From: Mark Brown <broonie@kernel.org>
To: Leonardo Bras <leo.bras@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
Joey Gouly <joey.gouly@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Shuah Khan <shuah@kernel.org>, Oliver Upton <oupton@kernel.org>,
Fuad Tabba <fuad.tabba@linux.dev>,
Peter Maydell <peter.maydell@linaro.org>,
Wei-Lin Chang <weilin.chang@arm.com>,
Yao Yuan <yaoyuan@linux.alibaba.com>,
linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
kvmarm@lists.linux.dev, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v20 09/14] KVM: arm64: Allow GCS to be enabled for guests
Date: Wed, 9 Sep 2026 17:45:52 +0100 [thread overview]
Message-ID: <a48e936b-29c9-410e-a0c7-84cd5143d3d5@sirena.org.uk> (raw)
In-Reply-To: <aqGKnQZOe6leuXgG@LeoBrasDK>
[-- Attachment #1: Type: text/plain, Size: 1302 bytes --]
On Wed, Sep 09, 2026 at 05:34:37PM +0100, Leonardo Bras wrote:
> On Tue, Sep 01, 2026 at 10:47:07PM +0100, Mark Brown wrote:
> > @@ -2193,10 +2193,12 @@ static u64 sanitise_id_aa64pfr1_el1(const struct kvm_vcpu *vcpu, u64 val)
> > val &= ~ID_AA64PFR1_EL1_THE;
> > val &= ~ID_AA64PFR1_EL1_MTEX;
> > val &= ~ID_AA64PFR1_EL1_PFAR;
> And here it says to only mask the feature bit if it's not available.
> IIUC this sanitize function is called when resetting a vcpu, is that right?
Yes.
> > @@ -3444,7 +3446,6 @@ static const struct sys_reg_desc sys_reg_descs[] = {
> > ~(ID_AA64PFR1_EL1_PFAR |
> > ID_AA64PFR1_EL1_MTEX |
> > ID_AA64PFR1_EL1_THE |
> > - ID_AA64PFR1_EL1_GCS |
> > ID_AA64PFR1_EL1_MTE_frac |
> > ID_AA64PFR1_EL1_NMI |
> > ID_AA64PFR1_EL1_RNDR_trap |
> This one looks like to be a mask that's used to compare with
> arm64_ftr_regs[] on arm64_check_features(). That seems to be called on
> set_id_aa64pfr1_el1() which is used when we get an ioclt to set a system
> register.
> So, basically, does it use this mask to check if the set value is valid?
Yes, this excludes values that are never supported.
> Reviewed-by: Leonardo Bras <leo.bras@arm.com>
Thanks!
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next prev parent reply other threads:[~2026-09-09 16:46 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-01 21:46 [PATCH v20 00/14] KVM: arm64: Provide guest support for GCS Mark Brown
2026-09-01 21:46 ` [PATCH v20 01/14] arm64/gcs: Ensure FGTs for EL1 GCS instructions are disabled Mark Brown
2026-09-03 16:10 ` Lorenzo Stoakes (ARM)
2026-09-01 21:47 ` [PATCH v20 02/14] KVM: arm64: Fix FGT mapping for HFGITR_EL2.nGCSEPP Mark Brown
2026-09-03 16:23 ` Lorenzo Stoakes (ARM)
2026-09-03 19:29 ` Mark Brown
2026-09-01 21:47 ` [PATCH v20 03/14] KVM: arm64: Manage GCS access and registers for guests Mark Brown
2026-09-02 16:44 ` Leonardo Bras
2026-09-03 20:52 ` Mark Brown
2026-09-03 18:13 ` Lorenzo Stoakes (ARM)
2026-09-03 20:41 ` Mark Brown
2026-09-04 8:54 ` Lorenzo Stoakes (ARM)
2026-09-04 21:07 ` Mark Brown
2026-09-07 14:14 ` Lorenzo Stoakes (ARM)
2026-09-07 14:55 ` Mark Brown
2026-09-09 11:34 ` Lorenzo Stoakes (ARM)
2026-09-01 21:47 ` [PATCH v20 04/14] KVM: arm64: Ensure GCS memory effects are visible Mark Brown
2026-09-02 16:30 ` Leonardo Bras
2026-09-04 12:16 ` Lorenzo Stoakes (ARM)
2026-09-01 21:47 ` [PATCH v20 05/14] KVM: arm64: Set PSTATE.EXLOCK when entering an exception Mark Brown
2026-09-03 14:25 ` Leonardo Bras
2026-09-03 16:20 ` Mark Brown
2026-09-03 16:40 ` Leonardo Bras
2026-09-04 13:04 ` Lorenzo Stoakes (ARM)
2026-09-01 21:47 ` [PATCH v20 06/14] KVM: arm64: Validate GCS exception lock when emulating ERET Mark Brown
2026-09-03 15:37 ` Leonardo Bras
2026-09-03 19:22 ` Mark Brown
2026-09-04 13:16 ` Leonardo Bras
2026-09-04 21:56 ` Mark Brown
2026-09-07 10:55 ` Leonardo Bras
2026-09-01 21:47 ` [PATCH v20 07/14] KVM: arm64: Forward GCS exceptions to nested guests Mark Brown
2026-09-09 13:00 ` Leonardo Bras
2026-09-01 21:47 ` [PATCH v20 08/14] KVM: arm64: Enforce EXLOCK for SPSR and ELR Mark Brown
2026-09-09 14:35 ` Leonardo Bras
2026-09-01 21:47 ` [PATCH v20 09/14] KVM: arm64: Allow GCS to be enabled for guests Mark Brown
2026-09-09 16:34 ` Leonardo Bras
2026-09-09 16:45 ` Mark Brown [this message]
2026-09-01 21:47 ` [PATCH v20 10/14] KVM: selftests: arm64: Add GCS registers to get-reg-list Mark Brown
2026-09-09 16:46 ` Leonardo Bras
2026-09-01 21:47 ` [PATCH v20 11/14] KVM: selftests: arm64: Add GCS to set_id_regs Mark Brown
2026-09-09 16:55 ` Leonardo Bras
2026-09-01 21:47 ` [PATCH v20 12/14] KVM: selftests: arm64: Only restore SPSR_EL1 and ELR_EL1 if they change Mark Brown
2026-09-09 17:03 ` Leonardo Bras
2026-09-01 21:47 ` [PATCH v20 13/14] tools: Synchronise the kernel esr.h Mark Brown
2026-09-10 11:10 ` Leonardo Bras
2026-09-01 21:47 ` [PATCH v20 14/14] KVM: selftests: arm64: Add GCS EXLOCK exception emulation test Mark Brown
2026-09-10 17:20 ` Leonardo Bras
2026-09-10 18:26 ` Mark Brown
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