linux-kernel - [PATCH v5 2/9] scatterlist: Add a flag for the restricted memory

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Date: Wed, 15 May 2024 19:23:01 +0800
From: Yong Wu <yong.wu@...iatek.com>
To: Rob Herring <robh+dt@...nel.org>, Matthias Brugger
	<matthias.bgg@...il.com>, <christian.koenig@....com>, Sumit Semwal
	<sumit.semwal@...aro.org>, Andrew Morton <akpm@...ux-foundation.org>
CC: Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley
	<conor+dt@...nel.org>, Benjamin Gaignard <benjamin.gaignard@...labora.com>,
	Brian Starkey <Brian.Starkey@....com>, John Stultz <jstultz@...gle.com>,
	<tjmercier@...gle.com>, AngeloGioacchino Del Regno
	<angelogioacchino.delregno@...labora.com>, Yong Wu <yong.wu@...iatek.com>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-media@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
	<linaro-mm-sig@...ts.linaro.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-mediatek@...ts.infradead.org>, Robin Murphy <robin.murphy@....com>,
	Vijayanand Jitta <quic_vjitta@...cinc.com>, Joakim Bech
	<joakim.bech@...aro.org>, Jeffrey Kardatzke <jkardatzke@...gle.com>, Pavel
 Machek <pavel@....cz>, Simon Ser <contact@...rsion.fr>, Pekka Paalanen
	<ppaalanen@...il.com>, <willy@...radead.org>, Logan Gunthorpe
	<logang@...tatee.com>, Daniel Vetter <daniel@...ll.ch>,
	<jianjiao.zeng@...iatek.com>, <kuohong.wang@...iatek.com>,
	<youlin.pei@...iatek.com>
Subject: [PATCH v5 2/9] scatterlist: Add a flag for the restricted memory

Introduce a FLAG for the restricted memory which means the memory is
protected by TEE or hypervisor, then it's inaccessiable for kernel.

Currently we don't use sg_dma_unmark_restricted, thus this interface
has not been added.

Signed-off-by: Yong Wu <yong.wu@...iatek.com>
---
 include/linux/scatterlist.h | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 77df3d7b18a6..a6ad9018eca0 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -282,6 +282,7 @@ static inline void sg_unmark_end(struct scatterlist *sg)
 
 #define SG_DMA_BUS_ADDRESS	(1 << 0)
 #define SG_DMA_SWIOTLB		(1 << 1)
+#define SG_DMA_RESTRICTED	(2 << 1)
 
 /**
  * sg_dma_is_bus_address - Return whether a given segment was marked
@@ -352,6 +353,31 @@ static inline void sg_dma_mark_swiotlb(struct scatterlist *sg)
 	sg->dma_flags |= SG_DMA_SWIOTLB;
 }
 
+/**
+ * sg_dma_mark_restricted - Mark the scatterlist for restricted buffer.
+ * @sg:		SG entry
+ *
+ * Description:
+ *   Marks a a scatterlist for the restricted buffer that may be inaccessiable
+ *   in kernel if it is protected.
+ */
+static inline void sg_dma_mark_restricted(struct scatterlist *sg)
+{
+	sg->dma_flags |= SG_DMA_RESTRICTED;
+}
+
+/**
+ * sg_dma_is_restricted - Return whether the scatterlist was marked as restricted
+ *                        buffer.
+ * @sg:		SG entry
+ *
+ * Description:
+ *   Returns true if the scatterlist was marked as restricted buffer.
+ */
+static inline bool sg_dma_is_restricted(struct scatterlist *sg)
+{
+	return sg->dma_flags & SG_DMA_RESTRICTED;
+}
 #else
 
 static inline bool sg_dma_is_bus_address(struct scatterlist *sg)
@@ -372,6 +398,14 @@ static inline void sg_dma_mark_swiotlb(struct scatterlist *sg)
 {
 }
 
+static inline bool sg_dma_is_restricted(struct scatterlist *sg)
+{
+	return false;
+}
+
+static inline void sg_dma_mark_restrited(struct scatterlist *sg)
+{
+}
 #endif	/* CONFIG_NEED_SG_DMA_FLAGS */
 
 /**
-- 
2.25.1