linux-kernel - [PATCH] habanalabs: fix bug in checking huge page optimization

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Message-Id: <20190530081314.19904-1-oded.gabbay@gmail.com>
Date:   Thu, 30 May 2019 11:13:14 +0300
From:   Oded Gabbay <oded.gabbay@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     gregkh@...uxfoundation.org
Subject: [PATCH] habanalabs: fix bug in checking huge page optimization

This patch fix a bug in the mmu code that checks whether we can use huge
page mappings for host pages.

The code is supposed to enable huge page mappings only if ALL DMA
addresses are aligned to 2MB AND the number of pages in each DMA chunk is
a modulo of the number of pages in 2MB. However, the code ignored the
first requirement for the first DMA chunk.

This patch fix that issue by making sure the requirement of address
alignment is validated against all DMA chunks.

Signed-off-by: Oded Gabbay <oded.gabbay@...il.com>
---
 drivers/misc/habanalabs/memory.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/misc/habanalabs/memory.c b/drivers/misc/habanalabs/memory.c
index d67d24c13efd..693877e37fd8 100644
--- a/drivers/misc/habanalabs/memory.c
+++ b/drivers/misc/habanalabs/memory.c
@@ -675,11 +675,6 @@ static int init_phys_pg_pack_from_userptr(struct hl_ctx *ctx,
 
 		total_npages += npages;
 
-		if (first) {
-			first = false;
-			dma_addr &= PAGE_MASK_2MB;
-		}
-
 		if ((npages % PGS_IN_2MB_PAGE) ||
 					(dma_addr & (PAGE_SIZE_2MB - 1)))
 			is_huge_page_opt = false;
@@ -704,7 +699,6 @@ static int init_phys_pg_pack_from_userptr(struct hl_ctx *ctx,
 	phys_pg_pack->total_size = total_npages * page_size;
 
 	j = 0;
-	first = true;
 	for_each_sg(userptr->sgt->sgl, sg, userptr->sgt->nents, i) {
 		npages = get_sg_info(sg, &dma_addr);
 
-- 
2.17.1