Re: [PATCH v9 05/13] iommu/amd: Add function copy_dev_tables()

Joerg Roedel
2017-08-04T12:09:13Z

Hi Baoquan,

On Tue, Aug 01, 2017 at 07:37:21PM +0800, Baoquan He wrote:
> + for_each_iommu(iommu) {
> + /* All IOMMUs should use the same device table with the same size */
> + lo = readl(iommu->mmio_base + MMIO_DEV_TABLE_OFFSET);
> + hi = readl(iommu->mmio_base + MMIO_DEV_TABLE_OFFSET + 4);
> + entry = (((u64) hi) << 32) + lo;
> + if (last_entry && last_entry != entry) {
> + pr_err("IOMMU:%d should use the same dev table as others!/n",
> + iommu->index);
> + return -1;
> + }
> + last_entry = entry;
> +
> + old_devtb_size = ((entry & ~PAGE_MASK) + 1) << 12;
> + if (old_devtb_size != dev_table_size) {
> + pr_err("The device table size of IOMMU:%d is not expected!/n",
> + iommu->index);
> + return -1;
> + }
> +
> + if (copied)
> + continue;
> +
> + old_devtb_phys = entry & PAGE_MASK;
> + old_devtb = memremap(old_devtb_phys, dev_table_size, MEMREMAP_WB);
> + if (!old_devtb)
> + return -1;

You forgot to check whether the old device table is also below 4GB.

> +
> + gfp_flag = GFP_KERNEL | __GFP_ZERO;
> + old_dev_tbl_cpy = (void *)__get_free_pages(gfp_flag,
> + get_order(dev_table_size));
> + if (old_dev_tbl_cpy == NULL) {
> + pr_err("Failed to allocate memory for copying old device table!/n");
> + return -1;
> + }
> +
> + for (devid = 0; devid <= amd_iommu_last_bdf; ++devid) {
> + old_dev_tbl_cpy[devid] = old_devtb[devid];
> + dom_id = old_devtb[devid].data[1] & DEV_DOMID_MASK;
> + dte_v = old_devtb[devid].data[0] & DTE_FLAG_V;
> + if (dte_v && dom_id)
> + __set_bit(dom_id, amd_iommu_pd_alloc_bitmap);
> + }
> + memunmap(old_devtb);
> + copied = 1;

And this one should be outside of the loop, then you can get rid of the
'copied' variable. Also I don't really understand why you need a
temporary copy of the old device-table. Can't you just smart-copy the
contents of the old table to the real new one?

Regards,

Joerg