From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Janosch Frank <frankja@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
kvm@vger.kernel.org
Cc: cohuck@redhat.com, thuth@redhat.com, pasic@linux.ibm.com,
david@redhat.com, linux-s390@vger.kernel.org,
linux-kernel@vger.kernel.org, Ulrich.Weigand@de.ibm.com
Subject: Re: [PATCH v5 00/14] KVM: s390: pv: implement lazy destroy for reboot
Date: Tue, 5 Oct 2021 16:15:20 +0200 [thread overview]
Message-ID: <566654e2-92fd-4e91-325e-ced6a89b7a0e@de.ibm.com> (raw)
In-Reply-To: <fcfd5d04-1a08-f91e-7bc2-8878c6dcd1eb@linux.ibm.com>
Am 05.10.21 um 15:26 schrieb Janosch Frank:
> On 9/20/21 15:24, Claudio Imbrenda wrote:
>> Previously, when a protected VM was rebooted or when it was shut down,
>> its memory was made unprotected, and then the protected VM itself was
>> destroyed. Looping over the whole address space can take some time,
>> considering the overhead of the various Ultravisor Calls (UVCs). This
>> means that a reboot or a shutdown would take a potentially long amount
>> of time, depending on the amount of used memory.
>>
>> This patchseries implements a deferred destroy mechanism for protected
>> guests. When a protected guest is destroyed, its memory is cleared in
>> background, allowing the guest to restart or terminate significantly
>> faster than before.
>>
>> There are 2 possibilities when a protected VM is torn down:
>> * it still has an address space associated (reboot case)
>> * it does not have an address space anymore (shutdown case)
>>
>> For the reboot case, the reference count of the mm is increased, and
>> then a background thread is started to clean up. Once the thread went
>> through the whole address space, the protected VM is actually
>> destroyed.
>>
>> This means that the same address space can have memory belonging to
>> more than one protected guest, although only one will be running, the
>> others will in fact not even have any CPUs.
>>
>> The shutdown case is more controversial, and it will be dealt with in a
>> future patchseries.
>>
>> When a guest is destroyed, its memory still counts towards its memory
>> control group until it's actually freed (I tested this experimentally)
>
>
> @Christian: I'd like to have #1-3 in early so we can focus on the more complicated stuff.
Yes, makes perfect sense.
prev parent reply other threads:[~2021-10-05 14:15 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-20 13:24 [PATCH v5 00/14] KVM: s390: pv: implement lazy destroy for reboot Claudio Imbrenda
2021-09-20 13:24 ` [PATCH v5 01/14] KVM: s390: pv: add macros for UVC CC values Claudio Imbrenda
2021-10-05 13:08 ` Janosch Frank
2021-09-20 13:24 ` [PATCH v5 02/14] KVM: s390: pv: avoid double free of sida page Claudio Imbrenda
2021-10-05 13:11 ` Janosch Frank
2021-10-05 13:38 ` Christian Borntraeger
2021-09-20 13:24 ` [PATCH v5 03/14] KVM: s390: pv: avoid stalls for kvm_s390_pv_init_vm Claudio Imbrenda
2021-10-05 13:20 ` Janosch Frank
2021-09-20 13:24 ` [PATCH v5 04/14] KVM: s390: pv: avoid stalls when making pages secure Claudio Imbrenda
2021-10-06 15:54 ` Christian Borntraeger
2021-10-06 16:14 ` Claudio Imbrenda
2021-10-12 7:43 ` Janosch Frank
2021-10-12 8:59 ` Christian Borntraeger
2021-09-20 13:24 ` [PATCH v5 05/14] KVM: s390: pv: leak the topmost page table when destroy fails Claudio Imbrenda
2021-10-12 7:58 ` Janosch Frank
2021-10-12 8:33 ` Claudio Imbrenda
2021-09-20 13:24 ` [PATCH v5 06/14] KVM: s390: pv: properly handle page flags for protected guests Claudio Imbrenda
2021-10-12 7:59 ` Janosch Frank
2021-10-26 11:53 ` Christian Borntraeger
2021-09-20 13:24 ` [PATCH v5 07/14] KVM: s390: pv: handle secure storage violations " Claudio Imbrenda
2021-09-20 13:24 ` [PATCH v5 08/14] KVM: s390: pv: handle secure storage exceptions for normal guests Claudio Imbrenda
2021-10-12 8:16 ` Janosch Frank
2021-10-12 8:35 ` Claudio Imbrenda
2021-10-12 12:31 ` Janosch Frank
2021-09-20 13:24 ` [PATCH v5 09/14] KVM: s390: pv: refactor s390_reset_acc Claudio Imbrenda
2021-09-20 13:24 ` [PATCH v5 10/14] KVM: s390: pv: usage counter instead of flag Claudio Imbrenda
2021-09-20 13:24 ` [PATCH v5 11/14] KVM: s390: pv: add export before import Claudio Imbrenda
2021-09-20 13:25 ` [PATCH v5 12/14] KVM: s390: pv: module parameter to fence lazy destroy Claudio Imbrenda
2021-09-20 13:25 ` [PATCH v5 13/14] KVM: s390: pv: lazy destroy for reboot Claudio Imbrenda
2021-09-20 13:25 ` [PATCH v5 14/14] KVM: s390: pv: avoid export before import if possible Claudio Imbrenda
2021-10-05 13:26 ` [PATCH v5 00/14] KVM: s390: pv: implement lazy destroy for reboot Janosch Frank
2021-10-05 14:15 ` Christian Borntraeger [this message]
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