[PATCH v5 14/19] arm64: Enforce bounce buffers for realm DMA
From: Steven Price <steven.price@arm.com>
Date: 2024-08-19 13:20:41
Also in:
kvm, kvmarm, linux-coco, lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
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. This adds a call to swiotlb_update_mem_attributes() which calls set_memory_decrypted() to ensure the bounce buffer memory is shared with the host. For non-realm guests or hosts this is a no-op. 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 | 1 + arch/arm64/mm/init.c | 10 +++++++++- 2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index 5c2c977a50fb..69d8d9791c65 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c@@ -6,6 +6,7 @@ #include <linux/jump_label.h> #include <linux/memblock.h> #include <linux/psci.h> +#include <linux/swiotlb.h> #include <asm/io.h> #include <asm/rsi.h>
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 9b5ab6818f7f..1d595b63da71 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c@@ -41,6 +41,7 @@ #include <asm/kvm_host.h> #include <asm/memory.h> #include <asm/numa.h> +#include <asm/rsi.h> #include <asm/sections.h> #include <asm/setup.h> #include <linux/sizes.h>
@@ -369,8 +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
@@ -382,7 +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();
--
2.34.1