[PATCH v2 0/4] iommu/vt-d: Disable igfx iommu superpage on bxt/skl/glk

[PATCH v2 0/4] iommu/vt-d: Disable igfx iommu superpage on bxt/skl/glk

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

I ran into some kind of fail with VT-d superpage on Geminlake igfx,
so without any better ideas let's just disable it.

Additionally Skylake/Broxton igfx have known issues with VT-d
superpage as well, so let's disable it there as well. This should
let us re-enable frame buffer compression (FBC) for some extra
power savings when the display is on.

v2: disable superpage only for the igfx iommu

Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: iommu@lists.linux-foundation.org

Ville Syrjälä (4):
  iommu/vt-d: Disable superpage for Geminilake igfx
  iommu/vt-d: Disable superpage for Broxton igfx
  iommu/vt-d: Disable superpage for Skylake igfx
  drm/i915/fbc: Allow FBC + VT-d on SKL/BXT

 drivers/gpu/drm/i915/display/intel_fbc.c | 16 ------
 drivers/iommu/intel/iommu.c              | 68 +++++++++++++++++++++++-
 2 files changed, 67 insertions(+), 17 deletions(-)

-- 
2.31.1

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[PATCH v2 1/4] iommu/vt-d: Disable superpage for Geminilake igfx

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

While running "gem_exec_big --r single" from igt-gpu-tools on
Geminilake as soon as a 2M mapping is made I tend to get a DMAR
write fault. Strangely the faulting address is always a 4K page
and usually very far away from the 2M page that got mapped.
But if no 2M mappings get used I can't reproduce the fault.

I also tried to dump the PTE for the faulting address but it actually
looks correct to me (ie. definitely seems to have the write bit set):
 DMAR: DRHD: handling fault status reg 2
 DMAR: [DMA Write] Request device [00:02.0] PASID ffffffff fault addr 7fa8a78000 [fault reason 05] PTE Write access is not set
 DMAR: fault 7fa8a78000 (level=1) PTE = 149efc003

So not really sure what's going on and this might just be full on duct
tape, but it seems to work here. The machine has now survived a whole day
running that test whereas with superpage enabled it fails in less than
a minute usually.

Credit to Lu Baolu for the mechanism to disable superpage just
for the igfx iommu.

TODO: would be nice to use the macros from include/drm/i915_pciids.h,
      but can't do that with DECLARE_PCI_FIXUP_HEADER()

Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: iommu@lists.linux-foundation.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index b04bfb0d9409..08ba412053e3 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -365,6 +365,7 @@ static int intel_iommu_strict;
 static int intel_iommu_superpage = 1;
 static int iommu_identity_mapping;
 static int iommu_skip_te_disable;
+static int iommu_skip_igfx_superpage;
 
 #define IDENTMAP_GFX		2
 #define IDENTMAP_AZALIA		4
@@ -674,6 +675,27 @@ static bool domain_update_iommu_snooping(struct intel_iommu *skip)
 	return ret;
 }
 
+static bool domain_use_super_page(struct dmar_domain *domain)
+{
+	struct dmar_drhd_unit *drhd;
+	struct intel_iommu *iommu;
+	bool ret = true;
+
+	if (!intel_iommu_superpage)
+		return false;
+
+	rcu_read_lock();
+	for_each_active_iommu(iommu, drhd) {
+		if (drhd->gfx_dedicated && iommu_skip_igfx_superpage) {
+			ret = false;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	return ret;
+}
+
 static int domain_update_iommu_superpage(struct dmar_domain *domain,
 					 struct intel_iommu *skip)
 {
@@ -681,7 +703,7 @@ static int domain_update_iommu_superpage(struct dmar_domain *domain,
 	struct intel_iommu *iommu;
 	int mask = 0x3;
 
-	if (!intel_iommu_superpage)
+	if (!domain_use_super_page(domain))
 		return 0;
 
 	/* set iommu_superpage to the smallest common denominator */
@@ -5653,6 +5675,16 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1632, quirk_iommu_igfx);
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x163A, quirk_iommu_igfx);
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x163D, quirk_iommu_igfx);
 
+static void quirk_skip_igfx_superpage(struct pci_dev *dev)
+{
+	pci_info(dev, "Disabling IOMMU superpage for graphics on this chipset\n");
+	iommu_skip_igfx_superpage = 1;
+}
+
+/* Geminilake igfx appears to have issues with superpage */
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x3184, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x3185, quirk_skip_igfx_superpage);
+
 static void quirk_iommu_rwbf(struct pci_dev *dev)
 {
 	if (risky_device(dev))
-- 
2.31.1

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[PATCH v2 2/4] iommu/vt-d: Disable superpage for Broxton igfx

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Broxton has known issues with VT-d superpage. Namely frame buffer
compression (FBC) can't be safely used when superpage is enabled.
Currently we're disabling FBC entirely when VT-d is active, but
I think just disabling superpage would be better since FBC can
save some power.

TODO: would be nice to use the macros from include/drm/i915_pciids.h,
      but can't do that with DECLARE_PCI_FIXUP_HEADER()

Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: iommu@lists.linux-foundation.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 08ba412053e3..ef717908647d 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -5681,6 +5681,13 @@ static void quirk_skip_igfx_superpage(struct pci_dev *dev)
 	iommu_skip_igfx_superpage = 1;
 }
 
+/* Broxton igfx has issues with superpage */
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0A84, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1A84, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1A85, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x5A84, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x5A85, quirk_skip_igfx_superpage);
+
 /* Geminilake igfx appears to have issues with superpage */
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x3184, quirk_skip_igfx_superpage);
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x3185, quirk_skip_igfx_superpage);
-- 
2.31.1

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[PATCH v2 3/4] iommu/vt-d: Disable superpage for Skylake igfx

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Skylake has known issues with VT-d superpage. Namely frame buffer
compression (FBC) can't be safely used when superpage is enabled.
Currently we're disabling FBC entirely when VT-d is active, but
I think just disabling superpage would be better since FBC can
save some power.

TODO: would be nice to use the macros from include/drm/i915_pciids.h,
      but can't do that with DECLARE_PCI_FIXUP_HEADER()

Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: iommu@lists.linux-foundation.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index ef717908647d..ea9c69dc13f5 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -5681,6 +5681,33 @@ static void quirk_skip_igfx_superpage(struct pci_dev *dev)
 	iommu_skip_igfx_superpage = 1;
 }
 
+/* Skylake igfx has issues with superpage */
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1906, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1913, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x190E, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1915, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1902, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x190A, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x190B, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1917, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1916, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1921, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x191E, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1912, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x191A, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x191B, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x191D, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1923, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1926, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1927, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x192A, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x192B, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x192D, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1932, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x193A, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x193B, quirk_skip_igfx_superpage);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x193D, quirk_skip_igfx_superpage);
+
 /* Broxton igfx has issues with superpage */
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0A84, quirk_skip_igfx_superpage);
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1A84, quirk_skip_igfx_superpage);
-- 
2.31.1

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[PATCH v2 4/4] drm/i915/fbc: Allow FBC + VT-d on SKL/BXT

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

With the iommu driver disabling VT-d superpage it should be
safe to use FBC on SKL/BXT with VT-d otherwise enabled.

Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: iommu@lists.linux-foundation.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_fbc.c | 16 ----------------
 1 file changed, 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
index 82effb64a3b9..de44f93a33d0 100644
--- a/drivers/gpu/drm/i915/display/intel_fbc.c
+++ b/drivers/gpu/drm/i915/display/intel_fbc.c
@@ -1448,19 +1448,6 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
 	return 0;
 }
 
-static bool need_fbc_vtd_wa(struct drm_i915_private *dev_priv)
-{
-	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */
-	if (intel_vtd_active() &&
-	    (IS_SKYLAKE(dev_priv) || IS_BROXTON(dev_priv))) {
-		drm_info(&dev_priv->drm,
-			 "Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
-		return true;
-	}
-
-	return false;
-}
-
 /**
  * intel_fbc_init - Initialize FBC
  * @dev_priv: the i915 device
@@ -1478,9 +1465,6 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
 	if (!drm_mm_initialized(&dev_priv->mm.stolen))
 		mkwrite_device_info(dev_priv)->display.has_fbc = false;
 
-	if (need_fbc_vtd_wa(dev_priv))
-		mkwrite_device_info(dev_priv)->display.has_fbc = false;
-
 	dev_priv->params.enable_fbc = intel_sanitize_fbc_option(dev_priv);
 	drm_dbg_kms(&dev_priv->drm, "Sanitized enable_fbc value: %d\n",
 		    dev_priv->params.enable_fbc);
-- 
2.31.1

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