linux-kernel - [PATCH v2] PCI: vmd: Honor ACPI

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Date:   Thu,  2 Dec 2021 11:04:49 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     bhelgaas@...gle.com
Cc:     linux-pm@...r.kernel.org,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Nirmal Patel <nirmal.patel@...ux.intel.com>,
        Jonathan Derrick <jonathan.derrick@...ux.dev>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] PCI: vmd: Honor ACPI _OSC on PCIe features

When Samsung PCIe Gen4 NVMe is connected to Intel ADL VMD, the
combination causes AER message flood and drags the system performance
down.

The issue doesn't happen when VMD mode is disabled in BIOS, since AER
isn't enabled by acpi_pci_root_create() . When VMD mode is enabled, AER
is enabled regardless of _OSC:
[    0.410076] acpi PNP0A08:00: _OSC: platform does not support [AER]
...
[    1.486704] pcieport 10000:e0:06.0: AER: enabled with IRQ 146

Since VMD is an aperture to regular PCIe root ports, honor ACPI _OSC to
disable PCIe features accordingly to resolve the issue.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215027
Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
v2:
 - Use pci_find_host_bridge() instead of open coding.

 drivers/pci/controller/vmd.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index a45e8e59d3d48..acf847cb825c0 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -671,6 +671,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	resource_size_t offset[2] = {0};
 	resource_size_t membar2_offset = 0x2000;
 	struct pci_bus *child;
+	struct pci_host_bridge *root_bridge, *vmd_bridge;
 	int ret;
 
 	/*
@@ -798,6 +799,17 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 		return -ENODEV;
 	}
 
+	vmd_bridge = to_pci_host_bridge(vmd->bus->bridge);
+
+	root_bridge = pci_find_host_bridge(vmd->dev->bus);
+
+	vmd_bridge->native_pcie_hotplug = root_bridge->native_pcie_hotplug;
+	vmd_bridge->native_shpc_hotplug = root_bridge->native_shpc_hotplug;
+	vmd_bridge->native_aer = root_bridge->native_aer;
+	vmd_bridge->native_pme = root_bridge->native_pme;
+	vmd_bridge->native_ltr = root_bridge->native_ltr;
+	vmd_bridge->native_dpc = root_bridge->native_dpc;
+
 	vmd_attach_resources(vmd);
 	if (vmd->irq_domain)
 		dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
-- 
2.32.0