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From: Joerg Roedel <joro@8bytes.org>
To: iommu@lists.linux-foundation.org
Cc: Joerg Roedel <jroedel@suse.de>,
	linux-kernel@vger.kernel.org,
	Maxim Levitsky <mlevitsk@redhat.com>,
	Will Deacon <will@kernel.org>
Subject: [PATCH] iommu/amd: Fix loop timeout issue in iommu_ga_log_enable()
Date: Mon, 31 Jan 2022 17:17:49 +0100	[thread overview]
Message-ID: <20220131161749.4021-1-joro@8bytes.org> (raw)

From: Joerg Roedel <jroedel@suse.de>

The polling loop for the register change in iommu_ga_log_enable() needs
to have a udelay() in it.  Otherwise the CPU might be faster than the
IOMMU hardware and wrongly trigger the WARN_ON() further down the code
stream.

Fixes: 8bda0cfbdc1a ("iommu/amd: Detect and initialize guest vAPIC log")
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/amd/init.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index dc338acf3338..d2e09d53851f 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -834,6 +834,7 @@ static int iommu_ga_log_enable(struct amd_iommu *iommu)
 		status = readl(iommu->mmio_base + MMIO_STATUS_OFFSET);
 		if (status & (MMIO_STATUS_GALOG_RUN_MASK))
 			break;
+		udelay(1);
 	}
 
 	if (WARN_ON(i >= LOOP_TIMEOUT))
-- 
2.34.1

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WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro@8bytes.org>
To: iommu@lists.linux-foundation.org
Cc: Joerg Roedel <joro@8bytes.org>,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
	Will Deacon <will@kernel.org>,
	linux-kernel@vger.kernel.org,
	Maxim Levitsky <mlevitsk@redhat.com>,
	Joerg Roedel <jroedel@suse.de>
Subject: [PATCH] iommu/amd: Fix loop timeout issue in iommu_ga_log_enable()
Date: Mon, 31 Jan 2022 17:17:49 +0100	[thread overview]
Message-ID: <20220131161749.4021-1-joro@8bytes.org> (raw)

From: Joerg Roedel <jroedel@suse.de>

The polling loop for the register change in iommu_ga_log_enable() needs
to have a udelay() in it.  Otherwise the CPU might be faster than the
IOMMU hardware and wrongly trigger the WARN_ON() further down the code
stream.

Fixes: 8bda0cfbdc1a ("iommu/amd: Detect and initialize guest vAPIC log")
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/amd/init.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index dc338acf3338..d2e09d53851f 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -834,6 +834,7 @@ static int iommu_ga_log_enable(struct amd_iommu *iommu)
 		status = readl(iommu->mmio_base + MMIO_STATUS_OFFSET);
 		if (status & (MMIO_STATUS_GALOG_RUN_MASK))
 			break;
+		udelay(1);
 	}
 
 	if (WARN_ON(i >= LOOP_TIMEOUT))
-- 
2.34.1


             reply	other threads:[~2022-01-31 16:17 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-31 16:17 Joerg Roedel [this message]
2022-01-31 16:17 ` [PATCH] iommu/amd: Fix loop timeout issue in iommu_ga_log_enable() Joerg Roedel
2022-01-31 17:06 ` John Garry via iommu
2022-01-31 17:06   ` John Garry
2022-02-04 11:34   ` Joerg Roedel
2022-02-04 11:34     ` Joerg Roedel
2022-02-01  7:01 ` kernel test robot
2022-02-01  7:01   ` kernel test robot
2022-02-01  7:01   ` kernel test robot

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