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Subject[PATCH v2 3/4] drm/ttm, drm/vmwgfx: Correctly support support AMD memory encryption
Date
From: Thomas Hellstrom <thellstrom@vmware.com>

With TTM pages allocated out of the DMA pool, use the
force_dma_unencrypted function to be able to set up the correct
page-protection. Previously it was unconditionally set to encrypted,
which only works with SME encryption on devices with a large enough DMA
mask.

Tested with vmwgfx and sev-es. Screen garbage without this patch and normal
functionality with it.

Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
drivers/gpu/drm/ttm/ttm_bo_util.c | 17 +++++++++++++----
drivers/gpu/drm/ttm/ttm_bo_vm.c | 21 ++++++++++-----------
drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 4 ++++
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, 37 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index fe81c565e7ef..d5ad8f03b63f 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__)
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 76eedb963693..194d8d618d23 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -226,12 +226,7 @@ static vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
* by mmap_sem in write mode.
*/
cvma = *vma;
- cvma.vm_page_prot = vm_get_page_prot(cvma.vm_flags);
-
- if (bo->mem.bus.is_iomem) {
- cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
- cvma.vm_page_prot);
- } else {
+ if (!bo->mem.bus.is_iomem) {
struct ttm_operation_ctx ctx = {
.interruptible = false,
.no_wait_gpu = false,
@@ -240,14 +235,18 @@ static vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
};

ttm = bo->ttm;
- cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
- cvma.vm_page_prot);
-
- /* Allocate all page at once, most common usage */
- if (ttm_tt_populate(ttm, &ctx)) {
+ if (ttm_tt_populate(bo->ttm, &ctx)) {
ret = VM_FAULT_OOM;
goto out_io_unlock;
}
+ cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
+ ttm->page_flags,
+ cvma.vm_page_prot);
+ } else {
+ /* Iomem should not be marked encrypted */
+ cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
+ TTM_PAGE_FLAG_DECRYPTED,
+ cvma.vm_page_prot);
}

/*
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
index 7d78e6deac89..9b15df8ecd49 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
@@ -48,6 +48,7 @@
#include <linux/atomic.h>
#include <linux/device.h>
#include <linux/kthread.h>
+#include <linux/dma-direct.h>
#include <drm/ttm/ttm_bo_driver.h>
#include <drm/ttm/ttm_page_alloc.h>
#include <drm/ttm/ttm_set_memory.h>
@@ -984,6 +985,9 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
}

ttm->state = tt_unbound;
+ if (force_dma_unencrypted(dev))
+ 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 bb46ca0c458f..d3ced89a37e9 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 6f536caea368..68ead1bd3042 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -893,13 +893,15 @@ 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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