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From:   Kuppuswamy Sathyanarayanan 
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Subject: [PATCH v5 11/16] asm/io.h: Add ioremap_host_shared fallback
Date:   Fri,  8 Oct 2021 17:37:06 -0700
Message-Id: <20211009003711.1390019-12-sathyanarayanan.kuppuswamy@linux.intel.com>
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From: Andi Kleen <ak@linux.intel.com>

This function is for declaring memory that should be shared with
a hypervisor in a confidential guest. If the architecture doesn't
implement it it's just ioremap.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---

Changes since v4:
 * Renamed ioremap_shared to ioremap_host_shared
 * Added documentation for ioremap_host_shared().

 Documentation/driver-api/device-io.rst | 7 +++++++
 arch/alpha/include/asm/io.h            | 2 ++
 arch/mips/include/asm/io.h             | 2 ++
 arch/parisc/include/asm/io.h           | 2 ++
 arch/sparc/include/asm/io_64.h         | 2 ++
 include/asm-generic/io.h               | 5 +++++
 6 files changed, 20 insertions(+)

diff --git a/Documentation/driver-api/device-io.rst b/Documentation/driver-api/device-io.rst
index e9f04b1815d1..9f77a036fc2f 100644
--- a/Documentation/driver-api/device-io.rst
+++ b/Documentation/driver-api/device-io.rst
@@ -429,6 +429,13 @@ of the linear kernel memory area to a regular pointer.
 
 Portable drivers should avoid the use of ioremap_cache().
 
+ioremap_host_shared()
+---------------------
+
+ioremap_host_shared() maps I/O memory so that it can be shared with the host
+in a confidential guest platform. It is mainly used in platforms like
+Trusted Domain Extensions (TDX).
+
 Architecture example
 --------------------
 
diff --git a/arch/alpha/include/asm/io.h b/arch/alpha/include/asm/io.h
index 0fab5ac90775..81952ef50667 100644
--- a/arch/alpha/include/asm/io.h
+++ b/arch/alpha/include/asm/io.h
@@ -283,6 +283,8 @@ static inline void __iomem *ioremap(unsigned long port, unsigned long size)
 }
 
 #define ioremap_wc ioremap
+/* Share memory with host in confidential guest platforms */
+#define ioremap_host_shared ioremap
 #define ioremap_uc ioremap
 
 static inline void iounmap(volatile void __iomem *addr)
diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
index 6f5c86d2bab4..83f638fb48c5 100644
--- a/arch/mips/include/asm/io.h
+++ b/arch/mips/include/asm/io.h
@@ -179,6 +179,8 @@ void iounmap(const volatile void __iomem *addr);
 #define ioremap(offset, size)						\
 	ioremap_prot((offset), (size), _CACHE_UNCACHED)
 #define ioremap_uc		ioremap
+/* Share memory with host in confidential guest platforms */
+#define ioremap_host_shared	ioremap
 
 /*
  * ioremap_cache -	map bus memory into CPU space
diff --git a/arch/parisc/include/asm/io.h b/arch/parisc/include/asm/io.h
index 0b5259102319..ef516ee06238 100644
--- a/arch/parisc/include/asm/io.h
+++ b/arch/parisc/include/asm/io.h
@@ -129,6 +129,8 @@ static inline void gsc_writeq(unsigned long long val, unsigned long addr)
  */
 void __iomem *ioremap(unsigned long offset, unsigned long size);
 #define ioremap_wc			ioremap
+/* Share memory with host in confidential guest platforms */
+#define ioremap_host_shared		ioremap
 #define ioremap_uc			ioremap
 
 extern void iounmap(const volatile void __iomem *addr);
diff --git a/arch/sparc/include/asm/io_64.h b/arch/sparc/include/asm/io_64.h
index 5ffa820dcd4d..5b73b877f832 100644
--- a/arch/sparc/include/asm/io_64.h
+++ b/arch/sparc/include/asm/io_64.h
@@ -409,6 +409,8 @@ static inline void __iomem *ioremap(unsigned long offset, unsigned long size)
 #define ioremap_uc(X,Y)			ioremap((X),(Y))
 #define ioremap_wc(X,Y)			ioremap((X),(Y))
 #define ioremap_wt(X,Y)			ioremap((X),(Y))
+/* Share memory with host in confidential guest platforms */
+#define ioremap_host_shared(X, Y)	ioremap((X), (Y))
 static inline void __iomem *ioremap_np(unsigned long offset, unsigned long size)
 {
 	return NULL;
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index e93375c710b9..26b48fe23769 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -982,6 +982,11 @@ static inline void __iomem *ioremap(phys_addr_t addr, size_t size)
 #define ioremap_wt ioremap
 #endif
 
+/* Share memory with host in confidential guest platforms */
+#ifndef ioremap_host_shared
+#define ioremap_host_shared ioremap
+#endif
+
 /*
  * ioremap_uc is special in that we do require an explicit architecture
  * implementation.  In general you do not want to use this function in a
-- 
2.25.1