[Qemu-devel] [RFC/RFT PATCH v2 1/3] arm/arm64: pageattr: add set_memory_nc

[Andrew Jones <drjones@redhat.com>]

Provide a method to change normal, cacheable memory to non-cacheable.
KVM will make use of this to keep emulated device memory regions
coherent with the guest.

Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 arch/arm/include/asm/cacheflush.h   | 1 +
 arch/arm/mm/pageattr.c              | 7 +++++++
 arch/arm64/include/asm/cacheflush.h | 1 +
 arch/arm64/mm/pageattr.c            | 8 ++++++++
 4 files changed, 17 insertions(+)

diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
index 2d46862e7bef7..682a8b13d6019 100644
--- a/arch/arm/include/asm/cacheflush.h
+++ b/arch/arm/include/asm/cacheflush.h
@@ -486,6 +486,7 @@ int set_memory_ro(unsigned long addr, int numpages);
 int set_memory_rw(unsigned long addr, int numpages);
 int set_memory_x(unsigned long addr, int numpages);
 int set_memory_nx(unsigned long addr, int numpages);
+int set_memory_nc(unsigned long addr, int numpages);
 
 #ifdef CONFIG_DEBUG_RODATA
 void mark_rodata_ro(void);
diff --git a/arch/arm/mm/pageattr.c b/arch/arm/mm/pageattr.c
index cf30daff89325..9f9f752cab871 100644
--- a/arch/arm/mm/pageattr.c
+++ b/arch/arm/mm/pageattr.c
@@ -92,3 +92,10 @@ int set_memory_x(unsigned long addr, int numpages)
 					__pgprot(0),
 					__pgprot(L_PTE_XN));
 }
+
+int set_memory_nc(unsigned long addr, int numpages)
+{
+	return change_memory_common(addr, numpages,
+					__pgprot(L_PTE_MT_BUFFERABLE),
+					__pgprot(L_PTE_MT_MASK));
+}
diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
index 67d309cc3b6b8..ef671f38c19ad 100644
--- a/arch/arm64/include/asm/cacheflush.h
+++ b/arch/arm64/include/asm/cacheflush.h
@@ -152,6 +152,7 @@ int set_memory_ro(unsigned long addr, int numpages);
 int set_memory_rw(unsigned long addr, int numpages);
 int set_memory_x(unsigned long addr, int numpages);
 int set_memory_nx(unsigned long addr, int numpages);
+int set_memory_nc(unsigned long addr, int numpages);
 
 #ifdef CONFIG_DEBUG_RODATA
 void mark_rodata_ro(void);
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index e47ed1c5dce1b..c837adcf26fc6 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -96,3 +96,11 @@ int set_memory_x(unsigned long addr, int numpages)
 					__pgprot(PTE_PXN));
 }
 EXPORT_SYMBOL_GPL(set_memory_x);
+
+int set_memory_nc(unsigned long addr, int numpages)
+{
+	return change_memory_common(addr, numpages,
+					__pgprot(PTE_ATTRINDX(MT_NORMAL_NC)),
+					__pgprot(PTE_ATTRINDX_MASK));
+}
+EXPORT_SYMBOL_GPL(set_memory_nc);
-- 
2.1.0