RISC-V: ACPI: Enhance acpi_os_ioremap with MMIO remapping

Enhance the acpi_os_ioremap() to support opregions in MMIO space. Also,
have strict checks using EFI memory map to allow remapping the RAM similar
to arm64.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231018124007.1306159-2-sunilvl@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index d607ab0f7c6dafa4f754f34a910ef66464e5a06d..805c8ab7f23be6784f411fe3f431a02a332d2754 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -39,6 +39,7 @@ config RISCV
        select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
        select ARCH_HAS_UBSAN_SANITIZE_ALL
        select ARCH_HAS_VDSO_DATA
+       select ARCH_KEEP_MEMBLOCK if ACPI
        select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
        select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
        select ARCH_STACKWALK

diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
index 56cb2c986c4857a9990fbfec9301df90f410162e..e619edc8b0cc972c1a83809c9f0ebeb10c3331a6 100644 (file)
--- a/arch/riscv/kernel/acpi.c
+++ b/arch/riscv/kernel/acpi.c
@@ -14,9 +14,10 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/efi.h>
 #include <linux/io.h>
+#include <linux/memblock.h>
 #include <linux/pci.h>
-#include <linux/efi.h>
 
 int acpi_noirq = 1;            /* skip ACPI IRQ initialization */
 int acpi_disabled = 1;
@@ -217,7 +218,89 @@ void __init __acpi_unmap_table(void __iomem *map, unsigned long size)
 
 void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size)
 {
-       return (void __iomem *)memremap(phys, size, MEMREMAP_WB);
+       efi_memory_desc_t *md, *region = NULL;
+       pgprot_t prot;
+
+       if (WARN_ON_ONCE(!efi_enabled(EFI_MEMMAP)))
+               return NULL;
+
+       for_each_efi_memory_desc(md) {
+               u64 end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT);
+
+               if (phys < md->phys_addr || phys >= end)
+                       continue;
+
+               if (phys + size > end) {
+                       pr_warn(FW_BUG "requested region covers multiple EFI memory regions\n");
+                       return NULL;
+               }
+               region = md;
+               break;
+       }
+
+       /*
+        * It is fine for AML to remap regions that are not represented in the
+        * EFI memory map at all, as it only describes normal memory, and MMIO
+        * regions that require a virtual mapping to make them accessible to
+        * the EFI runtime services.
+        */
+       prot = PAGE_KERNEL_IO;
+       if (region) {
+               switch (region->type) {
+               case EFI_LOADER_CODE:
+               case EFI_LOADER_DATA:
+               case EFI_BOOT_SERVICES_CODE:
+               case EFI_BOOT_SERVICES_DATA:
+               case EFI_CONVENTIONAL_MEMORY:
+               case EFI_PERSISTENT_MEMORY:
+                       if (memblock_is_map_memory(phys) ||
+                           !memblock_is_region_memory(phys, size)) {
+                               pr_warn(FW_BUG "requested region covers kernel memory\n");
+                               return NULL;
+                       }
+
+                       /*
+                        * Mapping kernel memory is permitted if the region in
+                        * question is covered by a single memblock with the
+                        * NOMAP attribute set: this enables the use of ACPI
+                        * table overrides passed via initramfs.
+                        * This particular use case only requires read access.
+                        */
+                       fallthrough;
+
+               case EFI_RUNTIME_SERVICES_CODE:
+                       /*
+                        * This would be unusual, but not problematic per se,
+                        * as long as we take care not to create a writable
+                        * mapping for executable code.
+                        */
+                       prot = PAGE_KERNEL_RO;
+                       break;
+
+               case EFI_ACPI_RECLAIM_MEMORY:
+                       /*
+                        * ACPI reclaim memory is used to pass firmware tables
+                        * and other data that is intended for consumption by
+                        * the OS only, which may decide it wants to reclaim
+                        * that memory and use it for something else. We never
+                        * do that, but we usually add it to the linear map
+                        * anyway, in which case we should use the existing
+                        * mapping.
+                        */
+                       if (memblock_is_map_memory(phys))
+                               return (void __iomem *)__va(phys);
+                       fallthrough;
+
+               default:
+                       if (region->attribute & EFI_MEMORY_WB)
+                               prot = PAGE_KERNEL;
+                       else if ((region->attribute & EFI_MEMORY_WC) ||
+                                (region->attribute & EFI_MEMORY_WT))
+                               prot = pgprot_writecombine(PAGE_KERNEL);
+               }
+       }
+
+       return ioremap_prot(phys, size, pgprot_val(prot));
 }
 
 #ifdef CONFIG_PCI