From: Oliver Upton <oliver.upton@linux.dev>
To: Jing Zhang <jingzhangos@google.com>
Cc: Marc Zyngier <maz@kernel.org>, Cornelia Huck <cohuck@redhat.com>,
KVM <kvm@vger.kernel.org>, KVMARM <kvmarm@lists.linux.dev>,
ARMLinux <linux-arm-kernel@lists.infradead.org>,
Will Deacon <will@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Fuad Tabba <tabba@google.com>, Reiji Watanabe <reijiw@google.com>,
Raghavendra Rao Ananta <rananta@google.com>,
Suraj Jitindar Singh <surajjs@amazon.com>
Subject: Re: [PATCH v6 3/6] KVM: arm64: Enable writable for ID_AA64DFR0_EL1 and ID_DFR0_EL1
Date: Fri, 21 Jul 2023 21:10:05 +0000 [thread overview]
Message-ID: <ZLr0LcQENZmIGMAt@linux.dev> (raw)
In-Reply-To: <CAAdAUtjNW6Q+phGbc6jXWTERRhYo7E3H4Ws0iDSngc17Sac0uA@mail.gmail.com>
On Fri, Jul 21, 2023 at 11:22:35AM -0700, Jing Zhang wrote:
> On Fri, Jul 21, 2023 at 2:31 AM Marc Zyngier <maz@kernel.org> wrote:
> > My preference would be a single ioctl that returns the full list of
> > writeable masks in the ID reg range. It is big, but not crazy big
> > (1536 bytes, if I haven't messed up), and includes the non ID_*_EL1
> > sysreg such as MPIDR_EL1, CTR_EL1, SMIDR_EL1.
> Just want to double confirm that would the ioclt return the list of
> only writable masks, not the list of {idreg_name, mask} pair? So, the
> VMM will need to index idreg's writable mask by op1, CRm, op2?
I generally agree with the approach Marc is proposing, but I wonder if
it makes sense to have userspace ask the kernel for this information on
a per-register basis.
What I had in mind was something similar to the KVM_GET_ONE_REG ioctl,
but instead of returning the register value it'd return the mask of the
register. This would keep the kernel implementation dead simple (I'm
lazy) and more easily allow for future expansion in case we want to
start describing more registers this way. Userspace would iterate the ID
register space and ask the kernel for the mask of registers it wants to
change.
Thoughts?
--
Thanks,
Oliver
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-07-21 21:10 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-18 16:45 [PATCH v6 0/6] Enable writable for idregs DFR0,PFR0, MMFR{0,1,2, 3} Jing Zhang
2023-07-18 16:45 ` [PATCH v6 1/6] KVM: arm64: Use guest ID register values for the sake of emulation Jing Zhang
2023-07-18 16:45 ` [PATCH v6 2/6] KVM: arm64: Reject attempts to set invalid debug arch version Jing Zhang
2023-07-21 21:18 ` Oliver Upton
2023-07-21 22:26 ` Jing Zhang
2023-07-18 16:45 ` [PATCH v6 3/6] KVM: arm64: Enable writable for ID_AA64DFR0_EL1 and ID_DFR0_EL1 Jing Zhang
2023-07-20 8:52 ` Cornelia Huck
2023-07-20 16:39 ` Jing Zhang
2023-07-21 8:38 ` Cornelia Huck
2023-07-21 9:31 ` Marc Zyngier
2023-07-21 9:48 ` Cornelia Huck
2023-07-29 10:36 ` Marc Zyngier
2023-07-31 20:51 ` Jing Zhang
2023-07-21 18:22 ` Jing Zhang
2023-07-21 21:10 ` Oliver Upton [this message]
[not found] ` <87edkxg0jr.fsf@redhat.com>
[not found] ` <ZMFWsvWzfkkz2VNB@thinky-boi>
2023-07-27 9:34 ` Cornelia Huck
2023-07-18 16:45 ` [PATCH v6 4/6] KVM: arm64: Enable writable for ID_AA64PFR0_EL1 Jing Zhang
2023-07-18 16:45 ` [PATCH v6 5/6] KVM: arm64: Enable writable for ID_AA64MMFR{0, 1, 2, 3}_EL1 Jing Zhang
2023-07-18 16:45 ` [PATCH v6 6/6] KVM: arm64: selftests: Test for setting ID register from usersapce Jing Zhang
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=ZLr0LcQENZmIGMAt@linux.dev \
--to=oliver.upton@linux.dev \
--cc=alexandru.elisei@arm.com \
--cc=cohuck@redhat.com \
--cc=james.morse@arm.com \
--cc=jingzhangos@google.com \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.linux.dev \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=maz@kernel.org \
--cc=pbonzini@redhat.com \
--cc=rananta@google.com \
--cc=reijiw@google.com \
--cc=surajjs@amazon.com \
--cc=suzuki.poulose@arm.com \
--cc=tabba@google.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 NNTP newsgroup(s).