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Re: [Qemu-devel] [PATCH for-2.10 0/5] x86/vIOMMU: move init back to mach
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH for-2.10 0/5] x86/vIOMMU: move init back to machine init phase |
Date: |
Fri, 31 Mar 2017 19:17:34 +0300 |
On Fri, Mar 31, 2017 at 03:36:28PM +0800, Peter Xu wrote:
> At the very beginning, the x86 vIOMMUs are created via "-M iommu=on".
> We moved one step further a year ago to have the vIOMMUs just like a
> general device, so that we can init them with far more specific
> parameters with "-device" interface.
>
> However, gradually we found that problem starts to occur due to this.
> The main issue is that the DMA address space of any PCI device is
> postponed to be init after device realization, while some devices'
> realizations would depend on this address space. That looks like a
> dead lock. We have patches and solutions for different single problem,
> but, maybe it's time we can consider to solve the root cause this
> time, of course after 2.9 release.
>
> This series tries to solve the root cause, and move vIOMMU inits back
> to machine init for x86 platforms. Then, we'll have solid DMA address
> space for each device even during realization.
>
> Please kindly review. Thanks.
I think it's a clean way to do it at a high level.
However I would like to set a tag in the class
rather than listing specific devices.
Also, init order should be consistent for all machines
not just q35.
> Peter Xu (5):
> QemuOpts: introduce qemu_opts_extract()
> util: export device_init_func()
> util: propagate error for device_func_init()
> q35: init vIOMMU during machine init
> pci: move dma_as init back to bus realize
>
> hw/pci-host/q35.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
> hw/pci/pci.c | 21 +--------------------
> include/hw/pci/pci_bus.h | 2 --
> include/qemu-common.h | 1 +
> include/qemu/option.h | 2 ++
> include/sysemu/sysemu.h | 1 -
> util/qemu-option.c | 24 ++++++++++++++++++++++++
> vl.c | 9 ++-------
> 8 files changed, 75 insertions(+), 30 deletions(-)
>
> --
> 2.7.4
- [Qemu-devel] [PATCH for-2.10 0/5] x86/vIOMMU: move init back to machine init phase, Peter Xu, 2017/03/31
- [Qemu-devel] [PATCH for-2.10 1/5] QemuOpts: introduce qemu_opts_extract(), Peter Xu, 2017/03/31
- [Qemu-devel] [PATCH for-2.10 2/5] util: export device_init_func(), Peter Xu, 2017/03/31
- [Qemu-devel] [PATCH for-2.10 3/5] util: propagate error for device_func_init(), Peter Xu, 2017/03/31
- [Qemu-devel] [PATCH for-2.10 4/5] q35: init vIOMMU during machine init, Peter Xu, 2017/03/31
- [Qemu-devel] [PATCH for-2.10 5/5] pci: move dma_as init back to bus realize, Peter Xu, 2017/03/31
- Re: [Qemu-devel] [PATCH for-2.10 0/5] x86/vIOMMU: move init back to machine init phase,
Michael S. Tsirkin <=