pve-kernel-lowlatency-qoup/patches/kernel/0009-allow-opt-in-to-allow-pass-through-on-broken-hardwar.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: kiler129 <grzegorz@noflash.pl>
Date: Mon, 18 Sep 2023 15:19:26 +0200
Subject: [PATCH] allow opt-in to allow pass-through on broken hardware..

adapted from https://github.com/kiler129/relax-intel-rmrr , licensed under MIT or GPL 2.0+

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
 drivers/iommu/intel/iommu.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index a377f8e0a414..3be334d34317 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -298,6 +298,7 @@ static int dmar_map_gfx = 1;
 static int dmar_map_ipu = 1;
 static int intel_iommu_superpage = 1;
 static int iommu_identity_mapping;
+static int intel_relaxable_rmrr = 0;
 static int iommu_skip_te_disable;
 
 #define IDENTMAP_GFX		2
@@ -359,6 +360,9 @@ static int __init intel_iommu_setup(char *str)
 		} else if (!strncmp(str, "tboot_noforce", 13)) {
 			pr_info("Intel-IOMMU: not forcing on after tboot. This could expose security risk for tboot\n");
 			intel_iommu_tboot_noforce = 1;
+		} else if (!strncmp(str, "relax_rmrr", 10)) {
+			pr_info("Intel-IOMMU: assuming all RMRRs are relaxable. This can lead to instability or data loss\n");
+			intel_relaxable_rmrr = 1;
 		} else {
 			pr_notice("Unknown option - '%s'\n", str);
 		}
@@ -2503,7 +2507,7 @@ static bool device_rmrr_is_relaxable(struct device *dev)
 		return false;
 
 	pdev = to_pci_dev(dev);
-	if (IS_USB_DEVICE(pdev) || IS_GFX_DEVICE(pdev))
+	if (intel_relaxable_rmrr || IS_USB_DEVICE(pdev) || IS_GFX_DEVICE(pdev))
 		return true;
 	else
 		return false;