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Subject[PATCH v6 28/34] x86, drm, fbdev: Do not specify encrypted memory for video mappings
Date
Since video memory needs to be accessed decrypted, be sure that the
memory encryption mask is not set for the video ranges.

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);
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