2020-05-08 14:52:40 +00:00
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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2020-04-23 20:47:21 +00:00
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From: Laura Abbott <labbott@redhat.com>
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Date: Mon, 20 May 2019 22:21:02 -0400
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Subject: [PATCH] iommu/arm-smmu: workaround DMA mode issues
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Message-id: <20190520222102.19488-1-labbott@redhat.com>
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Patchwork-id: 259215
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O-Subject: [ARK INTERNAL PATCH] iommu/arm-smmu: workaround DMA mode issues
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Bugzilla:
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RH-Acked-by: Mark Langsdorf <mlangsdo@redhat.com>
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RH-Acked-by: Mark Salter <msalter@redhat.com>
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From: Mark Salter <msalter@redhat.com>
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Rebased for v5.2-rc1
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Bugzilla: 1652259
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Brew: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=19244562
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Upstream status: RHEL only.
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rhel8 commit 65feb1ed0ec9a088a63a90d46c0f7563ac96ad0f
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Author: Mark Salter <msalter@redhat.com>
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Date: Wed Nov 21 17:15:59 2018 +0100
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[iommu] iommu/arm-smmu: workaround DMA mode issues
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1624077
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Brew: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=18112820
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Testing: Verified iommu.passthrough=1 no longer needed on gigabyte platforms.
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Upstream Status: RHEL-only
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In RHEL_ALT 7.5 we carried a RHEL-only patch which forced the arm smmuv2
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into bypass mode due to performance issues on CN88xx. This was intended
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to be a temporary hack until the issues were resolved. Another vendor
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had issues with the iommu in bypass mode so we reverted the RHEL-only
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patch so that iommu is in DMA mode by default (upstream default).
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It turns on that there are remaining SMMU DMA mode issues on Gigabyte
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platformws with CN88xx cpus. The problem manifests itself by pcie
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card drivers failing to initialize the cards when SMMU is in DMA mode.
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The root cause has not been determined yet, but looks likely to be
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a hw or firmware issue. This patch forces bypass mode for Gigabyte
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platforms. CN88xx isn't officially supported in RHEL but we have a
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lot of them being used internally for testing, so I think we want
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this to support that use case in RHEL8.
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Signed-off-by: Mark Salter <msalter@redhat.com>
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Signed-off-by: Herton R. Krzesinski <herton@redhat.com>
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Acked-by: Mark Salter <msalter@redhat.com>
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Acked-by: Donald Dutile <ddutile@redhat.com>
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Upstream Status: RHEL only
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Signed-off-by: Laura Abbott <labbott@redhat.com>
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---
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drivers/iommu/iommu.c | 22 ++++++++++++++++++++++
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1 file changed, 22 insertions(+)
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diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
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2020-07-14 15:52:28 +00:00
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index b6858adc4f17..4c2da9f17514 100644
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2020-04-23 20:47:21 +00:00
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--- a/drivers/iommu/iommu.c
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+++ b/drivers/iommu/iommu.c
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@@ -7,6 +7,7 @@
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#define pr_fmt(fmt) "iommu: " fmt
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2020-06-30 14:24:22 +00:00
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2020-04-23 20:47:21 +00:00
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#include <linux/device.h>
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+#include <linux/dmi.h>
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#include <linux/kernel.h>
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#include <linux/bug.h>
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#include <linux/types.h>
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2020-06-10 22:01:45 +00:00
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@@ -2838,3 +2839,24 @@ int iommu_sva_get_pasid(struct iommu_sva *handle)
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2020-04-23 20:47:21 +00:00
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return ops->sva_get_pasid(handle);
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}
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EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
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+
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+#ifdef CONFIG_ARM64
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+static int __init iommu_quirks(void)
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+{
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+ const char *vendor, *name;
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+
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+ vendor = dmi_get_system_info(DMI_SYS_VENDOR);
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+ name = dmi_get_system_info(DMI_PRODUCT_NAME);
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+
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+ if (vendor &&
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+ (strncmp(vendor, "GIGABYTE", 8) == 0 && name &&
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+ (strncmp(name, "R120", 4) == 0 ||
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+ strncmp(name, "R270", 4) == 0))) {
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+ pr_warn("Gigabyte %s detected, force iommu passthrough mode", name);
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+ iommu_def_domain_type = IOMMU_DOMAIN_IDENTITY;
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+ }
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+
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+ return 0;
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+}
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+arch_initcall(iommu_quirks);
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+#endif
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--
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2020-06-30 14:24:22 +00:00
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2.26.2
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2020-04-23 20:47:21 +00:00
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