Revert "pseries/iommu: Remove DDW on kexec"

After reverting 25ebc45b93452d0bc60271f178237123c4b26808
("powerpc/pseries/iommu: remove default window before attempting DDW
manipulation"), we no longer remove the base window in enable_ddw.
Therefore, we no longer need to reset the DMA window state in
find_existing_ddw_windows(). We can instead go back to what was done
before, which simply reuses the previous configuration, if any. Further,
this removes the final caller of the reset-pe-dma-windows call, so
remove those functions.

This fixes an EEH on kdump with the ipr driver. The EEH occurs, because
the initcall removes the DDW configuration (64-bit DMA window), but
doesn't ensure the ops are via the IOMMU -- a DMA operation occurs
during probe (still investigating this) and we EEH.

This reverts commit 14b6f00f8a4fdec5ccd45a0710284de301a61628.

Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 14 insertions, 49 deletions

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index bb2e16c5ae27..33b552ffbe57 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -787,68 +787,33 @@ static u64 find_existing_ddw(struct device_node *pdn)
         return dma_addr;
 }
 
-static void __restore_default_window(struct eeh_dev *edev,
-                                                u32 ddw_restore_token)
-{
-        u32 cfg_addr;
-        u64 buid;
-        int ret;
-
-        /*
-         * Get the config address and phb buid of the PE window.
-         * Rely on eeh to retrieve this for us.
-         * Retrieve them from the pci device, not the node with the
-         * dma-window property
-         */
-        cfg_addr = edev->config_addr;
-        if (edev->pe_config_addr)
-                cfg_addr = edev->pe_config_addr;
-        buid = edev->phb->buid;
-
-        do {
-                ret = rtas_call(ddw_restore_token, 3, 1, NULL, cfg_addr,
-                                        BUID_HI(buid), BUID_LO(buid));
-        } while (rtas_busy_delay(ret));
-        pr_info("ibm,reset-pe-dma-windows(%x) %x %x %x returned %d\n",
-                 ddw_restore_token, cfg_addr, BUID_HI(buid), BUID_LO(buid), ret);
-}
-
 static int find_existing_ddw_windows(void)
 {
+        int len;
         struct device_node *pdn;
+        struct direct_window *window;
         const struct dynamic_dma_window_prop *direct64;
-        const u32 *ddw_extensions;
 
         if (!firmware_has_feature(FW_FEATURE_LPAR))
                 return 0;
 
         for_each_node_with_property(pdn, DIRECT64_PROPNAME) {
-                direct64 = of_get_property(pdn, DIRECT64_PROPNAME, NULL);
+                direct64 = of_get_property(pdn, DIRECT64_PROPNAME, &len);
                 if (!direct64)
                         continue;
 
-                /*
-                 * We need to ensure the IOMMU table is active when we
-                 * return from the IOMMU setup so that the common code
-                 * can clear the table or find the holes. To that end,
-                 * first, remove any existing DDW configuration.
-                 */
-                remove_ddw(pdn);
+                window = kzalloc(sizeof(*window), GFP_KERNEL);
+                if (!window || len < sizeof(struct dynamic_dma_window_prop)) {
+                        kfree(window);
+                        remove_ddw(pdn);
+                        continue;
+                }
 
-                /*
-                 * Second, if we are running on a new enough level of
-                 * firmware where the restore API is present, use it to
-                 * restore the 32-bit window, which was removed in
-                 * create_ddw.
-                 * If the API is not present, then create_ddw couldn't
-                 * have removed the 32-bit window in the first place, so
-                 * removing the DDW configuration should be sufficient.
-                 */
-                ddw_extensions = of_get_property(pdn, "ibm,ddw-extensions",
-                                                                        NULL);
-                if (ddw_extensions && ddw_extensions[0] > 0)
-                        __restore_default_window(of_node_to_eeh_dev(pdn),
-                                                        ddw_extensions[1]);
+                window->device = pdn;
+                window->prop = direct64;
+                spin_lock(&direct_window_list_lock);
+                list_add(&window->list, &direct_window_list);
+                spin_unlock(&direct_window_list_lock);
         }
 
         return 0;