linux-kernel - [PATCH] s390/pci: Fix reset of IOMMU software counters

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Message-Id: <20231004-dma_iommu_fix-v1-1-129777cd8232@linux.ibm.com>
Date:   Wed, 04 Oct 2023 10:56:12 +0200
From:   Niklas Schnelle <schnelle@...ux.ibm.com>
To:     Robin Murphy <robin.murphy@....com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Gerd Bayer <gbayer@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
        Joerg Roedel <jroedel@...e.de>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        iommu@...ts.linux.dev, Niklas Schnelle <schnelle@...ux.ibm.com>
Subject: [PATCH] s390/pci: Fix reset of IOMMU software counters

Together with enabling the Function Measurement Block
zpci_fmb_enable_device() also resets the software counters. This allows
to use "echo 0 > /sys/kernel/debug/pci/<dev>/statistics" followed by
echo "1 > /../statistics" to reset all counters. In commit c76c067e488c
("s390/pci: Use dma-iommu layer") this use of the now obsolete counters
in struct zpci_device was missed as was their removal. Fix this by
resetting the new counters and removing the old ones.

Fixes: c76c067e488c ("s390/pci: Use dma-iommu layer")
Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
---
Note: This is based on and references commit IDs from Joerg Roedel's
iommu/next branch and should go in via the iommu tree.
---
 arch/s390/include/asm/pci.h |  4 ----
 arch/s390/pci/pci.c         | 13 ++++++++++---
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
index 3f74f1cf37df..e91cd6bbc330 100644
--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -173,10 +173,6 @@ struct zpci_dev {
 	struct zpci_fmb *fmb;
 	u16		fmb_update;	/* update interval */
 	u16		fmb_length;
-	/* software counters */
-	atomic64_t allocated_pages;
-	atomic64_t mapped_pages;
-	atomic64_t unmapped_pages;
 
 	u8		version;
 	enum pci_bus_speed max_bus_speed;
diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index 563cb72d9ed0..63fd9e1d9f22 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -157,6 +157,7 @@ int zpci_unregister_ioat(struct zpci_dev *zdev, u8 dmaas)
 int zpci_fmb_enable_device(struct zpci_dev *zdev)
 {
 	u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_SET_MEASURE);
+	struct zpci_iommu_ctrs *ctrs;
 	struct zpci_fib fib = {0};
 	u8 cc, status;
 
@@ -169,9 +170,15 @@ int zpci_fmb_enable_device(struct zpci_dev *zdev)
 	WARN_ON((u64) zdev->fmb & 0xf);
 
 	/* reset software counters */
-	atomic64_set(&zdev->allocated_pages, 0);
-	atomic64_set(&zdev->mapped_pages, 0);
-	atomic64_set(&zdev->unmapped_pages, 0);
+	ctrs = zpci_get_iommu_ctrs(zdev);
+	if (ctrs) {
+		atomic64_set(&ctrs->mapped_pages, 0);
+		atomic64_set(&ctrs->unmapped_pages, 0);
+		atomic64_set(&ctrs->global_rpcits, 0);
+		atomic64_set(&ctrs->sync_map_rpcits, 0);
+		atomic64_set(&ctrs->sync_rpcits, 0);
+	}
+
 
 	fib.fmb_addr = virt_to_phys(zdev->fmb);
 	fib.gd = zdev->gisa;

---
base-commit: 8e5ab3f54a1061c2be3e1fbcda01fbe604c3450e
change-id: 20231002-dma_iommu_fix-0a5397992f15

Best regards,
-- 
Niklas Schnelle
Linux on Z Development

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