[PATCH v8 RESEND 29/38] x86, drm, fbdev: Do not specify encrypted memory for video mappings

Tom Lendacky
2017-06-27T15:13:01Z

Since video memory needs to be accessed decrypted, be sure that the
memory encryption mask is not set for the video ranges.

Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
arch/x86/include/asm/vga.h | 14 +++++++++++++-
arch/x86/mm/pageattr.c | 2 ++
drivers/gpu/drm/drm_gem.c | 2 ++
drivers/gpu/drm/drm_vm.c | 4 ++++
drivers/gpu/drm/ttm/ttm_bo_vm.c | 7 +++++--
drivers/gpu/drm/udl/udl_fb.c | 4 ++++
drivers/video/fbdev/core/fbmem.c | 12 ++++++++++++
7 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/vga.h b/arch/x86/include/asm/vga.h
index c4b9dc2..9f42bee 100644
--- a/arch/x86/include/asm/vga.h
+++ b/arch/x86/include/asm/vga.h
@@ -7,12 +7,24 @@
#ifndef _ASM_X86_VGA_H
#define _ASM_X86_VGA_H

+#include <asm/set_memory.h>
+
/*
* On the PC, we can just recalculate addresses and then
* access the videoram directly without any black magic.
+ * To support memory encryption however, we need to access
+ * the videoram as decrypted memory.
*/

-#define VGA_MAP_MEM(x, s) (unsigned long)phys_to_virt(x)
+#define VGA_MAP_MEM(x, s) \
+({ \
+ unsigned long start = (unsigned long)phys_to_virt(x); \
+ \
+ if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) \
+ set_memory_decrypted(start, (s) >> PAGE_SHIFT); \
+ \
+ start; \
+})

#define vga_readb(x) (*(x))
#define vga_writeb(x, y) (*(y) = (x))
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index d9e09fb..13fc5db 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -1825,11 +1825,13 @@ int set_memory_encrypted(unsigned long addr, int numpages)
{
return __set_memory_enc_dec(addr, numpages, true);
}
+EXPORT_SYMBOL_GPL(set_memory_encrypted);

int set_memory_decrypted(unsigned long addr, int numpages)
{
return __set_memory_enc_dec(addr, numpages, false);
}
+EXPORT_SYMBOL_GPL(set_memory_decrypted);

int set_pages_uc(struct page *page, int numpages)
{
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index b1e28c9..019f48c 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -36,6 +36,7 @@
#include <linux/pagemap.h>
#include <linux/shmem_fs.h>
#include <linux/dma-buf.h>
+#include <linux/mem_encrypt.h>
#include <drm/drmP.h>
#include <drm/drm_vma_manager.h>
#include <drm/drm_gem.h>
@@ -928,6 +929,7 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
vma->vm_ops = dev->driver->gem_vm_ops;
vma->vm_private_data = obj;
vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
+ vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);

/* Take a ref for this mapping of the object, so that the fault
* handler can dereference the mmap offset's pointer to the object.
diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
index 1170b32..ed4bcbf 100644
--- a/drivers/gpu/drm/drm_vm.c
+++ b/drivers/gpu/drm/drm_vm.c
@@ -40,6 +40,7 @@
#include <linux/efi.h>
#include <linux/slab.h>
#endif
+#include <linux/mem_encrypt.h>
#include <asm/pgtable.h>
#include "drm_internal.h"
#include "drm_legacy.h"
@@ -58,6 +59,9 @@ static pgprot_t drm_io_prot(struct drm_local_map *map,
{
pgprot_t tmp = vm_get_page_prot(vma->vm_flags);

+ /* We don't want graphics memory to be mapped encrypted */
+ tmp = pgprot_decrypted(tmp);
+
#if defined(__i386__) || defined(__x86_64__) || defined(__powerpc__)
if (map->type == _DRM_REGISTERS && !(map->flags & _DRM_WRITE_COMBINING))
tmp = pgprot_noncached(tmp);
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 9f53df9..622dab6 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -39,6 +39,7 @@
#include <linux/rbtree.h>
#include <linux/module.h>
#include <linux/uaccess.h>
+#include <linux/mem_encrypt.h>

#define TTM_BO_VM_NUM_PREFAULT 16

@@ -230,9 +231,11 @@ static int ttm_bo_vm_fault(struct vm_fault *vmf)
* first page.
*/
for (i = 0; i < TTM_BO_VM_NUM_PREFAULT; ++i) {
- if (bo->mem.bus.is_iomem)
+ if (bo->mem.bus.is_iomem) {
+ /* Iomem should not be marked encrypted */
+ cvma.vm_page_prot = pgprot_decrypted(cvma.vm_page_prot);
pfn = bdev->driver->io_mem_pfn(bo, page_offset);
- else {
+ } else {
page = ttm->pages[page_offset];
if (unlikely(!page && i == 0)) {
retval = VM_FAULT_OOM;
diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c
index 4a65003..92e1690 100644
--- a/drivers/gpu/drm/udl/udl_fb.c
+++ b/drivers/gpu/drm/udl/udl_fb.c
@@ -14,6 +14,7 @@
#include <linux/slab.h>
#include <linux/fb.h>
#include <linux/dma-buf.h>
+#include <linux/mem_encrypt.h>

#include <drm/drmP.h>
#include <drm/drm_crtc.h>
@@ -169,6 +170,9 @@ static int udl_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
pr_notice("mmap() framebuffer addr:%lu size:%lu\n",
pos, size);

+ /* We don't want the framebuffer to be mapped encrypted */
+ vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
+
while (size > 0) {
page = vmalloc_to_pfn((void *)pos);
if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 069fe79..b5e7c33 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -32,6 +32,7 @@
#include <linux/device.h>
#include <linux/efi.h>
#include <linux/fb.h>
+#include <linux/mem_encrypt.h>

#include <asm/fb.h>

@@ -1405,6 +1406,12 @@ static long fb_compat_ioctl(struct file *file, unsigned int cmd,
mutex_lock(&info->mm_lock);
if (fb->fb_mmap) {
int res;
+
+ /*
+ * The framebuffer needs to be accessed decrypted, be sure
+ * SME protection is removed ahead of the call
+ */
+ vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
res = fb->fb_mmap(info, vma);
mutex_unlock(&info->mm_lock);
return res;
@@ -1430,6 +1437,11 @@ static long fb_compat_ioctl(struct file *file, unsigned int cmd,
mutex_unlock(&info->mm_lock);

vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+ /*
+ * The framebuffer needs to be accessed decrypted, be sure
+ * SME protection is removed
+ */
+ vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
fb_pgprotect(file, vma, start);

return vm_iomap_memory(vma, start, len);