Re: [PATCH v3 4/6] powerpc/pseries/iommu: Remove default DMA window before creating DDW
In fact, the changes over the last patch are more complex than the
current patch.
Just for reference, that's how enable_ddw() currently patches:
@@ -1087,7 +1119,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct
device_node *pdn)
struct device_node *dn;
u32 ddw_avail[DDW_APPLICABLE_SIZE];
struct direct_window *window;
- struct property *win64;
+ struct property *win64, *default_win = NULL;
struct dynamic_dma_window_prop *ddwprop;
struct failed_ddw_pdn *fpdn;
@@ -1133,14 +1165,38 @@ 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, "no free dynamic windows");
- goto out_failed;
+ int reset_win_ext;
+
+ default_win = of_find_property(pdn, "ibm,dma-window",
NULL);
+ if (!default_win)
+ goto out_failed;
+
+ reset_win_ext = ddw_read_ext(pdn,
DDW_EXT_RESET_DMA_WIN, NULL);
+ if (reset_win_ext) {
+ default_win = NULL;
+ goto out_failed;
+ }
+
+ remove_dma_window(pdn, ddw_avail, default_win);
+
+ /* Query again, to check if the window is available */
+ ret = query_ddw(dev, ddw_avail, , pdn);
+ if (ret != 0)
+ goto out_failed;
+
+ if (query.windows_available == 0) {
+ /* no windows are available for this device. */
+ dev_dbg(>dev, "no free dynamic windows");
+ goto out_failed;
+ }
}
if (query.page_size & 4) {
page_shift = 24; /* 16MB */
@@ -1231,6 +1287,8 @@ static u64 enable_ddw(struct pci_dev *dev, struct
device_node *pdn)
kfree(win64);
out_failed:
+ if (default_win)
+ reset_dma_window(dev, pdn);
fpdn = kzalloc(sizeof(*fpdn), GFP_KERNEL);
if (!fpdn)
Re: [PATCH v3 4/6] powerpc/pseries/iommu: Remove default DMA window before creating DDW
On Tue, 2020-07-14 at 14:52 +1000, Alexey Kardashevskiy wrote:
>
> On 14/07/2020 12:40, Leonardo Bras wrote:
> > Thank you for this feedback Alexey!
> >
> > On Mon, 2020-07-13 at 17:33 +1000, Alexey Kardashevskiy wrote:
> > > [...]
> > > > - int len, ret;
> > > > + int len, ret, reset_win_ext;
> > >
> > > Make it "reset_token".
> >
> > Oh, it's not a token here, it just checks if the reset_win extension
> > exists. The token would be returned in *value, but since we did not
> > need it here, it's not copied.
>
> ah right, so it is a bool actually.
In fact I did it a int, as it's the return value of ddw_read_ext(),
which can return 0 on success and -error otherwise.
> > > > [...]
> > > > -out_failed:
> > > > +out_restore_defwin:
> > > > + if (default_win && reset_win_ext == 0)
> > >
> > > reset_win_ext potentially may be uninitialized here. Yeah I know it is
> > > tied to default_win but still.
> >
> > I can't see it being used uninitialized here, as you said it's tied to
> > default_win.
>
> Where it is declared - it is not initialized so in theory it can skip
> "if (query.windows_available == 0)".
Humm, I thought doing if (default_win && reset_win_ext == 0) would
guarantee default_win to be tested before reset_win_ext is ever tested,
so I could control it using default_win.
>
>
> > Could you please tell me how it can be used uninitialized here, or what
> > is bad by doing this way?
> >
> > > After looking at this function for a few minutes, it could use some
> > > refactoring (way too many gotos) such as:
> >
> > Yes, I agree.
> >
> > > 1. move (query.page_size & xx) checks before "if
> > > (query.windows_available == 0)"
> >
> > Moving 'page_size selection' above 'checking windows available' will
> > need us to duplicate the 'page_size selection' after the new query,
> > inside the if.
>
> page_size selection is not going to change, why?
In theory, a query after freeing the default DMA window could have a
different (bigger) page size, so we should test again.
>
>
> > I mean, as query will be done again, it will need to get the (new) page
> > size.
> >
> > > 2. move "win64 = kzalloc(sizeof(struct property), GFP_KERNEL)" before
> > > "if (query.windows_available == 0)"
> > > 3. call "reset_dma_window(dev, pdn)" inside the "if
> > > (query.windows_available == 0)" branch.
> > > Then you can drop all "goto out_restore_defwin" and move default_win and
> > > reset_win_ext inside "if (query.windows_available == 0)".
> >
> > I did all changes suggested locally and did some analysis in the
> > result:
> >
> > I did not see a way to put default_win and reset_win_ext inside
> > "if (query.windows_available == 0)", because if we still need a way to
> > know if the default window was removed, and if so, restore in case
> > anything ever fails ahead (like creating the node property).
>
> Ah, I missed that new out_restore_defwin label is between other exit
> labels. Sorry :-/
>
>
> > reset_win_ext = ddw_read_ext(pdn,
> > DDW_EXT_RESET_DMA_WIN, NULL);
> > - if (reset_win_ext)
> > + if (reset_win_ext){
> > + default_win = NULL;
> > goto out_failed;
> > + }
>
> This says "if we can reset, then we fail", no?
Here ddw_read_ext() should return 0 if extension was found, and
(-EINVAL, -ENODATA or -EOVERFLOW) otherwise.
So it should return nonzero if we can't find the extension, in which
case we should fail.
>
> > remove_dma_window(pdn, ddw_avail, default_win);
>
> I think you can do "default_win=NULL" here and later at
> out_restore_defwin check if it is NULL - then call reset.
Currently I initialize 'default_win = NULL', and it only changes when I
read the default DMA window. If reset is not available I restore it to
NULL, so it will be not-NULL only when the have removed the default DMA
window.
If I make it NULL here, we either never reset the default DMA window
(as it is now "if (default_win)" ) or we may always reset it (in case
"if (default_win == NULL)").
If you think it's better, I can create a bool variable like
"default_win_removed", initialized with 'false', which can be assigned
here with 'true' and test in the end if(default_win_removed) reset();
This would allow to move default_win inside this 'if block'.
What do you think?
> > [...]
> >
> > -out_restore_defwin:
> > - if (default_win && reset_win_ext == 0)
> > +out_failed:
> > + if (default_win)
> > reset_dma_window(dev, pdn);
> >
> > -out_failed:
> > fpdn = kzalloc(sizeof(*fpdn), GFP_KERNEL);
> > if (!fpdn)
> > goto out_unlock;
> >
> > #
> >
> > What do you think?
> >
> >
> >
> > > The rest of the series is good as it is,
> >
> > Thank you :)
> >
> > > however it may conflict with
> > > https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20200713062348.100552-1-...@ozlabs.ru/
> > > and the patchset
Re: [PATCH v3 4/6] powerpc/pseries/iommu: Remove default DMA window before creating DDW
On 14/07/2020 12:40, Leonardo Bras wrote:
> Thank you for this feedback Alexey!
>
> On Mon, 2020-07-13 at 17:33 +1000, Alexey Kardashevskiy wrote:
>> [...]
>>> - int len, ret;
>>> + int len, ret, reset_win_ext;
>>
>> Make it "reset_token".
>
> Oh, it's not a token here, it just checks if the reset_win extension
> exists. The token would be returned in *value, but since we did not
> need it here, it's not copied.
ah right, so it is a bool actually.
>
>>> [...]
>>> -out_failed:
>>> +out_restore_defwin:
>>> + if (default_win && reset_win_ext == 0)
>>
>> reset_win_ext potentially may be uninitialized here. Yeah I know it is
>> tied to default_win but still.
>
> I can't see it being used uninitialized here, as you said it's tied to
> default_win.
Where it is declared - it is not initialized so in theory it can skip
"if (query.windows_available == 0)".
> Could you please tell me how it can be used uninitialized here, or what
> is bad by doing this way?
>
>> After looking at this function for a few minutes, it could use some
>> refactoring (way too many gotos) such as:
>
> Yes, I agree.
>
>> 1. move (query.page_size & xx) checks before "if
>> (query.windows_available == 0)"
>
> Moving 'page_size selection' above 'checking windows available' will
> need us to duplicate the 'page_size selection' after the new query,
> inside the if.
page_size selection is not going to change, why?
> I mean, as query will be done again, it will need to get the (new) page
> size.
>
>> 2. move "win64 = kzalloc(sizeof(struct property), GFP_KERNEL)" before
>> "if (query.windows_available == 0)"
>
>> 3. call "reset_dma_window(dev, pdn)" inside the "if
>> (query.windows_available == 0)" branch.
>
>> Then you can drop all "goto out_restore_defwin" and move default_win and
>> reset_win_ext inside "if (query.windows_available == 0)".
>
> I did all changes suggested locally and did some analysis in the
> result:
>
> I did not see a way to put default_win and reset_win_ext inside
> "if (query.windows_available == 0)", because if we still need a way to
> know if the default window was removed, and if so, restore in case
> anything ever fails ahead (like creating the node property).
Ah, I missed that new out_restore_defwin label is between other exit
labels. Sorry :-/
> But from that analysis I noted it's possible to remove all the new
> "goto out_restore_defwin", if we do default_win = NULL if
> ddw_read_ext() fails.
>
> So testing only default_win should always be enough to say if the
> default window was deleted, and reset_win_ext could be moved inside "if
> (query.windows_available == 0)".
> Also, it would avoid reset_win_ext being 'used uninitialized' and
> "out_restore_defwin:" would not be needed.
>
> Against the current patch, we would have something like this:
>
> #
>
> static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
> {
> - int len, ret, reset_win_ext;
> + int len, ret;
> struct ddw_query_response query;
> struct ddw_create_response create;
> int page_shift;
> @@ -1173,25 +1173,28 @@ static u64 enable_ddw(struct pci_dev *dev,
> struct device_node *pdn)
> * for extensions presence.
> */
> if (query.windows_available == 0) {
> + int reset_win_ext;
> default_win = of_find_property(pdn, "ibm,dma-window",
> NULL);
> if (!default_win)
> goto out_failed;
>
> reset_win_ext = ddw_read_ext(pdn,
> DDW_EXT_RESET_DMA_WIN, NULL);
> - if (reset_win_ext)
> + if (reset_win_ext){
> + default_win = NULL;
> goto out_failed;
> + }
This says "if we can reset, then we fail", no?
> remove_dma_window(pdn, ddw_avail, default_win);
I think you can do "default_win=NULL" here and later at
out_restore_defwin check if it is NULL - then call reset.
> /* Query again, to check if the window is available */
> ret = query_ddw(dev, ddw_avail, , pdn);
> if (ret != 0)
> - goto out_restore_defwin;
> + goto out_failed;
>
> if (query.windows_available == 0) {
> /* no windows are available for this device. */
> dev_dbg(>dev, "no free dynamic windows");
> - goto out_restore_defwin;
> + goto out_failed;
> }
> }
> if (query.page_size & 4) {
> @@ -1203,7 +1206,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct
> device_node *pdn)
> } else {
> dev_dbg(>dev, "no supported direct page size in
> mask %x",
> query.page_size);
> - goto out_restore_defwin;
> + goto out_failed;
> }
> /* verify the window * number of ptes will map the
Re: [PATCH v3 4/6] powerpc/pseries/iommu: Remove default DMA window before creating DDW
Thank you for this feedback Alexey!
On Mon, 2020-07-13 at 17:33 +1000, Alexey Kardashevskiy wrote:
> [...]
> > - int len, ret;
> > + int len, ret, reset_win_ext;
>
> Make it "reset_token".
Oh, it's not a token here, it just checks if the reset_win extension
exists. The token would be returned in *value, but since we did not
need it here, it's not copied.
> > [...]
> > -out_failed:
> > +out_restore_defwin:
> > + if (default_win && reset_win_ext == 0)
>
> reset_win_ext potentially may be uninitialized here. Yeah I know it is
> tied to default_win but still.
I can't see it being used uninitialized here, as you said it's tied to
default_win.
Could you please tell me how it can be used uninitialized here, or what
is bad by doing this way?
> After looking at this function for a few minutes, it could use some
> refactoring (way too many gotos) such as:
Yes, I agree.
> 1. move (query.page_size & xx) checks before "if
> (query.windows_available == 0)"
Moving 'page_size selection' above 'checking windows available' will
need us to duplicate the 'page_size selection' after the new query,
inside the if.
I mean, as query will be done again, it will need to get the (new) page
size.
> 2. move "win64 = kzalloc(sizeof(struct property), GFP_KERNEL)" before
> "if (query.windows_available == 0)"
> 3. call "reset_dma_window(dev, pdn)" inside the "if
> (query.windows_available == 0)" branch.
> Then you can drop all "goto out_restore_defwin" and move default_win and
> reset_win_ext inside "if (query.windows_available == 0)".
I did all changes suggested locally and did some analysis in the
result:
I did not see a way to put default_win and reset_win_ext inside
"if (query.windows_available == 0)", because if we still need a way to
know if the default window was removed, and if so, restore in case
anything ever fails ahead (like creating the node property).
But from that analysis I noted it's possible to remove all the new
"goto out_restore_defwin", if we do default_win = NULL if
ddw_read_ext() fails.
So testing only default_win should always be enough to say if the
default window was deleted, and reset_win_ext could be moved inside "if
(query.windows_available == 0)".
Also, it would avoid reset_win_ext being 'used uninitialized' and
"out_restore_defwin:" would not be needed.
Against the current patch, we would have something like this:
#
static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
{
- int len, ret, reset_win_ext;
+ int len, ret;
struct ddw_query_response query;
struct ddw_create_response create;
int page_shift;
@@ -1173,25 +1173,28 @@ static u64 enable_ddw(struct pci_dev *dev,
struct device_node *pdn)
* for extensions presence.
*/
if (query.windows_available == 0) {
+ int reset_win_ext;
default_win = of_find_property(pdn, "ibm,dma-window",
NULL);
if (!default_win)
goto out_failed;
reset_win_ext = ddw_read_ext(pdn,
DDW_EXT_RESET_DMA_WIN, NULL);
- if (reset_win_ext)
+ if (reset_win_ext){
+ default_win = NULL;
goto out_failed;
+ }
remove_dma_window(pdn, ddw_avail, default_win);
/* Query again, to check if the window is available */
ret = query_ddw(dev, ddw_avail, , pdn);
if (ret != 0)
- goto out_restore_defwin;
+ goto out_failed;
if (query.windows_available == 0) {
/* no windows are available for this device. */
dev_dbg(>dev, "no free dynamic windows");
- goto out_restore_defwin;
+ goto out_failed;
}
}
if (query.page_size & 4) {
@@ -1203,7 +1206,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct
device_node *pdn)
} else {
dev_dbg(>dev, "no supported direct page size in
mask %x",
query.page_size);
- goto out_restore_defwin;
+ goto out_failed;
}
/* verify the window * number of ptes will map the partition */
/* check largest block * page size > max memory hotplug addr */
@@ -1212,14 +1215,14 @@ static u64 enable_ddw(struct pci_dev *dev,
struct device_node *pdn)
dev_dbg(>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_restore_defwin;
+ goto out_failed;
}
len = order_base_2(max_addr);
win64 = kzalloc(sizeof(struct property), GFP_KERNEL);
if (!win64) {
dev_info(>dev,
"couldn't allocate property for 64bit dma
window\n");
-
Re: [PATCH v3 4/6] powerpc/pseries/iommu: Remove default DMA window before creating DDW
On 03/07/2020 16:18, 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 using DDW on devices in which hypervisor
> allows only 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
> ---
> arch/powerpc/platforms/pseries/iommu.c | 83 +-
> 1 file changed, 69 insertions(+), 14 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/iommu.c
> b/arch/powerpc/platforms/pseries/iommu.c
> index 4e33147825cc..5b520ac354c6 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -1066,6 +1066,38 @@ 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, reset_dma_win;
> + u64 buid;
> + struct device_node *dn;
> + struct pci_dn *pdn;
> +
> + ret = ddw_read_ext(par_dn, DDW_EXT_RESET_DMA_WIN, _dma_win);
> + 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(reset_dma_win, 3, 1, NULL, cfg_addr, BUID_HI(buid),
> + BUID_LO(buid));
> + if (ret)
> + dev_info(>dev,
> + "ibm,reset-pe-dma-windows(%x) %x %x %x returned %d ",
> + reset_dma_win, 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,
> @@ -1079,7 +,7 @@ static phys_addr_t ddw_memory_hotplug_max(void)
> */
> static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
> {
> - int len, ret;
> + int len, ret, reset_win_ext;
Make it "reset_token".
> struct ddw_query_response query;
> struct ddw_create_response create;
> int page_shift;
> @@ -1087,7 +1119,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct
> device_node *pdn)
> struct device_node *dn;
> u32 ddw_avail[DDW_APPLICABLE_SIZE];
> struct direct_window *window;
> - struct property *win64;
> + struct property *win64, *default_win = NULL;
> struct dynamic_dma_window_prop *ddwprop;
> struct failed_ddw_pdn *fpdn;
>
> @@ -1122,7 +1154,7 @@ 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
> @@ -1133,14 +1165,34 @@ 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, "no free dynamic windows");
> - goto out_failed;
> + default_win = of_find_property(pdn, "ibm,dma-window", NULL);
> + if (!default_win)
> + goto out_failed;
> +
> + reset_win_ext = ddw_read_ext(pdn,
[PATCH v3 4/6] powerpc/pseries/iommu: Remove default DMA window before creating DDW
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 using DDW on devices in which hypervisor
allows only 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
---
arch/powerpc/platforms/pseries/iommu.c | 83 +-
1 file changed, 69 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/iommu.c
b/arch/powerpc/platforms/pseries/iommu.c
index 4e33147825cc..5b520ac354c6 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1066,6 +1066,38 @@ 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, reset_dma_win;
+ u64 buid;
+ struct device_node *dn;
+ struct pci_dn *pdn;
+
+ ret = ddw_read_ext(par_dn, DDW_EXT_RESET_DMA_WIN, _dma_win);
+ 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(reset_dma_win, 3, 1, NULL, cfg_addr, BUID_HI(buid),
+ BUID_LO(buid));
+ if (ret)
+ dev_info(>dev,
+"ibm,reset-pe-dma-windows(%x) %x %x %x returned %d ",
+reset_dma_win, 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,
@@ -1079,7 +,7 @@ static phys_addr_t ddw_memory_hotplug_max(void)
*/
static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
{
- int len, ret;
+ int len, ret, reset_win_ext;
struct ddw_query_response query;
struct ddw_create_response create;
int page_shift;
@@ -1087,7 +1119,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct
device_node *pdn)
struct device_node *dn;
u32 ddw_avail[DDW_APPLICABLE_SIZE];
struct direct_window *window;
- struct property *win64;
+ struct property *win64, *default_win = NULL;
struct dynamic_dma_window_prop *ddwprop;
struct failed_ddw_pdn *fpdn;
@@ -1122,7 +1154,7 @@ 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
@@ -1133,14 +1165,34 @@ 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, "no free dynamic windows");
- goto out_failed;
+ default_win = of_find_property(pdn, "ibm,dma-window", NULL);
+ if (!default_win)
+ goto out_failed;
+
+ reset_win_ext = ddw_read_ext(pdn, DDW_EXT_RESET_DMA_WIN, NULL);
+ if (reset_win_ext)
+ goto out_failed;
+
+ remove_dma_window(pdn, ddw_avail, default_win);
+
+ /* Query again,
