[RFC 0/3] common/cnxk: remove dependence on VLA

[RFC 0/3] common/cnxk: remove dependence on VLA

[Stephen Hemminger]

While looking at LTO compile failures, it looks like the cnxk common
code can be modified to not use VLA's. This fixes one of the compile
problems there.

Compile tested only!

Stephen Hemminger (3):
  common/cnxk: replace variable length state array
  common/cnxk: replace variable length array
  common/cnxk: re-enable vla warnings

 drivers/common/cnxk/meson.build    | 2 --
 drivers/common/cnxk/roc_aes.c      | 3 ++-
 drivers/common/cnxk/roc_platform.c | 4 ++--
 3 files changed, 4 insertions(+), 5 deletions(-)

-- 
2.51.0

[RFC 1/3] common/cnxk: replace variable length state array

[Stephen Hemminger]

The cipher function is always called with in_len = 16
and there is an existing define for that.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 drivers/common/cnxk/roc_aes.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/common/cnxk/roc_aes.c b/drivers/common/cnxk/roc_aes.c
index d84feb546a..e51cf532d7 100644
--- a/drivers/common/cnxk/roc_aes.c
+++ b/drivers/common/cnxk/roc_aes.c
@@ -157,9 +157,10 @@ static void
 cipher(uint8_t *in, uint8_t *out, uint32_t *ks, uint32_t key_rounds, uint8_t in_len)
 {
 	uint8_t data_word_len = in_len / sizeof(uint32_t);
-	uint32_t state[data_word_len];
+	uint32_t state[AES_HASH_KEY_LEN / sizeof(uint32_t)];
 	unsigned int i, round;
 
+	RTE_ASSERT(data_word_len <= AES_HASH_KEY_LEN);
 	memcpy(state, in, sizeof(state));
 
 	/* AddRoundKey(state, w[0, Nb-1]) // See Sec. 5.1.4 */
-- 
2.51.0

[RFC 2/3] common/cnxk: replace variable length array

[Stephen Hemminger]

This fixes errors when compiled with LTO about large VLA.
../drivers/common/cnxk/roc_platform.c: In function ‘irq_init’:
../drivers/common/cnxk/roc_platform.c:92:14: warning: argument to variable-length array is too large [-Wvla-larger-than=]
   92 |         char irq_set_buf[MSIX_IRQ_SET_BUF_LEN];
      |              ^

Since the number of IRQ is limited by EAL max interrupt vectors
use that define that already exists rather than a function call
hidden in a macro.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 drivers/common/cnxk/roc_platform.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/common/cnxk/roc_platform.c b/drivers/common/cnxk/roc_platform.c
index e13cb42285..1fdbf8f051 100644
--- a/drivers/common/cnxk/roc_platform.c
+++ b/drivers/common/cnxk/roc_platform.c
@@ -17,8 +17,8 @@
 #include <sys/ioctl.h>
 #include <unistd.h>
 
-#define MSIX_IRQ_SET_BUF_LEN                                                                       \
-	(sizeof(struct vfio_irq_set) + sizeof(int) * (plt_intr_max_intr_get(intr_handle)))
+#define MSIX_IRQ_SET_BUF_LEN							\
+	(sizeof(struct vfio_irq_set) + sizeof(int) * PLT_MAX_RXTX_INTR_VEC_ID)
 
 static int
 irq_get_info(struct plt_intr_handle *intr_handle)
-- 
2.51.0

Re: [EXTERNAL] [RFC 2/3] common/cnxk: replace variable length array

[Harman Kalra]

Hi Stephen,

Please find response inline.

Thanks
Harman


________________________________________
From: Stephen Hemminger <stephen@networkplumber.org>
Sent: Friday, October 24, 2025 01:11
To: dev@dpdk.org
Cc: Stephen Hemminger; Nithin Kumar Dabilpuram; Kiran Kumar Kokkilagadda; Sunil Kumar Kori; Satha Koteswara Rao Kottidi; Harman Kalra
Subject: [EXTERNAL] [RFC 2/3] common/cnxk: replace variable length array

This fixes errors when compiled with LTO about large VLA. .. /drivers/common/cnxk/roc_platform. c: In function ‘irq_init’: .. /drivers/common/cnxk/roc_platform. c: 92: 14: warning: argument to variable-length array is too large [-Wvla-larger-than=]
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This fixes errors when compiled with LTO about large VLA.
../drivers/common/cnxk/roc_platform.c: In function ‘irq_init’:
../drivers/common/cnxk/roc_platform.c:92:14: warning: argument to variable-length array is too large [-Wvla-larger-than=]
   92 |         char irq_set_buf[MSIX_IRQ_SET_BUF_LEN];
      |              ^

Since the number of IRQ is limited by EAL max interrupt vectors
use that define that already exists rather than a function call
hidden in a macro.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 drivers/common/cnxk/roc_platform.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/common/cnxk/roc_platform.c b/drivers/common/cnxk/roc_platform.c
index e13cb42285..1fdbf8f051 100644
--- a/drivers/common/cnxk/roc_platform.c
+++ b/drivers/common/cnxk/roc_platform.c
@@ -17,8 +17,8 @@
 #include <sys/ioctl.h>
 #include <unistd.h>

-#define MSIX_IRQ_SET_BUF_LEN                                                                       \
-       (sizeof(struct vfio_irq_set) + sizeof(int) * (plt_intr_max_intr_get(intr_handle)))
+#define MSIX_IRQ_SET_BUF_LEN                                                   \
+       (sizeof(struct vfio_irq_set) + sizeof(int) * PLT_MAX_RXTX_INTR_VEC_ID)


[HK] The value of MSIX_IRQ_SET_BUF_LEN should be derived from the maximum number of interrupts configured for a PCI device,
as obtained via plt_intr_max_intr_get(intr_handle), which internally uses the VFIO_DEVICE_GET_IRQ_INFO ioctl.
In contrast, PLT_MAX_RXTX_INTR_VEC_ID is a fixed default value representing the maximum number of interrupt vectors.
This mismatch may lead to unexpected behaviour as on certain platforms (like cnxk) where the PCI device's MSIX capability
may exceed PLT_MAX_RXTX_INTR_VEC_ID.

 static int
 irq_get_info(struct plt_intr_handle *intr_handle)
--
2.51.0

[RFC 3/3] common/cnxk: re-enable vla warnings

[Stephen Hemminger]

The code in common/cnxk no longer uses VLA's.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 drivers/common/cnxk/meson.build | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/common/cnxk/meson.build b/drivers/common/cnxk/meson.build
index daffc15afd..58ebf4c99f 100644
--- a/drivers/common/cnxk/meson.build
+++ b/drivers/common/cnxk/meson.build
@@ -94,8 +94,6 @@ sources += files('cnxk_telemetry_bphy.c',
                  'cnxk_telemetry_sso.c',
 )
 
-cflags += no_wvla_cflag
-
 if meson.is_cross_build()
     soc_type = meson.get_external_property('platform', '')
 else
-- 
2.51.0