Re: [PATCH v2 -next 1/4] RISC-V: ACPI: Enhance acpi_os_ioremap with MMIO remapping

Conor Dooley
2023-10-02T15:53:19Z

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On Wed, Sep 27, 2023 at 10:30:12PM +0530, Sunil V L wrote:
> 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>

Thanks for resending this. If you respin, I think it would be worth
mentioning here that you are aligning things with arm64.

Acked-by: Conor Dooley <conor.dooley@microchip.com>

Cheer,
Conor.

> ---
> arch/riscv/Kconfig | 1 +
> arch/riscv/kernel/acpi.c | 87 +++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 86 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index d607ab0f7c6d..ac039cf8af7a 100644
> --- 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
> 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 56cb2c986c48..e619edc8b0cc 100644
> --- 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
> --
> 2.39.2
>

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