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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-06-30 13:40:59 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-07-27 12:29:02 +0200
commitb8fcd0e588fc256bed3d65a4e23017c5582ecf48 (patch)
treed505bb0f39fc19ecea7d38961656b113a7a4664e /drivers/acpi
parent1757659d022b7369b6a4b9a34ad992866a1bcbb0 (diff)
ACPICA: Preserve memory opregion mappings
The ACPICA's strategy with respect to the handling of memory mappings associated with memory operation regions is to avoid mapping the entire region at once which may be problematic at least in principle (for example, it may lead to conflicts with overlapping mappings having different attributes created by drivers). It may also be wasteful, because memory opregions on some systems take up vast chunks of address space while the fields in those regions actually accessed by AML are sparsely distributed. For this reason, a one-page "window" is mapped for a given opregion on the first memory access through it and if that "window" does not cover an address range accessed through that opregion subsequently, it is unmapped and a new "window" is mapped to replace it. Next, if the new "window" is not sufficient to acess memory through the opregion in question in the future, it will be replaced with yet another "window" and so on. That may lead to a suboptimal sequence of memory mapping and unmapping operations, for example if two fields in one opregion separated from each other by a sufficiently wide chunk of unused address space are accessed in an alternating pattern. The situation may still be suboptimal if the deferred unmapping introduced previously is supported by the OS layer. For instance, the alternating memory access pattern mentioned above may produce a relatively long list of mappings to release with substantial duplication among the entries in it, which could be avoided if acpi_ex_system_memory_space_handler() did not release the mapping used by it previously as soon as the current access was not covered by it. In order to improve that, modify acpi_ex_system_memory_space_handler() to preserve all of the memory mappings created by it until the memory regions associated with them go away. Accordingly, update acpi_ev_system_memory_region_setup() to unmap all memory associated with memory opregions that go away. Reported-by: Dan Williams <dan.j.williams@intel.com> Tested-by: Xiang Li <xiang.z.li@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/acpica/evrgnini.c14
-rw-r--r--drivers/acpi/acpica/exregion.c64
2 files changed, 54 insertions, 24 deletions
diff --git a/drivers/acpi/acpica/evrgnini.c b/drivers/acpi/acpica/evrgnini.c
index aefc0145e583..89be3ccdad53 100644
--- a/drivers/acpi/acpica/evrgnini.c
+++ b/drivers/acpi/acpica/evrgnini.c
@@ -38,6 +38,7 @@ acpi_ev_system_memory_region_setup(acpi_handle handle,
union acpi_operand_object *region_desc =
(union acpi_operand_object *)handle;
struct acpi_mem_space_context *local_region_context;
+ struct acpi_mem_mapping *mm;
ACPI_FUNCTION_TRACE(ev_system_memory_region_setup);
@@ -46,13 +47,14 @@ acpi_ev_system_memory_region_setup(acpi_handle handle,
local_region_context =
(struct acpi_mem_space_context *)*region_context;
- /* Delete a cached mapping if present */
+ /* Delete memory mappings if present */
- if (local_region_context->mapped_length) {
- acpi_os_unmap_memory(local_region_context->
- mapped_logical_address,
- local_region_context->
- mapped_length);
+ while (local_region_context->first_mm) {
+ mm = local_region_context->first_mm;
+ local_region_context->first_mm = mm->next_mm;
+ acpi_os_unmap_memory(mm->logical_address,
+ mm->length);
+ ACPI_FREE(mm);
}
ACPI_FREE(local_region_context);
*region_context = NULL;
diff --git a/drivers/acpi/acpica/exregion.c b/drivers/acpi/acpica/exregion.c
index d15a66de26c0..4914dbc44517 100644
--- a/drivers/acpi/acpica/exregion.c
+++ b/drivers/acpi/acpica/exregion.c
@@ -41,6 +41,7 @@ acpi_ex_system_memory_space_handler(u32 function,
acpi_status status = AE_OK;
void *logical_addr_ptr = NULL;
struct acpi_mem_space_context *mem_info = region_context;
+ struct acpi_mem_mapping *mm = mem_info->cur_mm;
u32 length;
acpi_size map_length;
acpi_size page_boundary_map_length;
@@ -96,20 +97,37 @@ acpi_ex_system_memory_space_handler(u32 function,
* Is 1) Address below the current mapping? OR
* 2) Address beyond the current mapping?
*/
- if ((address < mem_info->mapped_physical_address) ||
- (((u64) address + length) > ((u64)
- mem_info->mapped_physical_address +
- mem_info->mapped_length))) {
+ if (!mm || (address < mm->physical_address) ||
+ ((u64) address + length > (u64) mm->physical_address + mm->length)) {
/*
- * The request cannot be resolved by the current memory mapping;
- * Delete the existing mapping and create a new one.
+ * The request cannot be resolved by the current memory mapping.
+ *
+ * Look for an existing saved mapping covering the address range
+ * at hand. If found, save it as the current one and carry out
+ * the access.
*/
- if (mem_info->mapped_length) {
+ for (mm = mem_info->first_mm; mm; mm = mm->next_mm) {
+ if (mm == mem_info->cur_mm)
+ continue;
+
+ if (address < mm->physical_address)
+ continue;
- /* Valid mapping, delete it */
+ if ((u64) address + length >
+ (u64) mm->physical_address + mm->length)
+ continue;
- acpi_os_unmap_memory(mem_info->mapped_logical_address,
- mem_info->mapped_length);
+ mem_info->cur_mm = mm;
+ goto access;
+ }
+
+ /* Create a new mappings list entry */
+ mm = ACPI_ALLOCATE_ZEROED(sizeof(*mm));
+ if (!mm) {
+ ACPI_ERROR((AE_INFO,
+ "Unable to save memory mapping at 0x%8.8X%8.8X, size %u",
+ ACPI_FORMAT_UINT64(address), length));
+ return_ACPI_STATUS(AE_NO_MEMORY);
}
/*
@@ -143,29 +161,39 @@ acpi_ex_system_memory_space_handler(u32 function,
/* Create a new mapping starting at the address given */
- mem_info->mapped_logical_address =
- acpi_os_map_memory(address, map_length);
- if (!mem_info->mapped_logical_address) {
+ logical_addr_ptr = acpi_os_map_memory(address, map_length);
+ if (!logical_addr_ptr) {
ACPI_ERROR((AE_INFO,
"Could not map memory at 0x%8.8X%8.8X, size %u",
ACPI_FORMAT_UINT64(address),
(u32)map_length));
- mem_info->mapped_length = 0;
+ ACPI_FREE(mm);
return_ACPI_STATUS(AE_NO_MEMORY);
}
/* Save the physical address and mapping size */
- mem_info->mapped_physical_address = address;
- mem_info->mapped_length = map_length;
+ mm->logical_address = logical_addr_ptr;
+ mm->physical_address = address;
+ mm->length = map_length;
+
+ /*
+ * Add the new entry to the mappigs list and save it as the
+ * current mapping.
+ */
+ mm->next_mm = mem_info->first_mm;
+ mem_info->first_mm = mm;
+
+ mem_info->cur_mm = mm;
}
+access:
/*
* Generate a logical pointer corresponding to the address we want to
* access
*/
- logical_addr_ptr = mem_info->mapped_logical_address +
- ((u64) address - (u64) mem_info->mapped_physical_address);
+ logical_addr_ptr = mm->logical_address +
+ ((u64) address - (u64) mm->physical_address);
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"System-Memory (width %u) R/W %u Address=%8.8X%8.8X\n",