From: "Kalra, Ashish" <Ashish.Kalra@amd.com>
To: Sean Christopherson <seanjc@google.com>
Cc: "pbonzini@redhat.com" <pbonzini@redhat.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"rkrcmar@redhat.com" <rkrcmar@redhat.com>,
"joro@8bytes.org" <joro@8bytes.org>, "bp@suse.de" <bp@suse.de>,
"Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
"x86@kernel.org" <x86@kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"srutherford@google.com" <srutherford@google.com>,
"venu.busireddy@oracle.com" <venu.busireddy@oracle.com>,
"Singh, Brijesh" <brijesh.singh@amd.com>
Subject: RE: [PATCH v10 10/16] KVM: x86: Introduce KVM_GET_SHARED_PAGES_LIST ioctl
Date: Thu, 18 Feb 2021 17:05:23 +0000 [thread overview]
Message-ID: <SN6PR12MB2767A978C3A2B43982F2F4898E859@SN6PR12MB2767.namprd12.prod.outlook.com> (raw)
In-Reply-To: <YC6YOuJyNlSxKVR4@google.com>
[AMD Public Use]
-----Original Message-----
From: Sean Christopherson <seanjc@google.com>
Sent: Thursday, February 18, 2021 10:39 AM
To: Kalra, Ashish <Ashish.Kalra@amd.com>
Cc: pbonzini@redhat.com; tglx@linutronix.de; mingo@redhat.com; hpa@zytor.com; rkrcmar@redhat.com; joro@8bytes.org; bp@suse.de; Lendacky, Thomas <Thomas.Lendacky@amd.com>; x86@kernel.org; kvm@vger.kernel.org; linux-kernel@vger.kernel.org; srutherford@google.com; venu.busireddy@oracle.com; Singh, Brijesh <brijesh.singh@amd.com>
Subject: Re: [PATCH v10 10/16] KVM: x86: Introduce KVM_GET_SHARED_PAGES_LIST ioctl
On Thu, Feb 18, 2021, Kalra, Ashish wrote:
> From: Sean Christopherson <seanjc@google.com>
>
> On Wed, Feb 17, 2021, Kalra, Ashish wrote:
> >> From: Sean Christopherson <seanjc@google.com> On Thu, Feb 04, 2021,
> >> Ashish Kalra wrote:
> >> > From: Brijesh Singh <brijesh.singh@amd.com>
> >> >
> >> > The ioctl is used to retrieve a guest's shared pages list.
> >>
> >> >What's the performance hit to boot time if KVM_HC_PAGE_ENC_STATUS
> >> >is passed through to userspace? That way, userspace could manage
> >> >the set of pages >in whatever data structure they want, and these get/set ioctls go away.
> >>
> >> What is the advantage of passing KVM_HC_PAGE_ENC_STATUS through to
> >> user-space ?
> >>
> >> As such it is just a simple interface to get the shared page list
> >> via the get/set ioctl's. simply an array is passed to these ioctl
> >> to get/set the shared pages list.
>>
>> > It eliminates any probability of the kernel choosing the wrong data
>> > structure, and it's two fewer ioctls to maintain and test.
>>
>> The set shared pages list ioctl cannot be avoided as it needs to be
>> issued to setup the shared pages list on the migrated VM, it cannot be
>> achieved by passing KVM_HC_PAGE_ENC_STATUS through to user-space.
>Why's that? AIUI, KVM doesn't do anything with the list other than pass it back to userspace. Assuming that's the case, userspace can just hold onto the list >for the next migration.
KVM does use it as part of the SEV DBG_DECTYPT API, within sev_dbg_decrypt() to check if the guest page(s) are encrypted or not,
and accordingly use it to decide whether to decrypt the guest page(s) and return that back to user-space or just return it as it is.
Thanks,
Ashish
next prev parent reply other threads:[~2021-02-18 18:55 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-04 0:35 [PATCH v10 00/17] Add AMD SEV guest live migration support Ashish Kalra
2021-02-04 0:36 ` [PATCH v10 01/16] KVM: SVM: Add KVM_SEV SEND_START command Ashish Kalra
2021-02-04 0:36 ` [PATCH v10 02/16] KVM: SVM: Add KVM_SEND_UPDATE_DATA command Ashish Kalra
2021-02-04 0:37 ` [PATCH v10 03/16] KVM: SVM: Add KVM_SEV_SEND_FINISH command Ashish Kalra
2021-02-04 0:37 ` [PATCH v10 04/16] KVM: SVM: Add support for KVM_SEV_RECEIVE_START command Ashish Kalra
2021-02-04 0:37 ` [PATCH v10 05/16] KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command Ashish Kalra
2021-02-04 0:37 ` [PATCH v10 06/16] KVM: SVM: Add KVM_SEV_RECEIVE_FINISH command Ashish Kalra
2021-02-04 0:38 ` [PATCH v10 07/16] KVM: x86: Add AMD SEV specific Hypercall3 Ashish Kalra
2021-02-04 0:38 ` [PATCH v10 08/16] KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall Ashish Kalra
2021-02-04 16:03 ` Tom Lendacky
2021-02-05 1:44 ` Steve Rutherford
2021-02-05 3:32 ` Ashish Kalra
2021-02-04 0:39 ` [PATCH v10 09/16] mm: x86: Invoke hypercall when page encryption status is changed Ashish Kalra
2021-02-04 0:39 ` [PATCH v10 10/16] KVM: x86: Introduce KVM_GET_SHARED_PAGES_LIST ioctl Ashish Kalra
2021-02-04 16:14 ` Tom Lendacky
2021-02-04 16:34 ` Ashish Kalra
2021-02-17 1:03 ` Sean Christopherson
2021-02-17 14:00 ` Kalra, Ashish
2021-02-17 16:13 ` Sean Christopherson
2021-02-18 6:48 ` Kalra, Ashish
2021-02-18 16:39 ` Sean Christopherson
2021-02-18 17:05 ` Kalra, Ashish [this message]
2021-02-18 17:50 ` Sean Christopherson
2021-02-18 18:32 ` Kalra, Ashish
2021-02-24 17:51 ` Ashish Kalra
2021-02-24 18:22 ` Sean Christopherson
2021-02-25 20:20 ` Ashish Kalra
2021-02-25 22:59 ` Steve Rutherford
2021-02-25 23:24 ` Steve Rutherford
2021-02-26 14:04 ` Ashish Kalra
2021-02-26 17:44 ` Sean Christopherson
2021-03-02 14:55 ` Ashish Kalra
2021-03-02 15:15 ` Ashish Kalra
2021-03-03 18:54 ` Will Deacon
2021-03-03 19:32 ` Ashish Kalra
2021-03-09 19:10 ` Ashish Kalra
2021-03-11 18:14 ` Ashish Kalra
2021-03-11 20:48 ` Steve Rutherford
2021-03-19 17:59 ` Ashish Kalra
2021-04-02 1:40 ` Steve Rutherford
2021-04-02 11:09 ` Ashish Kalra
2021-03-08 10:40 ` Ashish Kalra
2021-03-08 19:51 ` Sean Christopherson
2021-03-08 21:05 ` Ashish Kalra
2021-03-08 21:11 ` Brijesh Singh
2021-03-08 21:32 ` Ashish Kalra
2021-03-08 21:51 ` Steve Rutherford
2021-03-09 19:42 ` Sean Christopherson
2021-03-10 3:42 ` Kalra, Ashish
2021-03-10 3:47 ` Steve Rutherford
2021-03-08 21:48 ` Steve Rutherford
2021-02-17 1:06 ` Sean Christopherson
2021-02-04 0:39 ` [PATCH v10 11/16] KVM: x86: Introduce KVM_SET_SHARED_PAGES_LIST ioctl Ashish Kalra
2021-02-04 0:39 ` [PATCH v10 12/16] KVM: x86: Introduce new KVM_FEATURE_SEV_LIVE_MIGRATION feature & Custom MSR Ashish Kalra
2021-02-05 0:56 ` Steve Rutherford
2021-02-05 3:07 ` Ashish Kalra
2021-02-06 2:54 ` Steve Rutherford
2021-02-06 4:49 ` Ashish Kalra
2021-02-06 5:46 ` Ashish Kalra
2021-02-06 13:56 ` Ashish Kalra
2021-02-08 0:28 ` Ashish Kalra
2021-02-08 22:50 ` Steve Rutherford
2021-02-10 20:36 ` Ashish Kalra
2021-02-10 22:01 ` Steve Rutherford
2021-02-10 22:05 ` Steve Rutherford
2021-02-16 23:20 ` Sean Christopherson
2021-02-04 0:40 ` [PATCH v10 13/16] EFI: Introduce the new AMD Memory Encryption GUID Ashish Kalra
2021-02-04 0:40 ` [PATCH v10 14/16] KVM: x86: Add guest support for detecting and enabling SEV Live Migration feature Ashish Kalra
2021-02-18 17:56 ` Sean Christopherson
2021-02-04 0:40 ` [PATCH v10 15/16] KVM: x86: Add kexec support for SEV Live Migration Ashish Kalra
2021-02-04 0:40 ` [PATCH v10 16/16] KVM: SVM: Bypass DBG_DECRYPT API calls for unencrypted guest memory Ashish Kalra
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