Commit 4be518d8 authored by Alexey Kardashevskiy's avatar Alexey Kardashevskiy Committed by Michael Ellerman
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powerpc/iommu: Do not immediately panic when failed IOMMU table allocation 



Most platforms allocate IOMMU table structures (specifically it_map)
at the boot time and when this fails - it is a valid reason for panic().

However the powernv platform allocates it_map after a device is returned
to the host OS after being passed through and this happens long after
the host OS booted. It is quite possible to trigger the it_map allocation
panic() and kill the host even though it is not necessary - the host OS
can still use the DMA bypass mode (requires a tiny fraction of it_map's
memory) and even if that fails, the host OS is runnnable as it was without
the device for which allocating it_map causes the panic.

Instead of immediately crashing in a powernv/ioda2 system, this prints
an error and continues. All other platforms still call panic().

Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Reviewed-by: default avatarLeonardo Bras <leobras.c@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210216033307.69863-3-aik@ozlabs.ru
parent 7f1fa82d

arch/powerpc/kernel/iommu.c

+4 −2
Original line number Diff line number Diff line
@@ -727,8 +727,10 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid, 
	sz = BITS_TO_LONGS(tbl->it_size) * sizeof(unsigned long);



	tbl->it_map = vzalloc_node(sz, nid);

	if (!tbl->it_map)

		panic("iommu_init_table: Can't allocate %ld bytes\n", sz);

	if (!tbl->it_map) {

		pr_err("%s: Can't allocate %ld bytes\n", __func__, sz);

		return NULL;

	}



	iommu_table_reserve_pages(tbl, res_start, res_end);

arch/powerpc/platforms/cell/iommu.c

+2 −1
Original line number Diff line number Diff line
@@ -486,7 +486,8 @@ cell_iommu_setup_window(struct cbe_iommu *iommu, struct device_node *np, 
	window->table.it_size = size >> window->table.it_page_shift;

	window->table.it_ops = &cell_iommu_ops;



	iommu_init_table(&window->table, iommu->nid, 0, 0);

	if (!iommu_init_table(&window->table, iommu->nid, 0, 0))

		panic("Failed to initialize iommu table");



	pr_debug("\tioid      %d\n", window->ioid);

	pr_debug("\tblocksize %ld\n", window->table.it_blocksize);

arch/powerpc/platforms/pasemi/iommu.c

+3 −1
Original line number Diff line number Diff line
@@ -146,7 +146,9 @@ static void iommu_table_iobmap_setup(void) 
	 */

	iommu_table_iobmap.it_blocksize = 4;

	iommu_table_iobmap.it_ops = &iommu_table_iobmap_ops;

	iommu_init_table(&iommu_table_iobmap, 0, 0, 0);

	if (!iommu_init_table(&iommu_table_iobmap, 0, 0, 0))

		panic("Failed to initialize iommu table");



	pr_debug(" <- %s\n", __func__);

}

arch/powerpc/platforms/powernv/pci-ioda.c

+8 −7
Original line number Diff line number Diff line
@@ -1762,7 +1762,8 @@ static void pnv_pci_ioda1_setup_dma_pe(struct pnv_phb *phb, 
	tbl->it_ops = &pnv_ioda1_iommu_ops;

	pe->table_group.tce32_start = tbl->it_offset << tbl->it_page_shift;

	pe->table_group.tce32_size = tbl->it_size << tbl->it_page_shift;

	iommu_init_table(tbl, phb->hose->node, 0, 0);

	if (!iommu_init_table(tbl, phb->hose->node, 0, 0))

		panic("Failed to initialize iommu table");



	pe->dma_setup_done = true;

	return;
@@ -1930,16 +1931,16 @@ static long pnv_pci_ioda2_setup_default_config(struct pnv_ioda_pe *pe) 
		res_start = pe->phb->ioda.m32_pci_base >> tbl->it_page_shift;

		res_end = min(window_size, SZ_4G) >> tbl->it_page_shift;

	}

	iommu_init_table(tbl, pe->phb->hose->node, res_start, res_end);



	if (iommu_init_table(tbl, pe->phb->hose->node, res_start, res_end))

		rc = pnv_pci_ioda2_set_window(&pe->table_group, 0, tbl);

	else

		rc = -ENOMEM;

	if (rc) {

		pe_err(pe, "Failed to configure 32-bit TCE table, err %ld\n",

				rc);

		pe_err(pe, "Failed to configure 32-bit TCE table, err %ld\n", rc);

		iommu_tce_table_put(tbl);

		return rc;

		tbl = NULL; /* This clears iommu_table_base below */

	}



	if (!pnv_iommu_bypass_disabled)

		pnv_pci_ioda2_set_bypass(pe, true);

arch/powerpc/platforms/pseries/iommu.c

+7 −3
Original line number Diff line number Diff line
@@ -638,7 +638,8 @@ static void pci_dma_bus_setup_pSeries(struct pci_bus *bus) 


	iommu_table_setparms(pci->phb, dn, tbl);

	tbl->it_ops = &iommu_table_pseries_ops;

	iommu_init_table(tbl, pci->phb->node, 0, 0);

	if (!iommu_init_table(tbl, pci->phb->node, 0, 0))

		panic("Failed to initialize iommu table");



	/* Divide the rest (1.75GB) among the children */

	pci->phb->dma_window_size = 0x80000000ul;
@@ -720,7 +721,8 @@ static void pci_dma_bus_setup_pSeriesLP(struct pci_bus *bus) 
		iommu_table_setparms_lpar(ppci->phb, pdn, tbl,

				ppci->table_group, dma_window);

		tbl->it_ops = &iommu_table_lpar_multi_ops;

		iommu_init_table(tbl, ppci->phb->node, 0, 0);

		if (!iommu_init_table(tbl, ppci->phb->node, 0, 0))

			panic("Failed to initialize iommu table");

		iommu_register_group(ppci->table_group,

				pci_domain_nr(bus), 0);

		pr_debug("  created table: %p\n", ppci->table_group);
@@ -749,7 +751,9 @@ static void pci_dma_dev_setup_pSeries(struct pci_dev *dev) 
		tbl = PCI_DN(dn)->table_group->tables[0];

		iommu_table_setparms(phb, dn, tbl);

		tbl->it_ops = &iommu_table_pseries_ops;

		iommu_init_table(tbl, phb->node, 0, 0);

		if (!iommu_init_table(tbl, phb->node, 0, 0))

			panic("Failed to initialize iommu table");



		set_iommu_table_base(&dev->dev, tbl);

		return;

	}