linux-kernel - Re: [PATCH v5 0/6] KVM: lockdep improvements

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Message-ID: <20250513114555.GF25763@noisy.programming.kicks-ass.net>
Date: Tue, 13 May 2025 13:45:55 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Maxim Levitsky <mlevitsk@...hat.com>
Cc: kvm@...r.kernel.org, Suzuki K Poulose <suzuki.poulose@....com>,
	Jing Zhang <jingzhangos@...gle.com>,
	"H. Peter Anvin" <hpa@...or.com>, Sebastian Ott <sebott@...hat.com>,
	Shusen Li <lishusen2@...wei.com>, Waiman Long <longman@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-arm-kernel@...ts.infradead.org,
	Bjorn Helgaas <bhelgaas@...gle.com>, Borislav Petkov <bp@...en8.de>,
	Anup Patel <anup@...infault.org>, Will Deacon <will@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Alexander Potapenko <glider@...gle.com>, kvmarm@...ts.linux.dev,
	Keisuke Nishimura <keisuke.nishimura@...ia.fr>,
	Zenghui Yu <yuzenghui@...wei.com>,
	Atish Patra <atishp@...shpatra.org>,
	Joey Gouly <joey.gouly@....com>, x86@...nel.org,
	Marc Zyngier <maz@...nel.org>,
	Sean Christopherson <seanjc@...gle.com>,
	Andre Przywara <andre.przywara@....com>,
	Kunkun Jiang <jiangkunkun@...wei.com>,
	linux-riscv@...ts.infradead.org,
	Randy Dunlap <rdunlap@...radead.org>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Alexandre Ghiti <alex@...ti.fr>, linux-kernel@...r.kernel.org,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	kvm-riscv@...ts.infradead.org, Ingo Molnar <mingo@...hat.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Albert Ou <aou@...s.berkeley.edu>
Subject: Re: [PATCH v5 0/6] KVM: lockdep improvements

On Mon, May 12, 2025 at 02:04:01PM -0400, Maxim Levitsky wrote:
> This is	a continuation of my 'extract lock_all_vcpus/unlock_all_vcpus'
> patch series.
> 
> Implement the suggestion of using lockdep's "nest_lock" feature
> when locking all KVM vCPUs by adding mutex_trylock_nest_lock() and
> mutex_lock_killable_nest_lock() and use these functions	in the
> implementation of the
> kvm_trylock_all_vcpus()/kvm_lock_all_vcpus()/kvm_unlock_all_vcpus().
> 
> Those changes allow removal of a custom workaround that was needed to
> silence the lockdep warning in the SEV code and also stop lockdep from
> complaining in case of ARM and RISC-V code which doesn't include the above
> mentioned workaround.
> 
> Finally, it's worth noting that this patch series removes a fair
> amount of duplicate code by implementing the logic in one place.
> 
> V5: addressed review feedback.
> 
> Best regards,
> 	Maxim Levitsky
> 
> Maxim Levitsky (6):
>   locking/mutex: implement mutex_trylock_nested
>   locking/mutex: implement mutex_lock_killable_nest_lock
>   KVM: add kvm_lock_all_vcpus and kvm_trylock_all_vcpus
>   x86: KVM: SVM: use kvm_lock_all_vcpus instead of a custom
>     implementation
>   KVM: arm64: use kvm_trylock_all_vcpus when locking all vCPUs
>   RISC-V: KVM: use kvm_trylock_all_vcpus when locking all vCPUs
> 
>  arch/arm64/include/asm/kvm_host.h     |  3 --
>  arch/arm64/kvm/arch_timer.c           |  4 +-
>  arch/arm64/kvm/arm.c                  | 43 ----------------
>  arch/arm64/kvm/vgic/vgic-init.c       |  4 +-
>  arch/arm64/kvm/vgic/vgic-its.c        |  8 +--
>  arch/arm64/kvm/vgic/vgic-kvm-device.c | 12 ++---
>  arch/riscv/kvm/aia_device.c           | 34 +------------
>  arch/x86/kvm/svm/sev.c                | 72 ++-------------------------
>  include/linux/kvm_host.h              |  4 ++
>  include/linux/mutex.h                 | 32 ++++++++++--
>  kernel/locking/mutex.c                | 21 +++++---
>  virt/kvm/kvm_main.c                   | 59 ++++++++++++++++++++++
>  12 files changed, 126 insertions(+), 170 deletions(-)

Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>