[dpdk-stable] [PATCH v2 1/2] sched: adds function to get 64 bits greatest common divisor

[dpdk-stable] [PATCH v2 1/2] sched: adds function to get 64 bits greatest common divisor

[Xueming Li]

This patch adds new function that compute the greatest common
divisor of 64 bits, also changes the original 32 bits function to call
this new 64 bits version.

Signed-off-by: Xueming Li <xuemingl@nvidia.com>
Cc: stable@dpdk.org
---
 lib/sched/rte_sched_common.h | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/lib/sched/rte_sched_common.h b/lib/sched/rte_sched_common.h
index 96706df7bd..340a0df312 100644
--- a/lib/sched/rte_sched_common.h
+++ b/lib/sched/rte_sched_common.h
@@ -51,10 +51,10 @@ rte_min_pos_4_u16(uint16_t *x)
  *    gcd(a, b) = gcd(b, a mod b)
  *
  */
-static inline uint32_t
-rte_get_gcd(uint32_t a, uint32_t b)
+static inline uint64_t
+rte_get_gcd64(uint64_t a, uint64_t b)
 {
-	uint32_t c;
+	uint64_t c;
 
 	if (a == 0)
 		return b;
@@ -76,6 +76,15 @@ rte_get_gcd(uint32_t a, uint32_t b)
 	return a;
 }
 
+/*
+ * 32bit version of Compute the Greatest Common Divisor (GCD).
+ */
+static inline uint32_t
+rte_get_gcd(uint32_t a, uint32_t b)
+{
+	return rte_get_gcd64(a, b);
+}
+
 /*
  * Compute the Lowest Common Denominator (LCD) of two numbers.
  * This implementation computes GCD first:
-- 
2.33.0

Re: [dpdk-stable] [PATCH v2 1/2] sched: adds function to get 64 bits greatest common divisor

[Kevin Traynor]

On 23/09/2021 09:11, Xueming Li wrote:
> This patch adds new function that compute the greatest common
> divisor of 64 bits, also changes the original 32 bits function to call
> this new 64 bits version.
> 
> Signed-off-by: Xueming Li <xuemingl@nvidia.com>
> Cc: stable@dpdk.org
> ---

lgtm.

Acked-by: Kevin Traynor <ktraynor@redhat.com>

[dpdk-stable] [PATCH v2 2/2] vdpa/mlx5: fix large VM memory region registration

[Xueming Li]

When VM size larger than 4G(u32) and memory region larger than 4G, the
32 bits GCD function overflow and returned wrong value that resulted
memory registration failed.

This patch calls 64 bits GCD function to avoid overflow.

Fixes: cc07a42da250 ("vdpa/mlx5: prepare memory regions")
Cc: matan@mellanox.com
Cc: stable@dpdk.org
Reviewed-by: Matan Azrad <matan@nvidia.com>

Signed-off-by: Xueming Li <xuemingl@nvidia.com>
---
 drivers/vdpa/mlx5/mlx5_vdpa_mem.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/vdpa/mlx5/mlx5_vdpa_mem.c b/drivers/vdpa/mlx5/mlx5_vdpa_mem.c
index 59ce4e891c..a06681b494 100644
--- a/drivers/vdpa/mlx5/mlx5_vdpa_mem.c
+++ b/drivers/vdpa/mlx5/mlx5_vdpa_mem.c
@@ -103,15 +103,15 @@ mlx5_vdpa_vhost_mem_regions_prepare(int vid, uint8_t *mode, uint64_t *mem_size,
 			size = mem->regions[i].guest_phys_addr -
 				(mem->regions[i - 1].guest_phys_addr +
 				 mem->regions[i - 1].size);
-			*gcd = rte_get_gcd(*gcd, size);
+			*gcd = rte_get_gcd64(*gcd, size);
 			klm_entries_num += KLM_NUM_MAX_ALIGN(size);
 		}
 		size = mem->regions[i].size;
-		*gcd = rte_get_gcd(*gcd, size);
+		*gcd = rte_get_gcd64(*gcd, size);
 		klm_entries_num += KLM_NUM_MAX_ALIGN(size);
 	}
 	if (*gcd > MLX5_MAX_KLM_BYTE_COUNT)
-		*gcd = rte_get_gcd(*gcd, MLX5_MAX_KLM_BYTE_COUNT);
+		*gcd = rte_get_gcd64(*gcd, MLX5_MAX_KLM_BYTE_COUNT);
 	if (!RTE_IS_POWER_OF_2(*gcd)) {
 		uint64_t candidate_gcd = rte_align64prevpow2(*gcd);
 
-- 
2.33.0