iommu/amd: Remove amd_iommu_domain_update() from page table freeing

BugLink: https://bugs.launchpad.net/bugs/2101915

[ Upstream commit 322d889ae7d39f8538a6deac35869aa3be1855bd ]

It is a serious bug if the domain is still mapped to any DTEs when it is
freed as we immediately start freeing page table memory, so any remaining
HW touch will UAF.

If it is not mapped then dev_list is empty and amd_iommu_domain_update()
does nothing.

Remove it and add a WARN_ON() to catch this class of bug.

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4-v2-831cdc4d00f3+1a315-amd_iopgtbl_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Stable-dep-of: 016991606aa0 ("iommu/amd/pgtbl_v2: Take protection domain lock before invalidating TLB")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/iommu/amd/io_pgtable.c

@@ -577,9 +577,6 @@ static void v1_free_pgtable(struct io_pgtable *iop)
 
 	/* Update data structure */
 	amd_iommu_domain_clr_pt_root(dom);
-
-	/* Make changes visible to IOMMUs */
-	amd_iommu_domain_update(dom);
 }
 
 static struct io_pgtable *v1_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)

drivers/iommu/amd/iommu.c

@@ -2065,6 +2065,8 @@ static void protection_domain_free(struct protection_domain *domain)
 	if (!domain)
 		return;
 
+	WARN_ON(!list_empty(&domain->dev_list));
+
 	if (domain->iop.pgtbl_cfg.tlb)
 		free_io_pgtable_ops(&domain->iop.iop.ops);