From: Christoph Hellwig <hch@lst.de>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Srinath Mannam <srinath.mannam@broadcom.com>,
Sinan Kaya <okaya@codeaurora.org>, Christoph Hellwig <hch@lst.de>,
Bjorn Helgaas <bhelgaas@google.com>,
Abhishek Shah <abhishek.shah@broadcom.com>,
Vikram Prakash <vikram.prakash@broadcom.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-nvme@lists.infradead.org, kvm@vger.kernel.org,
linux-pci-owner@vger.kernel.org
Subject: Re: Requirement to get BAR pci_bus_address in user space
Date: Thu, 14 Jun 2018 16:59:42 +0200 [thread overview]
Message-ID: <20180614145942.GA4885@lst.de> (raw)
In-Reply-To: <20180614085015.3f39b367@w520.home>
On Thu, Jun 14, 2018 at 08:50:15AM -0600, Alex Williamson wrote:
> I don't understand the CQ vs CMB, but I think I gather that there's some
> sort of buffer that's allocated from within the devices MMIO BAR and
> some programming of the device needs to reference that buffer.
> Wouldn't you therefore use the vfio type1 IOMMU MAP_DMA ioctl to map
> the BAR into the IOVA address space and you can then use the IOVA +
> offset into the BAR for the device to reference the buffer? It seems
> this is the same way we'd setup a peer-to-peer mapping, but we're using
> it for the device to reference itself effectively. Thanks,
That's exactly what I meant..
next prev parent reply other threads:[~2018-06-14 14:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-14 10:07 Requirement to get BAR pci_bus_address in user space Srinath Mannam
2018-06-14 10:20 ` Christoph Hellwig
2018-06-14 10:29 ` Srinath Mannam
2018-06-14 10:33 ` okaya
2018-06-14 10:48 ` Srinath Mannam
2018-06-14 14:42 ` Keith Busch
2018-06-14 14:50 ` Alex Williamson
2018-06-14 14:59 ` Christoph Hellwig [this message]
2018-06-14 20:04 ` Walker, Benjamin
2018-06-15 6:11 ` Srinath Mannam
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