Re: [Resend RFC PATCH V2 11/12] HV/Netvsc: Add Isolation VM support for netvsc driver

From: Christoph Hellwig <hch@lst.de>
To: Tianyu Lan <ltykernel@gmail.com>
Cc: kys@microsoft.com, haiyangz@microsoft.com,
	sthemmin@microsoft.com, wei.liu@kernel.org, tglx@linutronix.de,
	mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com,
	arnd@arndb.de, akpm@linux-foundation.org,
	gregkh@linuxfoundation.org, konrad.wilk@oracle.com, hch@lst.de,
	m.szyprowski@samsung.com, robin.murphy@arm.com, joro@8bytes.org,
	will@kernel.org, davem@davemloft.net, kuba@kernel.org,
	jejb@linux.ibm.com, martin.petersen@oracle.com,
	Tianyu Lan <Tianyu.Lan@microsoft.com>,
	iommu@lists.linux-foundation.org, linux-arch@vger.kernel.org,
	linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, linux-scsi@vger.kernel.org,
	netdev@vger.kernel.org, vkuznets@redhat.com,
	thomas.lendacky@amd.com, brijesh.singh@amd.com,
	sunilmut@microsoft.com
Subject: Re: [Resend RFC PATCH V2 11/12] HV/Netvsc: Add Isolation VM support for netvsc driver
Date: Wed, 14 Apr 2021 17:50:16 +0200	[thread overview]
Message-ID: <20210414155016.GE32045@lst.de> (raw)
In-Reply-To: <20210414144945.3460554-12-ltykernel@gmail.com>

> +struct dma_range {
> +	dma_addr_t dma;
> +	u32 mapping_size;
> +};

That's a rather generic name that is bound to create a conflict sooner
or later.

>  #include "hyperv_net.h"
>  #include "netvsc_trace.h"
> +#include "../../hv/hyperv_vmbus.h"

Please move public interfaces out of the private header rather than doing
this.

> +	if (hv_isolation_type_snp()) {
> +		area = get_vm_area(buf_size, VM_IOREMAP);

Err, no.  get_vm_area is private a for a reason.

> +		if (!area)
> +			goto cleanup;
> +
> +		vaddr = (unsigned long)area->addr;
> +		for (i = 0; i < buf_size / HV_HYP_PAGE_SIZE; i++) {
> +			extra_phys = (virt_to_hvpfn(net_device->recv_buf + i * HV_HYP_PAGE_SIZE)
> +				<< HV_HYP_PAGE_SHIFT) + ms_hyperv.shared_gpa_boundary;
> +			ret |= ioremap_page_range(vaddr + i * HV_HYP_PAGE_SIZE,
> +					   vaddr + (i + 1) * HV_HYP_PAGE_SIZE,
> +					   extra_phys, PAGE_KERNEL_IO);
> +		}
> +
> +		if (ret)
> +			goto cleanup;

And this is not something a driver should ever do.  I think you are badly
reimplementing functionality that should be in the dma coherent allocator
here.