acpica: add acpi_os_map_memory_opregion

In confidential computing scenarios operation regions
need to be shared with the host in order for the
host to pass data via such regions to the guest.
Since by default all guest mappings are private, define
a new acpi_os_map_memory_opregion interface that maps
operation regions as shared in case we are executing
in a confidential guest. This avoids mapping rest of the
ACPI structures as shared and only shares the operation
regions.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>

drivers/acpi/acpica/exregion.c

@@ -161,7 +161,7 @@ acpi_ex_system_memory_space_handler(u32 function,
 
 		/* Create a new mapping starting at the address given */
 
-		logical_addr_ptr = acpi_os_map_memory(address, map_length);
+		logical_addr_ptr = acpi_os_map_memory_opregion(address, map_length);
 		if (!logical_addr_ptr) {
 			ACPI_ERROR((AE_INFO,
 				    "Could not map memory at 0x%8.8X%8.8X, size %u",

drivers/acpi/osl.c

@@ -30,6 +30,7 @@
 #include <linux/jiffies.h>
 #include <linux/semaphore.h>
 #include <linux/security.h>
+#include <linux/cc_platform.h>
 
 #include <asm/io.h>
 #include <linux/uaccess.h>
@@ -307,21 +308,8 @@ static void acpi_unmap(acpi_physical_address pg_off, void __iomem *vaddr)
 		iounmap(vaddr);
 }
 
-/**
- * acpi_os_map_iomem - Get a virtual address for a given physical address range.
- * @phys: Start of the physical address range to map.
- * @size: Size of the physical address range to map.
- *
- * Look up the given physical address range in the list of existing ACPI memory
- * mappings.  If found, get a reference to it and return a pointer to it (its
- * virtual address).  If not found, map it, add it to that list and return a
- * pointer to it.
- *
- * During early init (when acpi_permanent_mmap has not been set yet) this
- * routine simply calls __acpi_map_table() to get the job done.
- */
-void __iomem __ref
-*acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
+static void __iomem __ref
+*__acpi_os_map_iomem(acpi_physical_address phys, acpi_size size, bool map_shared)
 {
 	struct acpi_ioremap *map;
 	void __iomem *virt;
@@ -352,7 +340,10 @@ void __iomem __ref
 
 	pg_off = round_down(phys, PAGE_SIZE);
 	pg_sz = round_up(phys + size, PAGE_SIZE) - pg_off;
-	virt = acpi_map(phys, size);
+	if (map_shared)
+		virt = ioremap_cache_shared(phys, size);
+	else
+		virt = acpi_map(phys, size);
 	if (!virt) {
 		mutex_unlock(&acpi_ioremap_lock);
 		kfree(map);
@@ -371,6 +362,25 @@ void __iomem __ref
 	mutex_unlock(&acpi_ioremap_lock);
 	return map->virt + (phys - map->phys);
 }
+
+/**
+ * acpi_os_map_iomem - Get a virtual address for a given physical address range.
+ * @phys: Start of the physical address range to map.
+ * @size: Size of the physical address range to map.
+ *
+ * Look up the given physical address range in the list of existing ACPI memory
+ * mappings.  If found, get a reference to it and return a pointer to it (its
+ * virtual address).  If not found, map it, add it to that list and return a
+ * pointer to it.
+ *
+ * During early init (when acpi_permanent_mmap has not been set yet) this
+ * routine simply calls __acpi_map_table() to get the job done.
+ */
+void __iomem __ref
+*acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
+{
+	return (void *)__acpi_os_map_iomem(phys, size, false);
+}
 EXPORT_SYMBOL_GPL(acpi_os_map_iomem);
 
 void *__ref acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
@@ -379,6 +389,32 @@ void *__ref acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
 }
 EXPORT_SYMBOL_GPL(acpi_os_map_memory);
 
+/**
+ * acpi_os_map_memory_opregion - Get a virtual address for a given physical
+ * address range. This function is intended to be used only for AML operation
+ * regions. In a confidential computing guest such regions needs to be explicitly
+ * shared with the host to avoid breaking the communication. 
+ *
+ * @phys: Start of the physical address range to map.
+ * @size: Size of the physical address range to map.
+ *
+ * Look up the given physical address range in the list of existing ACPI memory
+ * mappings.  If found, get a reference to it and return a pointer to it (its
+ * virtual address).  If not found, map it, add it to that list and return a
+ * pointer to it.
+ *
+ * During early init (when acpi_permanent_mmap has not been set yet) this
+ * routine simply calls __acpi_map_table() to get the job done.
+ */
+void *__ref acpi_os_map_memory_opregion(acpi_physical_address phys, acpi_size size)
+{
+	if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
+		return (void *)__acpi_os_map_iomem(phys, size, false);
+	else
+		return (void *)__acpi_os_map_iomem(phys, size, true);
+}
+EXPORT_SYMBOL_GPL(acpi_os_map_memory_opregion);
+
 static void acpi_os_map_remove(struct work_struct *work)
 {
 	struct acpi_ioremap *map = container_of(to_rcu_work(work),

include/acpi/acpiosxf.h

@@ -183,6 +183,11 @@ void acpi_os_free(void *memory);
 void *acpi_os_map_memory(acpi_physical_address where, acpi_size length);
 #endif
 
+#ifndef ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_map_memory_opregion
+# define acpi_os_map_memory_opregion(address, length)	\
+	acpi_os_map_memory(address, length)
+#endif
+
 #ifndef ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_unmap_memory
 void acpi_os_unmap_memory(void *logical_address, acpi_size size);
 #endif

include/acpi/platform/aclinux.h

@@ -142,6 +142,7 @@
 #define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_delete_raw_lock
 #define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_acquire_raw_lock
 #define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_release_raw_lock
+#define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_map_memory_opregion
 
 /*
  * OSL interfaces used by debugger/disassembler

include/acpi/platform/aclinuxex.h

@@ -135,6 +135,8 @@ static inline void acpi_os_terminate_debugger(void)
 	return;
 }
 
+void *__ref acpi_os_map_memory_opregion(acpi_physical_address phys, acpi_size size);
+
 /*
  * OSL interfaces added by Linux
  */