linux-kernel - [PATCH RFC PREVIEW 5/6] iommu/vt-d: drop pasid requirement for prq initialization

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Message-Id: <20240826-iopf-for-all-v1-5-59174e6a7528@samsung.com>
Date: Mon, 26 Aug 2024 13:40:31 +0200
From: Klaus Jensen <its@...elevant.dk>
To: David Woodhouse <dwmw2@...radead.org>, 
 Lu Baolu <baolu.lu@...ux.intel.com>, 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: Minwoo Im <minwoo.im@...sung.com>, linux-kernel@...r.kernel.org, 
 iommu@...ts.linux.dev, Joel Granados <j.granados@...sung.com>, 
 Klaus Jensen <k.jensen@...sung.com>
Subject: [PATCH RFC PREVIEW 5/6] iommu/vt-d: drop pasid requirement for prq
 initialization

From: Klaus Jensen <k.jensen@...sung.com>

PASID support within the IOMMU is not required to enable the Page
Request Queue, only the PRS capability.

Signed-off-by: Klaus Jensen <k.jensen@...sung.com>
---
 drivers/iommu/intel/iommu.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index ada3507d2831..bc1a369c2cf4 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1487,10 +1487,8 @@ static void free_dmar_iommu(struct intel_iommu *iommu)
 	/* free context mapping */
 	free_context_table(iommu);
 
-	if (pasid_supported(iommu)) {
-		if (ecap_prs(iommu->ecap))
-			intel_finish_prq(iommu);
-	}
+	if (ecap_prs(iommu->ecap))
+		intel_finish_prq(iommu);
 }
 
 /*
@@ -2478,7 +2476,7 @@ static int __init init_dmars(void)
 
 		iommu_flush_write_buffer(iommu);
 
-		if (pasid_supported(iommu) && ecap_prs(iommu->ecap)) {
+		if (ecap_prs(iommu->ecap)) {
 			/*
 			 * Call dmar_alloc_hwirq() with dmar_global_lock held,
 			 * could cause possible lock race condition.
@@ -2919,7 +2917,7 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
 	intel_iommu_init_qi(iommu);
 	iommu_flush_write_buffer(iommu);
 
-	if (pasid_supported(iommu) && ecap_prs(iommu->ecap)) {
+	if (ecap_prs(iommu->ecap)) {
 		ret = intel_enable_prq(iommu);
 		if (ret)
 			goto disable_iommu;

-- 
2.45.2