linux-kernel - Re: [PATCH v10 32/43] arm64: RME: Enable PMU support with a realm guest

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Message-ID: <59d78787-1871-41ba-9a2e-30d1596c021f@redhat.com>
Date: Mon, 22 Sep 2025 10:03:32 +1000
From: Gavin Shan <gshan@...hat.com>
To: Steven Price <steven.price@....com>, kvm@...r.kernel.org,
 kvmarm@...ts.linux.dev
Cc: Catalin Marinas <catalin.marinas@....com>, Marc Zyngier <maz@...nel.org>,
 Will Deacon <will@...nel.org>, James Morse <james.morse@....com>,
 Oliver Upton <oliver.upton@...ux.dev>,
 Suzuki K Poulose <suzuki.poulose@....com>, Zenghui Yu
 <yuzenghui@...wei.com>, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, Joey Gouly <joey.gouly@....com>,
 Alexandru Elisei <alexandru.elisei@....com>,
 Christoffer Dall <christoffer.dall@....com>, Fuad Tabba <tabba@...gle.com>,
 linux-coco@...ts.linux.dev,
 Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
 Shanker Donthineni <sdonthineni@...dia.com>, Alper Gun
 <alpergun@...gle.com>, "Aneesh Kumar K . V" <aneesh.kumar@...nel.org>,
 Emi Kisanuki <fj0570is@...itsu.com>, Vishal Annapurve <vannapurve@...gle.com>
Subject: Re: [PATCH v10 32/43] arm64: RME: Enable PMU support with a realm
 guest

On 8/21/25 12:55 AM, Steven Price wrote:
> Use the PMU registers from the RmiRecExit structure to identify when an
> overflow interrupt is due and inject it into the guest. Also hook up the
> configuration option for enabling the PMU within the guest.
> 
> When entering a realm guest with a PMU interrupt pending, it is
> necessary to disable the physical interrupt. Otherwise when the RMM
> restores the PMU state the physical interrupt will trigger causing an
> immediate exit back to the host. The guest is expected to acknowledge
> the interrupt causing a host exit (to update the GIC state) which gives
> the opportunity to re-enable the physical interrupt before the next PMU
> event.
> 
> Number of PMU counters is configured by the VMM by writing to PMCR.N.
> 
> Signed-off-by: Steven Price <steven.price@....com>
> ---
> Changes since v2:
>   * Add a macro kvm_pmu_get_irq_level() to avoid compile issues when PMU
>     support is disabled.
> ---
>   arch/arm64/kvm/arm.c      | 11 +++++++++++
>   arch/arm64/kvm/guest.c    |  7 +++++++
>   arch/arm64/kvm/pmu-emul.c |  3 +++
>   arch/arm64/kvm/rme.c      |  8 ++++++++
>   arch/arm64/kvm/sys_regs.c |  5 +++--
>   include/kvm/arm_pmu.h     |  4 ++++
>   6 files changed, 36 insertions(+), 2 deletions(-)
> 

Reviewed-by: Gavin Shan <gshan@...hat.com>