linux-kernel - [PATCH v15 2/6] iommu: Print strict or lazy mode at init time

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Date:   Mon, 12 Jul 2021 19:12:16 +0800
From:   John Garry <john.garry@...wei.com>
To:     <joro@...tes.org>, <will@...nel.org>, <dwmw2@...radead.org>,
        <baolu.lu@...ux.intel.com>, <robin.murphy@....com>,
        <corbet@....net>
CC:     <linux-kernel@...r.kernel.org>, <iommu@...ts.linux-foundation.org>,
        <linuxarm@...wei.com>, <thunder.leizhen@...wei.com>,
        <chenxiang66@...ilicon.com>, <linux-doc@...r.kernel.org>,
        <dianders@...omium.org>, John Garry <john.garry@...wei.com>
Subject: [PATCH v15 2/6] iommu: Print strict or lazy mode at init time

As well as the default domain type, it's useful to know whether strict
or lazy for DMA domains, so add this info in a separate print.

The (stict/lazy) mode may be also set via iommu.strict earlyparm, but
this will be processed prior to iommu_subsys_init(), so that print will be
accurate for drivers which don't set the mode via custom means.

For the drivers which set the mode via custom means - AMD and Intel drivers
- they maintain prints to inform a change in policy or that custom cmdline
methods to change policy are deprecated.

Signed-off-by: John Garry <john.garry@...wei.com>
Reviewed-by: Robin Murphy <robin.murphy@....com>
Reviewed-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/iommu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 5419c4b9f27a..cf58949cc2f3 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -138,6 +138,11 @@ static int __init iommu_subsys_init(void)
 		(iommu_cmd_line & IOMMU_CMD_LINE_DMA_API) ?
 			"(set via kernel command line)" : "");
 
+	pr_info("DMA domain TLB invalidation policy: %s mode %s\n",
+		iommu_dma_strict ? "strict" : "lazy",
+		(iommu_cmd_line & IOMMU_CMD_LINE_STRICT) ?
+			"(set via kernel command line)" : "");
+
 	return 0;
 }
 subsys_initcall(iommu_subsys_init);
-- 
2.26.2