[PATCH 1/2] x86/PCI: Disable enhanced atomics on some AMD PCIe ports

[Mario Limonciello <mario.limonciello@amd.com>]

There have been multiple reports of data corruption that can occur
with 64-bit DMA when the IOMMU is enabled. This occurs due to some
BIOSes enabling enhanced atomic operations on PCIe ports.

When enhanced atomic operations are enabled on PCIe ports for some
models, data corruption occurs when the 32-bit IOVA space is exhausted.
The problem is reported on storage devices, but can affect any device
that uses 64 bit DMA.

Disable enhanced atomics using SMN for NBIO 7.7 and 7.11 based models.

Cc: david.laight.linux@gmail.com
Cc: John Smith <imjohnsmith4000@gmail.com>
Cc: Lennert Buytenhek <kernel@wantstofly.org>
Cc: Niklas Cassel <cassel@kernel.org>
Cc: Roland Waltersson <roland.waltersson@netinsight.net>
Reported-by: Mikael Etienne <mikael1022bzh@gmail.com>
Closes: https://lore.kernel.org/all/178789300872.392066.15963676631650361573@gmail.com/
Reported-by: Arthur Husband <artmoty@gmail.com>
Closes: https://lore.kernel.org/linux-ide/20260406222335.379935-1-artmoty@gmail.com/
Reported-by: Alvin Lim <alvinwylim@gmail.com>
Closes: https://lore.kernel.org/linux-ide/20260621100844.1224301-1-alvinwylim@gmail.com/
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 arch/x86/pci/fixup.c | 93 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)

diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
index b301c6c8df753..0857fd9365ec2 100644
--- a/arch/x86/pci/fixup.c
+++ b/arch/x86/pci/fixup.c
@@ -886,6 +886,99 @@ static void quirk_clear_strap_no_soft_reset_dev2_f0(struct pci_dev *dev)
 	}
 }
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD, 0x15b8, quirk_clear_strap_no_soft_reset_dev2_f0);
+
+/*
+ * Enhanced atomic operations can cause corruption with 64-bit IOVA
+ * on these devices.
+ */
+#define RX_ENH_ATOMIC_EN		BIT(8)
+
+static const u32 nbio_7_7_pcie_smn_addrs[] = {
+	0x111401d0,
+	0x111411d0,
+	0x111421d0,
+	0x111431d0,
+	0x111441d0,
+	0x112401d0,
+	0x112411d0,
+	0x112421d0,
+	0x112431d0,
+	0x112441d0,
+	0x112451d0,
+	0x113401d0,
+	0x114401d0,
+};
+
+static const u32 nbio_7_11_pcie_smn_addrs[] = {
+	0x112401d0,
+	0x112411d0,
+	0x112421d0,
+	0x112431d0,
+	0x112441d0,
+	0x112451d0,
+	0x113401d0,
+	0x113411d0,
+	0x113421d0,
+	0x113431d0,
+	0x113441d0,
+	0x113451d0,
+};
+
+static void quirk_amd_nbio_enhanced_atomic(struct pci_dev *host_bridge,
+					   const u32 *smn_addrs,
+					   size_t nr_smn_addrs)
+{
+	bool changed = false;
+	size_t i;
+	u32 data;
+	int ret;
+
+	for (i = 0; i < nr_smn_addrs; i++) {
+		ret = amd_smn_read(0, smn_addrs[i], &data);
+		if (ret)
+			continue;
+		if (!(data & RX_ENH_ATOMIC_EN))
+			continue;
+		data = data & ~RX_ENH_ATOMIC_EN;
+		ret = amd_smn_write(0, smn_addrs[i], data);
+		if (ret)
+			continue;
+		if (changed)
+			continue;
+		ret = amd_smn_read(0, smn_addrs[i], &data);
+		if (ret)
+			continue;
+		if (data & RX_ENH_ATOMIC_EN)
+			continue;
+		changed = true;
+	}
+
+	if (changed)
+		pci_info(host_bridge, "enhanced atomics disabled\n");
+}
+
+static void quirk_amd_nbio_7_7_disable_enhanced_atomic(struct pci_dev *dev)
+{
+	quirk_amd_nbio_enhanced_atomic(dev, nbio_7_7_pcie_smn_addrs,
+				       ARRAY_SIZE(nbio_7_7_pcie_smn_addrs));
+}
+
+static void quirk_amd_nbio_7_11_disable_enhanced_atomic(struct pci_dev *dev)
+{
+	quirk_amd_nbio_enhanced_atomic(dev, nbio_7_11_pcie_smn_addrs,
+				       ARRAY_SIZE(nbio_7_11_pcie_smn_addrs));
+}
+
+/* Phoenix, Hawk Point (NBIO 7.7) */
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD, 0x14E8,
+			quirk_amd_nbio_7_7_disable_enhanced_atomic);
+
+/* Strix, Krackan, Strix Halo (NBIO 7.11) */
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD, 0x1507,
+			quirk_amd_nbio_7_11_disable_enhanced_atomic);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD, 0x1122,
+			quirk_amd_nbio_7_11_disable_enhanced_atomic);
+
 #endif
 
 /*
-- 
2.43.0