From: Will Deacon <will.deacon@arm.com>
To: Sinan Kaya <okaya@codeaurora.org>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
Linux PCI <linux-pci@vger.kernel.org>,
linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
Nate Watterson <nwatters@codeaurora.org>,
"shankerd@codeaurora.org" <shankerd@codeaurora.org>,
Vikram Sethi <vikrams@codeaurora.org>,
"Goel, Sameer" <sgoel@codeaurora.org>,
kexec@lists.infradead.org, Joerg Roedel <joro@8bytes.org>,
iommu@lists.linux-foundation.org,
David Woodhouse <dwmw2@infradead.org>
Subject: Re: RFC on Kdump and PCIe on ARM64
Date: Fri, 2 Mar 2018 18:02:20 +0000 [thread overview]
Message-ID: <20180302180219.GB20579@arm.com> (raw)
In-Reply-To: <84121a8d-5294-0567-6c6b-f57e85dc4961@codeaurora.org>
On Fri, Mar 02, 2018 at 09:12:29AM -0500, Sinan Kaya wrote:
> On 3/2/2018 5:30 AM, Will Deacon wrote:
> >> Do you really have to reset the IOMMU? Can you just give it new page
> >> tables that start out with all IOVAs from all devices being invalid,
> >> then add valid mappings as drivers need them (presumably after the
> >> driver has done whatever it needs to so the device stops using the old
> >> DMA addresses)?
> > We already have the option to do that via the command line using the
> > disable_bypass option, so it just sounds like we need to take this into
> > account when resetting the SMMU to take care that GBPA is configured so
> > that transactions are terminated when SMMUEN=0.
>
> How about the points that Baoquan highlighted in his email regarding the
> solution from AMD and X86?
Which specific points do you think this proposal doesn't address?
> I have not read the entire thread but, is this just a matter of following
> what Bjorn recommended or there is more to it?
I'm trying to say how I think Bjorn's idea can be implemented for SMMUv3.
I basically want to avoid a situation where the SMMU driver tries to walk
the in-memory data structures left by a previous kernel and infer the
setup from that.
Will
next prev parent reply other threads:[~2018-03-02 18:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-01 17:44 RFC on Kdump and PCIe on ARM64 Sinan Kaya
2018-03-01 19:05 ` Bjorn Helgaas
2018-03-01 19:19 ` Sinan Kaya
2018-03-02 0:03 ` Bjorn Helgaas
2018-03-02 10:30 ` Will Deacon
2018-03-02 14:12 ` Sinan Kaya
2018-03-02 18:02 ` Will Deacon [this message]
2018-03-02 18:37 ` Sinan Kaya
2018-03-02 14:20 ` Sinan Kaya
2018-03-02 1:44 ` Baoquan He
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