[RFC PATCH] drm/ttm, drm/vmwgfx: Have TTM support AMD SEV encryption
Thomas Hellström (VMware)
thomas at shipmail.org
Fri May 24 08:11:14 UTC 2019
From: Thomas Hellstrom <thellstrom at vmware.com>
With SEV encryption, all DMA memory must be marked decrypted
(AKA "shared") for devices to be able to read it. In the future we might
want to be able to switch normal (encrypted) memory to decrypted in exactly
the same way as we handle caching states, and that would require additional
memory pools. But for now, rely on memory allocated with
dma_alloc_coherent() which is already decrypted with SEV enabled. Set up
the page protection accordingly. Drivers must detect SEV enabled and switch
to the dma page pool.
This patch has not yet been tested. As a follow-up, we might want to
cache decrypted pages in the dma page pool regardless of their caching
state.
Cc: Christian König <christian.koenig at amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
---
drivers/gpu/drm/ttm/ttm_bo_util.c | 17 +++++++++++++----
drivers/gpu/drm/ttm/ttm_bo_vm.c | 6 ++++--
drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 3 +++
drivers/gpu/drm/vmwgfx/vmwgfx_blit.c | 6 ++++--
include/drm/ttm/ttm_bo_driver.h | 8 +++++---
include/drm/ttm/ttm_tt.h | 1 +
6 files changed, 30 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index 895d77d799e4..1d6643bd0b01 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -419,11 +419,13 @@ int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
page = i * dir + add;
if (old_iomap == NULL) {
pgprot_t prot = ttm_io_prot(old_mem->placement,
+ ttm->page_flags,
PAGE_KERNEL);
ret = ttm_copy_ttm_io_page(ttm, new_iomap, page,
prot);
} else if (new_iomap == NULL) {
pgprot_t prot = ttm_io_prot(new_mem->placement,
+ ttm->page_flags,
PAGE_KERNEL);
ret = ttm_copy_io_ttm_page(ttm, old_iomap, page,
prot);
@@ -526,11 +528,11 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
return 0;
}
-pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp)
+pgprot_t ttm_io_prot(u32 caching_flags, u32 tt_page_flags, pgprot_t tmp)
{
/* Cached mappings need no adjustment */
if (caching_flags & TTM_PL_FLAG_CACHED)
- return tmp;
+ goto check_encryption;
#if defined(__i386__) || defined(__x86_64__)
if (caching_flags & TTM_PL_FLAG_WC)
@@ -548,6 +550,11 @@ pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp)
#if defined(__sparc__) || defined(__mips__)
tmp = pgprot_noncached(tmp);
#endif
+
+check_encryption:
+ if (tt_page_flags & TTM_PAGE_FLAG_DECRYPTED)
+ tmp = pgprot_decrypted(tmp);
+
return tmp;
}
EXPORT_SYMBOL(ttm_io_prot);
@@ -594,7 +601,8 @@ static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo,
if (ret)
return ret;
- if (num_pages == 1 && (mem->placement & TTM_PL_FLAG_CACHED)) {
+ if (num_pages == 1 && (mem->placement & TTM_PL_FLAG_CACHED) &&
+ !(ttm->page_flags & TTM_PAGE_FLAG_DECRYPTED)) {
/*
* We're mapping a single page, and the desired
* page protection is consistent with the bo.
@@ -608,7 +616,8 @@ static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo,
* We need to use vmap to get the desired page protection
* or to make the buffer object look contiguous.
*/
- prot = ttm_io_prot(mem->placement, PAGE_KERNEL);
+ prot = ttm_io_prot(mem->placement, ttm->page_flags,
+ PAGE_KERNEL);
map->bo_kmap_type = ttm_bo_map_vmap;
map->virtual = vmap(ttm->pages + start_page, num_pages,
0, prot);
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 2d9862fcf6fd..e12247edd243 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -245,7 +245,6 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
goto out_io_unlock;
}
- cvma.vm_page_prot = ttm_io_prot(bo->mem.placement, prot);
if (!bo->mem.bus.is_iomem) {
struct ttm_operation_ctx ctx = {
.interruptible = false,
@@ -255,13 +254,16 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
};
ttm = bo->ttm;
+ cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
+ ttm->page_flags, prot);
if (ttm_tt_populate(bo->ttm, &ctx)) {
ret = VM_FAULT_OOM;
goto out_io_unlock;
}
} else {
/* Iomem should not be marked encrypted */
- cvma.vm_page_prot = pgprot_decrypted(cvma.vm_page_prot);
+ cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
+ TTM_PAGE_FLAG_DECRYPTED, prot);
}
/*
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
index 98d100fd1599..1a8a09c05805 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
@@ -979,6 +979,9 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
}
ttm->state = tt_unbound;
+ if (sev_active())
+ ttm->page_flags |= TTM_PAGE_FLAG_DECRYPTED;
+
return 0;
}
EXPORT_SYMBOL_GPL(ttm_dma_populate);
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c b/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c
index fc6673cde289..11c8cd248530 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c
@@ -483,8 +483,10 @@ int vmw_bo_cpu_blit(struct ttm_buffer_object *dst,
d.src_pages = src->ttm->pages;
d.dst_num_pages = dst->num_pages;
d.src_num_pages = src->num_pages;
- d.dst_prot = ttm_io_prot(dst->mem.placement, PAGE_KERNEL);
- d.src_prot = ttm_io_prot(src->mem.placement, PAGE_KERNEL);
+ d.dst_prot = ttm_io_prot(dst->mem.placement, dst->ttm->page_flags,
+ PAGE_KERNEL);
+ d.src_prot = ttm_io_prot(src->mem.placement, src->ttm->page_flags,
+ PAGE_KERNEL);
d.diff = diff;
for (j = 0; j < h; ++j) {
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index 53fe95be5b32..261cc89c024e 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -889,13 +889,15 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo);
/**
* ttm_io_prot
*
- * @c_state: Caching state.
+ * @caching_flags: The caching flags of the map.
+ * @tt_page_flags: The tt_page_flags of the map, TTM_PAGE_FLAG_*
* @tmp: Page protection flag for a normal, cached mapping.
*
* Utility function that returns the pgprot_t that should be used for
- * setting up a PTE with the caching model indicated by @c_state.
+ * setting up a PTE with the caching model indicated by @caching_flags,
+ * and encryption state indicated by @tt_page_flags,
*/
-pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp);
+pgprot_t ttm_io_prot(u32 caching_flags, u32 tt_page_flags, pgprot_t tmp);
extern const struct ttm_mem_type_manager_func ttm_bo_manager_func;
diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h
index c0e928abf592..45cc26355513 100644
--- a/include/drm/ttm/ttm_tt.h
+++ b/include/drm/ttm/ttm_tt.h
@@ -41,6 +41,7 @@ struct ttm_operation_ctx;
#define TTM_PAGE_FLAG_DMA32 (1 << 7)
#define TTM_PAGE_FLAG_SG (1 << 8)
#define TTM_PAGE_FLAG_NO_RETRY (1 << 9)
+#define TTM_PAGE_FLAG_DECRYPTED (1 << 10)
enum ttm_caching_state {
tt_uncached,
--
2.20.1
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