From: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Use the memory encryption APIs to trigger a RSI call to request a
transition between protected memory and shared memory (or vice versa)
and updating the kernel's linear map of modified pages to flip the top
bit of the IPA. This requires that block mappings are not used in the
direct map for realm guests.
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Co-developed-by: Steven Price <steven.price@xxxxxxx>
Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
Changed since v4:
* Reworked to use the new dispatcher for the mem_encrypt API
Changes since v3:
* Provide pgprot_{de,en}crypted() macros
* Rename __set_memory_encrypted() to __set_memory_enc_dec() since it
both encrypts and decrypts.
Changes since v2:
* Fix location of set_memory_{en,de}crypted() and export them.
* Break-before-make when changing the top bit of the IPA for
transitioning to/from shared.
---
arch/arm64/Kconfig | 3 ++
arch/arm64/include/asm/mem_encrypt.h | 9 ++++
arch/arm64/include/asm/pgtable.h | 5 ++
arch/arm64/include/asm/set_memory.h | 3 ++
arch/arm64/kernel/rsi.c | 16 ++++++
arch/arm64/mm/pageattr.c | 76 ++++++++++++++++++++++++++--
6 files changed, 109 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 68d77a2f4d1a..03d3dae34277 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -21,6 +21,7 @@ config ARM64
select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
select ARCH_HAS_CACHE_LINE_SIZE
+ select ARCH_HAS_CC_PLATFORM
select ARCH_HAS_CURRENT_STACK_POINTER
select ARCH_HAS_DEBUG_VIRTUAL
select ARCH_HAS_DEBUG_VM_PGTABLE
@@ -43,6 +44,8 @@ config ARM64
select ARCH_HAS_SETUP_DMA_OPS
select ARCH_HAS_SET_DIRECT_MAP
select ARCH_HAS_SET_MEMORY
+ select ARCH_HAS_MEM_ENCRYPT
+ select ARCH_HAS_FORCE_DMA_UNENCRYPTED
select ARCH_STACKWALK
select ARCH_HAS_STRICT_KERNEL_RWX
select ARCH_HAS_STRICT_MODULE_RWX
diff --git a/arch/arm64/include/asm/mem_encrypt.h b/arch/arm64/include/asm/mem_encrypt.h
index b0c9a86b13a4..f8f78f622dd2 100644
--- a/arch/arm64/include/asm/mem_encrypt.h
+++ b/arch/arm64/include/asm/mem_encrypt.h
@@ -2,6 +2,8 @@
#ifndef __ASM_MEM_ENCRYPT_H
#define __ASM_MEM_ENCRYPT_H
+#include <asm/rsi.h>
+
struct arm64_mem_crypt_ops {
int (*encrypt)(unsigned long addr, int numpages);
int (*decrypt)(unsigned long addr, int numpages);
@@ -12,4 +14,11 @@ int arm64_mem_crypt_ops_register(const struct arm64_mem_crypt_ops *ops);
int set_memory_encrypted(unsigned long addr, int numpages);
int set_memory_decrypted(unsigned long addr, int numpages);
+int realm_register_memory_enc_ops(void);
+
+static inline bool force_dma_unencrypted(struct device *dev)
+{
+ return is_realm_world();
+}
+
#endif /* __ASM_MEM_ENCRYPT_H */
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index f39a4cbbf73a..4e8c648f5213 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -636,6 +636,11 @@ static inline void set_pud_at(struct mm_struct *mm, unsigned long addr,
#define pgprot_nx(prot) \
__pgprot_modify(prot, PTE_MAYBE_GP, PTE_PXN)
+#define pgprot_decrypted(prot) \
+ __pgprot_modify(prot, PROT_NS_SHARED, PROT_NS_SHARED)
+#define pgprot_encrypted(prot) \
+ __pgprot_modify(prot, PROT_NS_SHARED, 0)
+
/*
* Mark the prot value as uncacheable and unbufferable.
*/
diff --git a/arch/arm64/include/asm/set_memory.h b/arch/arm64/include/asm/set_memory.h
index 917761feeffd..37774c793006 100644
--- a/arch/arm64/include/asm/set_memory.h
+++ b/arch/arm64/include/asm/set_memory.h
@@ -15,4 +15,7 @@ int set_direct_map_invalid_noflush(struct page *page);
int set_direct_map_default_noflush(struct page *page);
bool kernel_page_present(struct page *page);
+int set_memory_encrypted(unsigned long addr, int numpages);
+int set_memory_decrypted(unsigned long addr, int numpages);
+
#endif /* _ASM_ARM64_SET_MEMORY_H */
diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index 69d8d9791c65..9cb3353e5cbf 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -7,8 +7,10 @@
#include <linux/memblock.h>
#include <linux/psci.h>
#include <linux/swiotlb.h>
+#include <linux/cc_platform.h>
#include <asm/io.h>
+#include <asm/mem_encrypt.h>
#include <asm/rsi.h>
struct realm_config config;
@@ -21,6 +23,17 @@ unsigned int phys_mask_shift = CONFIG_ARM64_PA_BITS;
DEFINE_STATIC_KEY_FALSE_RO(rsi_present);
EXPORT_SYMBOL(rsi_present);
+bool cc_platform_has(enum cc_attr attr)
+{
+ switch (attr) {
+ case CC_ATTR_MEM_ENCRYPT:
+ return is_realm_world();
+ default:
+ return false;
+ }
+}
+EXPORT_SYMBOL_GPL(cc_platform_has);
+
static bool rsi_version_matches(void)
{
unsigned long ver_lower, ver_higher;
@@ -128,6 +141,9 @@ void __init arm64_rsi_init(void)
if (arm64_ioremap_prot_hook_register(realm_ioremap_hook))
return;
+ if (realm_register_memory_enc_ops())
+ return;
+
static_branch_enable(&rsi_present);
}
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 547a9e0b46c2..d11f5dc4c2c5 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -5,10 +5,12 @@
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
+#include <linux/mem_encrypt.h>
#include <linux/sched.h>
#include <linux/vmalloc.h>
#include <asm/cacheflush.h>
+#include <asm/pgtable-prot.h>
#include <asm/set_memory.h>
#include <asm/tlbflush.h>
#include <asm/kfence.h>
@@ -23,14 +25,16 @@ bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED
bool can_set_direct_map(void)
{
/*
- * rodata_full and DEBUG_PAGEALLOC require linear map to be
- * mapped at page granularity, so that it is possible to
+ * rodata_full, DEBUG_PAGEALLOC and a Realm guest all require linear
+ * map to be mapped at page granularity, so that it is possible to
* protect/unprotect single pages.
*
* KFENCE pool requires page-granular mapping if initialized late.
+ *
+ * Realms need to make pages shared/protected at page granularity.
*/
return rodata_full || debug_pagealloc_enabled() ||
- arm64_kfence_can_set_direct_map();
+ arm64_kfence_can_set_direct_map() || is_realm_world();
}
static int change_page_range(pte_t *ptep, unsigned long addr, void *data)
@@ -198,6 +202,72 @@ int set_direct_map_default_noflush(struct page *page)
PAGE_SIZE, change_page_range, &data);
}
+static int __set_memory_enc_dec(unsigned long addr,
+ int numpages,
+ bool encrypt)
+{
+ unsigned long set_prot = 0, clear_prot = 0;
+ phys_addr_t start, end;
+ int ret;
+
+ if (!is_realm_world())
+ return 0;
+
+ if (!__is_lm_address(addr))
+ return -EINVAL;
+
+ start = __virt_to_phys(addr);
+ end = start + numpages * PAGE_SIZE;
+
+ if (encrypt)
+ clear_prot = PROT_NS_SHARED;
+ else
+ set_prot = PROT_NS_SHARED;
+
+ /*
+ * Break the mapping before we make any changes to avoid stale TLB
+ * entries or Synchronous External Aborts caused by RIPAS_EMPTY
+ */
+ ret = __change_memory_common(addr, PAGE_SIZE * numpages,
+ __pgprot(set_prot),
+ __pgprot(clear_prot | PTE_VALID));
+
+ if (ret)
+ return ret;
+
+ if (encrypt)
+ ret = rsi_set_memory_range_protected(start, end);
+ else
+ ret = rsi_set_memory_range_shared(start, end);
+
+ if (ret)
+ return ret;
+
+ return __change_memory_common(addr, PAGE_SIZE * numpages,
+ __pgprot(PTE_VALID),
+ __pgprot(0));
+}
+
+static int realm_set_memory_encrypted(unsigned long addr, int numpages)
+{
+ return __set_memory_enc_dec(addr, numpages, true);
+}
+
+static int realm_set_memory_decrypted(unsigned long addr, int numpages)
+{
+ return __set_memory_enc_dec(addr, numpages, false);
+}
+
+static const struct arm64_mem_crypt_ops realm_crypt_ops = {
+ .encrypt = realm_set_memory_encrypted,
+ .decrypt = realm_set_memory_decrypted,
+};
+
+int realm_register_memory_enc_ops(void)
+{
+ return arm64_mem_crypt_ops_register(&realm_crypt_ops);
+}
+
#ifdef CONFIG_DEBUG_PAGEALLOC
void __kernel_map_pages(struct page *page, int numpages, int enable)
{
--
2.34.1
