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Fix slowdowns and crashes for AMD GPUs in pre-PCIe-v3 slots

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Jeremy Cline 2018-11-30 10:22:38 -05:00
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81
PCI-Fix-incorrect-value-returned-from-pcie_get_speed.patch Normal file
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@ -0,0 +1,81 @@
From b8f56153d6d66e01e52f9f703ab0c6f8c8637354 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Thu, 29 Nov 2018 17:24:17 -0600
Subject: [PATCH] PCI: Fix incorrect value returned from pcie_get_speed_cap()
The macros PCI_EXP_LNKCAP_SLS_*GB are values, not bit masks. We must mask
the register and compare it against them.
This fixes errors like this:
amdgpu: [powerplay] failed to send message 261 ret is 0
when a PCIe-v3 card is plugged into a PCIe-v1 slot, because the slot is
being incorrectly reported as PCIe-v3 capable.
6cf57be0f78e, which appeared in v4.17, added pcie_get_speed_cap() with the
incorrect test of PCI_EXP_LNKCAP_SLS as a bitmask. 5d9a63304032, which
appeared in v4.19, changed amdgpu to use pcie_get_speed_cap(), so the
amdgpu bug reports below are regressions in v4.19.
Fixes: 6cf57be0f78e ("PCI: Add pcie_get_speed_cap() to find max supported link speed")
Fixes: 5d9a63304032 ("drm/amdgpu: use pcie functions for link width and speed")
Link: https://bugs.freedesktop.org/show_bug.cgi?id=108704
Link: https://bugs.freedesktop.org/show_bug.cgi?id=108778
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
[bhelgaas: update comment, remove use of PCI_EXP_LNKCAP_SLS_8_0GB and
PCI_EXP_LNKCAP_SLS_16_0GB since those should be covered by PCI_EXP_LNKCAP2,
remove test of PCI_EXP_LNKCAP for zero, since that register is required]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org # v4.17+
Signed-off-by: Jeremy Cline <jcline@redhat.com>
---
drivers/pci/pci.c | 24 +++++++++++-------------
1 file changed, 11 insertions(+), 13 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index d068f11d08a7..c9d8e3c837de 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5556,9 +5556,13 @@ enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev)
u32 lnkcap2, lnkcap;
/*
- * PCIe r4.0 sec 7.5.3.18 recommends using the Supported Link
- * Speeds Vector in Link Capabilities 2 when supported, falling
- * back to Max Link Speed in Link Capabilities otherwise.
+ * Link Capabilities 2 was added in PCIe r3.0, sec 7.8.18. The
+ * implementation note there recommends using the Supported Link
+ * Speeds Vector in Link Capabilities 2 when supported.
+ *
+ * Without Link Capabilities 2, i.e., prior to PCIe r3.0, software
+ * should use the Supported Link Speeds field in Link Capabilities,
+ * where only 2.5 GT/s and 5.0 GT/s speeds were defined.
*/
pcie_capability_read_dword(dev, PCI_EXP_LNKCAP2, &lnkcap2);
if (lnkcap2) { /* PCIe r3.0-compliant */
@@ -5574,16 +5578,10 @@ enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev)
}
pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap);
- if (lnkcap) {
- if (lnkcap & PCI_EXP_LNKCAP_SLS_16_0GB)
- return PCIE_SPEED_16_0GT;
- else if (lnkcap & PCI_EXP_LNKCAP_SLS_8_0GB)
- return PCIE_SPEED_8_0GT;
- else if (lnkcap & PCI_EXP_LNKCAP_SLS_5_0GB)
- return PCIE_SPEED_5_0GT;
- else if (lnkcap & PCI_EXP_LNKCAP_SLS_2_5GB)
- return PCIE_SPEED_2_5GT;
- }
+ if ((lnkcap & PCI_EXP_LNKCAP_SLS) == PCI_EXP_LNKCAP_SLS_5_0GB)
+ return PCIE_SPEED_5_0GT;
+ else if ((lnkcap & PCI_EXP_LNKCAP_SLS) == PCI_EXP_LNKCAP_SLS_2_5GB)
+ return PCIE_SPEED_2_5GT;
return PCI_SPEED_UNKNOWN;
}
--
2.19.2

5
kernel.spec
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@ -636,6 +636,10 @@ Patch513: CVE-2018-19407.patch
# rhbz 1650984, in linux-next and Cc'd for stable
Patch514: net-phy-add-workaround-for-issue-where-PHY-driver-do.patch
# In the PCI tree and Cc'd for stable, fixes an issue with amdgpu
# https://patchwork.freedesktop.org/patch/259364/
Patch515: PCI-Fix-incorrect-value-returned-from-pcie_get_speed.patch
# END OF PATCH DEFINITIONS
%endif
@ -1889,6 +1893,7 @@ fi
%changelog
* Thu Nov 29 2018 Jeremy Cline <jeremy@jcline.org>
- Fix a problem with some rtl8168 chips (rhbz 1650984)
- Fix slowdowns and crashes for AMD GPUs in pre-PCIe-v3 slots
* Tue Nov 27 2018 Jeremy Cline <jcline@redhat.com> - 4.19.5-300
- Linux v4.19.5