Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 02 Aug 2023 16:55:05 +0100
Message-ID: <877cqdqw12.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     Sean Christopherson <seanjc@google.com>
Cc:     Raghavendra Rao Ananta <rananta@google.com>,
        Oliver Upton <oliver.upton@linux.dev>,
        James Morse <james.morse@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Huacai Chen <chenhuacai@kernel.org>,
        Zenghui Yu <yuzenghui@huawei.com>,
        Anup Patel <anup@brainfault.org>,
        Atish Patra <atishp@atishpatra.org>,
        Jing Zhang <jingzhangos@google.com>,
        Reiji Watanabe <reijiw@google.com>,
        Colton Lewis <coltonlewis@google.com>,
        David Matlack <dmatlack@google.com>,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
        linux-mips@vger.kernel.org, kvm-riscv@lists.infradead.org,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Subject: Re: [PATCH v7 02/12] KVM: arm64: Use kvm_arch_flush_remote_tlbs()
In-Reply-To: <ZMgsjx8dwKd4xBGe@google.com>
References: <20230722022251.3446223-1-rananta@google.com>
        <20230722022251.3446223-3-rananta@google.com>
        <87tttpr6qy.wl-maz@kernel.org>
        <ZMgsjx8dwKd4xBGe@google.com>
User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue)
 FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/28.2
 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO)
MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue")
Content-Type: text/plain; charset=US-ASCII
Precedence: bulk

On Mon, 31 Jul 2023 22:50:07 +0100,
Sean Christopherson <seanjc@google.com> wrote:
> 
> On Thu, Jul 27, 2023, Marc Zyngier wrote:
> > On Sat, 22 Jul 2023 03:22:41 +0100,
> > Raghavendra Rao Ananta <rananta@google.com> wrote:
> > > 
> > > Stop depending on CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL and opt to
> > > standardize on kvm_arch_flush_remote_tlbs() since it avoids
> > > duplicating the generic TLB stats across architectures that implement
> > > their own remote TLB flush.
> > > 
> > > This adds an extra function call to the ARM64 kvm_flush_remote_tlbs()
> > > path, but that is a small cost in comparison to flushing remote TLBs.
> > 
> > Well, there is no such thing as a "remote TLB" anyway. We either have
> > a non-shareable or inner-shareable invalidation. The notion of remote
> > would imply that we track who potentially has a TLB, which we
> > obviously don't.
> 
> Maybe kvm_arch_flush_vm_tlbs()?  The "remote" part is misleading even on x86 when
> running on Hyper-V, as the flush may be done via a single hypercall and by kicking
> "remote" vCPUs.

Yup, this would be much better.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.