Re: [PATCH v4 4/7] powerpc/pseries/iommu: Remove default DMA window before creating DDW
On Thu, 2020-07-16 at 04:16 -0300, 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 | 73 +++-
> --
> 1 file changed, 66 insertions(+), 7 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/iommu.c
> b/arch/powerpc/platforms/pseries/iommu.c
> index 4e33147825cc..fc8d0555e2e9 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,
> @@ -1090,6 +1122,7 @@ static u64 enable_ddw(struct pci_dev *dev,
> struct device_node *pdn)
> struct property *win64;
> struct dynamic_dma_window_prop *ddwprop;
> struct failed_ddw_pdn *fpdn;
> + bool default_win_removed = false;
>
> mutex_lock(_window_init_mutex);
>
> @@ -1133,14 +1166,38 @@ 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;
> + struct property *default_win;
> + 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)
> + goto out_failed;
> +
> + remove_dma_window(pdn, ddw_avail, default_win);
> + default_win_removed = true;
> +
> + /* 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;
> + }
>
[PATCH v4 4/7] 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 | 73 +++---
1 file changed, 66 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/iommu.c
b/arch/powerpc/platforms/pseries/iommu.c
index 4e33147825cc..fc8d0555e2e9 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,
@@ -1090,6 +1122,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct
device_node *pdn)
struct property *win64;
struct dynamic_dma_window_prop *ddwprop;
struct failed_ddw_pdn *fpdn;
+ bool default_win_removed = false;
mutex_lock(_window_init_mutex);
@@ -1133,14 +1166,38 @@ 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;
+ struct property *default_win;
+ 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)
+ goto out_failed;
+
+ remove_dma_window(pdn, ddw_avail, default_win);
+ default_win_removed = true;
+
+ /* 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 +1288,8 @@ static u64 enable_ddw(struct pci_dev *dev, struct
device_node *pdn)
kfree(win64);
out_failed:
+
