From c2e8dc1222c2136e714d5d972dce7e64924e4ed8 Mon Sep 17 00:00:00 2001 From: Sairaj Kodilkar Date: Fri, 21 Nov 2025 14:41:15 +0530 Subject: [PATCH] amd/iommu: Preserve domain ids inside the kdump kernel Currently AMD IOMMU driver does not reserve domain ids programmed in the DTE while reusing the device table inside kdump kernel. This can cause reallocation of these domain ids for newer domains that are created by the kdump kernel, which can lead to potential IO_PAGE_FAULTs Hence reserve these ids inside pdom_ids. Fixes: 38e5f33ee359 ("iommu/amd: Reuse device table for kdump") Signed-off-by: Sairaj Kodilkar Reported-by: Jason Gunthorpe Reviewed-by: Vasant Hegde Reviewed-by: Jason Gunthorpe Signed-off-by: Joerg Roedel --- drivers/iommu/amd/init.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c index 4b29534189770..106ee3cf30388 100644 --- a/drivers/iommu/amd/init.c +++ b/drivers/iommu/amd/init.c @@ -1136,9 +1136,13 @@ static void set_dte_bit(struct dev_table_entry *dte, u8 bit) static bool __reuse_device_table(struct amd_iommu *iommu) { struct amd_iommu_pci_seg *pci_seg = iommu->pci_seg; - u32 lo, hi, old_devtb_size; + struct dev_table_entry *old_dev_tbl_entry; + u32 lo, hi, old_devtb_size, devid; phys_addr_t old_devtb_phys; + u16 dom_id; + bool dte_v; u64 entry; + int ret; /* Each IOMMU use separate device table with the same size */ lo = readl(iommu->mmio_base + MMIO_DEV_TABLE_OFFSET); @@ -1173,6 +1177,23 @@ static bool __reuse_device_table(struct amd_iommu *iommu) return false; } + for (devid = 0; devid <= pci_seg->last_bdf; devid++) { + old_dev_tbl_entry = &pci_seg->old_dev_tbl_cpy[devid]; + dte_v = FIELD_GET(DTE_FLAG_V, old_dev_tbl_entry->data[0]); + dom_id = FIELD_GET(DEV_DOMID_MASK, old_dev_tbl_entry->data[1]); + + if (!dte_v || !dom_id) + continue; + /* + * ID reservation can fail with -ENOSPC when there + * are multiple devices present in the same domain, + * hence check only for -ENOMEM. + */ + ret = ida_alloc_range(&pdom_ids, dom_id, dom_id, GFP_KERNEL); + if (ret == -ENOMEM) + return false; + } + return true; } -- 2.47.3