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Commit f87a8864 authored by Alexey Kardashevskiy's avatar Alexey Kardashevskiy Committed by Michael Ellerman
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vfio: powerpc/spapr/iommu/powernv/ioda2: Rework IOMMU ownership control 



This adds tce_iommu_take_ownership() and tce_iommu_release_ownership
which call in a loop iommu_take_ownership()/iommu_release_ownership()
for every table on the group. As there is just one now, no change in
behaviour is expected.

At the moment the iommu_table struct has a set_bypass() which enables/
disables DMA bypass on IODA2 PHB. This is exposed to POWERPC IOMMU code
which calls this callback when external IOMMU users such as VFIO are
about to get over a PHB.

The set_bypass() callback is not really an iommu_table function but
IOMMU/PE function. This introduces a iommu_table_group_ops struct and
adds take_ownership()/release_ownership() callbacks to it which are
called when an external user takes/releases control over the IOMMU.

This replaces set_bypass() with ownership callbacks as it is not
necessarily just bypass enabling, it can be something else/more
so let's give it more generic name.

The callbacks is implemented for IODA2 only. Other platforms (P5IOC2,
IODA1) will use the old iommu_take_ownership/iommu_release_ownership API.
The following patches will replace iommu_take_ownership/
iommu_release_ownership calls in IODA2 with full IOMMU table release/
create.

As we here and touching bypass control, this removes
pnv_pci_ioda2_setup_bypass_pe() as it does not do much
more compared to pnv_pci_ioda2_set_bypass. This moves tce_bypass_base
initialization to pnv_pci_ioda2_setup_dma_pe.

Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
[aw: for the vfio related changes]
Acked-by: default avatarAlex Williamson <alex.williamson@redhat.com>
Reviewed-by: default avatarGavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 0eaf4def

arch/powerpc/include/asm/iommu.h

+10 −1
Original line number Diff line number Diff line
@@ -93,7 +93,6 @@ struct iommu_table { 
	unsigned long  it_page_shift;/* table iommu page size */

	struct list_head it_group_list;/* List of iommu_table_group_link */

	struct iommu_table_ops *it_ops;

	void (*set_bypass)(struct iommu_table *tbl, bool enable);

};



/* Pure 2^n version of get_order */
@@ -126,6 +125,15 @@ extern struct iommu_table *iommu_init_table(struct iommu_table * tbl, 
					    int nid);

#define IOMMU_TABLE_GROUP_MAX_TABLES	1



struct iommu_table_group;



struct iommu_table_group_ops {

	/* Switch ownership from platform code to external user (e.g. VFIO) */

	void (*take_ownership)(struct iommu_table_group *table_group);

	/* Switch ownership from external user (e.g. VFIO) back to core */

	void (*release_ownership)(struct iommu_table_group *table_group);

};



struct iommu_table_group_link {

	struct list_head next;

	struct rcu_head rcu;
@@ -135,6 +143,7 @@ struct iommu_table_group_link { 
struct iommu_table_group {

	struct iommu_group *group;

	struct iommu_table *tables[IOMMU_TABLE_GROUP_MAX_TABLES];

	struct iommu_table_group_ops *ops;

};



#ifdef CONFIG_IOMMU_API

arch/powerpc/kernel/iommu.c

+0 −12
Original line number Diff line number Diff line
@@ -1047,14 +1047,6 @@ int iommu_take_ownership(struct iommu_table *tbl) 


	memset(tbl->it_map, 0xff, sz);



	/*

	 * Disable iommu bypass, otherwise the user can DMA to all of

	 * our physical memory via the bypass window instead of just

	 * the pages that has been explicitly mapped into the iommu

	 */

	if (tbl->set_bypass)

		tbl->set_bypass(tbl, false);



	return 0;

}

EXPORT_SYMBOL_GPL(iommu_take_ownership);
@@ -1068,10 +1060,6 @@ void iommu_release_ownership(struct iommu_table *tbl) 
	/* Restore bit#0 set by iommu_init_table() */

	if (tbl->it_offset == 0)

		set_bit(0, tbl->it_map);



	/* The kernel owns the device now, we can restore the iommu bypass */

	if (tbl->set_bypass)

		tbl->set_bypass(tbl, true);

}

EXPORT_SYMBOL_GPL(iommu_release_ownership);

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

+28 −15
Original line number Diff line number Diff line
@@ -1919,13 +1919,8 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb, 
	}

}



static void pnv_pci_ioda2_set_bypass(struct iommu_table *tbl, bool enable)

static void pnv_pci_ioda2_set_bypass(struct pnv_ioda_pe *pe, bool enable)

{

	struct iommu_table_group_link *tgl = list_first_entry_or_null(

			&tbl->it_group_list, struct iommu_table_group_link,

			next);

	struct pnv_ioda_pe *pe = container_of(tgl->table_group,

			struct pnv_ioda_pe, table_group);

	uint16_t window_id = (pe->pe_number << 1 ) + 1;

	int64_t rc;
@@ -1952,19 +1947,31 @@ static void pnv_pci_ioda2_set_bypass(struct iommu_table *tbl, bool enable) 
		pe->tce_bypass_enabled = enable;

}



static void pnv_pci_ioda2_setup_bypass_pe(struct pnv_phb *phb,

					  struct pnv_ioda_pe *pe)

#ifdef CONFIG_IOMMU_API

static void pnv_ioda2_take_ownership(struct iommu_table_group *table_group)

{

	/* TVE #1 is selected by PCI address bit 59 */

	pe->tce_bypass_base = 1ull << 59;

	struct pnv_ioda_pe *pe = container_of(table_group, struct pnv_ioda_pe,

						table_group);



	iommu_take_ownership(table_group->tables[0]);

	pnv_pci_ioda2_set_bypass(pe, false);

}



	/* Install set_bypass callback for VFIO */

	pe->table_group.tables[0]->set_bypass = pnv_pci_ioda2_set_bypass;

static void pnv_ioda2_release_ownership(struct iommu_table_group *table_group)

{

	struct pnv_ioda_pe *pe = container_of(table_group, struct pnv_ioda_pe,

						table_group);



	/* Enable bypass by default */

	pnv_pci_ioda2_set_bypass(pe->table_group.tables[0], true);

	iommu_release_ownership(table_group->tables[0]);

	pnv_pci_ioda2_set_bypass(pe, true);

}



static struct iommu_table_group_ops pnv_pci_ioda2_ops = {

	.take_ownership = pnv_ioda2_take_ownership,

	.release_ownership = pnv_ioda2_release_ownership,

};

#endif



static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,

				       struct pnv_ioda_pe *pe)

{
@@ -1979,6 +1986,9 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb, 
	if (WARN_ON(pe->tce32_seg >= 0))

		return;



	/* TVE #1 is selected by PCI address bit 59 */

	pe->tce_bypass_base = 1ull << 59;



	tbl = pnv_pci_table_alloc(phb->hose->node);

	iommu_register_group(&pe->table_group, phb->hose->global_number,

			pe->pe_number);
@@ -2033,6 +2043,9 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb, 
	}

	tbl->it_ops = &pnv_ioda2_iommu_ops;

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

#ifdef CONFIG_IOMMU_API

	pe->table_group.ops = &pnv_pci_ioda2_ops;

#endif



	if (pe->flags & PNV_IODA_PE_DEV) {

		/*
@@ -2047,7 +2060,7 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb, 


	/* Also create a bypass window */

	if (!pnv_iommu_bypass_disabled)

		pnv_pci_ioda2_setup_bypass_pe(phb, pe);

		pnv_pci_ioda2_set_bypass(pe, true);



	return;

fail:

drivers/vfio/vfio_iommu_spapr_tce.c

+65 −5
Original line number Diff line number Diff line
@@ -486,6 +486,61 @@ static long tce_iommu_ioctl(void *iommu_data, 
	return -ENOTTY;

}



static void tce_iommu_release_ownership(struct tce_container *container,

		struct iommu_table_group *table_group)

{

	int i;



	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {

		struct iommu_table *tbl = table_group->tables[i];



		if (!tbl)

			continue;



		tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);

		if (tbl->it_map)

			iommu_release_ownership(tbl);

	}

}



static int tce_iommu_take_ownership(struct tce_container *container,

		struct iommu_table_group *table_group)

{

	int i, j, rc = 0;



	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {

		struct iommu_table *tbl = table_group->tables[i];



		if (!tbl || !tbl->it_map)

			continue;



		rc = iommu_take_ownership(tbl);

		if (rc) {

			for (j = 0; j < i; ++j)

				iommu_release_ownership(

						table_group->tables[j]);



			return rc;

		}

	}



	return 0;

}



static void tce_iommu_release_ownership_ddw(struct tce_container *container,

		struct iommu_table_group *table_group)

{

	table_group->ops->release_ownership(table_group);

}



static long tce_iommu_take_ownership_ddw(struct tce_container *container,

		struct iommu_table_group *table_group)

{

	table_group->ops->take_ownership(table_group);



	return 0;

}



static int tce_iommu_attach_group(void *iommu_data,

		struct iommu_group *iommu_group)

{
@@ -518,7 +573,12 @@ static int tce_iommu_attach_group(void *iommu_data, 
		goto unlock_exit;

	}



	ret = iommu_take_ownership(table_group->tables[0]);

	if (!table_group->ops || !table_group->ops->take_ownership ||

			!table_group->ops->release_ownership)

		ret = tce_iommu_take_ownership(container, table_group);

	else

		ret = tce_iommu_take_ownership_ddw(container, table_group);



	if (!ret)

		container->grp = iommu_group;
@@ -533,7 +593,6 @@ static void tce_iommu_detach_group(void *iommu_data, 
{

	struct tce_container *container = iommu_data;

	struct iommu_table_group *table_group;

	struct iommu_table *tbl;



	mutex_lock(&container->lock);

	if (iommu_group != container->grp) {
@@ -556,9 +615,10 @@ static void tce_iommu_detach_group(void *iommu_data, 
	table_group = iommu_group_get_iommudata(iommu_group);

	BUG_ON(!table_group);



	tbl = table_group->tables[0];

	tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);

	iommu_release_ownership(tbl);

	if (!table_group->ops || !table_group->ops->release_ownership)

		tce_iommu_release_ownership(container, table_group);

	else

		tce_iommu_release_ownership_ddw(container, table_group);



unlock_exit:

	mutex_unlock(&container->lock);