From: Janosch Frank <frankja@linux.ibm.com>
To: Claudio Imbrenda <imbrenda@linux.ibm.com>, kvm@vger.kernel.org
Cc: cohuck@redhat.com, borntraeger@de.ibm.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 15:26:23 +0200 [thread overview]
Message-ID: <fcfd5d04-1a08-f91e-7bc2-8878c6dcd1eb@linux.ibm.com> (raw)
In-Reply-To: <20210920132502.36111-1-imbrenda@linux.ibm.com>
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.
next prev parent reply other threads:[~2021-10-05 13:26 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 ` Janosch Frank [this message]
2021-10-05 14:15 ` [PATCH v5 00/14] KVM: s390: pv: implement lazy destroy for reboot Christian Borntraeger
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