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From: Peter Xu <peterx@redhat.com>
To: Marc Zyngier <maz@kernel.org>
Cc: kvm@vger.kernel.org, catalin.marinas@arm.com,
	andrew.jones@linux.dev, will@kernel.org, shan.gavin@gmail.com,
	bgardon@google.com, dmatlack@google.com, pbonzini@redhat.com,
	zhenyzha@redhat.com, shuah@kernel.org,
	kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH 3/6] KVM: x86: Select CONFIG_HAVE_KVM_DIRTY_RING_ORDERED
Date: Fri, 23 Sep 2022 18:46:40 -0400	[thread overview]
Message-ID: <Yy43UM/+qTxc+/qt@x1n> (raw)
In-Reply-To: <20220922170133.2617189-4-maz@kernel.org>

On Thu, Sep 22, 2022 at 06:01:30PM +0100, Marc Zyngier wrote:
> Since x86 is TSO (give or take), allow it to advertise the new
> ORDERED version of the dirty ring capability. No other change is
> required for it.
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  arch/x86/kvm/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
> index e3cbd7706136..eb63bc31ed1d 100644
> --- a/arch/x86/kvm/Kconfig
> +++ b/arch/x86/kvm/Kconfig
> @@ -29,6 +29,7 @@ config KVM
>  	select HAVE_KVM_PFNCACHE
>  	select HAVE_KVM_IRQFD
>  	select HAVE_KVM_DIRTY_RING
> +	select HAVE_KVM_DIRTY_RING_ORDERED
>  	select IRQ_BYPASS_MANAGER
>  	select HAVE_KVM_IRQ_BYPASS
>  	select HAVE_KVM_IRQ_ROUTING

Before patch 2-3, we only have HAVE_KVM_DIRTY_RING.

After that, we'll have:

HAVE_KVM_DIRTY_LOG
HAVE_KVM_DIRTY_RING
HAVE_KVM_DIRTY_RING_ORDERED

I'm wondering whether we can just keep using the old HAVE_KVM_DIRTY_RING,
but just declare a new KVM_CAP_DIRTY_LOG_RING_ORDERED only after all memory
barrier patches merged (after patch 1).

IIUC it's a matter of whether any of the arch would like to support
!ORDERED version of dirty ring at all, but then IIUC we'll need to have the
memory barriers conditional too or not sure how it'll help.

Thanks,

-- 
Peter Xu

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  reply	other threads:[~2022-09-23 22:46 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-22 17:01 [PATCH 0/6] KVM: Fix dirty-ring ordering on weakly ordered architectures Marc Zyngier
2022-09-22 17:01 ` [PATCH 1/6] KVM: Use acquire/release semantics when accessing dirty ring GFN state Marc Zyngier
2022-09-22 21:38   ` Peter Xu
2022-09-22 23:46     ` Gavin Shan
2022-09-23 14:40       ` Marc Zyngier
2022-09-23 14:19     ` Marc Zyngier
2022-09-23 14:22       ` Paolo Bonzini
2022-09-22 17:01 ` [PATCH 2/6] KVM: Add KVM_CAP_DIRTY_LOG_RING_ORDERED capability and config option Marc Zyngier
2022-09-22 21:48   ` Peter Xu
2022-09-23  0:04     ` Gavin Shan
2022-09-23 14:28     ` Marc Zyngier
2022-09-23 18:26       ` Peter Xu
2022-09-23 21:23         ` Paolo Bonzini
2022-09-23 22:34           ` Peter Xu
2022-09-24  8:51         ` Marc Zyngier
2022-09-24 11:26           ` Marc Zyngier
2022-09-24 13:22             ` Peter Xu
2022-09-24 18:57               ` Marc Zyngier
2022-09-25 23:17                 ` Gavin Shan
2022-09-22 17:01 ` [PATCH 3/6] KVM: x86: Select CONFIG_HAVE_KVM_DIRTY_RING_ORDERED Marc Zyngier
2022-09-23 22:46   ` Peter Xu [this message]
2022-09-24  8:47     ` Marc Zyngier
2022-09-24 13:29       ` Peter Xu
2022-09-22 17:01 ` [PATCH 4/6] KVM: Document weakly ordered architecture requirements for dirty ring Marc Zyngier
2022-09-22 17:01 ` [PATCH 5/6] KVM: selftests: dirty-log: Upgrade dirty_gfn_set_collected() to store-release Marc Zyngier
2022-09-22 21:38   ` Paolo Bonzini
2022-09-23 14:49     ` Marc Zyngier
2022-09-22 17:01 ` [PATCH 6/6] KVM: selftests: dirty-log: Use KVM_CAP_DIRTY_LOG_RING_ORDERED of available Marc Zyngier

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