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From: Tianyu Lan <ltykernel@gmail.com>
To: Christoph Hellwig <hch@lst.de>
Cc: dave.hansen@linux.intel.com, luto@kernel.org,
	peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com,
	bp@alien8.de, x86@kernel.org, hpa@zytor.com, jgross@suse.com,
	sstabellini@kernel.org, boris.ostrovsky@oracle.com,
	kys@microsoft.com, haiyangz@microsoft.com,
	sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com,
	joro@8bytes.org, will@kernel.org, davem@davemloft.net,
	kuba@kernel.org, jejb@linux.ibm.com, martin.petersen@oracle.com,
	m.szyprowski@samsung.com, robin.murphy@arm.com,
	xen-devel@lists.xenproject.org, michael.h.kelley@microsoft.com,
	Tianyu Lan <Tianyu.Lan@microsoft.com>,
	iommu@lists.linux-foundation.org, linux-hyperv@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
	netdev@vger.kernel.org, vkuznets@redhat.com,
	brijesh.singh@amd.com, konrad.wilk@oracle.com,
	parri.andrea@gmail.com, thomas.lendacky@amd.com,
	dave.hansen@intel.com
Subject: Re: [PATCH 3/5] hyperv/IOMMU: Enable swiotlb bounce buffer for Isolation VM
Date: Fri, 26 Nov 2021 19:39:03 +0800	[thread overview]
Message-ID: <e874b4c3-1d09-8d2a-bd59-80bae7e554d6@gmail.com> (raw)
In-Reply-To: <20211126074022.GA23659@lst.de>

On 11/26/2021 3:40 PM, Christoph Hellwig wrote:
> On Wed, Nov 17, 2021 at 10:00:08PM +0800, Tianyu Lan wrote:
>> On 11/17/2021 6:01 PM, Christoph Hellwig wrote:
>>> This doesn't really have much to do with normal DMA mapping,
>>> so why does this direct through the dma ops?
>>>
>>
>> According to the previous discussion, dma_alloc_noncontigous()
>> and dma_vmap_noncontiguous() may be used to handle the noncontigous
>> memory alloc/map in the netvsc driver. So add alloc/free and vmap/vunmap
>> callbacks here to handle the case. The previous patch v4 & v5 handles
>> the allocation and map in the netvsc driver. If this should not go though
>> dma ops, We also may make it as vmbus specific function and keep
>> the function in the vmbus driver.
> 
> But that only makes sense if they can actually use the normal DMA ops.
> If you implement your own incomplete ops and require to use them you
> do nothing but adding indirect calls to your fast path and making the
> code convoluted.
> 

Because the generic part implementation can't meet the netvsc driver
requests that allocate 16M memory and map pages via vmap_pfn(). So add 
Hyperv alloc_noncontiguous and vmap_noncontiguous callbacks. If this is
not a right way. we should call these hyper-V functions in the netvsc
driver directly, right?

Could you have a look at Michael summary about this series we made and
give some guides?

https://www.mail-archive.com/xen-devel@lists.xenproject.org/msg109284.html

Thanks.






  reply	other threads:[~2021-11-26 12:12 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-16 15:39 [PATCH 0/5] x86/Hyper-V: Add Hyper-V Isolation VM support(Second part) Tianyu Lan
2021-11-16 15:39 ` [PATCH 1/5] x86/Swiotlb: Add Swiotlb bounce buffer remap function for HV IVM Tianyu Lan
2021-11-17  9:59   ` Christoph Hellwig
2021-11-17 13:32     ` Tianyu Lan
2021-11-16 15:39 ` [PATCH 2/5] dma-mapping: Add vmap/vunmap_noncontiguous() callback in dma ops Tianyu Lan
2021-11-16 15:39 ` [PATCH 3/5] hyperv/IOMMU: Enable swiotlb bounce buffer for Isolation VM Tianyu Lan
2021-11-16 19:12   ` Borislav Petkov
2021-11-17 13:22     ` Tianyu Lan
2021-11-17 10:01   ` Christoph Hellwig
2021-11-17 14:00     ` Tianyu Lan
2021-11-19 14:23       ` Tianyu Lan
2021-11-26  7:40       ` Christoph Hellwig
2021-11-26 11:39         ` Tianyu Lan [this message]
2021-11-16 15:39 ` [PATCH 4/5] net: netvsc: Add Isolation VM support for netvsc driver Tianyu Lan
2021-11-16 15:39 ` [PATCH 5/5] scsi: storvsc: Add Isolation VM support for storvsc driver Tianyu Lan

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