Re: [PATCH 03/10] accel/ivpu: Add debug prints for MMU map/unmap operations

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On 1/5/2024 4:22 AM, Jacek Lawrynowicz wrote:
From: "Wachowski, Karol" <karol.wachowski@xxxxxxxxx>

It is common need to be able to  see IOVA/physical to VPU addresses

Errant double space between "to" and "see"

mappings. Especially when debugging different kind of memory related
issues. Lack of such logs forces user to modify and recompile KMD manually.

This commit adds those logs under MMU debug mask which can be turned on
dynamically with module param during KMD load.
As far as I understand, the preference is to not expose any kind of raw addresses as it is seen as a security issue, and usually the addresses don't have any real value to someone reading logs, etc. I beleive I picked this up from GregKH.

However, this commit text suggests there is value, and I see that one needs to be root to enable this which could probably be considered a sufficent gate to avoiding the data getting into the wrong hands.

Is it possible to provide more details as a justification for this? Perhaps an example of a past issue where this data was necessary for debug?


Signed-off-by: Wachowski, Karol <karol.wachowski@xxxxxxxxx>
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@xxxxxxxxxxxxxxx>
---
  drivers/accel/ivpu/ivpu_drv.h         | 1 +
  drivers/accel/ivpu/ivpu_mmu_context.c | 9 +++++++++
  2 files changed, 10 insertions(+)

diff --git a/drivers/accel/ivpu/ivpu_drv.h b/drivers/accel/ivpu/ivpu_drv.h
index ebc4b84f27b2..9b6e336626e3 100644
--- a/drivers/accel/ivpu/ivpu_drv.h
+++ b/drivers/accel/ivpu/ivpu_drv.h
@@ -56,6 +56,7 @@
  #define IVPU_DBG_JSM	 BIT(10)
  #define IVPU_DBG_KREF	 BIT(11)
  #define IVPU_DBG_RPM	 BIT(12)
+#define IVPU_DBG_MMU_MAP BIT(13)
#define ivpu_err(vdev, fmt, ...) \
  	drm_err(&(vdev)->drm, "%s(): " fmt, __func__, ##__VA_ARGS__)
diff --git a/drivers/accel/ivpu/ivpu_mmu_context.c b/drivers/accel/ivpu/ivpu_mmu_context.c
index 12a8c09d4547..fe6161299236 100644
--- a/drivers/accel/ivpu/ivpu_mmu_context.c
+++ b/drivers/accel/ivpu/ivpu_mmu_context.c
@@ -355,6 +355,9 @@ ivpu_mmu_context_map_sgt(struct ivpu_device *vdev, struct ivpu_mmu_context *ctx,
  		dma_addr_t dma_addr = sg_dma_address(sg) - sg->offset;
  		size_t size = sg_dma_len(sg) + sg->offset;
+ ivpu_dbg(vdev, MMU_MAP, "Map ctx: %u dma_addr: 0x%llx vpu_addr: 0x%llx size: %lu\n",
+			 ctx->id, dma_addr, vpu_addr, size);
+
  		ret = ivpu_mmu_context_map_pages(vdev, ctx, vpu_addr, dma_addr, size, prot);
  		if (ret) {
  			ivpu_err(vdev, "Failed to map context pages\n");
@@ -366,6 +369,7 @@ ivpu_mmu_context_map_sgt(struct ivpu_device *vdev, struct ivpu_mmu_context *ctx,
/* Ensure page table modifications are flushed from wc buffers to memory */
  	wmb();
+

This looks like an unrelated whitespace change (although I see it pairs with the whitespace change below).

  	mutex_unlock(&ctx->lock);
ret = ivpu_mmu_invalidate_tlb(vdev, ctx->id);
@@ -388,14 +392,19 @@ ivpu_mmu_context_unmap_sgt(struct ivpu_device *vdev, struct ivpu_mmu_context *ct
  	mutex_lock(&ctx->lock);
for_each_sgtable_dma_sg(sgt, sg, i) {
+		dma_addr_t dma_addr = sg_dma_address(sg) - sg->offset;
  		size_t size = sg_dma_len(sg) + sg->offset;
+ ivpu_dbg(vdev, MMU_MAP, "Unmap ctx: %u dma_addr: 0x%llx vpu_addr: 0x%llx size: %lu\n",
+			 ctx->id, dma_addr, vpu_addr, size);
+
  		ivpu_mmu_context_unmap_pages(ctx, vpu_addr, size);
  		vpu_addr += size;
  	}
/* Ensure page table modifications are flushed from wc buffers to memory */
  	wmb();
+

This looks like an unrelated whitespace change.

  	mutex_unlock(&ctx->lock);
ret = ivpu_mmu_invalidate_tlb(vdev, ctx->id);




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