linux-kernel - [PATCH 5.2 131/131] drm/i915/gvt: fix incorrect cache entry for guest page mapping

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Message-Id: <20190805125000.899343807@linuxfoundation.org>
Date:   Mon,  5 Aug 2019 15:03:38 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Zhenyu Wang <zhenyuw@...ux.intel.com>,
        Xiaolin Zhang <xiaolin.zhang@...el.com>
Subject: [PATCH 5.2 131/131] drm/i915/gvt: fix incorrect cache entry for guest page mapping

From: Xiaolin Zhang <xiaolin.zhang@...el.com>

commit 7366aeb77cd840f3edea02c65065d40affaa7f45 upstream.

GPU hang observed during the guest OCL conformance test which is caused
by THP GTT feature used durning the test.

It was observed the same GFN with different size (4K and 2M) requested
from the guest in GVT. So during the guest page dma map stage, it is
required to unmap first with orginal size and then remap again with
requested size.

Fixes: b901b252b6cf ("drm/i915/gvt: Add 2M huge gtt support")
Cc: stable@...r.kernel.org
Reviewed-by: Zhenyu Wang <zhenyuw@...ux.intel.com>
Signed-off-by: Xiaolin Zhang <xiaolin.zhang@...el.com>
Signed-off-by: Zhenyu Wang <zhenyuw@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/i915/gvt/kvmgt.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -1911,6 +1911,18 @@ static int kvmgt_dma_map_guest_page(unsi
 		ret = __gvt_cache_add(info->vgpu, gfn, *dma_addr, size);
 		if (ret)
 			goto err_unmap;
+	} else if (entry->size != size) {
+		/* the same gfn with different size: unmap and re-map */
+		gvt_dma_unmap_page(vgpu, gfn, entry->dma_addr, entry->size);
+		__gvt_cache_remove_entry(vgpu, entry);
+
+		ret = gvt_dma_map_page(vgpu, gfn, dma_addr, size);
+		if (ret)
+			goto err_unlock;
+
+		ret = __gvt_cache_add(info->vgpu, gfn, *dma_addr, size);
+		if (ret)
+			goto err_unmap;
 	} else {
 		kref_get(&entry->ref);
 		*dma_addr = entry->dma_addr;