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From: Marc Zyngier <maz@kernel.org>
To: Peter Xu <peterx@redhat.com>
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 v4 3/6] KVM: arm64: Enable ring-based dirty memory tracking
Date: Fri, 30 Sep 2022 10:28:34 +0100	[thread overview]
Message-ID: <86a66h6wjh.wl-maz@kernel.org> (raw)
In-Reply-To: <YzWsY3WtmP5fS9TJ@x1n>

On Thu, 29 Sep 2022 15:32:03 +0100,
Peter Xu <peterx@redhat.com> wrote:
> 
> > If I'm correct, Marc may be talking about SMMU, which is emulated in host
> > instead of QEMU. In this case, the DMA target pages are similar to those
> > pages for vgic/its tables. Both sets of pages are invisible from QEMU.
> 
> OK, I'm not aware the SMMU can also be emulated in the host kernel, thanks
> Gavin.  If so then we really need to think as I mentioned above since we
> will only sync this when switchover, and if the DMA range can cover a large
> portion of guest mem (assuming the physical pages to DMA can be randomly
> allocated by guest device drivers) then it may be another problem to cause
> drastic downtime.

I don't know where this is coming from. The kernel has no SMMU
emulation at all.

	  M.

-- 
Without deviation from the norm, progress is not possible.
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WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Peter Xu <peterx@redhat.com>
Cc: Gavin Shan <gshan@redhat.com>,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	catalin.marinas@arm.com, bgardon@google.com, shuah@kernel.org,
	andrew.jones@linux.dev, will@kernel.org, dmatlack@google.com,
	pbonzini@redhat.com, zhenyzha@redhat.com, shan.gavin@gmail.com,
	james.morse@arm.com, suzuki.poulose@arm.com,
	alexandru.elisei@arm.com, oliver.upton@linux.dev
Subject: Re: [PATCH v4 3/6] KVM: arm64: Enable ring-based dirty memory tracking
Date: Fri, 30 Sep 2022 10:28:34 +0100	[thread overview]
Message-ID: <86a66h6wjh.wl-maz@kernel.org> (raw)
In-Reply-To: <YzWsY3WtmP5fS9TJ@x1n>

On Thu, 29 Sep 2022 15:32:03 +0100,
Peter Xu <peterx@redhat.com> wrote:
> 
> > If I'm correct, Marc may be talking about SMMU, which is emulated in host
> > instead of QEMU. In this case, the DMA target pages are similar to those
> > pages for vgic/its tables. Both sets of pages are invisible from QEMU.
> 
> OK, I'm not aware the SMMU can also be emulated in the host kernel, thanks
> Gavin.  If so then we really need to think as I mentioned above since we
> will only sync this when switchover, and if the DMA range can cover a large
> portion of guest mem (assuming the physical pages to DMA can be randomly
> allocated by guest device drivers) then it may be another problem to cause
> drastic downtime.

I don't know where this is coming from. The kernel has no SMMU
emulation at all.

	  M.

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

  reply	other threads:[~2022-09-30  9:28 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-27  0:54 [PATCH v4 0/6] KVM: arm64: Enable ring-based dirty memory tracking Gavin Shan
2022-09-27  0:54 ` Gavin Shan
2022-09-27  0:54 ` [PATCH v4 1/6] KVM: x86: Introduce KVM_REQ_RING_SOFT_FULL Gavin Shan
2022-09-27  0:54   ` Gavin Shan
2022-09-27 10:26   ` Marc Zyngier
2022-09-27 10:26     ` Marc Zyngier
2022-09-27 11:31     ` Gavin Shan
2022-09-27 11:31       ` Gavin Shan
2022-09-27 16:00     ` Peter Xu
2022-09-27 16:00       ` Peter Xu
2022-09-27  0:54 ` [PATCH v4 2/6] KVM: x86: Move declaration of kvm_cpu_dirty_log_size() to kvm_dirty_ring.h Gavin Shan
2022-09-27  0:54   ` Gavin Shan
2022-09-27 16:00   ` Peter Xu
2022-09-27 16:00     ` Peter Xu
2022-09-27  0:54 ` [PATCH v4 3/6] KVM: arm64: Enable ring-based dirty memory tracking Gavin Shan
2022-09-27  0:54   ` Gavin Shan
2022-09-27 16:02   ` Peter Xu
2022-09-27 16:02     ` Peter Xu
2022-09-27 17:32     ` Marc Zyngier
2022-09-27 17:32       ` Marc Zyngier
2022-09-27 18:21       ` Peter Xu
2022-09-27 18:21         ` Peter Xu
2022-09-27 23:47         ` Gavin Shan
2022-09-27 23:47           ` Gavin Shan
2022-09-28  8:25           ` Marc Zyngier
2022-09-28  8:25             ` Marc Zyngier
2022-09-28 14:52             ` Peter Xu
2022-09-28 14:52               ` Peter Xu
2022-09-29  9:50               ` Gavin Shan
2022-09-29  9:50                 ` Gavin Shan
2022-09-29 11:31                 ` Gavin Shan
2022-09-29 11:31                   ` Gavin Shan
2022-09-29 14:44                   ` Marc Zyngier
2022-09-29 14:44                     ` Marc Zyngier
2022-09-29 14:32                 ` Peter Xu
2022-09-29 14:32                   ` Peter Xu
2022-09-30  9:28                   ` Marc Zyngier [this message]
2022-09-30  9:28                     ` Marc Zyngier
2022-09-29 14:42                 ` Marc Zyngier
2022-09-29 14:42                   ` Marc Zyngier
2022-10-04  4:26                   ` Gavin Shan
2022-10-04  4:26                     ` Gavin Shan
2022-10-04 13:26                     ` Peter Xu
2022-10-04 13:26                       ` Peter Xu
2022-10-04 15:45                     ` Marc Zyngier
2022-10-04 15:45                       ` Marc Zyngier
2022-09-29 14:34               ` Marc Zyngier
2022-09-29 14:34                 ` Marc Zyngier
2022-09-27  0:54 ` [PATCH v4 4/6] KVM: selftests: Use host page size to map ring buffer in dirty_log_test Gavin Shan
2022-09-27  0:54   ` Gavin Shan
2022-09-27  0:54 ` [PATCH v4 5/6] KVM: selftests: Clear dirty ring states between two modes " Gavin Shan
2022-09-27  0:54   ` Gavin Shan
2022-09-27  0:54 ` [PATCH v4 6/6] KVM: selftests: Automate choosing dirty ring size " Gavin Shan
2022-09-27  0:54   ` Gavin Shan
2022-09-27 10:30 ` [PATCH v4 0/6] KVM: arm64: Enable ring-based dirty memory tracking Marc Zyngier
2022-09-27 10:30   ` Marc Zyngier

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