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Date:   Thu, 27 Jul 2023 11:53:00 +0100
Message-ID: <87sf99r5gz.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     Raghavendra Rao Ananta <rananta@google.com>
Cc:     Oliver Upton <oliver.upton@linux.dev>,
        James Morse <james.morse@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.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, Gavin Shan <gshan@redhat.com>,
        Shaoqin Huang <shahuang@redhat.com>
Subject: Re: [PATCH v7 05/12] KVM: Move kvm_arch_flush_remote_tlbs_memslot() to common code
In-Reply-To: <20230722022251.3446223-6-rananta@google.com>
References: <20230722022251.3446223-1-rananta@google.com>
        <20230722022251.3446223-6-rananta@google.com>
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On Sat, 22 Jul 2023 03:22:44 +0100,
Raghavendra Rao Ananta <rananta@google.com> wrote:
> 
> From: David Matlack <dmatlack@google.com>
> 
> Move kvm_arch_flush_remote_tlbs_memslot() to common code and drop
> "arch_" from the name. kvm_arch_flush_remote_tlbs_memslot() is just a
> range-based TLB invalidation where the range is defined by the memslot.
> Now that kvm_flush_remote_tlbs_range() can be called from common code we
> can just use that and drop a bunch of duplicate code from the arch
> directories.
> 
> Note this adds a lockdep assertion for slots_lock being held when
> calling kvm_flush_remote_tlbs_memslot(), which was previously only
> asserted on x86. MIPS has calls to kvm_flush_remote_tlbs_memslot(),
> but they all hold the slots_lock, so the lockdep assertion continues to
> hold true.
> 
> Also drop the CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT ifdef gating
> kvm_flush_remote_tlbs_memslot(), since it is no longer necessary.
> 
> Signed-off-by: David Matlack <dmatlack@google.com>
> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
> ---
>  arch/arm64/kvm/arm.c     |  6 ------
>  arch/mips/kvm/mips.c     | 10 ++--------
>  arch/riscv/kvm/mmu.c     |  6 ------
>  arch/x86/kvm/mmu/mmu.c   | 16 +---------------
>  arch/x86/kvm/x86.c       |  2 +-
>  include/linux/kvm_host.h |  7 +++----
>  virt/kvm/kvm_main.c      | 18 ++++++++++++++++--
>  7 files changed, 23 insertions(+), 42 deletions(-)
>

[...]

> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 804470fccac7..58213cc4b9b9 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -379,6 +379,20 @@ void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t gfn, u64 pages)
>  	kvm_flush_remote_tlbs(kvm);
>  }
>  
> +void kvm_flush_remote_tlbs_memslot(struct kvm *kvm,
> +				   const struct kvm_memory_slot *memslot)
> +{
> +	/*
> +	 * All current use cases for flushing the TLBs for a specific memslot
> +	 * related to dirty logging, and many do the TLB flush out of mmu_lock.

I appreciate this is a copy paste of an existing comment, but I can't
parse it. My command of the English language is notoriously
approximate, but it feels that something is missing in the first
sentence, such as a verb.

	M.

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