[PATCH v2] common/mlx5: use intrinsics instead of inline assembly

Andre Muezerie andremue at linux.microsoft.com
Wed Jun 4 16:15:25 CEST 2025


When compiling with MSVC the errors below are hit because msvc does not
support inline assembly:

1)
../drivers/common/mlx5/mlx5_common.c(86): warning C4013: '__asm__'
    undefined; assuming extern returning int
../drivers/common/mlx5/mlx5_common.c(87): error C2143: syntax error:
     missing ')' before ':'

2)
../drivers/net/mlx5/mlx5_txpp.c(510): error C2065: '__asm__':
    undeclared identifier
../drivers/net/mlx5/mlx5_txpp.c(510): error C2143: syntax error:
    missing ';' before 'volatile'

The fix for (1) is to use compiler intrinsic __cpuid and for (2)
intrinsic _InterlockedCompareExchange128 can be used.

Signed-off-by: Andre Muezerie <andremue at linux.microsoft.com>
---
 drivers/common/mlx5/mlx5_common.c | 13 +++++++++++--
 drivers/net/mlx5/mlx5_txpp.c      | 11 +++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/common/mlx5/mlx5_common.c b/drivers/common/mlx5/mlx5_common.c
index ebe327a950..fbe1578a84 100644
--- a/drivers/common/mlx5/mlx5_common.c
+++ b/drivers/common/mlx5/mlx5_common.c
@@ -75,9 +75,18 @@ static inline void mlx5_cpu_id(unsigned int level,
 				unsigned int *eax, unsigned int *ebx,
 				unsigned int *ecx, unsigned int *edx)
 {
+#ifdef RTE_TOOLCHAIN_MSVC
+	int data[4];
+	__cpuid(data, level);
+	*eax = data[0];
+	*ebx = data[1];
+	*ecx = data[2];
+	*edx = data[3];
+#else
 	__asm__("cpuid\n\t"
-		: "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
-		: "0" (level));
+	: "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
+	: "0" (level));
+#endif
 }
 #endif
 
diff --git a/drivers/net/mlx5/mlx5_txpp.c b/drivers/net/mlx5/mlx5_txpp.c
index e6d3ad83e9..0e99b58bde 100644
--- a/drivers/net/mlx5/mlx5_txpp.c
+++ b/drivers/net/mlx5/mlx5_txpp.c
@@ -486,6 +486,16 @@ mlx5_txpp_cq_arm(struct mlx5_dev_ctx_shared *sh)
 }
 
 #if defined(RTE_ARCH_X86_64)
+#ifdef RTE_TOOLCHAIN_MSVC
+static inline int
+mlx5_atomic128_compare_exchange(rte_int128_t *dst,
+				rte_int128_t *exp,
+				const rte_int128_t *src)
+{
+	return (int)_InterlockedCompareExchange128((int64_t volatile *)dst,
+	       src->val[1], src->val[0], (int64_t *)exp);
+}
+#else
 static inline int
 mlx5_atomic128_compare_exchange(rte_int128_t *dst,
 				rte_int128_t *exp,
@@ -510,6 +520,7 @@ mlx5_atomic128_compare_exchange(rte_int128_t *dst,
 	return res;
 }
 #endif
+#endif
 
 static inline void
 mlx5_atomic_read_cqe(rte_int128_t *from, rte_int128_t *ts)
-- 
2.49.0.vfs.0.3



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