[xen staging] Arm/optee: don't open-code xzalloc_flex_struct()

[patchbot@xxxxxxx]

commit 7a2b787880bddbb3bd68b18efe1d6fe339df6ff1
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri May 7 10:45:14 2021 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri May 7 10:45:14 2021 +0200

    Arm/optee: don't open-code xzalloc_flex_struct()
    
    The current use of xzalloc_bytes() in optee is nearly an open-coded
    version  of xzalloc_flex_struct(), which was introduced after the driver
    was merged.
    
    The main difference is xzalloc_bytes() will also force the allocation to
    be SMP_CACHE_BYTES aligned and therefore avoid sharing the cache line.
    While sharing the cache line can have an impact on the performance, this
    is also true for most of the other users of x*alloc(), x*alloc_array(),
    and x*alloc_flex_struct(). So if we want to prevent sharing cache lines,
    arranging for this should be done in the allocator itself.
    
    In this case, we don't need stricter alignment than what the allocator
    provides. Hence replace the call to xzalloc_bytes() with one of
    xzalloc_flex_struct().
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Signed-off-by: Julien Grall <julien@xxxxxxx>
    Acked-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
---
 xen/arch/arm/tee/optee.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/xen/arch/arm/tee/optee.c b/xen/arch/arm/tee/optee.c
index 9570dc6771..980eebe847 100644
--- a/xen/arch/arm/tee/optee.c
+++ b/xen/arch/arm/tee/optee.c
@@ -529,8 +529,7 @@ static struct optee_shm_buf *allocate_optee_shm_buf(struct 
optee_domain *ctx,
     while ( unlikely(old != atomic_cmpxchg(&ctx->optee_shm_buf_pages,
                                            old, new)) );
 
-    optee_shm_buf = xzalloc_bytes(sizeof(struct optee_shm_buf) +
-                                  pages_cnt * sizeof(struct page *));
+    optee_shm_buf = xzalloc_flex_struct(struct optee_shm_buf, pages, 
pages_cnt);
     if ( !optee_shm_buf )
     {
         err_code = -ENOMEM;
--
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