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[v3,08/14] arm64: Enforce bounce buffers for realm DMA

Message ID 20240605093006.145492-9-steven.price@arm.com (mailing list archive)
State New, archived
Headers show
Series arm64: Support for running as a guest in Arm CCA | expand

Commit Message

Steven Price June 5, 2024, 9:30 a.m. UTC 
Within a realm guest it's not possible for a device emulated by the VMM
to access arbitrary guest memory. So force the use of bounce buffers to
ensure that the memory the emulated devices are accessing is in memory
which is explicitly shared with the host.

Co-developed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
v3: Simplify mem_init() by using a 'flags' variable.
---
 arch/arm64/kernel/rsi.c | 2 ++
 arch/arm64/mm/init.c    | 9 ++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index c5c03e8e341a..5cb42609219f 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -5,6 +5,8 @@ 
 
 #include <linux/jump_label.h>
 #include <linux/memblock.h>
+#include <linux/swiotlb.h>
+
 #include <asm/rsi.h>
 
 struct realm_config config;
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 9d8d38e3bee2..1d595b63da71 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -370,8 +370,14 @@  void __init bootmem_init(void)
  */
 void __init mem_init(void)
 {
+	unsigned int flags = SWIOTLB_VERBOSE;
 	bool swiotlb = max_pfn > PFN_DOWN(arm64_dma_phys_limit);
 
+	if (is_realm_world()) {
+		swiotlb = true;
+		flags |= SWIOTLB_FORCE;
+	}
+
 	if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb) {
 		/*
 		 * If no bouncing needed for ZONE_DMA, reduce the swiotlb
@@ -383,7 +389,8 @@  void __init mem_init(void)
 		swiotlb = true;
 	}
 
-	swiotlb_init(swiotlb, SWIOTLB_VERBOSE);
+	swiotlb_init(swiotlb, flags);
+	swiotlb_update_mem_attributes();
 
 	/* this will put all unused low memory onto the freelists */
 	memblock_free_all();