[PATCHv4 6/8] x86/mm: Provide helpers for unaccepted memory

["Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>]

Core-mm requires few helpers to support unaccepted memory:

 - accept_memory() checks the range of addresses against the bitmap and
   accept memory if needed.

 - memory_is_unaccepted() check if anything within the range requires
   acceptance.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/page.h              |  5 +++
 arch/x86/include/asm/unaccepted_memory.h |  1 +
 arch/x86/mm/Makefile                     |  2 +
 arch/x86/mm/unaccepted_memory.c          | 53 ++++++++++++++++++++++++
 4 files changed, 61 insertions(+)
 create mode 100644 arch/x86/mm/unaccepted_memory.c

diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
index 9cc82f305f4b..9ae0064f97e5 100644
--- a/arch/x86/include/asm/page.h
+++ b/arch/x86/include/asm/page.h
@@ -19,6 +19,11 @@
 struct page;
 
 #include <linux/range.h>
+
+#ifdef CONFIG_UNACCEPTED_MEMORY
+#include <asm/unaccepted_memory.h>
+#endif
+
 extern struct range pfn_mapped[];
 extern int nr_pfn_mapped;
 
diff --git a/arch/x86/include/asm/unaccepted_memory.h b/arch/x86/include/asm/unaccepted_memory.h
index f1f835d3cd78..a8d12ef1bda8 100644
--- a/arch/x86/include/asm/unaccepted_memory.h
+++ b/arch/x86/include/asm/unaccepted_memory.h
@@ -10,5 +10,6 @@ struct boot_params;
 void mark_unaccepted(struct boot_params *params, u64 start, u64 num);
 
 void accept_memory(phys_addr_t start, phys_addr_t end);
+bool memory_is_unaccepted(phys_addr_t start, phys_addr_t end);
 
 #endif
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index fe3d3061fc11..e327f83e6bbf 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -60,3 +60,5 @@ obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt_amd.o
 
 obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt_identity.o
 obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt_boot.o
+
+obj-$(CONFIG_UNACCEPTED_MEMORY)	+= unaccepted_memory.o
diff --git a/arch/x86/mm/unaccepted_memory.c b/arch/x86/mm/unaccepted_memory.c
new file mode 100644
index 000000000000..3588a7cb954c
--- /dev/null
+++ b/arch/x86/mm/unaccepted_memory.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/memblock.h>
+#include <linux/mm.h>
+#include <linux/pfn.h>
+#include <linux/spinlock.h>
+
+#include <asm/io.h>
+#include <asm/setup.h>
+#include <asm/unaccepted_memory.h>
+
+static DEFINE_SPINLOCK(unaccepted_memory_lock);
+
+void accept_memory(phys_addr_t start, phys_addr_t end)
+{
+	unsigned long *unaccepted_memory;
+	unsigned long flags;
+	unsigned int rs, re;
+
+	if (!boot_params.unaccepted_memory)
+		return;
+
+	unaccepted_memory = __va(boot_params.unaccepted_memory);
+	rs = start / PMD_SIZE;
+
+	spin_lock_irqsave(&unaccepted_memory_lock, flags);
+	for_each_set_bitrange_from(rs, re, unaccepted_memory,
+				   DIV_ROUND_UP(end, PMD_SIZE)) {
+		/* Platform-specific memory-acceptance call goes here */
+		panic("Cannot accept memory");
+		bitmap_clear(unaccepted_memory, rs, re - rs);
+	}
+	spin_unlock_irqrestore(&unaccepted_memory_lock, flags);
+}
+
+bool memory_is_unaccepted(phys_addr_t start, phys_addr_t end)
+{
+	unsigned long *unaccepted_memory = __va(boot_params.unaccepted_memory);
+	unsigned long flags;
+	bool ret = false;
+
+	spin_lock_irqsave(&unaccepted_memory_lock, flags);
+	while (start < end) {
+		if (test_bit(start / PMD_SIZE, unaccepted_memory)) {
+			ret = true;
+			break;
+		}
+
+		start += PMD_SIZE;
+	}
+	spin_unlock_irqrestore(&unaccepted_memory_lock, flags);
+
+	return ret;
+}
-- 
2.35.1