[RFC,07/14] arm64: Override set_fixmap_io

Commit Message

Steven Price Jan. 27, 2023, 11:27 a.m. UTC

From: Suzuki K Poulose <[e-mail]>

Override the set_fixmap_io to set shared permission for the host
in case of a CC guest. For now we mark it shared unconditionally.
Future changes could filter the physical address and make the
decision accordingly.

Signed-off-by: Suzuki K Poulose <[e-mail]>
Signed-off-by: Steven Price <[e-mail]>
---
 arch/arm64/include/asm/fixmap.h |  2 ++
 arch/arm64/mm/mmu.c             | 13 +++++++++++++
 2 files changed, 15 insertions(+)

Patch

diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h
index 09ba9fe3b02c..1acafc1c7fae 100644
--- a/arch/arm64/include/asm/fixmap.h
+++ b/arch/arm64/include/asm/fixmap.h
@@ -107,6 +107,8 @@  void __init early_fixmap_init(void);
 #define __late_set_fixmap __set_fixmap
 #define __late_clear_fixmap(idx) __set_fixmap((idx), 0, FIXMAP_PAGE_CLEAR)
 
+#define set_fixmap_io set_fixmap_io
+void set_fixmap_io(enum fixed_addresses idx, phys_addr_t phys);
 void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot);
 
 #include <asm-generic/fixmap.h>
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 14c87e8d69d8..33fda73c669b 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1279,6 +1279,19 @@  void __set_fixmap(enum fixed_addresses idx,
 	}
 }
 
+void set_fixmap_io(enum fixed_addresses idx, phys_addr_t phys)
+{
+	pgprot_t prot = FIXMAP_PAGE_IO;
+
+	/*
+	 * For now we consider all I/O as non-secure. For future
+	 * filter the I/O base for setting appropriate permissions.
+	 */
+	prot = __pgprot(pgprot_val(prot) | PROT_NS_SHARED);
+
+	return __set_fixmap(idx, phys, prot);
+}
+
 void *__init fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot)
 {
 	const u64 dt_virt_base = __fix_to_virt(FIX_FDT);