From: Christoph Hellwig <hch@xxxxxxxxxxxxx> Sent: Wednesday, February 24, 2021 7:53 AM > > Shouldn't storvsc just use blk_queue_virt_boundary instead of all this > mess? The storvsc driver does set the virt boundary to PAGE_SIZE - 1. But the driver still has to translate the scatterlist into a list of guest physical frame numbers (each representing 4K bytes) that the Hyper-V host understands so it can do the I/O. This patch improves that translation so it can handle a single scatterlist entry that represents more than PAGE_SIZE bytes of data. Then the SCSI dma_boundary (which turns into the blk level segment_boundary) no longer needs to be set to restrict scatterlist entries to just PAGE_SIZE bytes. We also have to preserve the ability to run guests on ARM64 with PAGE_SIZE of 16K or 64K, while Hyper-V still expects each PFN to represent only 4K bytes. Michael
