pseries/iommu: Remove DDW on kexec

pseries/iommu: remove DDW on kexec

We currently insert a property in the device-tree when we successfully
configure DDW for a given slot. This was meant to be an optimization to
speed up kexec/kdump, so that we don't need to make the RTAS calls again
to re-configured DDW in the new kernel.

However, we end up tripping a plpar_tce_stuff failure on kexec/kdump
because we unconditionally parse the ibm,dma-window property for the
node at bus/dev setup time. This property contains the 32-bit DMA window
LIOBN, which is distinct from the DDW window's. We pass that LIOBN (via
iommu_table_init -> iommu_table_clear -> tce_free ->
tce_freemulti_pSeriesLP) to plpar_tce_stuff, which fails because that
32-bit window is no longer present after
25ebc45b93452d0bc60271f178237123c4b26808 ("powerpc/pseries/iommu: remove
default window before attempting DDW manipulation").

I believe the simplest, easiest-to-maintain fix is to just change our
initcall to, rather than detecting and updating the new kernel's DDW
knowledge, just remove all DDW configurations. When the drivers
re-initialize, we will set everything back up as it was before.

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

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index a8e99f9..1b2a174 100644 (file)
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -787,33 +787,68 @@ 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, &len);
+               direct64 = of_get_property(pdn, DIRECT64_PROPNAME, NULL);
                if (!direct64)
                        continue;
 
-               window = kzalloc(sizeof(*window), GFP_KERNEL);
-               if (!window || len < sizeof(struct dynamic_dma_window_prop)) {
-                       kfree(window);
-                       remove_ddw(pdn);
-                       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->device = pdn;
-               window->prop = direct64;
-               spin_lock(&direct_window_list_lock);
-               list_add(&window->list, &direct_window_list);
-               spin_unlock(&direct_window_list_lock);
+               /*
+                * 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]);
        }
 
        return 0;
@@ -886,30 +921,7 @@ static int create_ddw(struct pci_dev *dev, const u32 *ddw_avail,
 static void restore_default_window(struct pci_dev *dev,
                                        u32 ddw_restore_token)
 {
-       struct eeh_dev *edev;
-       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
-        */
-       edev = pci_dev_to_eeh_dev(dev);
-       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));
-       dev_info(&dev->dev,
-               "ibm,reset-pe-dma-windows(%x) %x %x %x returned %d\n",
-                ddw_restore_token, cfg_addr, BUID_HI(buid), BUID_LO(buid), ret);
+       __restore_default_window(pci_dev_to_eeh_dev(dev), ddw_restore_token);
 }
 
 /*