powerps/pseries/dma: Add support for 2M IOMMU page size

Started by Alexey Kardashevskiy on Sep 28, 2021 · 3 messages from 3 authors · Last reply Sep 29, 2021

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Message details and related content
The upcoming PAPR spec adds a 2M page size, bit 23 right after the 16G page
size in the "ibm,query-pe-dma-window" call.

This adds support for the new page size. Since the new page size is out
of sorted order, this changes the loop to not assume that shift[] is
sorted.

Signed-off-by: Alexey Kardashevskiy <redacted>
---

This might not work if PHYP keeps rejecting new window requests for less
than 32768 TCEs. This is needed:
https://github.com/aik/linux/commit/8cc8fa5ba5b3b4a18efbc9d81d9e5b85ca7c8a95


---
 arch/powerpc/platforms/pseries/iommu.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index c741689a5165..237bf405b0cb 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1159,14 +1159,15 @@ static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn)
 /* Return largest page shift based on "IO Page Sizes" output of ibm,query-pe-dma-window. */
 static int iommu_get_page_shift(u32 query_page_size)
 {
-	/* Supported IO page-sizes according to LoPAR */
+	/* Supported IO page-sizes according to LoPAR, note that 2M is out of order */
 	const int shift[] = {
 		__builtin_ctzll(SZ_4K),   __builtin_ctzll(SZ_64K), __builtin_ctzll(SZ_16M),
 		__builtin_ctzll(SZ_32M),  __builtin_ctzll(SZ_64M), __builtin_ctzll(SZ_128M),
-		__builtin_ctzll(SZ_256M), __builtin_ctzll(SZ_16G)
+		__builtin_ctzll(SZ_256M), __builtin_ctzll(SZ_16G), __builtin_ctzll(SZ_2M)
 	};
 
 	int i = ARRAY_SIZE(shift) - 1;
+	int ret = 0;
 
 	/*
 	 * On LoPAR, ibm,query-pe-dma-window outputs "IO Page Sizes" using a bit field:
@@ -1176,11 +1177,10 @@ static int iommu_get_page_shift(u32 query_page_size)
 	 */
 	for (; i >= 0 ; i--) {
 		if (query_page_size & (1 << i))
-			return shift[i];
+			ret = max(ret, shift[i]);
 	}
 
-	/* No valid page size found. */
-	return 0;
+	return ret;
 }
 
 static struct property *ddw_property_create(const char *propname, u32 liobn, u64 dma_addr,
-- 
2.30.2
Message details and related content
Hello Alexey,

On Tue, 2021-09-28 at 20:15 +1000, Alexey Kardashevskiy wrote:
quoted hunk
The upcoming PAPR spec adds a 2M page size, bit 23 right after the 16G
page
size in the "ibm,query-pe-dma-window" call.

This adds support for the new page size. Since the new page size is out
of sorted order, this changes the loop to not assume that shift[] is
sorted.

Signed-off-by: Alexey Kardashevskiy <redacted>
---

This might not work if PHYP keeps rejecting new window requests for
less
than 32768 TCEs. This is needed:
https://github.com/aik/linux/commit/8cc8fa5ba5b3b4a18efbc9d81d9e5b85ca7c8a95


---
 arch/powerpc/platforms/pseries/iommu.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/iommu.c
b/arch/powerpc/platforms/pseries/iommu.c
index c741689a5165..237bf405b0cb 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1159,14 +1159,15 @@ static void reset_dma_window(struct pci_dev
*dev, struct device_node *par_dn)
 /* Return largest page shift based on "IO Page Sizes" output of
ibm,query-pe-dma-window. */
 static int iommu_get_page_shift(u32 query_page_size)
 {
-       /* Supported IO page-sizes according to LoPAR */
+       /* Supported IO page-sizes according to LoPAR, note that 2M is
out of order */
        const int shift[] = {
                __builtin_ctzll(SZ_4K),   __builtin_ctzll(SZ_64K),
__builtin_ctzll(SZ_16M),
                __builtin_ctzll(SZ_32M),  __builtin_ctzll(SZ_64M),
__builtin_ctzll(SZ_128M),

27 more quoted lines

Looks great to me.

FWIW:
Reviewed-by: Leonardo Bras <redacted>

Best regards,
Leonardo

Message details and related content

On 28/09/2021 12:15, Alexey Kardashevskiy wrote:
The upcoming PAPR spec adds a 2M page size, bit 23 right after the 16G page
size in the "ibm,query-pe-dma-window" call.

This adds support for the new page size. Since the new page size is out
of sorted order, this changes the loop to not assume that shift[] is
sorted.

Signed-off-by: Alexey Kardashevskiy <redacted>
---

Looks ok to me
Reviewed-by: Frederic Barrat <redacted>

quoted hunk
This might not work if PHYP keeps rejecting new window requests for less
than 32768 TCEs. This is needed:
https://github.com/aik/linux/commit/8cc8fa5ba5b3b4a18efbc9d81d9e5b85ca7c8a95


---
  arch/powerpc/platforms/pseries/iommu.c | 10 +++++-----
  1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index c741689a5165..237bf405b0cb 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1159,14 +1159,15 @@ static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn)
  /* Return largest page shift based on "IO Page Sizes" output of ibm,query-pe-dma-window. */
  static int iommu_get_page_shift(u32 query_page_size)
  {
-	/* Supported IO page-sizes according to LoPAR */
+	/* Supported IO page-sizes according to LoPAR, note that 2M is out of order */
  	const int shift[] = {
  		__builtin_ctzll(SZ_4K),   __builtin_ctzll(SZ_64K), __builtin_ctzll(SZ_16M),
  		__builtin_ctzll(SZ_32M),  __builtin_ctzll(SZ_64M), __builtin_ctzll(SZ_128M),
-		__builtin_ctzll(SZ_256M), __builtin_ctzll(SZ_16G)
+		__builtin_ctzll(SZ_256M), __builtin_ctzll(SZ_16G), __builtin_ctzll(SZ_2M)
  	};
  
  	int i = ARRAY_SIZE(shift) - 1;
+	int ret = 0;
  
  	/*
  	 * On LoPAR, ibm,query-pe-dma-window outputs "IO Page Sizes" using a bit field:
@@ -1176,11 +1177,10 @@ static int iommu_get_page_shift(u32 query_page_size)
  	 */
  	for (; i >= 0 ; i--) {
  		if (query_page_size & (1 << i))
-			return shift[i];
+			ret = max(ret, shift[i]);
  	}
  

7 more quoted lines

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