Messages in this thread | | | From | "Wu, Feng" <> | Subject | RE: [v4 0/8] Add VT-d Posted-Interrupts support - IOMMU part | Date | Tue, 7 Apr 2015 05:02:55 +0000 |
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> -----Original Message----- > From: Li, ZhenHua [mailto:zhen-hual@hp.com] > Sent: Friday, April 03, 2015 4:13 PM > To: Wu, Feng > Cc: Joerg Roedel; dwmw2@infradead.org; jiang.liu@linux.intel.com; > iommu@lists.linux-foundation.org; linux-kernel@vger.kernel.org; Li, ZhenHua > Subject: Re: [v4 0/8] Add VT-d Posted-Interrupts support - IOMMU part > > Hi Feng Wu, > In my patchset, I created a new member ir_table->base_old_phys; In the > normal kernel, everything is the same. In kdump kernel, ir_table->base > is used for a buffer, and ir_table->base_old_phys is the physical > address of the tables used by the old kernel, also being used by the > current kernel. > > I did this in modify_irte(): > > set_64bit(&irte->high, irte_modified->high); > + > +#ifdef CONFIG_CRASH_DUMP > + if (is_kdump_kernel()) > + __iommu_update_old_irte(iommu, index); > +#endif > __iommu_flush_cache(iommu, irte, sizeof(*irte)); > > > Here the irte tables are stored in two places: > iommu->ir_table->base : It is a buffer in kdump kernel, which is the > running kernel; > iommu->ir_table->base_old_phys : It is the irte used by the old kernel; > > And function __iommu_update_old_irte is used to save the content of > iommu->ir_table->base to iommu->ir_table->base_old_phys. Because in > kdump kernel, the vt-d is using ir_table->base_old_phys, not > ir_table->base, so we need to copy the updated ir_table->base to > ir_table->base_old_phys . >
Hi Zhenhua,
Thanks very much for your clarification! Basically, the main purpose of my Patch-set is to provide an interface to KVM, so that KVM can update irte for posted-interrupts. In this interface, it calls modify_irte(). I also go through your patch set with the associated part, seems I cannot find any conflicts with your patches. What is your idea about this? Thanks a lot!
Thanks, Feng
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> > Thanks > Zhenhua > > On 04/02/2015 07:28 PM, Joerg Roedel wrote: > > On Mon, Feb 02, 2015 at 04:06:56PM +0800, Feng Wu wrote: > >> VT-d Posted-Interrupts is an enhancement to CPU side Posted-Interrupt. > >> With VT-d Posted-Interrupts enabled, external interrupts from > >> direct-assigned devices can be delivered to guests without VMM > >> intervention when guest is running in non-root mode. > >> > >> You can find the VT-d Posted-Interrtups Spec. in the following URL: > >> > http://www.intel.com/content/www/us/en/intelligent-systems/intel-technolog > y/vt-directed-io-spec.html > >> > >> This series was part of > http://thread.gmane.org/gmane.linux.kernel.iommu/7708. To make things > clear, send out IOMMU part here. > > > > Besides the modify_irte() changes I asked for the patch-set looks good. > > I just have some concerns what these changes mean for the VT-d kdump > > improvements Zhen-Hua Li is working on. Can you please discuss the > > implications of having both patch-sets applied with him and make sure > > they work together? I think in its current form your patch-set breaks > > the kdump support patches. I added Zhen-Hua to Cc. > > > > Thanks, > > > > Joerg > >
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