[PATCH v2 1/7] xen/acpi: Rework acpi_os_map_memory() and acpi_os_unmap_memory()

[Julien Grall <julien@xxxxxxx>]

From: Julien Grall <jgrall@xxxxxxxxxx>

The functions acpi_os_{un,}map_memory() are meant to be arch-agnostic
while the __acpi_os_{un,}map_memory() are meant to be arch-specific.

Currently, the former are still containing x86 specific code.

To avoid this rather strange split, the generic helpers are reworked so
they are arch-agnostic. This requires the introduction of a new helper
__acpi_os_unmap_memory() that will undo any mapping done by
__acpi_os_map_memory().

Currently, the arch-helper for unmap is basically a no-op so it only
returns whether the mapping was arch specific. But this will change
in the future.

Note that the x86 version of acpi_os_map_memory() was already able to
able the 1MB region. Hence why there is no addition of new code.

Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
Reviewed-by: Rahul Singh <rahul.singh@xxxxxxx>
Tested-by: Rahul Singh <rahul.singh@xxxxxxx>

---
    Changes in v2:
        - Constify ptr in __acpi_unmap_table()
        - Coding style fixes
        - Fix build on arm64
        - Use PAGE_OFFSET() rather than open-coding it
        - Add Rahul's tested-by and reviewed-by
---
 xen/arch/arm/acpi/lib.c | 12 ++++++++++++
 xen/arch/x86/acpi/lib.c | 18 ++++++++++++++++++
 xen/drivers/acpi/osl.c  | 34 ++++++++++++++++++----------------
 xen/include/xen/acpi.h  |  1 +
 4 files changed, 49 insertions(+), 16 deletions(-)

diff --git a/xen/arch/arm/acpi/lib.c b/xen/arch/arm/acpi/lib.c
index 4fc6e17322c1..fcc186b03399 100644
--- a/xen/arch/arm/acpi/lib.c
+++ b/xen/arch/arm/acpi/lib.c
@@ -30,6 +30,10 @@ char *__acpi_map_table(paddr_t phys, unsigned long size)
     unsigned long base, offset, mapped_size;
     int idx;
 
+    /* No arch specific implementation after early boot */
+    if ( system_state >= SYS_STATE_boot )
+        return NULL;
+
     offset = phys & (PAGE_SIZE - 1);
     mapped_size = PAGE_SIZE - offset;
     set_fixmap(FIXMAP_ACPI_BEGIN, maddr_to_mfn(phys), PAGE_HYPERVISOR);
@@ -49,6 +53,14 @@ char *__acpi_map_table(paddr_t phys, unsigned long size)
     return ((char *) base + offset);
 }
 
+bool __acpi_unmap_table(const void *ptr, unsigned long size)
+{
+    vaddr_t vaddr = (vaddr_t)ptr;
+
+    return ((vaddr >= FIXMAP_ADDR(FIXMAP_ACPI_BEGIN)) &&
+            (vaddr < (FIXMAP_ADDR(FIXMAP_ACPI_END) + PAGE_SIZE)));
+}
+
 /* True to indicate PSCI 0.2+ is implemented */
 bool __init acpi_psci_present(void)
 {
diff --git a/xen/arch/x86/acpi/lib.c b/xen/arch/x86/acpi/lib.c
index 265b9ad81905..a22414a05c13 100644
--- a/xen/arch/x86/acpi/lib.c
+++ b/xen/arch/x86/acpi/lib.c
@@ -46,6 +46,10 @@ char *__acpi_map_table(paddr_t phys, unsigned long size)
        if ((phys + size) <= (1 * 1024 * 1024))
                return __va(phys);
 
+       /* No further arch specific implementation after early boot */
+       if (system_state >= SYS_STATE_boot)
+               return NULL;
+
        offset = phys & (PAGE_SIZE - 1);
        mapped_size = PAGE_SIZE - offset;
        set_fixmap(FIX_ACPI_END, phys);
@@ -66,6 +70,20 @@ char *__acpi_map_table(paddr_t phys, unsigned long size)
        return ((char *) base + offset);
 }
 
+bool __acpi_unmap_table(const void *ptr, unsigned long size)
+{
+       unsigned long vaddr = (unsigned long)ptr;
+
+       if ((vaddr >= DIRECTMAP_VIRT_START) &&
+           (vaddr < DIRECTMAP_VIRT_END)) {
+               ASSERT(!((__pa(ptr) + size - 1) >> 20));
+               return true;
+       }
+
+       return ((vaddr >= __fix_to_virt(FIX_ACPI_END)) &&
+               (vaddr < (__fix_to_virt(FIX_ACPI_BEGIN) + PAGE_SIZE)));
+}
+
 unsigned int acpi_get_processor_id(unsigned int cpu)
 {
        unsigned int acpiid, apicid;
diff --git a/xen/drivers/acpi/osl.c b/xen/drivers/acpi/osl.c
index 4c8bb7839eda..389505f78666 100644
--- a/xen/drivers/acpi/osl.c
+++ b/xen/drivers/acpi/osl.c
@@ -92,27 +92,29 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
 void __iomem *
 acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
 {
-       if (system_state >= SYS_STATE_boot) {
-               mfn_t mfn = _mfn(PFN_DOWN(phys));
-               unsigned int offs = phys & (PAGE_SIZE - 1);
-
-               /* The low first Mb is always mapped on x86. */
-               if (IS_ENABLED(CONFIG_X86) && !((phys + size - 1) >> 20))
-                       return __va(phys);
-               return __vmap(&mfn, PFN_UP(offs + size), 1, 1,
-                             ACPI_MAP_MEM_ATTR, VMAP_DEFAULT) + offs;
-       }
-       return __acpi_map_table(phys, size);
+       void *ptr;
+       mfn_t mfn = _mfn(PFN_DOWN(phys));
+       unsigned int offs = PAGE_OFFSET(phys);
+
+       /* Try the arch specific implementation first */
+       ptr = __acpi_map_table(phys, size);
+       if (ptr)
+               return ptr;
+
+       /* No common implementation for early boot map */
+       if (unlikely(system_state < SYS_STATE_boot))
+               return NULL;
+
+       ptr = __vmap(&mfn, PFN_UP(offs + size), 1, 1,
+                    ACPI_MAP_MEM_ATTR, VMAP_DEFAULT);
+
+       return !ptr ? NULL : (ptr + offs);
 }
 
 void acpi_os_unmap_memory(void __iomem * virt, acpi_size size)
 {
-       if (IS_ENABLED(CONFIG_X86) &&
-           (unsigned long)virt >= DIRECTMAP_VIRT_START &&
-           (unsigned long)virt < DIRECTMAP_VIRT_END) {
-               ASSERT(!((__pa(virt) + size - 1) >> 20));
+       if (__acpi_unmap_table(virt, size))
                return;
-       }
 
        if (system_state >= SYS_STATE_boot)
                vunmap((void *)((unsigned long)virt & PAGE_MASK));
diff --git a/xen/include/xen/acpi.h b/xen/include/xen/acpi.h
index c945ab05c864..21d5e9feb5ae 100644
--- a/xen/include/xen/acpi.h
+++ b/xen/include/xen/acpi.h
@@ -68,6 +68,7 @@ typedef int (*acpi_table_entry_handler) (struct 
acpi_subtable_header *header, co
 
 unsigned int acpi_get_processor_id (unsigned int cpu);
 char * __acpi_map_table (paddr_t phys_addr, unsigned long size);
+bool __acpi_unmap_table(const void *ptr, unsigned long size);
 int acpi_boot_init (void);
 int acpi_boot_table_init (void);
 int acpi_numa_init (void);
-- 
2.17.1