fbdev/efifb: Honour UEFI memory map attributes when mapping the FB
If the framebuffer address provided by the Graphics Output Protocol (GOP) is covered by the UEFI memory map, it will tell us which memory attributes are permitted when mapping this region. In some cases, (KVM guest on ARM), violating this will result in loss of coherency, which means that updates sent to the framebuffer by the guest will not be observeable by the host, and the emulated display simply does not work. So if the memory map contains such a description, take the attributes field into account, and add support for creating WT or WB mappings of the framebuffer region. Tested-by:Laszlo Ersek <lersek@redhat.com> Signed-off-by:
Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by:
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Jones <pjones@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20180711094040.12506-9-ard.biesheuvel@linaro.org Signed-off-by:
Ingo Molnar <mingo@kernel.org>
parent
7e1550b8
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