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Commit 14b6f00f authored by Nishanth Aravamudan's avatar Nishanth Aravamudan Committed by Benjamin Herrenschmidt
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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
25ebc45b ("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: default avatarNishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent a1dabade

arch/powerpc/platforms/pseries/iommu.c

+50 −38
Original line number Original line Diff line number Diff line
@@ -787,33 +787,68 @@ static u64 find_existing_ddw(struct device_node *pdn) 
	return dma_addr;

	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)

static int find_existing_ddw_windows(void)

{

{

	int len;

	struct device_node *pdn;

	struct device_node *pdn;

	struct direct_window *window;

	const struct dynamic_dma_window_prop *direct64;

	const struct dynamic_dma_window_prop *direct64;

	const u32 *ddw_extensions;





	if (!firmware_has_feature(FW_FEATURE_LPAR))

	if (!firmware_has_feature(FW_FEATURE_LPAR))

		return 0;

		return 0;





	for_each_node_with_property(pdn, DIRECT64_PROPNAME) {

	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)

		if (!direct64)

			continue;

			continue;





		window = kzalloc(sizeof(*window), GFP_KERNEL);

		/*

		if (!window || len < sizeof(struct dynamic_dma_window_prop)) {

		 * We need to ensure the IOMMU table is active when we

			kfree(window);

		 * 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);

		remove_ddw(pdn);

			continue;

		}





		window->device = pdn;

		/*

		window->prop = direct64;

		 * Second, if we are running on a new enough level of

		spin_lock(&direct_window_list_lock);

		 * firmware where the restore API is present, use it to

		list_add(&window->list, &direct_window_list);

		 * restore the 32-bit window, which was removed in

		spin_unlock(&direct_window_list_lock);

		 * 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;

	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,

static void restore_default_window(struct pci_dev *dev,

					u32 ddw_restore_token)

					u32 ddw_restore_token)

{

{

	struct eeh_dev *edev;

	__restore_default_window(pci_dev_to_eeh_dev(dev), 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

	 */

	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);

}

}





/*

/*