soc/intel/skylake: Generate ACPI RMRR table

An ACPI RMRR table is requried for IOMMU to work properly with an
iGPU (without using passthrough mode), so create one along with the
DRHD DMAR table if the iGPU is present and enabled.

Test: build/boot google/chell and purism/librem13v2 with kernel
parameter 'intel_iommu=on' but without 'iommu=pt;' observe integrated
graphics functional without corruption.

Change-Id: I202fb3eb8618f99d41f3d1c5bbb83b2ec982aca4
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/27270
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Youness Alaoui <snifikino@gmail.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/src/soc/intel/skylake/acpi.c b/src/soc/intel/skylake/acpi.c
index 4ad483184d..5bed11878c 100644
--- a/src/soc/intel/skylake/acpi.c
+++ b/src/soc/intel/skylake/acpi.c
@@ -554,12 +554,20 @@ static unsigned long acpi_fill_dmar(unsigned long current)
 	/* iGFX has to be enabled, GFXVTBAR set and in 32-bit space. */
 	if (igfx_dev && igfx_dev->enabled && gfxvten &&
 	    gfx_vtbar && !MCHBAR32(GFXVTBAR + 4)) {
-		const unsigned long tmp = current;
+		unsigned long tmp = current;
 
 		current += acpi_create_dmar_drhd(current, 0, 0, gfx_vtbar);
 		current += acpi_create_dmar_ds_pci(current, 0, 2, 0);
 
 		acpi_dmar_drhd_fixup(tmp, current);
+
+		/* Add RMRR entry */
+		tmp = current;
+
+		current += acpi_create_dmar_rmrr(current, 0,
+				sa_get_gsm_base(), sa_get_tolud_base() - 1);
+		current += acpi_create_dmar_ds_pci(current, 0, 2, 0);
+		acpi_dmar_rmrr_fixup(tmp, current);
 	}
 
 	struct device *const p2sb_dev = dev_find_slot(0, PCH_DEVFN_P2SB);