From: Sebastian Ott <sebott@redhat.com>
To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
linux-kernel@vger.kernel.org
Cc: Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>
Subject: [PATCH v2 0/6] KVM: arm64: emulation for CTR_EL0
Date: Fri, 26 Apr 2024 12:49:44 +0200 [thread overview]
Message-ID: <20240426104950.7382-1-sebott@redhat.com> (raw)
Hej folks,
I'm looking into supporting migration between 2 Ampere Altra (Max)
machines (using Neoverse-N1). They are almost identical regarding
their feature id register state except for CTR_EL0.DIC which is set
on one machine but not the other.
CTR_EL0 is currently marked as invariant and migrating a VM between
those 2 machines using qemu fails.
Changes RFC [0] -> V1 [1]:
* store the emulated value per VM and not per VCPU
* allow to change more values than just the DIC bit
* only trap guest access to that reg when needed
* make sure to not present the guest with an inconsistent register set
Changes V1 -> V2:
* implemented Marc's suggestion for keeping registers consistent while
not breaking userspace ABI / expectations (I hope correctly this time)
* keep the shadowed value valid at all time
* unify the code to setup traps
Note:
* in order to switch off CTR_EL0.IDC userspace first has to set up
CLIDR_EL1 accordingly
* reading CCSIDR before and after changing the cache size in CTR_EL0
could result in different values (but only if CCSIDR was not changed
from the generated value)
* I'll prepare a testcase for the next revision
Thanks,
Sebastian
[0]: https://lore.kernel.org/all/20240318111636.10613-1-sebott@redhat.com/T/
[1]: https://lore.kernel.org/lkml/20240405120108.11844-1-sebott@redhat.com/T/
Sebastian Ott (6):
KVM: arm64: change return value in arm64_check_features()
KVM: arm64: unify trap setup code
KVM: arm64: maintain per VM value for CTR_EL0
KVM: arm64: add emulation for CTR_EL0 register
KVM: arm64: show writable masks for feature registers
KVM: arm64: rename functions for invariant sys regs
arch/arm64/include/asm/kvm_emulate.h | 37 -----
arch/arm64/include/asm/kvm_host.h | 4 +-
arch/arm64/kvm/arm.c | 3 +-
arch/arm64/kvm/sys_regs.c | 225 ++++++++++++++++++++-------
4 files changed, 173 insertions(+), 96 deletions(-)
--
2.42.0
next reply other threads:[~2024-04-26 10:49 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 10:49 Sebastian Ott [this message]
2024-04-26 10:49 ` [PATCH v2 1/6] KVM: arm64: change return value in arm64_check_features() Sebastian Ott
2024-04-26 10:49 ` [PATCH v2 2/6] KVM: arm64: unify trap setup code Sebastian Ott
2024-05-01 6:51 ` Oliver Upton
2024-05-03 15:06 ` Sebastian Ott
2024-04-26 10:49 ` [PATCH v2 3/6] KVM: arm64: maintain per VM value for CTR_EL0 Sebastian Ott
2024-04-26 10:49 ` [PATCH v2 4/6] KVM: arm64: add emulation for CTR_EL0 register Sebastian Ott
2024-05-01 8:15 ` Oliver Upton
2024-05-03 15:50 ` Marc Zyngier
2024-05-03 17:27 ` Oliver Upton
2024-05-08 15:17 ` Sebastian Ott
2024-05-08 17:18 ` Oliver Upton
2024-04-26 10:49 ` [PATCH v2 5/6] KVM: arm64: show writable masks for feature registers Sebastian Ott
2024-05-01 7:31 ` Oliver Upton
2024-05-03 11:03 ` Sebastian Ott
2024-04-26 10:49 ` [PATCH v2 6/6] KVM: arm64: rename functions for invariant sys regs Sebastian Ott
2024-05-01 8:17 ` [PATCH v2 0/6] KVM: arm64: emulation for CTR_EL0 Oliver Upton
2024-05-03 11:01 ` Sebastian Ott
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240426104950.7382-1-sebott@redhat.com \
--to=sebott@redhat.com \
--cc=catalin.marinas@arm.com \
--cc=james.morse@arm.com \
--cc=kvmarm@lists.linux.dev \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maz@kernel.org \
--cc=oliver.upton@linux.dev \
--cc=suzuki.poulose@arm.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).