From fa84e534c3ec2904d8718a83180294f7b5afecc7 Mon Sep 17 00:00:00 2001 From: Suzuki K Poulose Date: Thu, 18 Sep 2025 13:56:16 +0100 Subject: [PATCH 1/3] arm64: realm: ioremap: Allow mapping memory as encrypted For ioremap(), so far we only checked if it was a device (RIPAS_DEV) to choose an encrypted vs decrypted mapping. However, we may have firmware reserved memory regions exposed to the OS (e.g., EFI Coco Secret Securityfs, ACPI CCEL). We need to make sure that anything that is RIPAS_RAM (i.e., Guest protected memory with RMM guarantees) are also mapped as encrypted. Rephrasing the above, anything that is not RIPAS_EMPTY is guaranteed to be protected by the RMM. Thus we choose encrypted mapping for anything that is not RIPAS_EMPTY. While at it, rename the helper function __arm64_is_protected_mmio => arm64_rsi_is_protected to clearly indicate that this not an arm64 generic helper, but something to do with Realms. Cc: Sami Mujawar Cc: Will Deacon Cc: Catalin Marinas Cc: Aneesh Kumar K.V Cc: Steven Price Reviewed-by: Gavin Shan Reviewed-by: Steven Price Tested-by: Sami Mujawar Signed-off-by: Suzuki K Poulose Signed-off-by: Will Deacon --- arch/arm64/include/asm/io.h | 2 +- arch/arm64/include/asm/rsi.h | 2 +- arch/arm64/kernel/rsi.c | 26 ++++++++++++++++++++++---- 3 files changed, 24 insertions(+), 6 deletions(-) diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h index 9b96840fb979..82276282a3c7 100644 --- a/arch/arm64/include/asm/io.h +++ b/arch/arm64/include/asm/io.h @@ -311,7 +311,7 @@ extern bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size, static inline bool arm64_is_protected_mmio(phys_addr_t phys_addr, size_t size) { if (unlikely(is_realm_world())) - return __arm64_is_protected_mmio(phys_addr, size); + return arm64_rsi_is_protected(phys_addr, size); return false; } diff --git a/arch/arm64/include/asm/rsi.h b/arch/arm64/include/asm/rsi.h index b42aeac05340..88b50d660e85 100644 --- a/arch/arm64/include/asm/rsi.h +++ b/arch/arm64/include/asm/rsi.h @@ -16,7 +16,7 @@ DECLARE_STATIC_KEY_FALSE(rsi_present); void __init arm64_rsi_init(void); -bool __arm64_is_protected_mmio(phys_addr_t base, size_t size); +bool arm64_rsi_is_protected(phys_addr_t base, size_t size); static inline bool is_realm_world(void) { diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c index ce4778141ec7..c64a06f58c0b 100644 --- a/arch/arm64/kernel/rsi.c +++ b/arch/arm64/kernel/rsi.c @@ -84,7 +84,25 @@ static void __init arm64_rsi_setup_memory(void) } } -bool __arm64_is_protected_mmio(phys_addr_t base, size_t size) +/* + * Check if a given PA range is Trusted (e.g., Protected memory, a Trusted Device + * mapping, or an MMIO emulated in the Realm world). + * + * We can rely on the RIPAS value of the region to detect if a given region is + * protected. + * + * RIPAS_DEV - A trusted device memory or a trusted emulated MMIO (in the Realm + * world + * RIPAS_RAM - Memory (RAM), protected by the RMM guarantees. (e.g., Firmware + * reserved regions for data sharing). + * + * RIPAS_DESTROYED is a special case of one of the above, where the host did + * something without our permission and as such we can't do anything about it. + * + * The only case where something is emulated by the untrusted hypervisor or is + * backed by shared memory is indicated by RSI_RIPAS_EMPTY. + */ +bool arm64_rsi_is_protected(phys_addr_t base, size_t size) { enum ripas ripas; phys_addr_t end, top; @@ -101,18 +119,18 @@ bool __arm64_is_protected_mmio(phys_addr_t base, size_t size) break; if (WARN_ON(top <= base)) break; - if (ripas != RSI_RIPAS_DEV) + if (ripas == RSI_RIPAS_EMPTY) break; base = top; } return base >= end; } -EXPORT_SYMBOL(__arm64_is_protected_mmio); +EXPORT_SYMBOL(arm64_rsi_is_protected); static int realm_ioremap_hook(phys_addr_t phys, size_t size, pgprot_t *prot) { - if (__arm64_is_protected_mmio(phys, size)) + if (arm64_rsi_is_protected(phys, size)) *prot = pgprot_encrypted(*prot); else *prot = pgprot_decrypted(*prot); From 9e8a3df3e7f762966762a6fbf3282b9da2074127 Mon Sep 17 00:00:00 2001 From: Suzuki K Poulose Date: Thu, 18 Sep 2025 13:56:17 +0100 Subject: [PATCH 2/3] arm64: Enable EFI secret area Securityfs support Enable EFI COCO secrets support. Provide the ioremap_encrypted() support required by the driver. Cc: Sami Mujawar Cc: Will Deacon Cc: Catalin Marinas Cc: Aneesh Kumar K.V Cc: Steven Price Reviewed-by: Gavin Shan Tested-by: Sami Mujawar Signed-off-by: Suzuki K Poulose Signed-off-by: Will Deacon --- arch/arm64/include/asm/io.h | 4 ++++ drivers/virt/coco/efi_secret/Kconfig | 2 +- 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h index 82276282a3c7..83e03abbb2ca 100644 --- a/arch/arm64/include/asm/io.h +++ b/arch/arm64/include/asm/io.h @@ -274,6 +274,10 @@ int arm64_ioremap_prot_hook_register(const ioremap_prot_hook_t hook); #define ioremap_np(addr, size) \ ioremap_prot((addr), (size), __pgprot(PROT_DEVICE_nGnRnE)) + +#define ioremap_encrypted(addr, size) \ + ioremap_prot((addr), (size), PAGE_KERNEL) + /* * io{read,write}{16,32,64}be() macros */ diff --git a/drivers/virt/coco/efi_secret/Kconfig b/drivers/virt/coco/efi_secret/Kconfig index 4404d198f3b2..94d88e5da707 100644 --- a/drivers/virt/coco/efi_secret/Kconfig +++ b/drivers/virt/coco/efi_secret/Kconfig @@ -1,7 +1,7 @@ # SPDX-License-Identifier: GPL-2.0-only config EFI_SECRET tristate "EFI secret area securityfs support" - depends on EFI && X86_64 + depends on EFI && (X86_64 || ARM64) select EFI_COCO_SECRET select SECURITYFS help From d02c2e45b1e7767b177f6854026e4ad0d70b4a4d Mon Sep 17 00:00:00 2001 From: Suzuki K Poulose Date: Thu, 18 Sep 2025 13:56:18 +0100 Subject: [PATCH 3/3] arm64: acpi: Enable ACPI CCEL support Add support for ACPI CCEL by handling the EfiACPIMemoryNVS type memory. As per UEFI specifications NVS memory is reserved for Firmware use even after exiting boot services. Thus map the region as read-only. Cc: Sami Mujawar Cc: Will Deacon Cc: Catalin Marinas Cc: Aneesh Kumar K.V Cc: Steven Price Cc: Sudeep Holla Cc: Gavin Shan Reviewed-by: Gavin Shan Tested-by: Sami Mujawar Signed-off-by: Suzuki K Poulose Signed-off-by: Will Deacon --- arch/arm64/kernel/acpi.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index 4d529ff7ba51..b3195b3b895f 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -357,6 +357,16 @@ void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size) * as long as we take care not to create a writable * mapping for executable code. */ + fallthrough; + + case EFI_ACPI_MEMORY_NVS: + /* + * ACPI NVS marks an area reserved for use by the + * firmware, even after exiting the boot service. + * This may be used by the firmware for sharing dynamic + * tables/data (e.g., ACPI CCEL) with the OS. Map it + * as read-only. + */ prot = PAGE_KERNEL_RO; break;