[RFC PATCH v7 06/14] vtd: Remove MAP_ERROR_RECOVERY code path in domain_context_mapping_one

["Teddy Astie" <teddy.astie@xxxxxxxxxx>]

This logic is basically never called as the only possible failures are
- no memory to allocate the pagetable (if it isn't already allocated)
  this is fixed in this patch serie by ensuring that the pagetable is allocated
  when entering this function
- EILSEQ when there is a race condtion with hardware, which should not happen 
under
  normal circonstances

Remove this logic to simplify the error management of the function.

Signed-off-by: Teddy Astie <teddy.astie@xxxxxxxxxx>
---
This is fairly similar to [1], although we don't check for -EILSEQ.
Such failures can happen through me_wifi_quirk which can recursively
calls domain_context_mapping_one.

[1] 
https://lore.kernel.org/xen-devel/b0e81bd67c3f135a4102d12ed95a52ce56482992.1762961527.git.teddy.astie@xxxxxxxxxx/
---
 xen/drivers/passthrough/vtd/iommu.c | 20 --------------------
 xen/drivers/passthrough/vtd/vtd.h   |  3 +--
 2 files changed, 1 insertion(+), 22 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index f269fca9bf..986b05b9dd 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1627,26 +1627,6 @@ int domain_context_mapping_one(
     if ( !seg && !rc )
         rc = me_wifi_quirk(domain, bus, devfn, domid, pgd_maddr, mode);
 
-    if ( rc && !(mode & MAP_ERROR_RECOVERY) )
-    {
-        if ( !prev_dom ||
-             /*
-              * Unmapping here means DEV_TYPE_PCI devices with RMRRs (if such
-              * exist) would cause problems if such a region was actually
-              * accessed.
-              */
-             (prev_dom == dom_io && !pdev) )
-            ret = domain_context_unmap_one(domain, iommu, bus, devfn);
-        else
-            ret = domain_context_mapping_one(prev_dom, ctx, iommu, bus, devfn, 
pdev,
-                                             prev_dom->domain_id,
-                                             
iommu_default_context(prev_dom)->arch.vtd.pgd_maddr,
-                                             (mode & MAP_WITH_RMRR) |
-                                             MAP_ERROR_RECOVERY) < 0;
-
-        if ( !ret && pdev && pdev->devfn == devfn )
-            check_cleanup_domid_map(domain, pdev, iommu);
-    }
 
     if ( prev_dom )
         rcu_unlock_domain(prev_dom);
diff --git a/xen/drivers/passthrough/vtd/vtd.h 
b/xen/drivers/passthrough/vtd/vtd.h
index f0286b40c3..0178214929 100644
--- a/xen/drivers/passthrough/vtd/vtd.h
+++ b/xen/drivers/passthrough/vtd/vtd.h
@@ -28,8 +28,7 @@
  */
 #define MAP_WITH_RMRR         (1u << 0)
 #define MAP_OWNER_DYING       (1u << 1)
-#define MAP_ERROR_RECOVERY    (1u << 2)
-#define UNMAP_ME_PHANTOM_FUNC (1u << 3)
+#define UNMAP_ME_PHANTOM_FUNC (1u << 2)
 
 struct IO_APIC_route_remap_entry {
     union {
-- 
2.51.2



--
Teddy Astie | Vates XCP-ng Developer

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