linux-kernel - [PATCH 2/6] habanalabs: fix debugfs device memory MMU VA translation

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Date:   Mon,  4 Oct 2021 13:08:26 +0300
From:   Oded Gabbay <ogabbay@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Yuri Nudelman <ynudelman@...ana.ai>
Subject: [PATCH 2/6] habanalabs: fix debugfs device memory MMU VA translation

From: Yuri Nudelman <ynudelman@...ana.ai>

The translation in debugfs of device memory MMU virtual addresses was
wrong as it did not take into consideration the fact that the page
sizes there can be not power of 2.

Signed-off-by: Yuri Nudelman <ynudelman@...ana.ai>
Reviewed-by: Oded Gabbay <ogabbay@...nel.org>
Signed-off-by: Oded Gabbay <ogabbay@...nel.org>
---
 drivers/misc/habanalabs/common/mmu/mmu.c | 30 +++++++++++++-----------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/drivers/misc/habanalabs/common/mmu/mmu.c b/drivers/misc/habanalabs/common/mmu/mmu.c
index 792d25b79ea6..aa96917f62e5 100644
--- a/drivers/misc/habanalabs/common/mmu/mmu.c
+++ b/drivers/misc/habanalabs/common/mmu/mmu.c
@@ -501,23 +501,25 @@ static void hl_mmu_pa_page_with_offset(struct hl_ctx *ctx, u64 virt_addr,
 
 	if ((hops->range_type == HL_VA_RANGE_TYPE_DRAM) &&
 			!is_power_of_2(prop->dram_page_size)) {
-		unsigned long dram_page_size = prop->dram_page_size;
-		u64 page_offset_mask;
-		u64 phys_addr_mask;
-		u32 bit;
+		u64 dram_page_size, dram_base, abs_phys_addr, abs_virt_addr,
+			page_id, page_start;
+		u32 page_off;
 
 		/*
-		 * find last set bit in page_size to cover all bits of page
-		 * offset. note that 1 has to be added to bit index.
-		 * note that the internal ulong variable is used to avoid
-		 * alignment issue.
+		 * Bit arithmetics cannot be used for non power of two page
+		 * sizes. In addition, since bit arithmetics is not used,
+		 * we cannot ignore dram base. All that shall be considerd.
 		 */
-		bit = find_last_bit(&dram_page_size,
-					sizeof(dram_page_size) * BITS_PER_BYTE) + 1;
-		page_offset_mask = (BIT_ULL(bit) - 1);
-		phys_addr_mask = ~page_offset_mask;
-		*phys_addr = (tmp_phys_addr & phys_addr_mask) |
-				(virt_addr & page_offset_mask);
+
+		dram_page_size = prop->dram_page_size;
+		dram_base = prop->dram_base_address;
+		abs_phys_addr = tmp_phys_addr - dram_base;
+		abs_virt_addr = virt_addr - dram_base;
+		page_id = DIV_ROUND_DOWN_ULL(abs_phys_addr, dram_page_size);
+		page_start = page_id * dram_page_size;
+		div_u64_rem(abs_virt_addr, dram_page_size, &page_off);
+
+		*phys_addr = page_start + page_off + dram_base;
 	} else {
 		/*
 		 * find the correct hop shift field in hl_mmu_properties
-- 
2.17.1