Subject: Re: [PATCH v2 03/13] powerpc/spapr: vfio: Implement spapr_tce_iommu_ops

From: Alexey Kardashevskiy <[email-masked]>
Date: Thu, 25 Sep 2014 15:19:47 +1000

On 09/24/2014 06:42 AM, Alex Williamson wrote:
> On Tue, 2014-09-23 at 13:00 +1000, Alexey Kardashevskiy wrote:
>> Modern IBM POWERPC systems support multiple IOMMU tables per PE
>> so we need a more reliable way (compared to container_of()) to get
>> a PE pointer from the iommu_table struct pointer used in IOMMU functions.
>>
>> At the moment IOMMU group data points to an iommu_table struct. This
>> introduces a spapr_tce_iommu_group struct which keeps an iommu_owner
>> and a spapr_tce_iommu_ops struct. For IODA, iommu_owner is a pointer to
>> the pnv_ioda_pe struct, for others it is still a pointer to
>> the iommu_table struct. The ops structs correspond to the type which
>> iommu_owner points to.
>>
>> This defines a get_table() callback which returns an iommu_table
>> by its number.
>>
>> As the IOMMU group data pointer points to variable type instead of
>> iommu_table, VFIO SPAPR TCE driver is updated to use the new type.
>> This changes the tce_container struct to store iommu_group instead of
>> iommu_table.
>>
>> So, it was:
>> - iommu_table points to iommu_group via iommu_table::it_group;
>> - iommu_group points to iommu_table via iommu_group_get_iommudata();
>>
>> now it is:
>> - iommu_table points to iommu_group via iommu_table::it_group;
>> - iommu_group points to spapr_tce_iommu_group via
>> iommu_group_get_iommudata();
>> - spapr_tce_iommu_group points to either (depending on .get_table()):
>> 	- iommu_table;
>> 	- pnv_ioda_pe;
>>
>> This uses pnv_ioda1_iommu_get_table for both IODA1&2 but IODA2 will
>> have own pnv_ioda2_iommu_get_table soon and pnv_ioda1_iommu_get_table
>> will only be used for IODA1.
>>
>> Signed-off-by: Alexey Kardashevskiy <[email-masked]>
>> ---
>>  arch/powerpc/include/asm/iommu.h            |   6 ++
>>  arch/powerpc/include/asm/tce.h              |  13 +++
>>  arch/powerpc/kernel/iommu.c                 |  35 ++++++-
>>  arch/powerpc/platforms/powernv/pci-ioda.c   |  31 +++++-
>>  arch/powerpc/platforms/powernv/pci-p5ioc2.c |   1 +
>>  arch/powerpc/platforms/powernv/pci.c        |   2 +-
>>  arch/powerpc/platforms/pseries/iommu.c      |  10 +-
>>  drivers/vfio/vfio_iommu_spapr_tce.c         | 148 ++++++++++++++++++++++------
>>  8 files changed, 208 insertions(+), 38 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
>> index 42632c7..84ee339 100644
>> --- a/arch/powerpc/include/asm/iommu.h
>> +++ b/arch/powerpc/include/asm/iommu.h
>> @@ -108,13 +108,19 @@ extern void iommu_free_table(struct iommu_table *tbl, const char *node_name);
>>   */
>>  extern struct iommu_table *iommu_init_table(struct iommu_table * tbl,
>>  					    int nid);
>> +
>> +struct spapr_tce_iommu_ops;
>>  #ifdef CONFIG_IOMMU_API
>>  extern void iommu_register_group(struct iommu_table *tbl,
>> +				 void *iommu_owner,
>> +				 struct spapr_tce_iommu_ops *ops,
>>  				 int pci_domain_number, unsigned long pe_num);
>>  extern int iommu_add_device(struct device *dev);
>>  extern void iommu_del_device(struct device *dev);
>>  #else
>>  static inline void iommu_register_group(struct iommu_table *tbl,
>> +					void *iommu_owner,
>> +					struct spapr_tce_iommu_ops *ops,
>>  					int pci_domain_number,
>>  					unsigned long pe_num)
>>  {
>> diff --git a/arch/powerpc/include/asm/tce.h b/arch/powerpc/include/asm/tce.h
>> index 743f36b..9f159eb 100644
>> --- a/arch/powerpc/include/asm/tce.h
>> +++ b/arch/powerpc/include/asm/tce.h
>> @@ -50,5 +50,18 @@
>>  #define TCE_PCI_READ		0x1		/* read from PCI allowed */
>>  #define TCE_VB_WRITE		0x1		/* write from VB allowed */
>>  
>> +struct spapr_tce_iommu_group;
>> +
>> +struct spapr_tce_iommu_ops {
>> +	struct iommu_table *(*get_table)(
>> +			struct spapr_tce_iommu_group *data,
>> +			int num);
>> +};
>> +
>> +struct spapr_tce_iommu_group {
>> +	void *iommu_owner;
>> +	struct spapr_tce_iommu_ops *ops;
>> +};
>> +
>>  #endif /* __KERNEL__ */
>>  #endif /* _ASM_POWERPC_TCE_H */
>> diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
>> index b378f78..1c5dae7 100644
>> --- a/arch/powerpc/kernel/iommu.c
>> +++ b/arch/powerpc/kernel/iommu.c
>> @@ -878,24 +878,53 @@ void iommu_free_coherent(struct iommu_table *tbl, size_t size,
>>   */
>>  static void group_release(void *iommu_data)
>>  {
>> -	struct iommu_table *tbl = iommu_data;
>> -	tbl->it_group = NULL;
>> +	kfree(iommu_data);
>>  }
>>  
>> +static struct iommu_table *spapr_tce_default_get_table(
>> +		struct spapr_tce_iommu_group *data, int num)
>> +{
>> +	struct iommu_table *tbl = data->iommu_owner;
>> +
>> +	switch (num) {
>> +	case 0:
>> +		if (tbl->it_size)
>> +			return tbl;
>> +		/* fallthru */
>> +	default:
>> +		return NULL;
>> +	}
>> +}
>> +
>> +static struct spapr_tce_iommu_ops spapr_tce_default_ops = {
>> +	.get_table = spapr_tce_default_get_table
>> +};
>> +
>>  void iommu_register_group(struct iommu_table *tbl,
>> +		void *iommu_owner, struct spapr_tce_iommu_ops *ops,
>>  		int pci_domain_number, unsigned long pe_num)
>>  {
>>  	struct iommu_group *grp;
>>  	char *name;
>> +	struct spapr_tce_iommu_group *data;
>> +
>> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
>> +	if (!data)
>> +		return;
>> +
>> +	data->iommu_owner = iommu_owner ? iommu_owner : tbl;
>> +	data->ops = ops ? ops : &spapr_tce_default_ops;
>>  
>>  	grp = iommu_group_alloc();
>>  	if (IS_ERR(grp)) {
>>  		pr_warn("powerpc iommu api: cannot create new group, err=%ld\n",
>>  				PTR_ERR(grp));
>> +		kfree(data);
>>  		return;
>>  	}
>> +
>>  	tbl->it_group = grp;
>> -	iommu_group_set_iommudata(grp, tbl, group_release);
>> +	iommu_group_set_iommudata(grp, data, group_release);
>>  	name = kasprintf(GFP_KERNEL, "domain%d-pe%lx",
>>  			pci_domain_number, pe_num);
>>  	if (!name)
>> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
>> index 136e765..2d32a1c 100644
>> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
>> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
>> @@ -23,6 +23,7 @@
>>  #include <linux/io.h>
>>  #include <linux/msi.h>
>>  #include <linux/memblock.h>
>> +#include <linux/iommu.h>
>>  
>>  #include <asm/sections.h>
>>  #include <asm/io.h>
>> @@ -988,6 +989,26 @@ static void pnv_pci_ioda2_tce_invalidate(struct pnv_ioda_pe *pe,
>>  	}
>>  }
>>  
>> +static struct iommu_table *pnv_ioda1_iommu_get_table(
>> +		struct spapr_tce_iommu_group *data,
>> +		int num)
>> +{
>> +	struct pnv_ioda_pe *pe = data->iommu_owner;
>> +
>> +	switch (num) {
>> +	case 0:
>> +		if (pe->tce32.table.it_size)
>> +			return &pe->tce32.table;
>> +		/* fallthru */
>> +	default:
>> +		return NULL;
>> +	}
>> +}
>> +
>> +static struct spapr_tce_iommu_ops pnv_pci_ioda1_ops = {
>> +	.get_table = pnv_ioda1_iommu_get_table,
>> +};
>> +
>>  static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
>>  				      struct pnv_ioda_pe *pe, unsigned int base,
>>  				      unsigned int segs)
>> @@ -1067,7 +1088,8 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
>>  				 TCE_PCI_SWINV_PAIR);
>>  	}
>>  	iommu_init_table(tbl, phb->hose->node);
>> -	iommu_register_group(tbl, phb->hose->global_number, pe->pe_number);
>> +	iommu_register_group(tbl, pe, &pnv_pci_ioda1_ops,
>> +			phb->hose->global_number, pe->pe_number);
>>  
>>  	if (pe->pdev)
>>  		set_iommu_table_base_and_group(&pe->pdev->dev, tbl);
>> @@ -1137,6 +1159,10 @@ static void pnv_pci_ioda2_setup_bypass_pe(struct pnv_phb *phb,
>>  	pnv_pci_ioda2_set_bypass(&pe->tce32.table, true);
>>  }
>>  
>> +static struct spapr_tce_iommu_ops pnv_pci_ioda2_ops = {
>> +	.get_table = pnv_ioda1_iommu_get_table,
>> +};
>> +
>>  static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
>>  				       struct pnv_ioda_pe *pe)
>>  {
>> @@ -1202,7 +1228,8 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
>>  		tbl->it_type |= (TCE_PCI_SWINV_CREATE | TCE_PCI_SWINV_FREE);
>>  	}
>>  	iommu_init_table(tbl, phb->hose->node);
>> -	iommu_register_group(tbl, phb->hose->global_number, pe->pe_number);
>> +	iommu_register_group(tbl, pe, &pnv_pci_ioda2_ops,
>> +			phb->hose->global_number, pe->pe_number);
>>  
>>  	if (pe->pdev)
>>  		set_iommu_table_base_and_group(&pe->pdev->dev, tbl);
>> diff --git a/arch/powerpc/platforms/powernv/pci-p5ioc2.c b/arch/powerpc/platforms/powernv/pci-p5ioc2.c
>> index 94ce348..b79066d 100644
>> --- a/arch/powerpc/platforms/powernv/pci-p5ioc2.c
>> +++ b/arch/powerpc/platforms/powernv/pci-p5ioc2.c
>> @@ -89,6 +89,7 @@ static void pnv_pci_p5ioc2_dma_dev_setup(struct pnv_phb *phb,
>>  	if (phb->p5ioc2.iommu_table.it_map == NULL) {
>>  		iommu_init_table(&phb->p5ioc2.iommu_table, phb->hose->node);
>>  		iommu_register_group(&phb->p5ioc2.iommu_table,
>> +				NULL, NULL,
>>  				pci_domain_nr(phb->hose->bus), phb->opal_id);
>>  	}
>>  
>> diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
>> index 97895d4..6ffac79 100644
>> --- a/arch/powerpc/platforms/powernv/pci.c
>> +++ b/arch/powerpc/platforms/powernv/pci.c
>> @@ -723,7 +723,7 @@ static struct iommu_table *pnv_pci_setup_bml_iommu(struct pci_controller *hose)
>>  	pnv_pci_setup_iommu_table(tbl, __va(be64_to_cpup(basep)),
>>  				  be32_to_cpup(sizep), 0, IOMMU_PAGE_SHIFT_4K);
>>  	iommu_init_table(tbl, hose->node);
>> -	iommu_register_group(tbl, pci_domain_nr(hose->bus), 0);
>> +	iommu_register_group(tbl, NULL, NULL, pci_domain_nr(hose->bus), 0);
>>  
>>  	/* Deal with SW invalidated TCEs when needed (BML way) */
>>  	swinvp = of_get_property(hose->dn, "linux,tce-sw-invalidate-info",
>> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
>> index 4642d6a..b95f8cf 100644
>> --- a/arch/powerpc/platforms/pseries/iommu.c
>> +++ b/arch/powerpc/platforms/pseries/iommu.c
>> @@ -616,7 +616,7 @@ static void pci_dma_bus_setup_pSeries(struct pci_bus *bus)
>>  
>>  	iommu_table_setparms(pci->phb, dn, tbl);
>>  	pci->iommu_table = iommu_init_table(tbl, pci->phb->node);
>> -	iommu_register_group(tbl, pci_domain_nr(bus), 0);
>> +	iommu_register_group(tbl, NULL, NULL, pci_domain_nr(bus), 0);
>>  
>>  	/* Divide the rest (1.75GB) among the children */
>>  	pci->phb->dma_window_size = 0x80000000ul;
>> @@ -661,7 +661,7 @@ static void pci_dma_bus_setup_pSeriesLP(struct pci_bus *bus)
>>  				   ppci->phb->node);
>>  		iommu_table_setparms_lpar(ppci->phb, pdn, tbl, dma_window);
>>  		ppci->iommu_table = iommu_init_table(tbl, ppci->phb->node);
>> -		iommu_register_group(tbl, pci_domain_nr(bus), 0);
>> +		iommu_register_group(tbl, NULL, NULL, pci_domain_nr(bus), 0);
>>  		pr_debug("  created table: %p\n", ppci->iommu_table);
>>  	}
>>  }
>> @@ -688,7 +688,8 @@ static void pci_dma_dev_setup_pSeries(struct pci_dev *dev)
>>  				   phb->node);
>>  		iommu_table_setparms(phb, dn, tbl);
>>  		PCI_DN(dn)->iommu_table = iommu_init_table(tbl, phb->node);
>> -		iommu_register_group(tbl, pci_domain_nr(phb->bus), 0);
>> +		iommu_register_group(tbl, NULL, NULL,
>> +				pci_domain_nr(phb->bus), 0);
>>  		set_iommu_table_base_and_group(&dev->dev,
>>  					       PCI_DN(dn)->iommu_table);
>>  		return;
>> @@ -1105,7 +1106,8 @@ static void pci_dma_dev_setup_pSeriesLP(struct pci_dev *dev)
>>  				   pci->phb->node);
>>  		iommu_table_setparms_lpar(pci->phb, pdn, tbl, dma_window);
>>  		pci->iommu_table = iommu_init_table(tbl, pci->phb->node);
>> -		iommu_register_group(tbl, pci_domain_nr(pci->phb->bus), 0);
>> +		iommu_register_group(tbl, NULL, NULL,
>> +				pci_domain_nr(pci->phb->bus), 0);
>>  		pr_debug("  created table: %p\n", pci->iommu_table);
>>  	} else {
>>  		pr_debug("  found DMA window, table: %p\n", pci->iommu_table);
>> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
>> index 730b4ef..a8adfbd 100644
>> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
>> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
>> @@ -43,17 +43,51 @@ static void tce_iommu_detach_group(void *iommu_data,
>>   */
>>  struct tce_container {
>>  	struct mutex lock;
>> -	struct iommu_table *tbl;
>> +	struct iommu_group *grp;
>> +	long windows_num;
>>  	bool enabled;
>>  };
>>  
>> +static struct iommu_table *spapr_tce_find_table(
>> +		struct tce_container *container,
>> +		struct spapr_tce_iommu_group *data,
>> +		phys_addr_t ioba)
>> +{
>> +	long i;
>> +	struct iommu_table *ret = NULL;
>> +
>> +	mutex_lock(&container->lock);
>> +	for (i = 0; i < container->windows_num; ++i) {
>> +		struct iommu_table *tbl = data->ops->get_table(data, i);
>> +
>> +		if (tbl) {
>> +			unsigned long entry = ioba >> tbl->it_page_shift;
>> +			unsigned long start = tbl->it_offset;
>> +			unsigned long end = start + tbl->it_size;
>> +
>> +			if ((start <= entry) && (entry < end)) {
>> +				ret = tbl;
>> +				break;
>> +			}
>> +		}
>> +	}
>> +	mutex_unlock(&container->lock);
>> +
>> +	return ret;
>> +}
>> +
>>  static int tce_iommu_enable(struct tce_container *container)
>>  {
>>  	int ret = 0;
>>  	unsigned long locked, lock_limit, npages;
>> -	struct iommu_table *tbl = container->tbl;
>> +	struct iommu_table *tbl;
>> +	struct spapr_tce_iommu_group *data;
>>  
>> -	if (!container->tbl)
>> +	if (!container->grp)
>> +		return -ENXIO;
>> +
>> +	data = iommu_group_get_iommudata(container->grp);
>> +	if (!data || !data->iommu_owner || !data->ops->get_table)
>>  		return -ENXIO;
>>  
>>  	if (!current->mm)
>> @@ -80,6 +114,10 @@ static int tce_iommu_enable(struct tce_container *container)
>>  	 * that would effectively kill the guest at random points, much better
>>  	 * enforcing the limit based on the max that the guest can map.
>>  	 */
>> +	tbl = data->ops->get_table(data, 0);
> 
> Can we define an enum to avoid sprinkling magic zeros in the code?

Right. Missed it in one of iterations :-/

>> +	if (!tbl)
>> +		return -ENXIO;
>> +
>>  	down_write(&current->mm->mmap_sem);
>>  	npages = (tbl->it_size << IOMMU_PAGE_SHIFT_4K) >> PAGE_SHIFT;
>>  	locked = current->mm->locked_vm + npages;
>> @@ -89,7 +127,6 @@ static int tce_iommu_enable(struct tce_container *container)
>>  				rlimit(RLIMIT_MEMLOCK));
>>  		ret = -ENOMEM;
>>  	} else {
>> -
>>  		current->mm->locked_vm += npages;
>>  		container->enabled = true;
>>  	}
>> @@ -100,16 +137,27 @@ static int tce_iommu_enable(struct tce_container *container)
>>  
>>  static void tce_iommu_disable(struct tce_container *container)
>>  {
>> +	struct spapr_tce_iommu_group *data;
>> +	struct iommu_table *tbl;
>> +
>>  	if (!container->enabled)
>>  		return;
>>  
>>  	container->enabled = false;
>>  
>> -	if (!container->tbl || !current->mm)
>> +	if (!container->grp || !current->mm)
>> +		return;
>> +
>> +	data = iommu_group_get_iommudata(container->grp);
>> +	if (!data || !data->iommu_owner || !data->ops->get_table)
>> +		return;
>> +
>> +	tbl = data->ops->get_table(data, 0);
>> +	if (!tbl)
>>  		return;
>>  
>>  	down_write(&current->mm->mmap_sem);
>> -	current->mm->locked_vm -= (container->tbl->it_size <<
>> +	current->mm->locked_vm -= (tbl->it_size <<
>>  			IOMMU_PAGE_SHIFT_4K) >> PAGE_SHIFT;
>>  	up_write(&current->mm->mmap_sem);
>>  }
>> @@ -129,6 +177,8 @@ static void *tce_iommu_open(unsigned long arg)
>>  
>>  	mutex_init(&container->lock);
>>  
>> +	container->windows_num = 1;
>> +
>>  	return container;
>>  }
>>  
>> @@ -136,11 +186,11 @@ static void tce_iommu_release(void *iommu_data)
>>  {
>>  	struct tce_container *container = iommu_data;
>>  
>> -	WARN_ON(container->tbl && !container->tbl->it_group);
>> +	WARN_ON(container->grp);
>>  	tce_iommu_disable(container);
>>  
>> -	if (container->tbl && container->tbl->it_group)
>> -		tce_iommu_detach_group(iommu_data, container->tbl->it_group);
>> +	if (container->grp)
>> +		tce_iommu_detach_group(iommu_data, container->grp);
>>  
>>  	mutex_destroy(&container->lock);
>>  
>> @@ -169,8 +219,17 @@ static long tce_iommu_ioctl(void *iommu_data,
>>  
>>  	case VFIO_IOMMU_SPAPR_TCE_GET_INFO: {
>>  		struct vfio_iommu_spapr_tce_info info;
>> -		struct iommu_table *tbl = container->tbl;
>> +		struct iommu_table *tbl;
>> +		struct spapr_tce_iommu_group *data;
>>  
>> +		if (WARN_ON(!container->grp))
>> +			return -ENXIO;
>> +
>> +		data = iommu_group_get_iommudata(container->grp);
>> +		if (WARN_ON(!data || !data->iommu_owner || !data->ops))
>> +			return -ENXIO;
>> +
>> +		tbl = data->ops->get_table(data, 0);
>>  		if (WARN_ON(!tbl))
>>  			return -ENXIO;
>>  
>> @@ -194,13 +253,16 @@ static long tce_iommu_ioctl(void *iommu_data,
>>  	}
>>  	case VFIO_IOMMU_MAP_DMA: {
>>  		struct vfio_iommu_type1_dma_map param;
>> -		struct iommu_table *tbl = container->tbl;
>> +		struct iommu_table *tbl;
>> +		struct spapr_tce_iommu_group *data;
>>  		unsigned long tce, i;
>>  
>> -		if (!tbl)
>> +		if (WARN_ON(!container->grp))
> 
> If a user can get here by their own mistake, return an error and be
> done, no warning.  If a user can get here via a kernel ordering issue,
> it's a problem in the design.  Which is it?

I'll remove here and below these WARN's. I just cannot force myself to
start thinking of malicious userspace which can trigger many of those :)

> 
>>  			return -ENXIO;
>>  
>> -		BUG_ON(!tbl->it_group);
>> +		data = iommu_group_get_iommudata(container->grp);
>> +		if (WARN_ON(!data || !data->iommu_owner || !data->ops))
>> +			return -ENXIO;
> 
> Same
> 
>>  
>>  		minsz = offsetofend(struct vfio_iommu_type1_dma_map, size);
>>  
>> @@ -225,6 +287,11 @@ static long tce_iommu_ioctl(void *iommu_data,
>>  		if (param.flags & VFIO_DMA_MAP_FLAG_WRITE)
>>  			tce |= TCE_PCI_WRITE;
>>  
>> +		tbl = spapr_tce_find_table(container, data, param.iova);
> 
> Why aren't we using ops->find_table() here?

I am trying to keep spapr_tce_iommu_ops as simple as possible and now it
only provides a search-by-window-number callback and the helper to search
by IOBA uses it.

-- 
Alexey