[PATCH] swiotlb: check set_memory_decrypted()'s return value

Dexuan Cui
2022-11-21T19:49:28Z

swiotlb_update_mem_attributes() is called from a system where decrypted
swiotlb bounce buffers are required. Panic the system if
set_memory_decrypted() fails.

When rmem_swiotlb_device_init() -> set_memory_decrypted(), let's try
to handle it gracefully.

Not sure how to handle the failure in swiotlb_init_late(). Add a WARN().

Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
kernel/dma/swiotlb.c | 42 +++++++++++++++++++++++++++++-------------
1 file changed, 29 insertions(+), 13 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 339a990554e7..8e26c09c625c 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -248,12 +248,16 @@ void __init swiotlb_update_mem_attributes(void)
struct io_tlb_mem *mem = &io_tlb_default_mem;
void *vaddr;
unsigned long bytes;
+ int rc;

if (!mem->nslabs || mem->late_alloc)
return;
vaddr = phys_to_virt(mem->start);
bytes = PAGE_ALIGN(mem->nslabs << IO_TLB_SHIFT);
- set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
+
+ rc = set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
+ if (rc)
+ panic("Failed to decrypt swiotlb bounce buffers (%d)\n", rc);

mem->vaddr = swiotlb_mem_remap(mem, bytes);
if (!mem->vaddr)
@@ -447,8 +451,10 @@ int swiotlb_init_late(size_t size, gfp_t gfp_mask,
if (!mem->slots)
goto error_slots;

- set_memory_decrypted((unsigned long)vstart,
- (nslabs << IO_TLB_SHIFT) >> PAGE_SHIFT);
+ rc = set_memory_decrypted((unsigned long)vstart,
+ (nslabs << IO_TLB_SHIFT) >> PAGE_SHIFT);
+ WARN(rc, "Failed to decrypt swiotlb bounce buffers (%d)\n", rc);
+
swiotlb_init_io_tlb_mem(mem, virt_to_phys(vstart), nslabs, 0, true,
default_nareas);

@@ -986,6 +992,7 @@ static int rmem_swiotlb_device_init(struct reserved_mem *rmem,

/* Set Per-device io tlb area to one */
unsigned int nareas = 1;
+ int rc = -ENOMEM;

/*
* Since multiple devices can share the same pool, the private data,
@@ -998,21 +1005,22 @@ static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
return -ENOMEM;

mem->slots = kcalloc(nslabs, sizeof(*mem->slots), GFP_KERNEL);
- if (!mem->slots) {
- kfree(mem);
- return -ENOMEM;
- }
+ if (!mem->slots)
+ goto free_mem;

mem->areas = kcalloc(nareas, sizeof(*mem->areas),
GFP_KERNEL);
- if (!mem->areas) {
- kfree(mem->slots);
- kfree(mem);
- return -ENOMEM;
+ if (!mem->areas)
+ goto free_slots;
+
+ rc = set_memory_decrypted(
+ (unsigned long)phys_to_virt(rmem->base),
+ rmem->size >> PAGE_SHIFT);
+ if (rc) {
+ pr_err("Failed to decrypt rmem buffer (%d)\n", rc);
+ goto free_areas;
}

- set_memory_decrypted((unsigned long)phys_to_virt(rmem->base),
- rmem->size >> PAGE_SHIFT);
swiotlb_init_io_tlb_mem(mem, rmem->base, nslabs, SWIOTLB_FORCE,
false, nareas);
mem->for_alloc = true;
@@ -1025,6 +1033,14 @@ static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
dev->dma_io_tlb_mem = mem;

return 0;
+
+free_areas:
+ kfree(mem->areas);
+free_slots:
+ kfree(mem->slots);
+free_mem:
+ kfree(mem);
+ return rc;
}

static void rmem_swiotlb_device_release(struct reserved_mem *rmem,
--
2.25.1