1 files changed, 94 insertions, 4 deletions

diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 0e270a1c51e6..6ae6ae806454 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)
@@ -60,7 +64,13 @@ static int __change_memory_common(unsigned long start, unsigned long size,
 	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
 					&data);
 
-	flush_tlb_kernel_range(start, start + size);
+	/*
+	 * If the memory is being made valid without changing any other bits
+	 * then a TLBI isn't required as a non-valid entry cannot be cached in
+	 * the TLB.
+	 */
+	if (pgprot_val(set_mask) != PTE_VALID || pgprot_val(clear_mask))
+		flush_tlb_kernel_range(start, start + size);
 	return ret;
 }
 
@@ -192,6 +202,86 @@ 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)
+{
+	int ret = __set_memory_enc_dec(addr, numpages, true);
+
+	/*
+	 * If the request to change state fails, then the only sensible cause
+	 * of action for the caller is to leak the memory
+	 */
+	WARN(ret, "Failed to encrypt memory, %d pages will be leaked",
+	     numpages);
+
+	return ret;
+}
+
+static int realm_set_memory_decrypted(unsigned long addr, int numpages)
+{
+	int ret = __set_memory_enc_dec(addr, numpages, false);
+
+	WARN(ret, "Failed to decrypt memory, %d pages will be leaked",
+	     numpages);
+
+	return ret;
+}
+
+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)
 {