linux-kernel - [RFC PATCH 3/7] iommu/amd: Decouple the logic to enable PPR and GT

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Message-Id: <20210312090411.6030-4-suravee.suthikulpanit@amd.com>
Date:   Fri, 12 Mar 2021 03:04:07 -0600
From:   Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:     linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org
Cc:     joro@...tes.org, Jon.Grimm@....com, Wei.Huang2@....com,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Subject: [RFC PATCH 3/7] iommu/amd: Decouple the logic to enable PPR and GT

Currently, the function to enable iommu v2 (GT) assumes PPR log
must also be enabled. This is no longer the case since the IOMMU
v2 page table can be enabled without PRR support (for DMA-API
use case).

Therefore, separate the enabling logic for PPR and GT.
There is no functional change.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
---
 drivers/iommu/amd/init.c | 19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 9126efcbaf2c..5def566de6f6 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -898,14 +898,6 @@ static void iommu_enable_xt(struct amd_iommu *iommu)
 #endif /* CONFIG_IRQ_REMAP */
 }
 
-static void iommu_enable_gt(struct amd_iommu *iommu)
-{
-	if (!iommu_feature(iommu, FEATURE_GT))
-		return;
-
-	iommu_feature_enable(iommu, CONTROL_GT_EN);
-}
-
 /* sets a specific bit in the device table entry. */
 static void set_dev_entry_bit(u16 devid, u8 bit)
 {
@@ -1882,6 +1874,7 @@ static int __init iommu_init_pci(struct amd_iommu *iommu)
 			amd_iommu_max_glx_val = glxval;
 		else
 			amd_iommu_max_glx_val = min(amd_iommu_max_glx_val, glxval);
+		iommu_feature_enable(iommu, CONTROL_GT_EN);
 	}
 
 	if (iommu_feature(iommu, FEATURE_GT) &&
@@ -2530,21 +2523,19 @@ static void early_enable_iommus(void)
 #endif
 }
 
-static void enable_iommus_v2(void)
+static void enable_iommus_ppr(void)
 {
 	struct amd_iommu *iommu;
 
-	for_each_iommu(iommu) {
+	for_each_iommu(iommu)
 		iommu_enable_ppr_log(iommu);
-		iommu_enable_gt(iommu);
-	}
 }
 
 static void enable_iommus(void)
 {
 	early_enable_iommus();
 
-	enable_iommus_v2();
+	enable_iommus_ppr();
 }
 
 static void disable_iommus(void)
@@ -2935,7 +2926,7 @@ static int __init state_next(void)
 		register_syscore_ops(&amd_iommu_syscore_ops);
 		ret = amd_iommu_init_pci();
 		init_state = ret ? IOMMU_INIT_ERROR : IOMMU_PCI_INIT;
-		enable_iommus_v2();
+		enable_iommus_ppr();
 		break;
 	case IOMMU_PCI_INIT:
 		ret = amd_iommu_enable_interrupts();
-- 
2.17.1