Re: [PATCH v2 6/6] powerpc/pseries/iommu: Avoid errors when DDW starts at 0x00
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 > > > > 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-...@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 6/6] powerpc/pseries/iommu: Avoid errors when DDW starts at 0x00
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 > > 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-...@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
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 This patch has a bug in it. I will rework it soon. Please keep reviewing patches 1-5. Best regards, Leonardo
[PATCH v2 6/6] powerpc/pseries/iommu: Avoid errors when DDW starts at 0x00
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
---
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
