From: Oliver Upton <oliver.upton@linux.dev>
To: Kristina Martsenko <kristina.martsenko@arm.com>
Cc: kvm@vger.kernel.org, Marc Zyngier <maz@kernel.org>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>, Will Deacon <will@kernel.org>,
Cornelia Huck <cohuck@redhat.com>,
Jing Zhang <jingzhangos@google.com>,
kvmarm@lists.linux.dev
Subject: Re: [PATCH v10 06/12] KVM: arm64: Allow userspace to change ID_AA64ISAR{0-2}_EL1
Date: Fri, 22 Sep 2023 17:52:41 +0000 [thread overview]
Message-ID: <ZQ3UaYTsZ1lVeShQ@linux.dev> (raw)
In-Reply-To: <80140d61-82e7-2795-409d-2cf6dc4993bc@arm.com>
On Fri, Sep 22, 2023 at 06:18:37PM +0100, Kristina Martsenko wrote:
> On 20/09/2023 19:33, Oliver Upton wrote:
> > Almost all of the features described by the ISA registers have no KVM
> > involvement. Allow userspace to change the value of these registers with
> > a couple exceptions:
> >
> > - MOPS is not writable as KVM does not currently virtualize FEAT_MOPS.
> >
> > - The PAuth fields are not writable as KVM requires both address and
> > generic authentication be enabled.
> >
> > - Override the kernel's handling of BC to LOWER_SAFE.
> >
> > Co-developed-by: Jing Zhang <jingzhangos@google.com>
> > Signed-off-by: Jing Zhang <jingzhangos@google.com>
> > Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
> > ---
> > arch/arm64/kvm/sys_regs.c | 42 ++++++++++++++++++++++++++++-----------
> > 1 file changed, 30 insertions(+), 12 deletions(-)
> >
> > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> > index 10e3e6a736dc..71664bec2808 100644
> > --- a/arch/arm64/kvm/sys_regs.c
> > +++ b/arch/arm64/kvm/sys_regs.c
> > @@ -1225,6 +1225,10 @@ static s64 kvm_arm64_ftr_safe_value(u32 id, const struct arm64_ftr_bits *ftrp,
> > break;
> > }
> > break;
> > + case SYS_ID_AA64ISAR2_EL1:
> > + if (kvm_ftr.shift == ID_AA64ISAR2_EL1_BC_SHIFT)
> > + kvm_ftr.type = FTR_LOWER_SAFE;
> > + break;
> > case SYS_ID_DFR0_EL1:
> > if (kvm_ftr.shift == ID_DFR0_EL1_PerfMon_SHIFT)
> > kvm_ftr.type = FTR_LOWER_SAFE;
>
> Nit: it shouldn't be necessary to override BC anymore, as it was recently fixed
> in the arm64 code:
> https://lore.kernel.org/linux-arm-kernel/20230912133429.2606875-1-kristina.martsenko@arm.com/
Perfect, looks like that patch should go in 6.6 too. Thanks for the fix!
--
Thanks,
Oliver
next prev parent reply other threads:[~2023-09-22 17:54 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-20 18:32 [PATCH v10 00/12] KVM: arm64: Enable 'writable' ID registers Oliver Upton
2023-09-20 18:32 ` [PATCH v10 01/12] KVM: arm64: Allow userspace to get the writable masks for feature " Oliver Upton
2023-09-21 9:53 ` Cornelia Huck
2023-09-21 18:20 ` Oliver Upton
2023-09-20 18:32 ` [PATCH v10 02/12] KVM: arm64: Document KVM_ARM_GET_REG_WRITABLE_MASKS Oliver Upton
2023-09-21 9:56 ` Cornelia Huck
2023-09-20 18:33 ` [PATCH v10 03/12] KVM: arm64: Use guest ID register values for the sake of emulation Oliver Upton
2023-09-20 18:33 ` [PATCH v10 04/12] KVM: arm64: Reject attempts to set invalid debug arch version Oliver Upton
2023-09-20 18:33 ` [PATCH v10 05/12] KVM: arm64: Bump up the default KVM sanitised debug version to v8p8 Oliver Upton
2023-09-20 18:33 ` [PATCH v10 06/12] KVM: arm64: Allow userspace to change ID_AA64ISAR{0-2}_EL1 Oliver Upton
2023-09-22 17:18 ` Kristina Martsenko
2023-09-22 17:20 ` Kristina Martsenko
2023-09-22 17:52 ` Oliver Upton [this message]
2023-10-03 19:41 ` Oliver Upton
2023-09-20 18:33 ` [PATCH v10 07/12] KVM: arm64: Allow userspace to change ID_AA64MMFR{0-2}_EL1 Oliver Upton
2023-09-20 18:33 ` [PATCH v10 08/12] KVM: arm64: Allow userspace to change ID_AA64PFR0_EL1 Oliver Upton
2023-09-20 18:33 ` [PATCH v10 09/12] KVM: arm64: Allow userspace to change ID_AA64ZFR0_EL1 Oliver Upton
2023-09-20 18:33 ` [PATCH v10 10/12] KVM: arm64: Document vCPU feature selection UAPIs Oliver Upton
2023-09-27 2:45 ` kernel test robot
2023-10-03 19:37 ` Oliver Upton
2023-09-20 18:33 ` [PATCH v10 11/12] KVM: arm64: selftests: Import automatic generation of sysreg defs Oliver Upton
2023-09-20 18:33 ` [PATCH v10 12/12] KVM: arm64: selftests: Test for setting ID register from usersapce Oliver Upton
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