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Subject[RFC v1 23/26] x86/tdx: Make pages shared in ioremap()
Date
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

All ioremap()ed paged that are not backed by normal memory (NONE or
RESERVED) have to be mapped as shared.

Reuse the infrastructure we have for AMD SEV.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
arch/x86/include/asm/pgtable.h | 3 +++
arch/x86/mm/ioremap.c | 8 +++++---
2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index a02c67291cfc..a82bab48379e 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -21,6 +21,9 @@
#define pgprot_encrypted(prot) __pgprot(__sme_set(pgprot_val(prot)))
#define pgprot_decrypted(prot) __pgprot(__sme_clr(pgprot_val(prot)))

+/* Make the page accesable by VMM */
+#define pgprot_tdx_shared(prot) __pgprot(pgprot_val(prot) | tdx_shared_mask())
+
#ifndef __ASSEMBLY__
#include <asm/x86_init.h>
#include <asm/fpu/xstate.h>
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 9e5ccc56f8e0..a0ba760866d4 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -87,12 +87,12 @@ static unsigned int __ioremap_check_ram(struct resource *res)
}

/*
- * In a SEV guest, NONE and RESERVED should not be mapped encrypted because
- * there the whole memory is already encrypted.
+ * In a SEV or TDX guest, NONE and RESERVED should not be mapped encrypted (or
+ * private in TDX case) because there the whole memory is already encrypted.
*/
static unsigned int __ioremap_check_encrypted(struct resource *res)
{
- if (!sev_active())
+ if (!sev_active() && !is_tdx_guest())
return 0;

switch (res->desc) {
@@ -244,6 +244,8 @@ __ioremap_caller(resource_size_t phys_addr, unsigned long size,
prot = PAGE_KERNEL_IO;
if ((io_desc.flags & IORES_MAP_ENCRYPTED) || encrypted)
prot = pgprot_encrypted(prot);
+ else if (is_tdx_guest())
+ prot = pgprot_tdx_shared(prot);

switch (pcm) {
case _PAGE_CACHE_MODE_UC:
--
2.25.1
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