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From: Oliver Upton <oupton@kernel.org>
To: Fuad Tabba <fuad.tabba@linux.dev>
Cc: Marc Zyngier <maz@kernel.org>,
	kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
	Joey Gouly <joey.gouly@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Steffen Eiden <seiden@linux.ibm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Jing Zhang <jingzhangos@google.com>,
	Karl Mehltretter <kmehltretter@gmail.com>,
	Fuad Tabba <tabba@google.com>,
	kvm@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 01/10] KVM: arm64: Don't WARN on SMCCC filter reserved range allocation failure
Date: Mon, 28 Sep 2026 08:54:35 -0700	[thread overview]
Message-ID: <arqNu0rSxIz4-Mue@kernel.org> (raw)
In-Reply-To: <20260928152507.2116110-2-fuad.tabba@linux.dev>

Hi Fuad,

On Mon, Sep 28, 2026 at 04:24:58PM +0100, Fuad Tabba wrote:
> The first time userspace sets an SMCCC filter, kvm_smccc_set_filter()
> inserts the reserved architecture ranges into the maple tree and WARNs
> if that fails. The tree is empty and config_lock is held, so the only
> way it can fail is -ENOMEM. The allocation is GFP_KERNEL_ACCOUNT, so a
> memory cgroup limit is enough to hit the WARN from userspace.
> 
> The WARN goes back to when the ranges were inserted at VM creation and
> the error was dropped. Since commit d34b76489ea0c ("KVM: arm64: Only
> insert reserved ranges when SMCCC filter is used") the tree is emptied
> on failure and the error reaches userspace. Drop the WARN.

Eh, the warn is still useful. You could potentially add a check for
-ENOMEM but any other return value is a sign of something wrong in
KVM.

Thanks,
Oliver

  reply	other threads:[~2026-09-28 15:54 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-28 15:24 [PATCH v1 00/10] KVM: arm64: Nested stage-2 walk error handling and other small fixes Fuad Tabba
2026-09-28 15:24 ` [PATCH v1 01/10] KVM: arm64: Don't WARN on SMCCC filter reserved range allocation failure Fuad Tabba
2026-09-28 15:54   ` Oliver Upton [this message]
2026-09-28 16:14     ` Fuad Tabba
2026-09-28 15:24 ` [PATCH v1 02/10] KVM: arm64: nv: Don't WARN on an invalid VTCR_EL2 Fuad Tabba
2026-09-28 15:25 ` [PATCH v1 03/10] KVM: arm64: nv: Don't loop on AT S12E{0,1}{R,W} with " Fuad Tabba
2026-09-28 15:25 ` [PATCH v1 04/10] KVM: arm64: nv: Return a failed stage-2 descriptor read as a fault Fuad Tabba
2026-09-28 16:47   ` Oliver Upton
2026-09-28 17:46     ` Fuad Tabba
2026-09-28 15:25 ` [PATCH v1 05/10] KVM: arm64: selftests: Test AT S12E1R with an invalid VTCR_EL2.SL0 Fuad Tabba
2026-09-28 15:25 ` [PATCH v1 06/10] Documentation: KVM: Fix the name of the SMCCC filter attribute Fuad Tabba
2026-09-28 15:25 ` [PATCH v1 07/10] Documentation: KVM: Fix the name of KVM_ARM_SET_COUNTER_OFFSET Fuad Tabba
2026-09-28 15:25 ` [PATCH v1 08/10] Documentation: KVM: Fix the name of KVM_ARM_FEATURE_ID_RANGE_IDX Fuad Tabba
2026-09-28 15:25 ` [PATCH v1 09/10] KVM: arm64: selftests: Free the VMs in smccc_filter and psci_test Fuad Tabba
2026-09-28 15:25 ` [PATCH v1 10/10] KVM: arm64: selftests: Free the thread arrays in vgic_lpi_stress Fuad Tabba
2026-09-28 15:58 ` [PATCH v1 00/10] KVM: arm64: Nested stage-2 walk error handling and other small fixes Marc Zyngier
2026-09-28 16:12   ` Fuad Tabba

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