[PATCH] iommu/vt-d: Remove real DMA lookup in find_domain

[PATCH] iommu/vt-d: Remove real DMA lookup in find_domain

[Sushma Kalakota]

From: Jon Derrick <jonathan.derrick@intel.com>

commit 	bba9cc2cf82840bd3c9b3f4f7edac2dc8329ci241 upstream

By removing the real DMA indirection in find_domain(), we can allow
sub-devices of a real DMA device to have their own valid
device_domain_info. The dmar lookup and context entry removal paths have
been fixed to account for sub-devices.

Fixes: 2b0140c69637 ("iommu/vt-d: Use pci_real_dma_dev() for mapping")
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20200527165617.297470-4-jonathan.derrick@intel.com
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=207575
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sushma Kalakota <sushmax.kalakota@intel.com>
---
Hi,

Please apply this patch to 5.7 (and 5.6 if it's still being maintained).
This patch is part 3 of a 3-patch series, of which [1][2] have been
applied to 5.7. This patch is necessary to prevent kernel panics in
specific configurations.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8038bdb8553313ad53bfcffcf8294dd0ab44618f
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4fda230ecddc2573ed88632e98b69b0b9b68c0ad

 drivers/iommu/intel-iommu.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 11ed871dd255..fde7aba49b74 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2518,9 +2518,6 @@ struct dmar_domain *find_domain(struct device *dev)
 	if (unlikely(attach_deferred(dev) || iommu_dummy(dev)))
 		return NULL;
 
-	if (dev_is_pci(dev))
-		dev = &pci_real_dma_dev(to_pci_dev(dev))->dev;
-
 	/* No lock here, assumes no domain exit in normal case */
 	info = dev->archdata.iommu;
 	if (likely(info))
-- 
2.17.1

Re: [PATCH] iommu/vt-d: Remove real DMA lookup in find_domain

[Greg KH]

On Tue, Jun 23, 2020 at 01:27:33PM -0600, Sushma Kalakota wrote:
> From: Jon Derrick <jonathan.derrick@intel.com>
> 
> commit 	bba9cc2cf82840bd3c9b3f4f7edac2dc8329ci241 upstream

That commit id is not in Linus's tree :(