[PATCH v2 0/6] Remove default DMA window before creating DDW

[PATCH v2 0/6] Remove default DMA window before creating DDW

[Leonardo Bras]

There are some devices that only allow 1 DMA window to exist at a time,
and in those cases, a DDW is never created to them, since the default DMA
window keeps using this resource.

LoPAR recommends this procedure:
1. Remove the default DMA window,
2. Query for which configs the DDW can be created,
3. Create a DDW.

Patch #1:
Create defines for outputs of ibm,ddw-applicable, so it's easier to
identify them.

Patch #2:
- After LoPAR level 2.8, there is an extension that can make
  ibm,query-pe-dma-windows to have 6 outputs instead of 5. This changes the
  order of the outputs, and that can cause some trouble. 
- query_ddw() was updated to check how many outputs the 
  ibm,query-pe-dma-windows is supposed to have, update the rtas_call() and
  deal correctly with the outputs in both cases.
- This patch looks somehow unrelated to the series, but it can avoid future
  problems on DDW creation.

Patch #3 moves the window-removing code from remove_ddw() to
remove_dma_window(), creating a way to delete any DMA window, so it can be
used to delete the default DMA window.

Patch #4 makes use of the remove_dma_window() from patch #3 to remove the
default DMA window before query_ddw(). It also implements a new rtas call
to recover the default DMA window, in case anything fails after it was
removed, and a DDW couldn't be created.

Patch #5:
Instead of destroying the created DDW if it doesn't map the whole
partition, make use of it instead of the default DMA window.

Patch #6:
Changes the way iommu_bypass_supported_pSeriesLP() check for 
iommu_bypass: instead of checking the address returned by enable_ddw(),
it checks a new output value that reflects if the DDW created maps
the whole partition.


All patches were tested into an LPAR with an Ethernet VF:
4005:01:00.0 Ethernet controller: Mellanox Technologies MT27700 Family
[ConnectX-4 Virtual Function]

---
Changes since v1:
- Add defines for ibm,ddw-applicable and ibm,ddw-extensions outputs
- Merge aux function query_ddw_out_sz() into query_ddw()
- Merge reset_dma_window() patch (prev. #2) into remove default DMA
  window patch (#4).
- Keep device_node *np name instead of using pdn in remove_*()
- Rename 'device_node *pdn' into 'parent' in new functions
- Rename dfl_win to default_win
- Only remove the default DMA window if there is no window available
  in first query.
- Check if default DMA window can be restored before removing it.
- Fix 'unitialized use' (found by travis mpe:ci-test)
- New patches #5 and #6

Special thanks for Alexey Kardashevskiy and Oliver O'Halloran for
the feedback provided!

Leonardo Bras (6):
  powerpc/pseries/iommu: Create defines for operations in
    ibm,ddw-applicable
  powerpc/pseries/iommu: Update call to ibm,query-pe-dma-windows
  powerpc/pseries/iommu: Move window-removing part of remove_ddw into
    remove_dma_window
  powerpc/pseries/iommu: Remove default DMA window before creating DDW
  powerpc/pseries/iommu: Make use of DDW even if it does not map the
    partition
  powerpc/pseries/iommu: Avoid errors when DDW starts at 0x00

 arch/powerpc/platforms/pseries/iommu.c | 239 ++++++++++++++++++-------
 1 file changed, 176 insertions(+), 63 deletions(-)

-- 
2.25.4

[PATCH v2 1/6] powerpc/pseries/iommu: Create defines for operations in ibm,ddw-applicable

[Leonardo Bras]

Create defines to help handling ibm,ddw-applicable values, avoiding
confusion about the index of given operations.

Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
---
 arch/powerpc/platforms/pseries/iommu.c | 40 +++++++++++++++-----------
 1 file changed, 23 insertions(+), 17 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 6d47b4a3ce39..68d2aa9c71a8 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -39,6 +39,11 @@
 
 #include "pseries.h"
 
+#define DDW_QUERY_PE_DMA_WIN	0
+#define DDW_CREATE_PE_DMA_WIN	1
+#define DDW_REMOVE_PE_DMA_WIN	2
+#define DDW_APPLICABLE_SIZE	3
+
 static struct iommu_table_group *iommu_pseries_alloc_group(int node)
 {
 	struct iommu_table_group *table_group;
@@ -771,12 +776,12 @@ static void remove_ddw(struct device_node *np, bool remove_prop)
 {
 	struct dynamic_dma_window_prop *dwp;
 	struct property *win64;
-	u32 ddw_avail[3];
+	u32 ddw_avail[DDW_APPLICABLE_SIZE];
 	u64 liobn;
 	int ret = 0;
 
 	ret = of_property_read_u32_array(np, "ibm,ddw-applicable",
-					 &ddw_avail[0], 3);
+					 &ddw_avail[0], DDW_APPLICABLE_SIZE);
 
 	win64 = of_find_property(np, DIRECT64_PROPNAME, NULL);
 	if (!win64)
@@ -798,15 +803,15 @@ static void remove_ddw(struct device_node *np, bool remove_prop)
 		pr_debug("%pOF successfully cleared tces in window.\n",
 			 np);
 
-	ret = rtas_call(ddw_avail[2], 1, 1, NULL, liobn);
+	ret = rtas_call(ddw_avail[DDW_REMOVE_PE_DMA_WIN], 1, 1, NULL, liobn);
 	if (ret)
 		pr_warn("%pOF: failed to remove direct window: rtas returned "
 			"%d to ibm,remove-pe-dma-window(%x) %llx\n",
-			np, ret, ddw_avail[2], liobn);
+			np, ret, ddw_avail[DDW_REMOVE_PE_DMA_WIN], liobn);
 	else
 		pr_debug("%pOF: successfully removed direct window: rtas returned "
 			"%d to ibm,remove-pe-dma-window(%x) %llx\n",
-			np, ret, ddw_avail[2], liobn);
+			np, ret, ddw_avail[DDW_REMOVE_PE_DMA_WIN], liobn);
 
 delprop:
 	if (remove_prop)
@@ -889,11 +894,11 @@ static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
 	buid = pdn->phb->buid;
 	cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
 
-	ret = rtas_call(ddw_avail[0], 3, 5, (u32 *)query,
-		  cfg_addr, BUID_HI(buid), BUID_LO(buid));
+	ret = rtas_call(ddw_avail[DDW_QUERY_PE_DMA_WIN], 3, 5, (u32 *)query,
+			cfg_addr, BUID_HI(buid), BUID_LO(buid));
 	dev_info(&dev->dev, "ibm,query-pe-dma-windows(%x) %x %x %x"
-		" returned %d\n", ddw_avail[0], cfg_addr, BUID_HI(buid),
-		BUID_LO(buid), ret);
+		" returned %d\n", ddw_avail[DDW_QUERY_PE_DMA_WIN], cfg_addr,
+		 BUID_HI(buid), BUID_LO(buid), ret);
 	return ret;
 }
 
@@ -920,15 +925,16 @@ static int create_ddw(struct pci_dev *dev, const u32 *ddw_avail,
 
 	do {
 		/* extra outputs are LIOBN and dma-addr (hi, lo) */
-		ret = rtas_call(ddw_avail[1], 5, 4, (u32 *)create,
-				cfg_addr, BUID_HI(buid), BUID_LO(buid),
-				page_shift, window_shift);
+		ret = rtas_call(ddw_avail[DDW_CREATE_PE_DMA_WIN], 5, 4,
+				(u32 *)create, cfg_addr, BUID_HI(buid),
+				BUID_LO(buid), page_shift, window_shift);
 	} while (rtas_busy_delay(ret));
 	dev_info(&dev->dev,
 		"ibm,create-pe-dma-window(%x) %x %x %x %x %x returned %d "
-		"(liobn = 0x%x starting addr = %x %x)\n", ddw_avail[1],
-		 cfg_addr, BUID_HI(buid), BUID_LO(buid), page_shift,
-		 window_shift, ret, create->liobn, create->addr_hi, create->addr_lo);
+		"(liobn = 0x%x starting addr = %x %x)\n",
+		 ddw_avail[DDW_CREATE_PE_DMA_WIN], cfg_addr, BUID_HI(buid),
+		 BUID_LO(buid), page_shift, window_shift, ret, create->liobn,
+		 create->addr_hi, create->addr_lo);
 
 	return ret;
 }
@@ -996,7 +1002,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	int page_shift;
 	u64 dma_addr, max_addr;
 	struct device_node *dn;
-	u32 ddw_avail[3];
+	u32 ddw_avail[DDW_APPLICABLE_SIZE];
 	struct direct_window *window;
 	struct property *win64;
 	struct dynamic_dma_window_prop *ddwprop;
@@ -1029,7 +1035,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	 * the property is actually in the parent, not the PE
 	 */
 	ret = of_property_read_u32_array(pdn, "ibm,ddw-applicable",
-					 &ddw_avail[0], 3);
+					 &ddw_avail[0], DDW_APPLICABLE_SIZE);
 	if (ret)
 		goto out_failed;
 
-- 
2.25.4

Re: [PATCH v2 1/6] powerpc/pseries/iommu: Create defines for operations in ibm,ddw-applicable

[Alexey Kardashevskiy]

On 24/06/2020 16:24, Leonardo Bras wrote:
> Create defines to help handling ibm,ddw-applicable values, avoiding
> confusion about the index of given operations.
> 
> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> ---
>  arch/powerpc/platforms/pseries/iommu.c | 40 +++++++++++++++-----------
>  1 file changed, 23 insertions(+), 17 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 6d47b4a3ce39..68d2aa9c71a8 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -39,6 +39,11 @@
>  
>  #include "pseries.h"
>  
> +#define DDW_QUERY_PE_DMA_WIN	0
> +#define DDW_CREATE_PE_DMA_WIN	1
> +#define DDW_REMOVE_PE_DMA_WIN	2
> +#define DDW_APPLICABLE_SIZE	3


#define DDW_APPLICABLE_SIZE  (DDW_REMOVE_PE_DMA_WIN + 1)

thanks,


> +
>  static struct iommu_table_group *iommu_pseries_alloc_group(int node)
>  {
>  	struct iommu_table_group *table_group;
> @@ -771,12 +776,12 @@ static void remove_ddw(struct device_node *np, bool remove_prop)
>  {
>  	struct dynamic_dma_window_prop *dwp;
>  	struct property *win64;
> -	u32 ddw_avail[3];
> +	u32 ddw_avail[DDW_APPLICABLE_SIZE];
>  	u64 liobn;
>  	int ret = 0;
>  
>  	ret = of_property_read_u32_array(np, "ibm,ddw-applicable",
> -					 &ddw_avail[0], 3);
> +					 &ddw_avail[0], DDW_APPLICABLE_SIZE);
>  
>  	win64 = of_find_property(np, DIRECT64_PROPNAME, NULL);
>  	if (!win64)
> @@ -798,15 +803,15 @@ static void remove_ddw(struct device_node *np, bool remove_prop)
>  		pr_debug("%pOF successfully cleared tces in window.\n",
>  			 np);
>  
> -	ret = rtas_call(ddw_avail[2], 1, 1, NULL, liobn);
> +	ret = rtas_call(ddw_avail[DDW_REMOVE_PE_DMA_WIN], 1, 1, NULL, liobn);
>  	if (ret)
>  		pr_warn("%pOF: failed to remove direct window: rtas returned "
>  			"%d to ibm,remove-pe-dma-window(%x) %llx\n",
> -			np, ret, ddw_avail[2], liobn);
> +			np, ret, ddw_avail[DDW_REMOVE_PE_DMA_WIN], liobn);
>  	else
>  		pr_debug("%pOF: successfully removed direct window: rtas returned "
>  			"%d to ibm,remove-pe-dma-window(%x) %llx\n",
> -			np, ret, ddw_avail[2], liobn);
> +			np, ret, ddw_avail[DDW_REMOVE_PE_DMA_WIN], liobn);
>  
>  delprop:
>  	if (remove_prop)
> @@ -889,11 +894,11 @@ static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
>  	buid = pdn->phb->buid;
>  	cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
>  
> -	ret = rtas_call(ddw_avail[0], 3, 5, (u32 *)query,
> -		  cfg_addr, BUID_HI(buid), BUID_LO(buid));
> +	ret = rtas_call(ddw_avail[DDW_QUERY_PE_DMA_WIN], 3, 5, (u32 *)query,
> +			cfg_addr, BUID_HI(buid), BUID_LO(buid));
>  	dev_info(&dev->dev, "ibm,query-pe-dma-windows(%x) %x %x %x"
> -		" returned %d\n", ddw_avail[0], cfg_addr, BUID_HI(buid),
> -		BUID_LO(buid), ret);
> +		" returned %d\n", ddw_avail[DDW_QUERY_PE_DMA_WIN], cfg_addr,
> +		 BUID_HI(buid), BUID_LO(buid), ret);
>  	return ret;
>  }
>  
> @@ -920,15 +925,16 @@ static int create_ddw(struct pci_dev *dev, const u32 *ddw_avail,
>  
>  	do {
>  		/* extra outputs are LIOBN and dma-addr (hi, lo) */
> -		ret = rtas_call(ddw_avail[1], 5, 4, (u32 *)create,
> -				cfg_addr, BUID_HI(buid), BUID_LO(buid),
> -				page_shift, window_shift);
> +		ret = rtas_call(ddw_avail[DDW_CREATE_PE_DMA_WIN], 5, 4,
> +				(u32 *)create, cfg_addr, BUID_HI(buid),
> +				BUID_LO(buid), page_shift, window_shift);
>  	} while (rtas_busy_delay(ret));
>  	dev_info(&dev->dev,
>  		"ibm,create-pe-dma-window(%x) %x %x %x %x %x returned %d "
> -		"(liobn = 0x%x starting addr = %x %x)\n", ddw_avail[1],
> -		 cfg_addr, BUID_HI(buid), BUID_LO(buid), page_shift,
> -		 window_shift, ret, create->liobn, create->addr_hi, create->addr_lo);
> +		"(liobn = 0x%x starting addr = %x %x)\n",
> +		 ddw_avail[DDW_CREATE_PE_DMA_WIN], cfg_addr, BUID_HI(buid),
> +		 BUID_LO(buid), page_shift, window_shift, ret, create->liobn,
> +		 create->addr_hi, create->addr_lo);
>  
>  	return ret;
>  }
> @@ -996,7 +1002,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  	int page_shift;
>  	u64 dma_addr, max_addr;
>  	struct device_node *dn;
> -	u32 ddw_avail[3];
> +	u32 ddw_avail[DDW_APPLICABLE_SIZE];
>  	struct direct_window *window;
>  	struct property *win64;
>  	struct dynamic_dma_window_prop *ddwprop;
> @@ -1029,7 +1035,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  	 * the property is actually in the parent, not the PE
>  	 */
>  	ret = of_property_read_u32_array(pdn, "ibm,ddw-applicable",
> -					 &ddw_avail[0], 3);
> +					 &ddw_avail[0], DDW_APPLICABLE_SIZE);
>  	if (ret)
>  		goto out_failed;
>  
> 

-- 
Alexey

Re: [PATCH v2 1/6] powerpc/pseries/iommu: Create defines for operations in ibm,ddw-applicable

[Leonardo Bras]

On Wed, 2020-07-01 at 18:16 +1000, Alexey Kardashevskiy wrote:
> 
> On 24/06/2020 16:24, Leonardo Bras wrote:
> > Create defines to help handling ibm,ddw-applicable values, avoiding
> > confusion about the index of given operations.
> > 
> > Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> > ---
> >  arch/powerpc/platforms/pseries/iommu.c | 40 +++++++++++++++-----------
> >  1 file changed, 23 insertions(+), 17 deletions(-)
> > 
> > diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> > index 6d47b4a3ce39..68d2aa9c71a8 100644
> > --- a/arch/powerpc/platforms/pseries/iommu.c
> > +++ b/arch/powerpc/platforms/pseries/iommu.c
> > @@ -39,6 +39,11 @@
> >  
> >  #include "pseries.h"
> >  
> > +#define DDW_QUERY_PE_DMA_WIN	0
> > +#define DDW_CREATE_PE_DMA_WIN	1
> > +#define DDW_REMOVE_PE_DMA_WIN	2
> > +#define DDW_APPLICABLE_SIZE	3
> 
> #define DDW_APPLICABLE_SIZE  (DDW_REMOVE_PE_DMA_WIN + 1)
> 
> thanks,

Thanks for the feedback!
About this (and patch #2), would it be better to use enum ?
enum {
	DDW_QUERY_PE_DMA_WIN,
	DDW_CREATE_PE_DMA_WIN,
	DDW_REMOVE_PE_DMA_WIN,

	DDW_APPLICABLE_SIZE
}
IMO, it looks better than all the defines before.

What do you think?

Best regards,

Re: [PATCH v2 1/6] powerpc/pseries/iommu: Create defines for operations in ibm,ddw-applicable

[Alexey Kardashevskiy]

On 01/07/2020 23:28, Leonardo Bras wrote:
> On Wed, 2020-07-01 at 18:16 +1000, Alexey Kardashevskiy wrote:
>>
>> On 24/06/2020 16:24, Leonardo Bras wrote:
>>> Create defines to help handling ibm,ddw-applicable values, avoiding
>>> confusion about the index of given operations.
>>>
>>> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
>>> ---
>>>  arch/powerpc/platforms/pseries/iommu.c | 40 +++++++++++++++-----------
>>>  1 file changed, 23 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
>>> index 6d47b4a3ce39..68d2aa9c71a8 100644
>>> --- a/arch/powerpc/platforms/pseries/iommu.c
>>> +++ b/arch/powerpc/platforms/pseries/iommu.c
>>> @@ -39,6 +39,11 @@
>>>  
>>>  #include "pseries.h"
>>>  
>>> +#define DDW_QUERY_PE_DMA_WIN	0
>>> +#define DDW_CREATE_PE_DMA_WIN	1
>>> +#define DDW_REMOVE_PE_DMA_WIN	2
>>> +#define DDW_APPLICABLE_SIZE	3
>>
>> #define DDW_APPLICABLE_SIZE  (DDW_REMOVE_PE_DMA_WIN + 1)
>>
>> thanks,
> 
> Thanks for the feedback!
> About this (and patch #2), would it be better to use enum ?
> enum {
> 	DDW_QUERY_PE_DMA_WIN,
> 	DDW_CREATE_PE_DMA_WIN,
> 	DDW_REMOVE_PE_DMA_WIN,
> 
> 	DDW_APPLICABLE_SIZE
> }
> IMO, it looks better than all the defines before.
> 
> What do you think?

No, not really, these come from a binary interface so the reader of this
cares about absolute numbers and rather wants to see them explicitly.


-- 
Alexey

Re: [PATCH v2 1/6] powerpc/pseries/iommu: Create defines for operations in ibm,ddw-applicable

[Leonardo Bras]

On Thu, 2020-07-02 at 10:21 +1000, Alexey Kardashevskiy wrote:
> > enum {
> >        DDW_QUERY_PE_DMA_WIN,
> >        DDW_CREATE_PE_DMA_WIN,
> >        DDW_REMOVE_PE_DMA_WIN,
> > 
> >        DDW_APPLICABLE_SIZE
> > }
> > IMO, it looks better than all the defines before.
> > 
> > What do you think?
> 
> No, not really, these come from a binary interface so the reader of this
> cares about absolute numbers and rather wants to see them explicitly.

Makes sense to me.
I am still getting experience on where to use enum vs define. Thanks
for the tip!

Using something like 
enum {
	DDW_QUERY_PE_DMA_WIN = 0,
	DDW_CREATE_PE_DMA_WIN = 1,
	DDW_REMOVE_PE_DMA_WIN = 2,

	DDW_APPLICABLE_SIZE
};

would be fine too?
Or should one stick to #define in this case?

Thank you,

Re: [PATCH v2 1/6] powerpc/pseries/iommu: Create defines for operations in ibm,ddw-applicable

[Alexey Kardashevskiy]

On 02/07/2020 10:36, Leonardo Bras wrote:
> On Thu, 2020-07-02 at 10:21 +1000, Alexey Kardashevskiy wrote:
>>> enum {
>>>        DDW_QUERY_PE_DMA_WIN,
>>>        DDW_CREATE_PE_DMA_WIN,
>>>        DDW_REMOVE_PE_DMA_WIN,
>>>
>>>        DDW_APPLICABLE_SIZE
>>> }
>>> IMO, it looks better than all the defines before.
>>>
>>> What do you think?
>>
>> No, not really, these come from a binary interface so the reader of this
>> cares about absolute numbers and rather wants to see them explicitly.
> 
> Makes sense to me.
> I am still getting experience on where to use enum vs define. Thanks
> for the tip!
> 
> Using something like 
> enum {
> 	DDW_QUERY_PE_DMA_WIN = 0,
> 	DDW_CREATE_PE_DMA_WIN = 1,
> 	DDW_REMOVE_PE_DMA_WIN = 2,
> 
> 	DDW_APPLICABLE_SIZE
> };
> 
> would be fine too?


This is fine too.


> Or should one stick to #define in this case?

imho a matter of taste but after some grepping it feels like #define is
mostly used which does not mean it is a good idea. Keep it enum and see
if it passed mpe's filter :)



-- 
Alexey

Re: [PATCH v2 1/6] powerpc/pseries/iommu: Create defines for operations in ibm,ddw-applicable

[Leonardo Bras]

On Thu, 2020-07-02 at 10:43 +1000, Alexey Kardashevskiy wrote:
> > Or should one stick to #define in this case?
> 
> imho a matter of taste but after some grepping it feels like #define is
> mostly used which does not mean it is a good idea. Keep it enum and see
> if it passed mpe's filter :)

Good idea :)

Thanks !

[PATCH v2 2/6] powerpc/pseries/iommu: Update call to ibm,query-pe-dma-windows

[Leonardo Bras]

From LoPAR level 2.8, "ibm,ddw-extensions" index 3 can make the number of
outputs from "ibm,query-pe-dma-windows" go from 5 to 6.

This change of output size is meant to expand the address size of
largest_available_block PE TCE from 32-bit to 64-bit, which ends up
shifting page_size and migration_capable.

This ends up requiring the update of
ddw_query_response->largest_available_block from u32 to u64, and manually
assigning the values from the buffer into this struct, according to
output size.

Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
---
 arch/powerpc/platforms/pseries/iommu.c | 57 +++++++++++++++++++++-----
 1 file changed, 47 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 68d2aa9c71a8..558e5441c355 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -44,6 +44,10 @@
 #define DDW_REMOVE_PE_DMA_WIN	2
 #define DDW_APPLICABLE_SIZE	3
 
+#define DDW_EXT_SIZE		0
+#define DDW_EXT_RESET_DMA_WIN	1
+#define DDW_EXT_QUERY_OUT_SIZE	2
+
 static struct iommu_table_group *iommu_pseries_alloc_group(int node)
 {
 	struct iommu_table_group *table_group;
@@ -339,7 +343,7 @@ struct direct_window {
 /* Dynamic DMA Window support */
 struct ddw_query_response {
 	u32 windows_available;
-	u32 largest_available_block;
+	u64 largest_available_block;
 	u32 page_size;
 	u32 migration_capable;
 };
@@ -875,13 +879,29 @@ static int find_existing_ddw_windows(void)
 machine_arch_initcall(pseries, find_existing_ddw_windows);
 
 static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
-			struct ddw_query_response *query)
+		     struct ddw_query_response *query,
+		     struct device_node *parent)
 {
 	struct device_node *dn;
 	struct pci_dn *pdn;
-	u32 cfg_addr;
+	u32 cfg_addr, query_out[5], ddw_ext[DDW_EXT_QUERY_OUT_SIZE + 1];
 	u64 buid;
-	int ret;
+	int ret, out_sz;
+
+	/*
+	 * From LoPAR level 2.8, "ibm,ddw-extensions" index 3 can rule how many
+	 * output parameters ibm,query-pe-dma-windows will have, ranging from
+	 * 5 to 6.
+	 */
+
+	ret = of_property_read_u32_array(parent, "ibm,ddw-extensions",
+					 &ddw_ext[0],
+					 DDW_EXT_QUERY_OUT_SIZE + 1);
+	if (ret && ddw_ext[DDW_EXT_SIZE] > 1 &&
+	    ddw_ext[DDW_EXT_QUERY_OUT_SIZE] == 1)
+		out_sz = 6;
+	else
+		out_sz = 5;
 
 	/*
 	 * Get the config address and phb buid of the PE window.
@@ -894,11 +914,28 @@ static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
 	buid = pdn->phb->buid;
 	cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
 
-	ret = rtas_call(ddw_avail[DDW_QUERY_PE_DMA_WIN], 3, 5, (u32 *)query,
+	ret = rtas_call(ddw_avail[DDW_QUERY_PE_DMA_WIN], 3, out_sz, query_out,
 			cfg_addr, BUID_HI(buid), BUID_LO(buid));
-	dev_info(&dev->dev, "ibm,query-pe-dma-windows(%x) %x %x %x"
-		" returned %d\n", ddw_avail[DDW_QUERY_PE_DMA_WIN], cfg_addr,
-		 BUID_HI(buid), BUID_LO(buid), ret);
+	dev_info(&dev->dev, "ibm,query-pe-dma-windows(%x) %x %x %x returned %d\n",
+		 ddw_avail[DDW_QUERY_PE_DMA_WIN], cfg_addr, BUID_HI(buid),
+		 BUID_LO(buid), ret);
+
+	switch (out_sz) {
+	case 5:
+		query->windows_available = query_out[0];
+		query->largest_available_block = query_out[1];
+		query->page_size = query_out[2];
+		query->migration_capable = query_out[3];
+		break;
+	case 6:
+		query->windows_available = query_out[0];
+		query->largest_available_block = ((u64)query_out[1] << 32) |
+						 query_out[2];
+		query->page_size = query_out[3];
+		query->migration_capable = query_out[4];
+		break;
+	}
+
 	return ret;
 }
 
@@ -1046,7 +1083,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	 * of page sizes: supported and supported for migrate-dma.
 	 */
 	dn = pci_device_to_OF_node(dev);
-	ret = query_ddw(dev, ddw_avail, &query);
+	ret = query_ddw(dev, ddw_avail, &query, pdn);
 	if (ret != 0)
 		goto out_failed;
 
@@ -1074,7 +1111,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	/* check largest block * page size > max memory hotplug addr */
 	max_addr = ddw_memory_hotplug_max();
 	if (query.largest_available_block < (max_addr >> page_shift)) {
-		dev_dbg(&dev->dev, "can't map partition max 0x%llx with %u "
+		dev_dbg(&dev->dev, "can't map partition max 0x%llx with %llu "
 			  "%llu-sized pages\n", max_addr,  query.largest_available_block,
 			  1ULL << page_shift);
 		goto out_failed;
-- 
2.25.4

Re: [PATCH v2 2/6] powerpc/pseries/iommu: Update call to ibm,query-pe-dma-windows

[Alexey Kardashevskiy]

On 24/06/2020 16:24, Leonardo Bras wrote:
> From LoPAR level 2.8, "ibm,ddw-extensions" index 3 can make the number of
> outputs from "ibm,query-pe-dma-windows" go from 5 to 6.
> 
> This change of output size is meant to expand the address size of
> largest_available_block PE TCE from 32-bit to 64-bit, which ends up
> shifting page_size and migration_capable.
> 
> This ends up requiring the update of
> ddw_query_response->largest_available_block from u32 to u64, and manually
> assigning the values from the buffer into this struct, according to
> output size.
> 
> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> ---
>  arch/powerpc/platforms/pseries/iommu.c | 57 +++++++++++++++++++++-----
>  1 file changed, 47 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 68d2aa9c71a8..558e5441c355 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -44,6 +44,10 @@
>  #define DDW_REMOVE_PE_DMA_WIN	2
>  #define DDW_APPLICABLE_SIZE	3
>  
> +#define DDW_EXT_SIZE		0
> +#define DDW_EXT_RESET_DMA_WIN	1
> +#define DDW_EXT_QUERY_OUT_SIZE	2


#define DDW_EXT_LAST (DDW_EXT_QUERY_OUT_SIZE + 1)
...


> +
>  static struct iommu_table_group *iommu_pseries_alloc_group(int node)
>  {
>  	struct iommu_table_group *table_group;
> @@ -339,7 +343,7 @@ struct direct_window {
>  /* Dynamic DMA Window support */
>  struct ddw_query_response {
>  	u32 windows_available;
> -	u32 largest_available_block;
> +	u64 largest_available_block;
>  	u32 page_size;
>  	u32 migration_capable;
>  };
> @@ -875,13 +879,29 @@ static int find_existing_ddw_windows(void)
>  machine_arch_initcall(pseries, find_existing_ddw_windows);
>  
>  static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
> -			struct ddw_query_response *query)
> +		     struct ddw_query_response *query,
> +		     struct device_node *parent)
>  {
>  	struct device_node *dn;
>  	struct pci_dn *pdn;
> -	u32 cfg_addr;
> +	u32 cfg_addr, query_out[5], ddw_ext[DDW_EXT_QUERY_OUT_SIZE + 1];


... and use DDW_EXT_LAST here.


>  	u64 buid;
> -	int ret;
> +	int ret, out_sz;
> +
> +	/*
> +	 * From LoPAR level 2.8, "ibm,ddw-extensions" index 3 can rule how many
> +	 * output parameters ibm,query-pe-dma-windows will have, ranging from
> +	 * 5 to 6.
> +	 */
> +
> +	ret = of_property_read_u32_array(parent, "ibm,ddw-extensions",
> +					 &ddw_ext[0],
> +					 DDW_EXT_QUERY_OUT_SIZE + 1);
> +	if (ret && ddw_ext[DDW_EXT_SIZE] > 1 &&

>= DDW_EXT_QUERY_OUT_SIZE ?  Thanks,


> +	    ddw_ext[DDW_EXT_QUERY_OUT_SIZE] == 1)
> +		out_sz = 6;
> +	else
> +		out_sz = 5;
>  
>  	/*
>  	 * Get the config address and phb buid of the PE window.
> @@ -894,11 +914,28 @@ static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
>  	buid = pdn->phb->buid;
>  	cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
>  
> -	ret = rtas_call(ddw_avail[DDW_QUERY_PE_DMA_WIN], 3, 5, (u32 *)query,
> +	ret = rtas_call(ddw_avail[DDW_QUERY_PE_DMA_WIN], 3, out_sz, query_out,
>  			cfg_addr, BUID_HI(buid), BUID_LO(buid));
> -	dev_info(&dev->dev, "ibm,query-pe-dma-windows(%x) %x %x %x"
> -		" returned %d\n", ddw_avail[DDW_QUERY_PE_DMA_WIN], cfg_addr,
> -		 BUID_HI(buid), BUID_LO(buid), ret);
> +	dev_info(&dev->dev, "ibm,query-pe-dma-windows(%x) %x %x %x returned %d\n",
> +		 ddw_avail[DDW_QUERY_PE_DMA_WIN], cfg_addr, BUID_HI(buid),
> +		 BUID_LO(buid), ret);
> +
> +	switch (out_sz) {
> +	case 5:
> +		query->windows_available = query_out[0];
> +		query->largest_available_block = query_out[1];
> +		query->page_size = query_out[2];
> +		query->migration_capable = query_out[3];
> +		break;
> +	case 6:
> +		query->windows_available = query_out[0];
> +		query->largest_available_block = ((u64)query_out[1] << 32) |
> +						 query_out[2];
> +		query->page_size = query_out[3];
> +		query->migration_capable = query_out[4];
> +		break;
> +	}
> +
>  	return ret;
>  }
>  
> @@ -1046,7 +1083,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  	 * of page sizes: supported and supported for migrate-dma.
>  	 */
>  	dn = pci_device_to_OF_node(dev);
> -	ret = query_ddw(dev, ddw_avail, &query);
> +	ret = query_ddw(dev, ddw_avail, &query, pdn);
>  	if (ret != 0)
>  		goto out_failed;
>  
> @@ -1074,7 +1111,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  	/* check largest block * page size > max memory hotplug addr */
>  	max_addr = ddw_memory_hotplug_max();
>  	if (query.largest_available_block < (max_addr >> page_shift)) {
> -		dev_dbg(&dev->dev, "can't map partition max 0x%llx with %u "
> +		dev_dbg(&dev->dev, "can't map partition max 0x%llx with %llu "
>  			  "%llu-sized pages\n", max_addr,  query.largest_available_block,
>  			  1ULL << page_shift);
>  		goto out_failed;
> 

-- 
Alexey

Re: [PATCH v2 2/6] powerpc/pseries/iommu: Update call to ibm,query-pe-dma-windows

[Leonardo Bras]

On Wed, 2020-07-01 at 18:17 +1000, Alexey Kardashevskiy wrote:
> 
> > +#define DDW_EXT_SIZE		0
> > +#define DDW_EXT_RESET_DMA_WIN	1
> > +#define DDW_EXT_QUERY_OUT_SIZE	2
> 
> #define DDW_EXT_LAST (DDW_EXT_QUERY_OUT_SIZE + 1)
> ...
> 
> 
> > +
> >  static struct iommu_table_group *iommu_pseries_alloc_group(int node)
> >  {
> >  	struct iommu_table_group *table_group;
> > @@ -339,7 +343,7 @@ struct direct_window {
> >  /* Dynamic DMA Window support */
> >  struct ddw_query_response {
> >  	u32 windows_available;
> > -	u32 largest_available_block;
> > +	u64 largest_available_block;
> >  	u32 page_size;
> >  	u32 migration_capable;
> >  };
> > @@ -875,13 +879,29 @@ static int find_existing_ddw_windows(void)
> >  machine_arch_initcall(pseries, find_existing_ddw_windows);
> >  
> >  static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
> > -			struct ddw_query_response *query)
> > +		     struct ddw_query_response *query,
> > +		     struct device_node *parent)
> >  {
> >  	struct device_node *dn;
> >  	struct pci_dn *pdn;
> > -	u32 cfg_addr;
> > +	u32 cfg_addr, query_out[5], ddw_ext[DDW_EXT_QUERY_OUT_SIZE + 1];
> 
> ... and use DDW_EXT_LAST here.

Because of the growing nature of ddw-extensions, I intentionally let
this be (DDW_EXT_QUERY_OUT_SIZE + 1). If we create a DDW_EXT_LAST, it
will be incremented in the future if more extensions come to exist.

I mean, I previously saw no reason for allocating space for extensions
after the desired one, as they won't be used here.

> 
> 
> >  	u64 buid;
> > -	int ret;
> > +	int ret, out_sz;
> > +
> > +	/*
> > +	 * From LoPAR level 2.8, "ibm,ddw-extensions" index 3 can rule how many
> > +	 * output parameters ibm,query-pe-dma-windows will have, ranging from
> > +	 * 5 to 6.
> > +	 */
> > +
> > +	ret = of_property_read_u32_array(parent, "ibm,ddw-extensions",
> > +					 &ddw_ext[0],
> > +					 DDW_EXT_QUERY_OUT_SIZE + 1);

In this case, I made sure not to cross (DDW_EXT_QUERY_OUT_SIZE + 1)
while reading the extensions from the property.

What do you think about it? 

Best regards,
Leonardo 

Re: [PATCH v2 2/6] powerpc/pseries/iommu: Update call to ibm,query-pe-dma-windows

[Alexey Kardashevskiy]

On 02/07/2020 00:04, Leonardo Bras wrote:
> On Wed, 2020-07-01 at 18:17 +1000, Alexey Kardashevskiy wrote:
>>
>>> +#define DDW_EXT_SIZE		0
>>> +#define DDW_EXT_RESET_DMA_WIN	1
>>> +#define DDW_EXT_QUERY_OUT_SIZE	2
>>
>> #define DDW_EXT_LAST (DDW_EXT_QUERY_OUT_SIZE + 1)
>> ...
>>
>>
>>> +
>>>  static struct iommu_table_group *iommu_pseries_alloc_group(int node)
>>>  {
>>>  	struct iommu_table_group *table_group;
>>> @@ -339,7 +343,7 @@ struct direct_window {
>>>  /* Dynamic DMA Window support */
>>>  struct ddw_query_response {
>>>  	u32 windows_available;
>>> -	u32 largest_available_block;
>>> +	u64 largest_available_block;
>>>  	u32 page_size;
>>>  	u32 migration_capable;
>>>  };
>>> @@ -875,13 +879,29 @@ static int find_existing_ddw_windows(void)
>>>  machine_arch_initcall(pseries, find_existing_ddw_windows);
>>>  
>>>  static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
>>> -			struct ddw_query_response *query)
>>> +		     struct ddw_query_response *query,
>>> +		     struct device_node *parent)
>>>  {
>>>  	struct device_node *dn;
>>>  	struct pci_dn *pdn;
>>> -	u32 cfg_addr;
>>> +	u32 cfg_addr, query_out[5], ddw_ext[DDW_EXT_QUERY_OUT_SIZE + 1];
>>
>> ... and use DDW_EXT_LAST here.
> 
> Because of the growing nature of ddw-extensions, I intentionally let
> this be (DDW_EXT_QUERY_OUT_SIZE + 1). If we create a DDW_EXT_LAST, it
> will be incremented in the future if more extensions come to exist.
> 
> I mean, I previously saw no reason for allocating space for extensions
> after the desired one, as they won't be used here.

Ah, my bad, you're right.


> 
>>
>>
>>>  	u64 buid;
>>> -	int ret;
>>> +	int ret, out_sz;
>>> +
>>> +	/*
>>> +	 * From LoPAR level 2.8, "ibm,ddw-extensions" index 3 can rule how many
>>> +	 * output parameters ibm,query-pe-dma-windows will have, ranging from
>>> +	 * 5 to 6.
>>> +	 */
>>> +
>>> +	ret = of_property_read_u32_array(parent, "ibm,ddw-extensions",
>>> +					 &ddw_ext[0],
>>> +					 DDW_EXT_QUERY_OUT_SIZE + 1);
> 
> In this case, I made sure not to cross (DDW_EXT_QUERY_OUT_SIZE + 1)
> while reading the extensions from the property.
> 
> What do you think about it? 

I think you want something like:

static inline int ddw_read_ext(const struct device_node *np, int extnum,
u32 *ret)
{
retun of_property_read_u32_index(np, "ibm,ddw-extensions", extnum + 1, ret);
}

These "+1"'s all over the place are confusing.


-- 
Alexey

Re: [PATCH v2 2/6] powerpc/pseries/iommu: Update call to ibm,query-pe-dma-windows

[Leonardo Bras]

On Thu, 2020-07-02 at 10:18 +1000, Alexey Kardashevskiy wrote:
> 
> On 02/07/2020 00:04, Leonardo Bras wrote:
> > On Wed, 2020-07-01 at 18:17 +1000, Alexey Kardashevskiy wrote:
> > > > +#define DDW_EXT_SIZE		0
> > > > +#define DDW_EXT_RESET_DMA_WIN	1
> > > > +#define DDW_EXT_QUERY_OUT_SIZE	2
> > > 
> > > #define DDW_EXT_LAST (DDW_EXT_QUERY_OUT_SIZE + 1)
> > > ...
> > > 
> > > 
> > > > +
> > > >  static struct iommu_table_group *iommu_pseries_alloc_group(int node)
> > > >  {
> > > >  	struct iommu_table_group *table_group;
> > > > @@ -339,7 +343,7 @@ struct direct_window {
> > > >  /* Dynamic DMA Window support */
> > > >  struct ddw_query_response {
> > > >  	u32 windows_available;
> > > > -	u32 largest_available_block;
> > > > +	u64 largest_available_block;
> > > >  	u32 page_size;
> > > >  	u32 migration_capable;
> > > >  };
> > > > @@ -875,13 +879,29 @@ static int find_existing_ddw_windows(void)
> > > >  machine_arch_initcall(pseries, find_existing_ddw_windows);
> > > >  
> > > >  static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
> > > > -			struct ddw_query_response *query)
> > > > +		     struct ddw_query_response *query,
> > > > +		     struct device_node *parent)
> > > >  {
> > > >  	struct device_node *dn;
> > > >  	struct pci_dn *pdn;
> > > > -	u32 cfg_addr;
> > > > +	u32 cfg_addr, query_out[5], ddw_ext[DDW_EXT_QUERY_OUT_SIZE + 1];
> > > 
> > > ... and use DDW_EXT_LAST here.
> > 
> > Because of the growing nature of ddw-extensions, I intentionally let
> > this be (DDW_EXT_QUERY_OUT_SIZE + 1). If we create a DDW_EXT_LAST, it
> > will be incremented in the future if more extensions come to exist.
> > 
> > I mean, I previously saw no reason for allocating space for extensions
> > after the desired one, as they won't be used here.
> 
> Ah, my bad, you're right.
> 
> 
> > > 
> > > >  	u64 buid;
> > > > -	int ret;
> > > > +	int ret, out_sz;
> > > > +
> > > > +	/*
> > > > +	 * From LoPAR level 2.8, "ibm,ddw-extensions" index 3 can rule how many
> > > > +	 * output parameters ibm,query-pe-dma-windows will have, ranging from
> > > > +	 * 5 to 6.
> > > > +	 */
> > > > +
> > > > +	ret = of_property_read_u32_array(parent, "ibm,ddw-extensions",
> > > > +					 &ddw_ext[0],
> > > > +					 DDW_EXT_QUERY_OUT_SIZE + 1);
> > 
> > In this case, I made sure not to cross (DDW_EXT_QUERY_OUT_SIZE + 1)
> > while reading the extensions from the property.
> > 
> > What do you think about it? 
> 
> I think you want something like:
> 
> static inline int ddw_read_ext(const struct device_node *np, int extnum,
> u32 *ret)
> {
> retun of_property_read_u32_index(np, "ibm,ddw-extensions", extnum + 1, ret);
> }
> 
> These "+1"'s all over the place are confusing.

That's a great idea!

I was not aware it was possible to read a single value[index] directly
from the property, but it makes total sense to use it.

Thank you!

[PATCH v2 3/6] powerpc/pseries/iommu: Move window-removing part of remove_ddw into remove_dma_window

[Leonardo Bras]

Move the window-removing part of remove_ddw into a new function
(remove_dma_window), so it can be used to remove other DMA windows.

It's useful for removing DMA windows that don't create DIRECT64_PROPNAME
property, like the default DMA window from the device, which uses
"ibm,dma-window".

Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
---
 arch/powerpc/platforms/pseries/iommu.c | 45 +++++++++++++++-----------
 1 file changed, 27 insertions(+), 18 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 558e5441c355..a8840d9e1c35 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -776,25 +776,14 @@ static int __init disable_ddw_setup(char *str)
 
 early_param("disable_ddw", disable_ddw_setup);
 
-static void remove_ddw(struct device_node *np, bool remove_prop)
+static void remove_dma_window(struct device_node *np, u32 *ddw_avail,
+			      struct property *win)
 {
 	struct dynamic_dma_window_prop *dwp;
-	struct property *win64;
-	u32 ddw_avail[DDW_APPLICABLE_SIZE];
 	u64 liobn;
-	int ret = 0;
-
-	ret = of_property_read_u32_array(np, "ibm,ddw-applicable",
-					 &ddw_avail[0], DDW_APPLICABLE_SIZE);
-
-	win64 = of_find_property(np, DIRECT64_PROPNAME, NULL);
-	if (!win64)
-		return;
-
-	if (ret || win64->length < sizeof(*dwp))
-		goto delprop;
+	int ret;
 
-	dwp = win64->value;
+	dwp = win->value;
 	liobn = (u64)be32_to_cpu(dwp->liobn);
 
 	/* clear the whole window, note the arg is in kernel pages */
@@ -816,10 +805,30 @@ static void remove_ddw(struct device_node *np, bool remove_prop)
 		pr_debug("%pOF: successfully removed direct window: rtas returned "
 			"%d to ibm,remove-pe-dma-window(%x) %llx\n",
 			np, ret, ddw_avail[DDW_REMOVE_PE_DMA_WIN], liobn);
+}
+
+static void remove_ddw(struct device_node *np, bool remove_prop)
+{
+	struct property *win;
+	u32 ddw_avail[DDW_APPLICABLE_SIZE];
+	int ret = 0;
+
+	ret = of_property_read_u32_array(np, "ibm,ddw-applicable",
+					 &ddw_avail[0], DDW_APPLICABLE_SIZE);
+	if (ret)
+		return;
+
+	win = of_find_property(np, DIRECT64_PROPNAME, NULL);
+	if (!win)
+		return;
+
+	if (win->length >= sizeof(struct dynamic_dma_window_prop))
+		remove_dma_window(np, ddw_avail, win);
+
+	if (!remove_prop)
+		return;
 
-delprop:
-	if (remove_prop)
-		ret = of_remove_property(np, win64);
+	ret = of_remove_property(np, win);
 	if (ret)
 		pr_warn("%pOF: failed to remove direct window property: %d\n",
 			np, ret);
-- 
2.25.4

[PATCH v2 4/6] powerpc/pseries/iommu: Remove default DMA window before creating DDW

[Leonardo Bras]

On LoPAR "DMA Window Manipulation Calls", it's recommended to remove the
default DMA window for the device, before attempting to configure a DDW,
in order to make the maximum resources available for the next DDW to be
created.

This is a requirement for some devices to use DDW, given they only
allow one DMA window.

If setting up a new DDW fails anywhere after the removal of this
default DMA window, it's needed to restore the default DMA window.
For this, an implementation of ibm,reset-pe-dma-windows rtas call is
needed:

Platforms supporting the DDW option starting with LoPAR level 2.7 implement
ibm,ddw-extensions. The first extension available (index 2) carries the
token for ibm,reset-pe-dma-windows rtas call, which is used to restore
the default DMA window for a device, if it has been deleted.

It does so by resetting the TCE table allocation for the PE to it's
boot time value, available in "ibm,dma-window" device tree node.

Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
---
 arch/powerpc/platforms/pseries/iommu.c | 70 ++++++++++++++++++++++----
 1 file changed, 61 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index a8840d9e1c35..4fcf00016fb1 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1029,6 +1029,39 @@ static phys_addr_t ddw_memory_hotplug_max(void)
 	return max_addr;
 }
 
+/*
+ * Platforms supporting the DDW option starting with LoPAR level 2.7 implement
+ * ibm,ddw-extensions, which carries the rtas token for
+ * ibm,reset-pe-dma-windows.
+ * That rtas-call can be used to restore the default DMA window for the device.
+ */
+static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn)
+{
+	int ret;
+	u32 cfg_addr, ddw_ext[DDW_EXT_RESET_DMA_WIN + 1];
+	u64 buid;
+	struct device_node *dn;
+	struct pci_dn *pdn;
+
+	ret = of_property_read_u32_array(par_dn, "ibm,ddw-extensions",
+					 &ddw_ext[0], DDW_EXT_RESET_DMA_WIN + 1);
+	if (ret)
+		return;
+
+	dn = pci_device_to_OF_node(dev);
+	pdn = PCI_DN(dn);
+	buid = pdn->phb->buid;
+	cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
+
+	ret = rtas_call(ddw_ext[DDW_EXT_RESET_DMA_WIN], 3, 1, NULL, cfg_addr,
+			BUID_HI(buid), BUID_LO(buid));
+	if (ret)
+		dev_info(&dev->dev,
+			 "ibm,reset-pe-dma-windows(%x) %x %x %x returned %d ",
+			 ddw_ext[1], cfg_addr, BUID_HI(buid), BUID_LO(buid),
+			 ret);
+}
+
 /*
  * If the PE supports dynamic dma windows, and there is space for a table
  * that can map all pages in a linear offset, then setup such a table,
@@ -1049,8 +1082,9 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	u64 dma_addr, max_addr;
 	struct device_node *dn;
 	u32 ddw_avail[DDW_APPLICABLE_SIZE];
+
 	struct direct_window *window;
-	struct property *win64;
+	struct property *win64, *default_win = NULL, *ddw_ext = NULL;
 	struct dynamic_dma_window_prop *ddwprop;
 	struct failed_ddw_pdn *fpdn;
 
@@ -1085,7 +1119,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	if (ret)
 		goto out_failed;
 
-       /*
+	/*
 	 * Query if there is a second window of size to map the
 	 * whole partition.  Query returns number of windows, largest
 	 * block assigned to PE (partition endpoint), and two bitmasks
@@ -1096,15 +1130,31 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	if (ret != 0)
 		goto out_failed;
 
+	/*
+	 * If there is no window available, remove the default DMA window,
+	 * if it's present. This will make all the resources available to the
+	 * new DDW window.
+	 * If anything fails after this, we need to restore it, so also check
+	 * for extensions presence.
+	 */
 	if (query.windows_available == 0) {
-		/*
-		 * no additional windows are available for this device.
-		 * We might be able to reallocate the existing window,
-		 * trading in for a larger page size.
-		 */
-		dev_dbg(&dev->dev, "no free dynamic windows");
-		goto out_failed;
+		default_win = of_find_property(pdn, "ibm,dma-window", NULL);
+		ddw_ext = of_find_property(pdn, "ibm,ddw-extensions", NULL);
+		if (default_win && ddw_ext)
+			remove_dma_window(pdn, ddw_avail, default_win);
+
+		/* Query again, to check if the window is available */
+		ret = query_ddw(dev, ddw_avail, &query, pdn);
+		if (ret != 0)
+			goto out_failed;
+
+		if (query.windows_available == 0) {
+			/* no windows are available for this device. */
+			dev_dbg(&dev->dev, "no free dynamic windows");
+			goto out_failed;
+		}
 	}
+
 	if (query.page_size & 4) {
 		page_shift = 24; /* 16MB */
 	} else if (query.page_size & 2) {
@@ -1194,6 +1244,8 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	kfree(win64);
 
 out_failed:
+	if (default_win && ddw_ext)
+		reset_dma_window(dev, pdn);
 
 	fpdn = kzalloc(sizeof(*fpdn), GFP_KERNEL);
 	if (!fpdn)
-- 
2.25.4

Re: [PATCH v2 4/6] powerpc/pseries/iommu: Remove default DMA window before creating DDW

[Alexey Kardashevskiy]

On 24/06/2020 16:24, Leonardo Bras wrote:
> On LoPAR "DMA Window Manipulation Calls", it's recommended to remove the
> default DMA window for the device, before attempting to configure a DDW,
> in order to make the maximum resources available for the next DDW to be
> created.
> 
> This is a requirement for some devices to use DDW, given they only
> allow one DMA window.


Devices never know about these windows, it is purely PHB's side of
things. A device can access any address on the bus, the bus can generate
an exception if there is no window behind the address OR some other
device's MMIO. We could actually create a second window in addition to
the first one and allocate bus addresses from both, we just simplifying
this by merging two separate non-adjacent windows into one.


> 
> If setting up a new DDW fails anywhere after the removal of this
> default DMA window, it's needed to restore the default DMA window.
> For this, an implementation of ibm,reset-pe-dma-windows rtas call is
> needed:
> 
> Platforms supporting the DDW option starting with LoPAR level 2.7 implement
> ibm,ddw-extensions. The first extension available (index 2) carries the
> token for ibm,reset-pe-dma-windows rtas call, which is used to restore
> the default DMA window for a device, if it has been deleted.
> 
> It does so by resetting the TCE table allocation for the PE to it's
> boot time value, available in "ibm,dma-window" device tree node.
> 
> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> ---
>  arch/powerpc/platforms/pseries/iommu.c | 70 ++++++++++++++++++++++----
>  1 file changed, 61 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index a8840d9e1c35..4fcf00016fb1 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -1029,6 +1029,39 @@ static phys_addr_t ddw_memory_hotplug_max(void)
>  	return max_addr;
>  }
>  
> +/*
> + * Platforms supporting the DDW option starting with LoPAR level 2.7 implement
> + * ibm,ddw-extensions, which carries the rtas token for
> + * ibm,reset-pe-dma-windows.
> + * That rtas-call can be used to restore the default DMA window for the device.
> + */
> +static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn)
> +{
> +	int ret;
> +	u32 cfg_addr, ddw_ext[DDW_EXT_RESET_DMA_WIN + 1];
> +	u64 buid;
> +	struct device_node *dn;
> +	struct pci_dn *pdn;
> +
> +	ret = of_property_read_u32_array(par_dn, "ibm,ddw-extensions",
> +					 &ddw_ext[0], DDW_EXT_RESET_DMA_WIN + 1);
> +	if (ret)
> +		return;
> +
> +	dn = pci_device_to_OF_node(dev);
> +	pdn = PCI_DN(dn);
> +	buid = pdn->phb->buid;
> +	cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
> +
> +	ret = rtas_call(ddw_ext[DDW_EXT_RESET_DMA_WIN], 3, 1, NULL, cfg_addr,
> +			BUID_HI(buid), BUID_LO(buid));
> +	if (ret)
> +		dev_info(&dev->dev,
> +			 "ibm,reset-pe-dma-windows(%x) %x %x %x returned %d ",
> +			 ddw_ext[1], cfg_addr, BUID_HI(buid), BUID_LO(buid),


s/ddw_ext[1]/ddw_ext[DDW_EXT_RESET_DMA_WIN]/


> +			 ret);
> +}
> +
>  /*
>   * If the PE supports dynamic dma windows, and there is space for a table
>   * that can map all pages in a linear offset, then setup such a table,
> @@ -1049,8 +1082,9 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  	u64 dma_addr, max_addr;
>  	struct device_node *dn;
>  	u32 ddw_avail[DDW_APPLICABLE_SIZE];
> +

Unrelated new empty line.


>  	struct direct_window *window;
> -	struct property *win64;
> +	struct property *win64, *default_win = NULL, *ddw_ext = NULL;
>  	struct dynamic_dma_window_prop *ddwprop;
>  	struct failed_ddw_pdn *fpdn;
>  
> @@ -1085,7 +1119,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  	if (ret)
>  		goto out_failed;
>  
> -       /*
> +	/*
>  	 * Query if there is a second window of size to map the
>  	 * whole partition.  Query returns number of windows, largest
>  	 * block assigned to PE (partition endpoint), and two bitmasks
> @@ -1096,15 +1130,31 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  	if (ret != 0)
>  		goto out_failed;
>  
> +	/*
> +	 * If there is no window available, remove the default DMA window,
> +	 * if it's present. This will make all the resources available to the
> +	 * new DDW window.
> +	 * If anything fails after this, we need to restore it, so also check
> +	 * for extensions presence.
> +	 */
>  	if (query.windows_available == 0) {


Does phyp really always advertise 0 windows for these VFs? What is in
the largest_available_block when windows_available==0?


> -		/*
> -		 * no additional windows are available for this device.
> -		 * We might be able to reallocate the existing window,
> -		 * trading in for a larger page size.
> -		 */
> -		dev_dbg(&dev->dev, "no free dynamic windows");
> -		goto out_failed;
> +		default_win = of_find_property(pdn, "ibm,dma-window", NULL);
> +		ddw_ext = of_find_property(pdn, "ibm,ddw-extensions", NULL);
> +		if (default_win && ddw_ext)
> +			remove_dma_window(pdn, ddw_avail, default_win);
> +
> +		/* Query again, to check if the window is available */
> +		ret = query_ddw(dev, ddw_avail, &query, pdn);
> +		if (ret != 0)
> +			goto out_failed;
> +
> +		if (query.windows_available == 0) {
> +			/* no windows are available for this device. */
> +			dev_dbg(&dev->dev, "no free dynamic windows");
> +			goto out_failed;
> +		}
>  	}
> +


Unrelated new empty line. Thanks,

>  	if (query.page_size & 4) {
>  		page_shift = 24; /* 16MB */
>  	} else if (query.page_size & 2) {
> @@ -1194,6 +1244,8 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  	kfree(win64);
>  
>  out_failed:
> +	if (default_win && ddw_ext)
> +		reset_dma_window(dev, pdn);
>  
>  	fpdn = kzalloc(sizeof(*fpdn), GFP_KERNEL);
>  	if (!fpdn)
> 

-- 
Alexey

Re: [PATCH v2 4/6] powerpc/pseries/iommu: Remove default DMA window before creating DDW

[Leonardo Bras]

On Wed, 2020-07-01 at 18:17 +1000, Alexey Kardashevskiy wrote:
> 
> On 24/06/2020 16:24, Leonardo Bras wrote:
> > On LoPAR "DMA Window Manipulation Calls", it's recommended to remove the
> > default DMA window for the device, before attempting to configure a DDW,
> > in order to make the maximum resources available for the next DDW to be
> > created.
> > 
> > This is a requirement for some devices to use DDW, given they only
> > allow one DMA window.
> 
> Devices never know about these windows, it is purely PHB's side of
> things. A device can access any address on the bus, the bus can generate
> an exception if there is no window behind the address OR some other
> device's MMIO. We could actually create a second window in addition to
> the first one and allocate bus addresses from both, we just simplifying
> this by merging two separate non-adjacent windows into one.

That's interesting, I was not aware of this. 
I will try to improve this commit message with this info.
Thanks for sharing!

> > > > If setting up a new DDW fails anywhere after the removal of this
> > default DMA window, it's needed to restore the default DMA window.
> > For this, an implementation of ibm,reset-pe-dma-windows rtas call is
> > needed:
> > 
> > Platforms supporting the DDW option starting with LoPAR level 2.7 implement
> > ibm,ddw-extensions. The first extension available (index 2) carries the
> > token for ibm,reset-pe-dma-windows rtas call, which is used to restore
> > the default DMA window for a device, if it has been deleted.
> > 
> > It does so by resetting the TCE table allocation for the PE to it's
> > boot time value, available in "ibm,dma-window" device tree node.
> > 
> > Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> > ---
> >  arch/powerpc/platforms/pseries/iommu.c | 70 ++++++++++++++++++++++----
> >  1 file changed, 61 insertions(+), 9 deletions(-)
> > 
> > diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> > index a8840d9e1c35..4fcf00016fb1 100644
> > --- a/arch/powerpc/platforms/pseries/iommu.c
> > +++ b/arch/powerpc/platforms/pseries/iommu.c
> > @@ -1029,6 +1029,39 @@ static phys_addr_t ddw_memory_hotplug_max(void)
> >  	return max_addr;
> >  }
> >  
> > +/*
> > + * Platforms supporting the DDW option starting with LoPAR level 2.7 implement
> > + * ibm,ddw-extensions, which carries the rtas token for
> > + * ibm,reset-pe-dma-windows.
> > + * That rtas-call can be used to restore the default DMA window for the device.
> > + */
> > +static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn)
> > +{
> > +	int ret;
> > +	u32 cfg_addr, ddw_ext[DDW_EXT_RESET_DMA_WIN + 1];
> > +	u64 buid;
> > +	struct device_node *dn;
> > +	struct pci_dn *pdn;
> > +
> > +	ret = of_property_read_u32_array(par_dn, "ibm,ddw-extensions",
> > +					 &ddw_ext[0], DDW_EXT_RESET_DMA_WIN + 1);
> > +	if (ret)
> > +		return;
> > +
> > +	dn = pci_device_to_OF_node(dev);
> > +	pdn = PCI_DN(dn);
> > +	buid = pdn->phb->buid;
> > +	cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
> > +
> > +	ret = rtas_call(ddw_ext[DDW_EXT_RESET_DMA_WIN], 3, 1, NULL, cfg_addr,
> > +			BUID_HI(buid), BUID_LO(buid));
> > +	if (ret)
> > +		dev_info(&dev->dev,
> > +			 "ibm,reset-pe-dma-windows(%x) %x %x %x returned %d ",
> > +			 ddw_ext[1], cfg_addr, BUID_HI(buid), BUID_LO(buid),
> 
> s/ddw_ext[1]/ddw_ext[DDW_EXT_RESET_DMA_WIN]/

Good catch! I missed this one.

> 
> 
> > +			 ret);
> > +}
> > +
> >  /*
> >   * If the PE supports dynamic dma windows, and there is space for a table
> >   * that can map all pages in a linear offset, then setup such a table,
> > @@ -1049,8 +1082,9 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
> >  	u64 dma_addr, max_addr;
> >  	struct device_node *dn;
> >  	u32 ddw_avail[DDW_APPLICABLE_SIZE];
> > +
> 
> Unrelated new empty line.

Fixed!

> 
> 
> >  	struct direct_window *window;
> > -	struct property *win64;
> > +	struct property *win64, *default_win = NULL, *ddw_ext = NULL;
> >  	struct dynamic_dma_window_prop *ddwprop;
> >  	struct failed_ddw_pdn *fpdn;
> >  
> > @@ -1085,7 +1119,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
> >  	if (ret)
> >  		goto out_failed;
> >  
> > -       /*
> > +	/*
> >  	 * Query if there is a second window of size to map the
> >  	 * whole partition.  Query returns number of windows, largest
> >  	 * block assigned to PE (partition endpoint), and two bitmasks
> > @@ -1096,15 +1130,31 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
> >  	if (ret != 0)
> >  		goto out_failed;
> >  
> > +	/*
> > +	 * If there is no window available, remove the default DMA window,
> > +	 * if it's present. This will make all the resources available to the
> > +	 * new DDW window.
> > +	 * If anything fails after this, we need to restore it, so also check
> > +	 * for extensions presence.
> > +	 */
> >  	if (query.windows_available == 0) {
> 
> Does phyp really always advertise 0 windows for these VFs? What is in
> the largest_available_block when windows_available==0?

For this VF, it always advertise 0 windows before removing the default
DMA window. The largest available block size is the same as after the
removal (256GB). The only value that changes after removal is the
number of available windows. Here some debug prints:

[    3.473149] mlx5_core 4005:01:00.0: ibm,query-pe-dma-windows(53)
10000 8000000 29004005 returned 0
[    3.473162] mlx5_core 4005:01:00.0: windows_available = 0,
largest_block = 400000, page_size = 3, migration_capable = 3
[    3.473332] mlx5_core 4005:01:00.0: ibm,query-pe-dma-windows(53)
10000 8000000 29004005 returned 0
[    3.473345] mlx5_core 4005:01:00.0: windows_available = 1,
largest_block = 400000, page_size = 3, migration_capable = 3

> 
> 
> > -		/*
> > -		 * no additional windows are available for this device.
> > -		 * We might be able to reallocate the existing window,
> > -		 * trading in for a larger page size.
> > -		 */
> > -		dev_dbg(&dev->dev, "no free dynamic windows");
> > -		goto out_failed;
> > +		default_win = of_find_property(pdn, "ibm,dma-window", NULL);
> > +		ddw_ext = of_find_property(pdn, "ibm,ddw-extensions", NULL);
> > +		if (default_win && ddw_ext)
> > +			remove_dma_window(pdn, ddw_avail, default_win);
> > +
> > +		/* Query again, to check if the window is available */
> > +		ret = query_ddw(dev, ddw_avail, &query, pdn);
> > +		if (ret != 0)
> > +			goto out_failed;
> > +
> > +		if (query.windows_available == 0) {
> > +			/* no windows are available for this device. */
> > +			dev_dbg(&dev->dev, "no free dynamic windows");
> > +			goto out_failed;
> > +		}
> >  	}
> > +
> 
> Unrelated new empty line. Thanks,
Fixed!
Thank you!

> 
> >  	if (query.page_size & 4) {
> >  		page_shift = 24; /* 16MB */
> >  	} else if (query.page_size & 2) {
> > @@ -1194,6 +1244,8 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
> >  	kfree(win64);
> >  
> >  out_failed:
> > +	if (default_win && ddw_ext)
> > +		reset_dma_window(dev, pdn);
> >  
> >  	fpdn = kzalloc(sizeof(*fpdn), GFP_KERNEL);
> >  	if (!fpdn)
> > 

Re: [PATCH v2 4/6] powerpc/pseries/iommu: Remove default DMA window before creating DDW

[Alexey Kardashevskiy]

On 02/07/2020 05:48, Leonardo Bras wrote:
> On Wed, 2020-07-01 at 18:17 +1000, Alexey Kardashevskiy wrote:
>>
>> On 24/06/2020 16:24, Leonardo Bras wrote:
>>> On LoPAR "DMA Window Manipulation Calls", it's recommended to remove the
>>> default DMA window for the device, before attempting to configure a DDW,
>>> in order to make the maximum resources available for the next DDW to be
>>> created.
>>>
>>> This is a requirement for some devices to use DDW, given they only
>>> allow one DMA window.
>>
>> Devices never know about these windows, it is purely PHB's side of
>> things. A device can access any address on the bus, the bus can generate
>> an exception if there is no window behind the address OR some other
>> device's MMIO. We could actually create a second window in addition to
>> the first one and allocate bus addresses from both, we just simplifying
>> this by merging two separate non-adjacent windows into one.
> 
> That's interesting, I was not aware of this. 
> I will try to improve this commit message with this info.
> Thanks for sharing!
> 
>>>>> If setting up a new DDW fails anywhere after the removal of this
>>> default DMA window, it's needed to restore the default DMA window.
>>> For this, an implementation of ibm,reset-pe-dma-windows rtas call is
>>> needed:
>>>
>>> Platforms supporting the DDW option starting with LoPAR level 2.7 implement
>>> ibm,ddw-extensions. The first extension available (index 2) carries the
>>> token for ibm,reset-pe-dma-windows rtas call, which is used to restore
>>> the default DMA window for a device, if it has been deleted.
>>>
>>> It does so by resetting the TCE table allocation for the PE to it's
>>> boot time value, available in "ibm,dma-window" device tree node.
>>>
>>> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
>>> ---
>>>  arch/powerpc/platforms/pseries/iommu.c | 70 ++++++++++++++++++++++----
>>>  1 file changed, 61 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
>>> index a8840d9e1c35..4fcf00016fb1 100644
>>> --- a/arch/powerpc/platforms/pseries/iommu.c
>>> +++ b/arch/powerpc/platforms/pseries/iommu.c
>>> @@ -1029,6 +1029,39 @@ static phys_addr_t ddw_memory_hotplug_max(void)
>>>  	return max_addr;
>>>  }
>>>  
>>> +/*
>>> + * Platforms supporting the DDW option starting with LoPAR level 2.7 implement
>>> + * ibm,ddw-extensions, which carries the rtas token for
>>> + * ibm,reset-pe-dma-windows.
>>> + * That rtas-call can be used to restore the default DMA window for the device.
>>> + */
>>> +static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn)
>>> +{
>>> +	int ret;
>>> +	u32 cfg_addr, ddw_ext[DDW_EXT_RESET_DMA_WIN + 1];
>>> +	u64 buid;
>>> +	struct device_node *dn;
>>> +	struct pci_dn *pdn;
>>> +
>>> +	ret = of_property_read_u32_array(par_dn, "ibm,ddw-extensions",
>>> +					 &ddw_ext[0], DDW_EXT_RESET_DMA_WIN + 1);
>>> +	if (ret)
>>> +		return;
>>> +
>>> +	dn = pci_device_to_OF_node(dev);
>>> +	pdn = PCI_DN(dn);
>>> +	buid = pdn->phb->buid;
>>> +	cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
>>> +
>>> +	ret = rtas_call(ddw_ext[DDW_EXT_RESET_DMA_WIN], 3, 1, NULL, cfg_addr,
>>> +			BUID_HI(buid), BUID_LO(buid));
>>> +	if (ret)
>>> +		dev_info(&dev->dev,
>>> +			 "ibm,reset-pe-dma-windows(%x) %x %x %x returned %d ",
>>> +			 ddw_ext[1], cfg_addr, BUID_HI(buid), BUID_LO(buid),
>>
>> s/ddw_ext[1]/ddw_ext[DDW_EXT_RESET_DMA_WIN]/
> 
> Good catch! I missed this one.
> 
>>
>>
>>> +			 ret);
>>> +}
>>> +
>>>  /*
>>>   * If the PE supports dynamic dma windows, and there is space for a table
>>>   * that can map all pages in a linear offset, then setup such a table,
>>> @@ -1049,8 +1082,9 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>>>  	u64 dma_addr, max_addr;
>>>  	struct device_node *dn;
>>>  	u32 ddw_avail[DDW_APPLICABLE_SIZE];
>>> +
>>
>> Unrelated new empty line.
> 
> Fixed!
> 
>>
>>
>>>  	struct direct_window *window;
>>> -	struct property *win64;
>>> +	struct property *win64, *default_win = NULL, *ddw_ext = NULL;
>>>  	struct dynamic_dma_window_prop *ddwprop;
>>>  	struct failed_ddw_pdn *fpdn;
>>>  
>>> @@ -1085,7 +1119,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>>>  	if (ret)
>>>  		goto out_failed;
>>>  
>>> -       /*
>>> +	/*
>>>  	 * Query if there is a second window of size to map the
>>>  	 * whole partition.  Query returns number of windows, largest
>>>  	 * block assigned to PE (partition endpoint), and two bitmasks
>>> @@ -1096,15 +1130,31 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>>>  	if (ret != 0)
>>>  		goto out_failed;
>>>  
>>> +	/*
>>> +	 * If there is no window available, remove the default DMA window,
>>> +	 * if it's present. This will make all the resources available to the
>>> +	 * new DDW window.
>>> +	 * If anything fails after this, we need to restore it, so also check
>>> +	 * for extensions presence.
>>> +	 */
>>>  	if (query.windows_available == 0) {
>>
>> Does phyp really always advertise 0 windows for these VFs? What is in
>> the largest_available_block when windows_available==0?
> 
> For this VF, it always advertise 0 windows before removing the default
> DMA window. The largest available block size is the same as after the
> removal (256GB). The only value that changes after removal is the
> number of available windows. Here some debug prints:

> 
> [    3.473149] mlx5_core 4005:01:00.0: ibm,query-pe-dma-windows(53)
> 10000 8000000 29004005 returned 0
> [    3.473162] mlx5_core 4005:01:00.0: windows_available = 0,
> largest_block = 400000, page_size = 3, migration_capable = 3
> [    3.473332] mlx5_core 4005:01:00.0: ibm,query-pe-dma-windows(53)
> 10000 8000000 29004005 returned 0
> [    3.473345] mlx5_core 4005:01:00.0: windows_available = 1,
> largest_block = 400000, page_size = 3, migration_capable = 3



Ah, I see, thanks for the info. Ok, they really do not want us to have 2
windows. Oh well.



> 
>>
>>
>>> -		/*
>>> -		 * no additional windows are available for this device.
>>> -		 * We might be able to reallocate the existing window,
>>> -		 * trading in for a larger page size.
>>> -		 */
>>> -		dev_dbg(&dev->dev, "no free dynamic windows");
>>> -		goto out_failed;
>>> +		default_win = of_find_property(pdn, "ibm,dma-window", NULL);
>>> +		ddw_ext = of_find_property(pdn, "ibm,ddw-extensions", NULL);
>>> +		if (default_win && ddw_ext)
>>> +			remove_dma_window(pdn, ddw_avail, default_win);
>>> +
>>> +		/* Query again, to check if the window is available */
>>> +		ret = query_ddw(dev, ddw_avail, &query, pdn);
>>> +		if (ret != 0)
>>> +			goto out_failed;
>>> +
>>> +		if (query.windows_available == 0) {
>>> +			/* no windows are available for this device. */
>>> +			dev_dbg(&dev->dev, "no free dynamic windows");
>>> +			goto out_failed;
>>> +		}
>>>  	}
>>> +
>>
>> Unrelated new empty line. Thanks,
> Fixed!
> Thank you!
> 
>>
>>>  	if (query.page_size & 4) {
>>>  		page_shift = 24; /* 16MB */
>>>  	} else if (query.page_size & 2) {
>>> @@ -1194,6 +1244,8 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>>>  	kfree(win64);
>>>  
>>>  out_failed:
>>> +	if (default_win && ddw_ext)
>>> +		reset_dma_window(dev, pdn);
>>>  
>>>  	fpdn = kzalloc(sizeof(*fpdn), GFP_KERNEL);
>>>  	if (!fpdn)
>>>
> 

-- 
Alexey

[PATCH v2 5/6] powerpc/pseries/iommu: Make use of DDW even if it does not map the partition

[Leonardo Bras]

As of today, if a DDW is created and can't map the whole partition, it's
removed and the default DMA window "ibm,dma-window" is used instead.

Usually this DDW is bigger than the default DMA window, so it would be
better to make use of it instead.

Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
---
 arch/powerpc/platforms/pseries/iommu.c | 28 +++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 4fcf00016fb1..2d217cda4075 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -685,7 +685,7 @@ static void pci_dma_bus_setup_pSeriesLP(struct pci_bus *bus)
 	struct iommu_table *tbl;
 	struct device_node *dn, *pdn;
 	struct pci_dn *ppci;
-	const __be32 *dma_window = NULL;
+	const __be32 *dma_window = NULL, *alt_dma_window = NULL;
 
 	dn = pci_bus_to_OF_node(bus);
 
@@ -699,8 +699,13 @@ static void pci_dma_bus_setup_pSeriesLP(struct pci_bus *bus)
 			break;
 	}
 
+	/* If there is a DDW available, use it instead */
+	alt_dma_window = of_get_property(pdn, DIRECT64_PROPNAME, NULL);
+	if (alt_dma_window)
+		dma_window = alt_dma_window;
+
 	if (dma_window == NULL) {
-		pr_debug("  no ibm,dma-window property !\n");
+		pr_debug("  no ibm,dma-window nor linux,direct64-ddr-window-info property !\n");
 		return;
 	}
 
@@ -1166,16 +1171,19 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 			  query.page_size);
 		goto out_failed;
 	}
+
 	/* verify the window * number of ptes will map the partition */
-	/* check largest block * page size > max memory hotplug addr */
 	max_addr = ddw_memory_hotplug_max();
 	if (query.largest_available_block < (max_addr >> page_shift)) {
-		dev_dbg(&dev->dev, "can't map partition max 0x%llx with %llu "
-			  "%llu-sized pages\n", max_addr,  query.largest_available_block,
-			  1ULL << page_shift);
-		goto out_failed;
+		dev_dbg(&dev->dev, "can't map partition max 0x%llx with %llu %llu-sized pages\n",
+			max_addr, query.largest_available_block,
+			1ULL << page_shift);
+
+		len = order_base_2(query.largest_available_block << page_shift);
+	} else {
+		len = order_base_2(max_addr);
 	}
-	len = order_base_2(max_addr);
+
 	win64 = kzalloc(sizeof(struct property), GFP_KERNEL);
 	if (!win64) {
 		dev_info(&dev->dev,
@@ -1229,7 +1237,9 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	list_add(&window->list, &direct_window_list);
 	spin_unlock(&direct_window_list_lock);
 
-	dma_addr = be64_to_cpu(ddwprop->dma_base);
+	/* Only returns the dma_addr if DDW maps the whole partition */
+	if (len == order_base_2(max_addr))
+		dma_addr = be64_to_cpu(ddwprop->dma_base);
 	goto out_unlock;
 
 out_free_window:
-- 
2.25.4

Re: [PATCH v2 5/6] powerpc/pseries/iommu: Make use of DDW even if it does not map the partition

[Leonardo Bras]

On Wed, 2020-06-24 at 03:24 -0300, Leonardo Bras wrote:
> As of today, if a DDW is created and can't map the whole partition, it's
> removed and the default DMA window "ibm,dma-window" is used instead.
> 
> Usually this DDW is bigger than the default DMA window, so it would be
> better to make use of it instead.
> 
> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> ---

I tested this change with a 256GB DDW which did not map the whole
partition, with a MT27700 Family [ConnectX-4 Virtual Function].

I noticed the performance improvement is about the same as using DDW
with IOMMU bypass.

64 thread write throughput: +203.0%
64 thread read throughput: +17.5%
1 thread write throughput: +20.5%
1 thread read throughput: +3.43%
Averag
e write latency: -23.0%
Average read latency:  -2.26%

Re: [PATCH v2 5/6] powerpc/pseries/iommu: Make use of DDW even if it does not map the partition

[Leonardo Bras]

On Fri, 2020-06-26 at 12:23 -0300, Leonardo Bras wrote:
> On Wed, 2020-06-24 at 03:24 -0300, Leonardo Bras wrote:
> > As of today, if a DDW is created and can't map the whole partition, it's
> > removed and the default DMA window "ibm,dma-window" is used instead.
> > 
> > Usually this DDW is bigger than the default DMA window, so it would be
> > better to make use of it instead.
> > 
> > Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> > ---
> 
> I tested this change with a 256GB DDW which did not map the whole
> partition, with a MT27700 Family [ConnectX-4 Virtual Function].
> 
> I noticed the performance improvement is about the same as using DDW
> with IOMMU bypass.
> 
> 64 thread write throughput: +203.0%
> 64 thread read throughput: +17.5%
> 1 thread write throughput: +20.5%
> 1 thread read throughput: +3.43%
> Average write latency: -23.0%
> Average read latency:  -2.26%

The above improvements are based on the default DMA window, which is
currently used if DDW can't map the whole partition.

Those values are an average of 20 tests for each environment, 30
seconds each test.

I also did some intense testing, for 5 hour each:
64 thread write throughput 
64 thread read throughput

The throughput values are stable in the whole test, and I noticed no
error on dmesg / journalctl.

Re: [PATCH v2 5/6] powerpc/pseries/iommu: Make use of DDW even if it does not map the partition

[Alexey Kardashevskiy]

On 24/06/2020 16:24, Leonardo Bras wrote:
> As of today, if a DDW is created and can't map the whole partition, it's
> removed and the default DMA window "ibm,dma-window" is used instead.
> 
> Usually this DDW is bigger than the default DMA window, so it would be
> better to make use of it instead.
> 
> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> ---
>  arch/powerpc/platforms/pseries/iommu.c | 28 +++++++++++++++++---------
>  1 file changed, 19 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 4fcf00016fb1..2d217cda4075 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -685,7 +685,7 @@ static void pci_dma_bus_setup_pSeriesLP(struct pci_bus *bus)
>  	struct iommu_table *tbl;
>  	struct device_node *dn, *pdn;
>  	struct pci_dn *ppci;
> -	const __be32 *dma_window = NULL;
> +	const __be32 *dma_window = NULL, *alt_dma_window = NULL;
>  
>  	dn = pci_bus_to_OF_node(bus);
>  
> @@ -699,8 +699,13 @@ static void pci_dma_bus_setup_pSeriesLP(struct pci_bus *bus)
>  			break;
>  	}
>  
> +	/* If there is a DDW available, use it instead */
> +	alt_dma_window = of_get_property(pdn, DIRECT64_PROPNAME, NULL);


It is not necessarily "direct" anymore as the name suggests, you may
want to change that. DMA64_PROPNAME, may be. Thanks,


> +	if (alt_dma_window)
> +		dma_window = alt_dma_window;
> +
>  	if (dma_window == NULL) {
> -		pr_debug("  no ibm,dma-window property !\n");
> +		pr_debug("  no ibm,dma-window nor linux,direct64-ddr-window-info property !\n");
>  		return;
>  	}
>  
> @@ -1166,16 +1171,19 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  			  query.page_size);
>  		goto out_failed;
>  	}
> +
>  	/* verify the window * number of ptes will map the partition */
> -	/* check largest block * page size > max memory hotplug addr */
>  	max_addr = ddw_memory_hotplug_max();
>  	if (query.largest_available_block < (max_addr >> page_shift)) {
> -		dev_dbg(&dev->dev, "can't map partition max 0x%llx with %llu "
> -			  "%llu-sized pages\n", max_addr,  query.largest_available_block,
> -			  1ULL << page_shift);
> -		goto out_failed;
> +		dev_dbg(&dev->dev, "can't map partition max 0x%llx with %llu %llu-sized pages\n",
> +			max_addr, query.largest_available_block,
> +			1ULL << page_shift);
> +
> +		len = order_base_2(query.largest_available_block << page_shift);
> +	} else {
> +		len = order_base_2(max_addr);
>  	}
> -	len = order_base_2(max_addr);
> +
>  	win64 = kzalloc(sizeof(struct property), GFP_KERNEL);
>  	if (!win64) {
>  		dev_info(&dev->dev,
> @@ -1229,7 +1237,9 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  	list_add(&window->list, &direct_window_list);
>  	spin_unlock(&direct_window_list_lock);
>  
> -	dma_addr = be64_to_cpu(ddwprop->dma_base);
> +	/* Only returns the dma_addr if DDW maps the whole partition */
> +	if (len == order_base_2(max_addr))
> +		dma_addr = be64_to_cpu(ddwprop->dma_base);
>  	goto out_unlock;
>  
>  out_free_window:
> 

-- 
Alexey

Re: [PATCH v2 5/6] powerpc/pseries/iommu: Make use of DDW even if it does not map the partition

[Leonardo Bras]

On Wed, 2020-07-01 at 18:16 +1000, Alexey Kardashevskiy wrote:
> 
> On 24/06/2020 16:24, Leonardo Bras wrote:
> > As of today, if a DDW is created and can't map the whole partition, it's
> > removed and the default DMA window "ibm,dma-window" is used instead.
> > 
> > Usually this DDW is bigger than the default DMA window, so it would be
> > better to make use of it instead.
> > 
> > Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> > ---
> >  arch/powerpc/platforms/pseries/iommu.c | 28 +++++++++++++++++---------
> >  1 file changed, 19 insertions(+), 9 deletions(-)
> > 
> > diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> > index 4fcf00016fb1..2d217cda4075 100644
> > --- a/arch/powerpc/platforms/pseries/iommu.c
> > +++ b/arch/powerpc/platforms/pseries/iommu.c
> > @@ -685,7 +685,7 @@ static void pci_dma_bus_setup_pSeriesLP(struct pci_bus *bus)
> >  	struct iommu_table *tbl;
> >  	struct device_node *dn, *pdn;
> >  	struct pci_dn *ppci;
> > -	const __be32 *dma_window = NULL;
> > +	const __be32 *dma_window = NULL, *alt_dma_window = NULL;
> >  
> >  	dn = pci_bus_to_OF_node(bus);
> >  
> > @@ -699,8 +699,13 @@ static void pci_dma_bus_setup_pSeriesLP(struct pci_bus *bus)
> >  			break;
> >  	}
> >  
> > +	/* If there is a DDW available, use it instead */
> > +	alt_dma_window = of_get_property(pdn, DIRECT64_PROPNAME, NULL);
> 
> It is not necessarily "direct" anymore as the name suggests, you may
> want to change that. DMA64_PROPNAME, may be. Thanks,
> 

Yeah, you are right.
I will change this for next version, also changing the string name to
reflect this.

-#define DIRECT64_PROPNAME "linux,direct64-ddr-window-info"
+#define DMA64_PROPNAME "linux,dma64-ddr-window-info"

Is that ok?

Thank you for helping!

Re: [PATCH v2 5/6] powerpc/pseries/iommu: Make use of DDW even if it does not map the partition

[Leonardo Bras]

On Wed, 2020-07-01 at 16:57 -0300, Leonardo Bras wrote:
> > It is not necessarily "direct" anymore as the name suggests, you may
> > want to change that. DMA64_PROPNAME, may be. Thanks,
> > 
> 
> Yeah, you are right.
> I will change this for next version, also changing the string name to
> reflect this.
> 
> -#define DIRECT64_PROPNAME "linux,direct64-ddr-window-info"
> +#define DMA64_PROPNAME "linux,dma64-ddr-window-info"
> 
> Is that ok?
> 
> Thank you for helping!

In fact, there is a lot of places in this file where it's called direct
window. Should I replace everything?
Should it be in a separated patch?

Best regards,
Leonardo

Re: [PATCH v2 5/6] powerpc/pseries/iommu: Make use of DDW even if it does not map the partition

[Alexey Kardashevskiy]

On 02/07/2020 09:48, Leonardo Bras wrote:
> On Wed, 2020-07-01 at 16:57 -0300, Leonardo Bras wrote:
>>> It is not necessarily "direct" anymore as the name suggests, you may
>>> want to change that. DMA64_PROPNAME, may be. Thanks,
>>>
>>
>> Yeah, you are right.
>> I will change this for next version, also changing the string name to
>> reflect this.
>>
>> -#define DIRECT64_PROPNAME "linux,direct64-ddr-window-info"
>> +#define DMA64_PROPNAME "linux,dma64-ddr-window-info"
>>
>> Is that ok?
>>
>> Thank you for helping!
> 
> In fact, there is a lot of places in this file where it's called direct
> window. Should I replace everything?
> Should it be in a separated patch?

If it looks simple and you write a nice commit log explaining all that
and why you are not reusing the existing ibm,dma-window property (to
provide a clue what "reset" will reset to? is there any other reason?)
for that - sure, do it :)



-- 
Alexey

Re: [PATCH v2 5/6] powerpc/pseries/iommu: Make use of DDW even if it does not map the partition

[Leonardo Bras]

On Thu, 2020-07-02 at 10:31 +1000, Alexey Kardashevskiy wrote:
> > In fact, there is a lot of places in this file where it's called direct
> > window. Should I replace everything?
> > Should it be in a separated patch?
> 
> If it looks simple and you write a nice commit log explaining all that
> and why you are not reusing the existing ibm,dma-window property 
> for that - sure, do it :)

Nice, I will do that :)

> (to provide a clue what "reset" will reset to? is there any other
> reason?)

That's the main reason here. 

The way I perceive this, ibm,dma-window should only point to the
default DMA window, which is guaranteed to always be the same, even if
it's destroyed and re-created. So there I see no point destroying /
overwriting it.

On the other hand, I also thought about using a new node name for this
window, but it would be very troublesome and I could see no real gain.

Thanks !

Re: [PATCH v2 5/6] powerpc/pseries/iommu: Make use of DDW even if it does not map the partition

[Leonardo Bras]

On Thu, 2020-07-02 at 10:31 +1000, Alexey Kardashevskiy wrote:
> 
> On 02/07/2020 09:48, Leonardo Bras wrote:
> > On Wed, 2020-07-01 at 16:57 -0300, Leonardo Bras wrote:
> > > > It is not necessarily "direct" anymore as the name suggests, you may
> > > > want to change that. DMA64_PROPNAME, may be. Thanks,
> > > > 
> > > 
> > > Yeah, you are right.
> > > I will change this for next version, also changing the string name to
> > > reflect this.
> > > 
> > > -#define DIRECT64_PROPNAME "linux,direct64-ddr-window-info"
> > > +#define DMA64_PROPNAME "linux,dma64-ddr-window-info"
> > > 
> > > Is that ok?
> > > 
> > > Thank you for helping!
> > 
> > In fact, there is a lot of places in this file where it's called direct
> > window. Should I replace everything?
> > Should it be in a separated patch?
> 
> If it looks simple and you write a nice commit log explaining all that
> and why you are not reusing the existing ibm,dma-window property (to
> provide a clue what "reset" will reset to? is there any other reason?)
> for that - sure, do it :)
> 

v3 available here:
http://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=187348&state=%2A&archive=both

Best regards,
Leonardo

[PATCH v2 6/6] powerpc/pseries/iommu: Avoid errors when DDW starts at 0x00

[Leonardo Bras]

As of today, enable_ddw() will return a non-null DMA address if the
created DDW maps the whole partition. If the address is valid,
iommu_bypass_supported_pSeriesLP() will consider iommu bypass enabled.

This can cause some trouble if the DDW happens to start at 0x00.

Instead if checking if the address is non-null, check directly if
the DDW maps the whole partition, so it can bypass iommu.

Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
---
 arch/powerpc/platforms/pseries/iommu.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 2d217cda4075..967634a379b0 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1078,7 +1078,8 @@ static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn)
  *
  * returns the dma offset for use by the direct mapped DMA code.
  */
-static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
+static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn,
+		      bool *maps_partition)
 {
 	int len, ret;
 	struct ddw_query_response query;
@@ -1237,9 +1238,9 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	list_add(&window->list, &direct_window_list);
 	spin_unlock(&direct_window_list_lock);
 
-	/* Only returns the dma_addr if DDW maps the whole partition */
 	if (len == order_base_2(max_addr))
-		dma_addr = be64_to_cpu(ddwprop->dma_base);
+		*maps_partition = true;
+	dma_addr = be64_to_cpu(ddwprop->dma_base);
 	goto out_unlock;
 
 out_free_window:
@@ -1324,6 +1325,7 @@ static bool iommu_bypass_supported_pSeriesLP(struct pci_dev *pdev, u64 dma_mask)
 {
 	struct device_node *dn = pci_device_to_OF_node(pdev), *pdn;
 	const __be32 *dma_window = NULL;
+	bool ret = false;
 
 	/* only attempt to use a new window if 64-bit DMA is requested */
 	if (dma_mask < DMA_BIT_MASK(64))
@@ -1344,13 +1346,10 @@ static bool iommu_bypass_supported_pSeriesLP(struct pci_dev *pdev, u64 dma_mask)
 			break;
 	}
 
-	if (pdn && PCI_DN(pdn)) {
-		pdev->dev.archdata.dma_offset = enable_ddw(pdev, pdn);
-		if (pdev->dev.archdata.dma_offset)
-			return true;
-	}
+	if (pdn && PCI_DN(pdn))
+		pdev->dev.archdata.dma_offset = enable_ddw(pdev, pdn, &ret);
 
-	return false;
+	return ret;
 }
 
 static int iommu_mem_notifier(struct notifier_block *nb, unsigned long action,
-- 
2.25.4

Re: [PATCH v2 6/6] powerpc/pseries/iommu: Avoid errors when DDW starts at 0x00

[Leonardo Bras]

On Wed, 2020-06-24 at 03:24 -0300, Leonardo Bras wrote:
> As of today, enable_ddw() will return a non-null DMA address if the
> created DDW maps the whole partition. If the address is valid,
> iommu_bypass_supported_pSeriesLP() will consider iommu bypass enabled.
> 
> This can cause some trouble if the DDW happens to start at 0x00.
> 
> Instead if checking if the address is non-null, check directly if
> the DDW maps the whole partition, so it can bypass iommu.
> 
> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>

This patch has a bug in it. I will rework it soon.
Please keep reviewing patches 1-5.

Best regards,
Leonardo

Re: [PATCH v2 6/6] powerpc/pseries/iommu: Avoid errors when DDW starts at 0x00

[Alexey Kardashevskiy]

On 27/06/2020 03:46, Leonardo Bras wrote:
> On Wed, 2020-06-24 at 03:24 -0300, Leonardo Bras wrote:
>> As of today, enable_ddw() will return a non-null DMA address if the
>> created DDW maps the whole partition. If the address is valid,
>> iommu_bypass_supported_pSeriesLP() will consider iommu bypass enabled.
>>
>> This can cause some trouble if the DDW happens to start at 0x00.
>>
>> Instead if checking if the address is non-null, check directly if
>> the DDW maps the whole partition, so it can bypass iommu.
>>
>> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> 
> This patch has a bug in it. I will rework it soon.

I'd rather suggest this:

https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20180725095032.2196-2-aik@ozlabs.ru/

Although it does not look like you are actually going to have windows
starting at 0. Thanks,

> Please keep reviewing patches 1-5.
> 
> Best regards,
> Leonardo
> 

-- 
Alexey

Re: [PATCH v2 6/6] powerpc/pseries/iommu: Avoid errors when DDW starts at 0x00

[Leonardo Bras]

On Wed, 2020-07-01 at 18:04 +1000, Alexey Kardashevskiy wrote:
> 
> On 27/06/2020 03:46, Leonardo Bras wrote:
> > On Wed, 2020-06-24 at 03:24 -0300, Leonardo Bras wrote:
> > > As of today, enable_ddw() will return a non-null DMA address if the
> > > created DDW maps the whole partition. If the address is valid,
> > > iommu_bypass_supported_pSeriesLP() will consider iommu bypass enabled.
> > > 
> > > This can cause some trouble if the DDW happens to start at 0x00.
> > > 
> > > Instead if checking if the address is non-null, check directly if
> > > the DDW maps the whole partition, so it can bypass iommu.
> > > 
> > > Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> > 
> > This patch has a bug in it. I will rework it soon.
> 
> I'd rather suggest this:
> 
> https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20180725095032.2196-2-aik@ozlabs.ru/
> 
> Although it does not look like you are actually going to have windows
> starting at 0. Thanks,

Yeah, agree. 
I am thinking of dropping this one, as I don't see much good to be done
here.

Thank you!

Re: [PATCH v2 0/6] Remove default DMA window before creating DDW

[Leonardo Bras]

On Wed, 2020-06-24 at 03:24 -0300, Leonardo Bras wrote:
> Patch #5:
> Instead of destroying the created DDW if it doesn't map the whole
> partition, make use of it instead of the default DMA window.
> 
> Patch #6:
> Changes the way iommu_bypass_supported_pSeriesLP() check for 
> iommu_bypass: instead of checking the address returned by enable_ddw(),
> it checks a new output value that reflects if the DDW created maps
> the whole partition.

Patches #5 and #6 were sent more as a RFC, but since they depend on the
series, I decided adding them here.