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Subject[PATCH v5 11/16] asm/io.h: Add ioremap_host_shared fallback
Date
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
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