrcmar@redhat.com" <rkrcmar@redhat.com>,
	"joro@8bytes.org" <joro@8bytes.org>,
	"Schoenherr, Jan H." <jschoenh@amazon.de>,
	"Raslan, KarimAllah" <karahmed@amazon.de>,
	"Lukaszewicz, Rimas" <rimasluk@amazon.com>,
	"Grimm, Jon" <Jon.Grimm@amd.com>
Subject: Re: [PATCH v2 04/15] kvm: x86: Add per-VM APICv state debugfs
Date: Wed, 28 Aug 2019 19:36:03 +0000
Message-ID: <9A47CE02-18B0-40C3-962A-D317A32F2073@amazon.de> (raw)
In-Reply-To: <1bfccb79-5ace-0dba-a201-e069f77f740a@amd.com>



> Am 28.08.2019 um 20:41 schrieb Suthikulpanit, Suravee <Suravee.Suthikulpanit@amd.com>:
> 
> Alex,
> 
>> On 8/27/19 3:20 AM, Alexander Graf wrote:
>> 
>> 
>>> On 26.08.19 21:41, Suthikulpanit, Suravee wrote:
>>> Alex,
>>> 
>>>> On 8/19/2019 4:57 AM, Alexander Graf wrote:
>>>> 
>>>> 
>>>>> On 15.08.19 18:25, Suthikulpanit, Suravee wrote:
>>>>> Currently, there is no way to tell whether APICv is active
>>>>> on a particular VM. This often cause confusion since APICv
>>>>> can be deactivated at runtime.
>>>>> 
>>>>> Introduce a debugfs entry to report APICv state of a VM.
>>>>> This creates a read-only file:
>>>>> 
>>>>>      /sys/kernel/debug/kvm/70860-14/apicv-state
>>>>> 
>>>>> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
>>>> 
>>>> Shouldn't this first and foremost be a VM ioctl so that user space 
>>>> can inquire its own state?
>>>> 
>>>> 
>>>> Alex
>>> 
>>> I introduce this mainly for debugging similar to how KVM is currently 
>>> provides
>>> some per-VCPU information:
>>> 
>>>       /sys/kernel/debug/kvm/15957-14/vcpu0/
>>>           lapic_timer_advance_ns
>>>           tsc-offset
>>>           tsc-scaling-ratio
>>>           tsc-scaling-ratio-frac-bits
>>> 
>>> I'm not sure if this needs to be VM ioctl at this point. If this 
>>> information is
>>> useful for user-space tool to inquire via ioctl, we can also provide it.
>> 
>> I'm mostly thinking of something like "info apic" in QEMU which to me 
>> seems like the natural place for APIC information exposure to a user.
> 
> I could not find QEMU "info apic". I assume you meant "info lapic", 
> which provides information specific to each local APIC (i.e. per-vcpu).

Or maybe even "info kvm" :). I think you get the point.

> 
>> The problem with debugfs is that it's not accessible to the user that 
>> created the VM, but only root, right?
> 
> Hm, you are right. I'll also look into also adding ioctl interface then.

Thanks!

Alex




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  reply index

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-15 16:25 [PATCH v2 00/15] kvm: x86: Support AMD SVM AVIC w/ in-kernel irqchip mode Suthikulpanit, Suravee
2019-08-15 16:25 ` [PATCH v2 01/15] kvm: x86: Modify kvm_x86_ops.get_enable_apicv() to use struct kvm parameter Suthikulpanit, Suravee
2019-08-27  7:15   ` Vitaly Kuznetsov
2019-08-15 16:25 ` [PATCH v2 02/15] kvm: x86: Introduce KVM APICv state Suthikulpanit, Suravee
2019-08-19  9:49   ` Alexander Graf
2019-08-26 19:06     ` Suthikulpanit, Suravee
2019-08-15 16:25 ` [PATCH v2 03/15] kvm: Add arch-specific per-VM debugfs support Suthikulpanit, Suravee
2019-08-15 16:25 ` [PATCH v2 04/15] kvm: x86: Add per-VM APICv state debugfs Suthikulpanit, Suravee
2019-08-19  9:57   ` Alexander Graf
2019-08-26 19:41     ` Suthikulpanit, Suravee
2019-08-27  8:20       ` Alexander Graf
2019-08-28 18:39         ` Suthikulpanit, Suravee
2019-08-28 19:36           ` Graf (AWS), Alexander [this message]
2019-08-15 16:25 ` [PATCH v2 05/15] kvm: lapic: Introduce APICv update helper function Suthikulpanit, Suravee
2019-08-27  7:22   ` Vitaly Kuznetsov
2019-08-15 16:25 ` [PATCH v2 06/15] kvm: x86: Add support for activate/de-activate APICv at runtime Suthikulpanit, Suravee
2019-08-27  7:29   ` Vitaly Kuznetsov
2019-08-27  8:05     ` Alexander Graf
2019-08-15 16:25 ` [PATCH v2 07/15] kvm: x86: svm: Add support to activate/deactivate posted interrupts Suthikulpanit, Suravee
2019-08-15 16:25 ` [PATCH v2 08/15] svm: Add support for setup/destroy virutal APIC backing page for AVIC Suthikulpanit, Suravee
2019-08-15 16:25 ` [PATCH v2 09/15] svm: Add support for activate/deactivate AVIC at runtime Suthikulpanit, Suravee
2019-08-19 10:28   ` Alexander Graf
2019-08-15 16:25 ` [PATCH v2 10/15] kvm: x86: hyperv: Use APICv deactivate request interface Suthikulpanit, Suravee
2019-08-19 10:31   ` Alexander Graf
2019-08-15 16:25 ` [PATCH v2 11/15] svm: Temporary deactivate AVIC during ExtINT handling Suthikulpanit, Suravee
2019-08-19 10:35   ` Alexander Graf
2019-08-28 15:17     ` Suthikulpanit, Suravee
2019-08-28 19:37       ` Graf (AWS), Alexander
2019-09-10 15:46         ` Suthikulpanit, Suravee
2019-08-15 16:25 ` [PATCH v2 12/15] kvm: i8254: Check LAPIC EOI pending when injecting irq on SVM AVIC Suthikulpanit, Suravee
2019-08-19 10:42   ` Alexander Graf
2019-08-26 20:46     ` Suthikulpanit, Suravee
2019-08-27  9:10       ` Alexander Graf
2019-09-13 14:50         ` Suthikulpanit, Suravee
2019-08-15 16:25 ` [PATCH v2 13/15] kvm: lapic: Clean up APIC predefined macros Suthikulpanit, Suravee
2019-08-15 16:25 ` [PATCH v2 14/15] kvm: ioapic: Delay update IOAPIC EOI for RTC Suthikulpanit, Suravee
2019-08-19 11:00   ` Alexander Graf
2019-09-04  2:06     ` Suthikulpanit, Suravee
2019-08-15 16:25 ` [PATCH v2 15/15] svm: Allow AVIC with in-kernel irqchip mode Suthikulpanit, Suravee

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