From: Reiji Watanabe <reijiw@google.com>
To: Oliver Upton <oupton@google.com>
Cc: Marc Zyngier <maz@kernel.org>,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Will Deacon <will@kernel.org>, Andrew Jones <drjones@redhat.com>,
Peng Liang <liangpeng10@huawei.com>,
Peter Shier <pshier@google.com>,
Ricardo Koller <ricarkol@google.com>,
Jing Zhang <jingzhangos@google.com>,
Raghavendra Rao Anata <rananta@google.com>
Subject: Re: [RFC PATCH v2 18/28] KVM: arm64: Introduce KVM_CAP_ARM_ID_REG_WRITABLE capability
Date: Thu, 4 Nov 2021 21:07:25 -0700 [thread overview]
Message-ID: <CAAeT=FyowLxUTpLDoAxrETbOyCTCcfc1==hy-Q4F5fdswqS-yg@mail.gmail.com> (raw)
In-Reply-To: <YYQNGqpy1NiUEXYD@google.com>
On Thu, Nov 4, 2021 at 9:41 AM Oliver Upton <oupton@google.com> wrote:
>
> On Tue, Nov 02, 2021 at 11:25:10PM -0700, Reiji Watanabe wrote:
> > Introduce a new capability KVM_CAP_ARM_ID_REG_WRITABLE to indicate
> > that ID registers are writable by userspace.
> >
> > Signed-off-by: Reiji Watanabe <reijiw@google.com>
> > ---
> > Documentation/virt/kvm/api.rst | 8 ++++++++
> > arch/arm64/kvm/arm.c | 1 +
> > include/uapi/linux/kvm.h | 1 +
> > 3 files changed, 10 insertions(+)
> >
> > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> > index a6729c8cf063..f7dfb5127310 100644
> > --- a/Documentation/virt/kvm/api.rst
> > +++ b/Documentation/virt/kvm/api.rst
> > @@ -7265,3 +7265,11 @@ The argument to KVM_ENABLE_CAP is also a bitmask, and must be a subset
> > of the result of KVM_CHECK_EXTENSION. KVM will forward to userspace
> > the hypercalls whose corresponding bit is in the argument, and return
> > ENOSYS for the others.
> > +
> > +8.35 KVM_CAP_ARM_ID_REG_WRITABLE
> > +--------------------------------
>
> ID registers are technically already writable, KVM just rejects any
> value other than what it derives from sanitising the host ID registers.
> I agree that the nuance being added warrants a KVM_CAP, as it informs
> userspace it can deliberately configure ID registers with a more limited
> value than what KVM returns.
>
> KVM_CAP_ARM_ID_REG_CONFIGURABLE maybe? Naming is hard :)
Thank you for the suggestion. Yes, that sounds better.
I will change the name as you suggested.
Regards,
Reiji
next prev parent reply other threads:[~2021-11-05 4:07 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-03 6:24 [RFC PATCH v2 00/28] KVM: arm64: Make CPU ID registers writable by userspace Reiji Watanabe
2021-11-03 6:24 ` [RFC PATCH v2 01/28] KVM: arm64: Add has_reset_once flag for vcpu Reiji Watanabe
2021-11-04 16:10 ` Oliver Upton
2021-11-03 6:24 ` [RFC PATCH v2 02/28] KVM: arm64: Save ID registers' sanitized value per vCPU Reiji Watanabe
2021-11-04 16:14 ` Oliver Upton
2021-11-04 21:39 ` Reiji Watanabe
2021-11-05 1:33 ` Oliver Upton
2021-11-05 6:25 ` Reiji Watanabe
2021-11-03 6:24 ` [RFC PATCH v2 03/28] KVM: arm64: Introduce struct id_reg_info Reiji Watanabe
2021-11-03 6:24 ` [RFC PATCH v2 04/28] KVM: arm64: Keep consistency of ID registers between vCPUs Reiji Watanabe
2021-11-04 16:33 ` Oliver Upton
2021-11-08 7:45 ` Reiji Watanabe
2021-11-03 6:24 ` [RFC PATCH v2 05/28] KVM: arm64: Make ID_AA64PFR0_EL1 writable Reiji Watanabe
2021-11-03 6:24 ` [RFC PATCH v2 06/28] KVM: arm64: Make ID_AA64PFR1_EL1 writable Reiji Watanabe
2021-11-03 6:24 ` [RFC PATCH v2 07/28] KVM: arm64: Make ID_AA64ISAR0_EL1 writable Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 08/28] KVM: arm64: Make ID_AA64ISAR1_EL1 writable Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 09/28] KVM: arm64: Make ID_AA64MMFR0_EL1 writable Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 10/28] KVM: arm64: Hide IMPLEMENTATION DEFINED PMU support for the guest Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 11/28] KVM: arm64: Make ID_AA64DFR0_EL1 writable Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 12/28] KVM: arm64: Make ID_DFR0_EL1 writable Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 13/28] KVM: arm64: Make ID_DFR1_EL1 writable Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 14/28] KVM: arm64: Make ID_MMFR0_EL1 writable Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 15/28] KVM: arm64: Make MVFR1_EL1 writable Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 16/28] KVM: arm64: Make ID registers without id_reg_info writable Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 17/28] KVM: arm64: Add consistency checking for frac fields of ID registers Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 18/28] KVM: arm64: Introduce KVM_CAP_ARM_ID_REG_WRITABLE capability Reiji Watanabe
2021-11-04 16:40 ` Oliver Upton
2021-11-05 4:07 ` Reiji Watanabe [this message]
2021-11-03 6:25 ` [RFC PATCH v2 19/28] KVM: arm64: Use vcpu->arch cptr_el2 to track value of cptr_el2 for VHE Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 20/28] KVM: arm64: Use vcpu->arch.mdcr_el2 to track value of mdcr_el2 Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 21/28] KVM: arm64: Introduce framework to trap disabled features Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 22/28] KVM: arm64: Trap disabled features of ID_AA64PFR0_EL1 Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 23/28] KVM: arm64: Trap disabled features of ID_AA64PFR1_EL1 Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 24/28] KVM: arm64: Trap disabled features of ID_AA64DFR0_EL1 Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 25/28] KVM: arm64: Trap disabled features of ID_AA64MMFR1_EL1 Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 26/28] KVM: arm64: Trap disabled features of ID_AA64ISAR1_EL1 Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 27/28] KVM: arm64: Activate trapping of disabled CPU features for the guest Reiji Watanabe
2021-11-03 6:25 ` [RFC PATCH v2 28/28] KVM: arm64: selftests: Introduce id_reg_test Reiji Watanabe
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