From: Christoph Hellwig <hch@lst.de>
To: Ram Pai <linuxram@us.ibm.com>
Cc: andmike@us.ibm.com, mst@redhat.com,
Alexey Kardashevskiy <aik@ozlabs.ru>,
mdroth@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
ram.n.pai@gmail.com, cai@lca.pw, tglx@linutronix.de,
sukadev@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org,
hch@lst.de, bauerman@linux.ibm.com,
David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [PATCH v4 1/2] powerpc/pseries/iommu: Share the per-cpu TCE page with the hypervisor.
Date: Thu, 5 Dec 2019 09:28:37 +0100 [thread overview]
Message-ID: <20191205082837.GA20298@lst.de> (raw)
In-Reply-To: <20191204204232.GE5063@oc0525413822.ibm.com>
On Wed, Dec 04, 2019 at 12:42:32PM -0800, Ram Pai wrote:
> > The other approach we could use for that - which would still allow
> > H_PUT_TCE_INDIRECT, would be to allocate the TCE buffer page from the
> > same pool that we use for the bounce buffers. I assume there must
> > already be some sort of allocator for that?
>
> The allocator for swiotlb is buried deep in the swiotlb code. It is
> not exposed to the outside-swiotlb world. Will have to do major surgery
> to expose it.
I don't think it would require all that much changes, but I'd really
hate the layering of calling into it directly. Do we have a struct
device associated with the iommu that doesn't get iommu translations
themselves? If we do a dma_alloc_coherent on that you'll get the
memory pool for free.
next prev parent reply other threads:[~2019-12-05 8:30 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-02 6:45 [PATCH v4 0/2] Enable IOMMU support for pseries Secure VMs Ram Pai
2019-12-02 6:45 ` [PATCH v4 1/2] powerpc/pseries/iommu: Share the per-cpu TCE page with the hypervisor Ram Pai
2019-12-02 6:45 ` [PATCH v4 2/2] powerpc/pseries/iommu: Use dma_iommu_ops for Secure VMs aswell Ram Pai
2019-12-03 0:58 ` Alexey Kardashevskiy
2019-12-03 4:07 ` Ram Pai
2019-12-03 0:56 ` [PATCH v4 1/2] powerpc/pseries/iommu: Share the per-cpu TCE page with the hypervisor Alexey Kardashevskiy
2019-12-03 2:08 ` Ram Pai
2019-12-03 2:15 ` Alexey Kardashevskiy
2019-12-03 4:05 ` Ram Pai
2019-12-03 4:24 ` Alexey Kardashevskiy
2019-12-03 16:52 ` Ram Pai
2019-12-04 0:04 ` Alexey Kardashevskiy
2019-12-04 0:49 ` Ram Pai
2019-12-04 1:08 ` Alexey Kardashevskiy
2019-12-04 3:36 ` David Gibson
2019-12-04 20:42 ` Ram Pai
2019-12-04 22:26 ` Alexey Kardashevskiy
2019-12-05 2:15 ` [PATCH v4 1/2] powerpc/pseries/iommu: Share the per-cpu TCE page with the hypervisor.y Ram Pai
2019-12-06 23:10 ` [PATCH v4 1/2] powerpc/pseries/iommu: Share the per-cpu TCE page with the hypervisor Ram Pai
2019-12-05 8:28 ` Christoph Hellwig [this message]
2019-12-04 18:26 ` Leonardo Bras
2019-12-04 20:27 ` Ram Pai
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