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From: Reiji Watanabe <reijiw@google.com>
To: Marc Zyngier <maz@kernel.org>
Cc: Eric Auger <eauger@redhat.com>,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	 Will Deacon <will@kernel.org>, Peter Shier <pshier@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH v3 03/29] KVM: arm64: Introduce struct id_reg_info
Date: Mon, 22 Nov 2021 16:56:34 -0800	[thread overview]
Message-ID: <CAAeT=FyXc8WrSur5_c9d9Giq0=zJPQLm81g2AAAzs=4GAPe7Xw@mail.gmail.com> (raw)
In-Reply-To: <87ilwlsn0e.wl-maz@kernel.org>

On Sun, Nov 21, 2021 at 4:37 AM Marc Zyngier <maz@kernel.org> wrote:
>
> On Fri, 19 Nov 2021 04:47:53 +0000,
> Reiji Watanabe <reijiw@google.com> wrote:
> >
> > I am going to add the following comment. Does it look clear enough for you ?
> >
> >         /*
> >          * This is an optional ID register specific validation function.
> >          * When userspace tries to set the ID register, arm64_check_features()
> >          * will check if the requested value indicates any features that cannot
> >          * be supported by KVM on the host.  But, some ID register fields need
> >          * a special checking and this function can be used for such fields.
> >          * e.g. KVM_CREATE_DEVICE must be used to configure GICv3 for a guest.
> >          * ID_AA64PFR0_EL1.GIC shouldn't be set to 1 unless GICv3 is configured.
>
> There is no such requirement. GICv3 has a compatibility interface, and
> although KVM doesn't make use of it, there is no reason not to expose
> that GICv3 exists on the CPU even if not using it. Even more, this has
> been the case forever, and making this change now would probably break
> migration.

Shockingly, I somehow misunderstood what read_id_reg() did for GICv3...
I will use a different example for it.

Thanks,
Reiji

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  reply	other threads:[~2021-11-23  0:58 UTC|newest]

Thread overview: 109+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-17  6:43 [RFC PATCH v3 00/29] KVM: arm64: Make CPU ID registers writable by userspace Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 01/29] KVM: arm64: Add has_reset_once flag for vcpu Reiji Watanabe
2021-11-21 12:36   ` Marc Zyngier
2021-11-23  0:51     ` Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 02/29] KVM: arm64: Save ID registers' sanitized value per vCPU Reiji Watanabe
2021-11-18 20:36   ` Eric Auger
2021-11-18 22:00     ` Reiji Watanabe
2021-11-24 18:08       ` Eric Auger
2021-11-21 12:36   ` Marc Zyngier
2021-11-23  4:39     ` Reiji Watanabe
2021-11-23 10:03       ` Marc Zyngier
2021-11-23 17:12         ` Reiji Watanabe
2021-12-02 10:58   ` Eric Auger
2021-12-04  1:45     ` Reiji Watanabe
2021-12-07  9:34       ` Eric Auger
2021-12-08  5:57         ` Reiji Watanabe
2021-12-08  7:09           ` Eric Auger
2021-12-08  7:18             ` Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 03/29] KVM: arm64: Introduce struct id_reg_info Reiji Watanabe
2021-11-18 20:36   ` Eric Auger
2021-11-19  4:47     ` Reiji Watanabe
2021-11-21 12:37       ` Marc Zyngier
2021-11-23  0:56         ` Reiji Watanabe [this message]
2021-11-24 18:22       ` Eric Auger
2021-11-25  6:05         ` Reiji Watanabe
2021-11-21 12:37   ` Marc Zyngier
2021-11-25  5:27     ` Reiji Watanabe
2021-12-01 15:38       ` Alexandru Elisei
2021-12-02  4:32         ` Reiji Watanabe
2021-11-24 21:07   ` Eric Auger
2021-11-25  6:40     ` Reiji Watanabe
2021-12-02 12:51       ` Eric Auger
2021-12-01 15:24   ` Alexandru Elisei
2021-12-02  4:09     ` Reiji Watanabe
2021-12-02 12:51   ` Eric Auger
2021-12-04  4:35     ` Reiji Watanabe
2021-12-07  9:36       ` Eric Auger
2021-11-17  6:43 ` [RFC PATCH v3 04/29] KVM: arm64: Make ID_AA64PFR0_EL1 writable Reiji Watanabe
2021-11-21 12:37   ` Marc Zyngier
2021-11-24  6:11     ` Reiji Watanabe
2021-11-25 15:35   ` Eric Auger
2021-11-30  1:29     ` Reiji Watanabe
2021-12-02 13:02       ` Eric Auger
2021-12-04  7:59         ` Reiji Watanabe
2021-12-07  9:42           ` Eric Auger
2021-11-17  6:43 ` [RFC PATCH v3 05/29] KVM: arm64: Make ID_AA64PFR1_EL1 writable Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 06/29] KVM: arm64: Make ID_AA64ISAR0_EL1 writable Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 07/29] KVM: arm64: Make ID_AA64ISAR1_EL1 writable Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 08/29] KVM: arm64: Make ID_AA64MMFR0_EL1 writable Reiji Watanabe
2021-11-25 15:31   ` Eric Auger
2021-11-30  4:43     ` Reiji Watanabe
2021-11-25 16:06   ` Eric Auger
2021-11-17  6:43 ` [RFC PATCH v3 09/29] KVM: arm64: Hide IMPLEMENTATION DEFINED PMU support for the guest Reiji Watanabe
2021-11-25 20:30   ` Eric Auger
2021-11-30  5:32     ` Reiji Watanabe
2021-12-01 15:53       ` Alexandru Elisei
2021-12-01 16:09         ` Alexandru Elisei
2021-12-02  4:42           ` Reiji Watanabe
2021-12-02 10:57       ` Eric Auger
2021-12-04  1:04         ` Reiji Watanabe
2021-12-04 14:14           ` Eric Auger
2021-12-04 17:39             ` Reiji Watanabe
2021-12-04 23:38               ` Itaru Kitayama
2021-12-06  0:27                 ` Reiji Watanabe
2021-12-06  9:52               ` Alexandru Elisei
2021-12-06 10:25                 ` Eric Auger
2021-12-07  7:07                   ` Reiji Watanabe
2021-12-07  8:10                 ` Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 10/29] KVM: arm64: Make ID_AA64DFR0_EL1 writable Reiji Watanabe
2021-11-25 20:30   ` Eric Auger
2021-11-30  5:21     ` Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 11/29] KVM: arm64: Make ID_DFR0_EL1 writable Reiji Watanabe
2021-11-24 13:46   ` Eric Auger
2021-11-25  5:33     ` Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 12/29] KVM: arm64: Make ID_DFR1_EL1 writable Reiji Watanabe
2021-11-25 20:30   ` Eric Auger
2021-11-30  5:39     ` Reiji Watanabe
2021-12-02 13:11       ` Eric Auger
2021-11-17  6:43 ` [RFC PATCH v3 13/29] KVM: arm64: Make ID_MMFR0_EL1 writable Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 14/29] KVM: arm64: Make MVFR1_EL1 writable Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 15/29] KVM: arm64: Make ID registers without id_reg_info writable Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 16/29] KVM: arm64: Add consistency checking for frac fields of ID registers Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 17/29] KVM: arm64: Introduce KVM_CAP_ARM_ID_REG_CONFIGURABLE capability Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 18/29] KVM: arm64: Add kunit test for ID register validation Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 19/29] KVM: arm64: Use vcpu->arch cptr_el2 to track value of cptr_el2 for VHE Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 20/29] KVM: arm64: Use vcpu->arch.mdcr_el2 to track value of mdcr_el2 Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 21/29] KVM: arm64: Introduce framework to trap disabled features Reiji Watanabe
2021-11-21 18:46   ` Marc Zyngier
2021-11-23  7:27     ` Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 22/29] KVM: arm64: Trap disabled features of ID_AA64PFR0_EL1 Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 23/29] KVM: arm64: Trap disabled features of ID_AA64PFR1_EL1 Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 24/29] KVM: arm64: Trap disabled features of ID_AA64DFR0_EL1 Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 25/29] KVM: arm64: Trap disabled features of ID_AA64MMFR1_EL1 Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 26/29] KVM: arm64: Trap disabled features of ID_AA64ISAR1_EL1 Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 27/29] KVM: arm64: Initialize trapping of disabled CPU features for the guest Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 28/29] KVM: arm64: Add kunit test for trap initialization Reiji Watanabe
2021-11-17  6:43 ` [RFC PATCH v3 29/29] KVM: arm64: selftests: Introduce id_reg_test Reiji Watanabe
2021-11-18 20:34   ` Eric Auger
2021-11-20  6:39     ` Reiji Watanabe
2021-11-22 14:17       ` Eric Auger
2021-11-23  6:33         ` Reiji Watanabe
2021-11-23 16:00 ` [RFC PATCH v3 00/29] KVM: arm64: Make CPU ID registers writable by userspace Alexandru Elisei
2021-11-24  5:13   ` Reiji Watanabe
2021-11-24 10:50     ` Alexandru Elisei
2021-11-24 17:00       ` Reiji Watanabe
2021-11-23 16:27 ` Alexandru Elisei
2021-11-24  5:49   ` Reiji Watanabe
2021-11-24 10:48     ` Alexandru Elisei
2021-11-24 16:44       ` Reiji Watanabe

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