drm/vmwgfx: Fix guests running with TDX/SEV

[PATCH] drm/vmwgfx: Fix guests running with TDX/SEV

Posted by Zack Rusin 3 months, 3 weeks ago

From: Marko Kiiskila <marko.kiiskila@broadcom.com>

Commit 81256a50aa0f ("x86/mm: Make memremap(MEMREMAP_WB) map memory as
encrypted by default") changed the default behavior of
memremap(MEMREMAP_WB) and started mapping memory as encrypted.
The driver requires the fifo memory to be decrypted to communicate with
the host but was relaying on the old default behavior of
memremap(MEMREMAP_WB) and thus broke.

Fix it by explicitly specifying the desired behavior and passing
MEMREMAP_DEC to memremap.

Fixes: 81256a50aa0f ("x86/mm: Make memremap(MEMREMAP_WB) map memory as encrypted by default")
Signed-off-by: Marko Kiiskila <marko.kiiskila@broadcom.com>
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
index bc0342c58b4b..8ff958d119be 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -750,7 +750,7 @@ static int vmw_setup_pci_resources(struct vmw_private *dev,
 		dev->fifo_mem = devm_memremap(dev->drm.dev,
 					      fifo_start,
 					      fifo_size,
-					      MEMREMAP_WB);
+					      MEMREMAP_WB | MEMREMAP_DEC);
 
 		if (IS_ERR(dev->fifo_mem)) {
 			drm_err(&dev->drm,
-- 
2.48.1

Re: [PATCH] drm/vmwgfx: Fix guests running with TDX/SEV

Posted by Kirill A. Shutemov 3 months, 3 weeks ago

On Wed, Jun 18, 2025 at 03:29:26PM -0400, Zack Rusin wrote:
> From: Marko Kiiskila <marko.kiiskila@broadcom.com>
> 
> Commit 81256a50aa0f ("x86/mm: Make memremap(MEMREMAP_WB) map memory as
> encrypted by default") changed the default behavior of
> memremap(MEMREMAP_WB) and started mapping memory as encrypted.
> The driver requires the fifo memory to be decrypted to communicate with
> the host but was relaying on the old default behavior of
> memremap(MEMREMAP_WB) and thus broke.
> 
> Fix it by explicitly specifying the desired behavior and passing
> MEMREMAP_DEC to memremap.
> 
> Fixes: 81256a50aa0f ("x86/mm: Make memremap(MEMREMAP_WB) map memory as encrypted by default")
> Signed-off-by: Marko Kiiskila <marko.kiiskila@broadcom.com>
> Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

-- 
  Kiryl Shutsemau / Kirill A. Shutemov