[RFC,09/14] arm64: Enforce bounce buffers for realm DMA
Commit Message
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>
---
arch/arm64/kernel/rsi.c | 2 ++
arch/arm64/mm/init.c | 8 +++++++-
2 files changed, 9 insertions(+), 1 deletion(-)
@@ -5,6 +5,8 @@
#include <linux/jump_label.h>
#include <linux/memblock.h>
+#include <linux/swiotlb.h>
+
#include <asm/rsi.h>
struct realm_config __attribute((aligned(PAGE_SIZE))) config;
@@ -472,7 +472,13 @@ void __init bootmem_init(void)
*/
void __init mem_init(void)
{
- swiotlb_init(max_pfn > PFN_DOWN(arm64_dma_phys_limit), SWIOTLB_VERBOSE);
+ if (is_realm_world()) {
+ swiotlb_init(true, SWIOTLB_VERBOSE | SWIOTLB_FORCE);
+ swiotlb_update_mem_attributes();
+ } else {
+ swiotlb_init(max_pfn > PFN_DOWN(arm64_dma_phys_limit),
+ SWIOTLB_VERBOSE);
+ }
/* this will put all unused low memory onto the freelists */
memblock_free_all();