linux-kernel - [PATCH 20/20] iommu/vt-d: Remove domain_update_iommu

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Date: Wed, 29 May 2024 13:32:50 +0800
From: Lu Baolu <baolu.lu@...ux.intel.com>
To: Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Kevin Tian <kevin.tian@...el.com>
Cc: Yi Liu <yi.l.liu@...el.com>,
	David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	Kalle Valo <kvalo@...nel.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Mathieu Poirier <mathieu.poirier@...aro.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	mst@...hat.com,
	Jason Wang <jasowang@...hat.com>,
	Thierry Reding <thierry.reding@...il.com>,
	Jonathan Hunter <jonathanh@...dia.com>,
	Mikko Perttunen <mperttunen@...dia.com>,
	iommu@...ts.linux.dev,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH 20/20] iommu/vt-d: Remove domain_update_iommu_superpage()

The requirement for consistent super page support across all the IOMMU
hardware in the system has been removed. In the past, if a new IOMMU
was hot-added and lacked consistent super page capability, the hot-add
process would be aborted. However, with the updated attachment semantics,
it is now permissible for the super page capability to vary among
different IOMMU hardware units.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel/iommu.c | 39 +------------------------------------
 1 file changed, 1 insertion(+), 38 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 74e005b1c4b4..660d2b6c531b 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -366,36 +366,6 @@ static bool iommu_paging_structure_coherency(struct intel_iommu *iommu)
 			ecap_smpwc(iommu->ecap) : ecap_coherent(iommu->ecap);
 }
 
-static int domain_update_iommu_superpage(struct dmar_domain *domain,
-					 struct intel_iommu *skip)
-{
-	struct dmar_drhd_unit *drhd;
-	struct intel_iommu *iommu;
-	int mask = 0x3;
-
-	if (!intel_iommu_superpage)
-		return 0;
-
-	/* set iommu_superpage to the smallest common denominator */
-	rcu_read_lock();
-	for_each_active_iommu(iommu, drhd) {
-		if (iommu != skip) {
-			if (domain && domain->use_first_level) {
-				if (!cap_fl1gp_support(iommu->cap))
-					mask = 0x1;
-			} else {
-				mask &= cap_super_page_val(iommu->cap);
-			}
-
-			if (!mask)
-				break;
-		}
-	}
-	rcu_read_unlock();
-
-	return fls(mask);
-}
-
 /* Return the super pagesize bitmap if supported. */
 static unsigned long domain_super_pgsize_bitmap(struct dmar_domain *domain)
 {
@@ -2845,8 +2815,8 @@ int dmar_parse_one_satc(struct acpi_dmar_header *hdr, void *arg)
 
 static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
 {
-	int sp, ret;
 	struct intel_iommu *iommu = dmaru->iommu;
+	int ret;
 
 	ret = intel_cap_audit(CAP_AUDIT_HOTPLUG_DMAR, iommu);
 	if (ret)
@@ -2858,13 +2828,6 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
 		return -ENXIO;
 	}
 
-	sp = domain_update_iommu_superpage(NULL, iommu) - 1;
-	if (sp >= 0 && !(cap_super_page_val(iommu->cap) & (1 << sp))) {
-		pr_warn("%s: Doesn't support large page.\n",
-			iommu->name);
-		return -ENXIO;
-	}
-
 	/*
 	 * Disable translation if already enabled prior to OS handover.
 	 */
-- 
2.34.1