drm/vmwgfx: Fix guests running with TDX/SEV

JIRA: https://issues.redhat.com/browse/RHEL-101642
Upstream Status: https://gitlab.freedesktop.org/drm/misc/kernel.git

commit 7dfede7
Author:     Marko Kiiskila <marko.kiiskila@broadcom.com>
AuthorDate: Wed Jun 18 15:29:26 2025 -0400
Commit:     Zack Rusin <zack.rusin@broadcom.com>
CommitDate: Mon Jun 30 23:10:11 2025 -0400

    Commit 81256a5 ("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: 81256a5 ("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>
    Link: https://lore.kernel.org/r/20250618192926.1092450-1-zack.rusin@broadcom.com

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>

Author: Jocelyn Falempe

drivers/gpu/drm/vmwgfx/vmwgfx_drv.c

@@ -769,7 +769,7 @@ 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,