From 3c4b4c4fc3c71b375490233bb9209763d7094ee9 Mon Sep 17 00:00:00 2001
From: Yan Wang <wangyan122@huawei.com>
Date: Tue, 8 Feb 2022 16:10:31 +0800
Subject: [PATCH] pcie: Add pcie-root-port fast plug/unplug feature

If a device is plugged in the pcie-root-port when VM kernel is
booting, the kernel may wrongly disable the device.
This bug was brought in by two patches of the linux kernel:

https://patchwork.kernel.org/patch/10575355/
https://patchwork.kernel.org/patch/10766219/

VM runtime like kata uses this feature to boot microVM,
so we must fix it up. We hack into the pcie native hotplug
patch so that hotplug/unplug will work under this circumstance.

Signed-off-by: Ying Fang <fangying1@huawei.com>
Signed-off-by: Yan Wang <wangyan122@huawei.com>
---
 hw/core/machine.c                  |  2 ++
 hw/pci-bridge/gen_pcie_root_port.c |  2 ++
 hw/pci/pcie.c                      | 13 ++++++++++++-
 include/hw/pci/pcie_port.h         |  3 +++
 4 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 0c17398141..965682619b 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -160,6 +160,8 @@ const size_t hw_compat_4_0_len = G_N_ELEMENTS(hw_compat_4_0);
 GlobalProperty hw_compat_3_1[] = {
     { "pcie-root-port", "x-speed", "2_5" },
     { "pcie-root-port", "x-width", "1" },
+    { "pcie-root-port", "fast-plug", "0" },
+    { "pcie-root-port", "fast-unplug", "0" },
     { "memory-backend-file", "x-use-canonical-path-for-ramblock-id", "true" },
     { "memory-backend-memfd", "x-use-canonical-path-for-ramblock-id", "true" },
     { "tpm-crb", "ppi", "false" },
diff --git a/hw/pci-bridge/gen_pcie_root_port.c b/hw/pci-bridge/gen_pcie_root_port.c
index 1ce4e7beba..1e1ab5bb19 100644
--- a/hw/pci-bridge/gen_pcie_root_port.c
+++ b/hw/pci-bridge/gen_pcie_root_port.c
@@ -145,6 +145,8 @@ static Property gen_rp_props[] = {
                                 speed, PCIE_LINK_SPEED_16),
     DEFINE_PROP_PCIE_LINK_WIDTH("x-width", PCIESlot,
                                 width, PCIE_LINK_WIDTH_32),
+    DEFINE_PROP_UINT8("fast-plug", PCIESlot, fast_plug, 0),
+    DEFINE_PROP_UINT8("fast-unplug", PCIESlot, fast_unplug, 0),
     DEFINE_PROP_END_OF_LIST()
 };
 
diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index dccf204451..04fbd794a8 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -555,6 +555,7 @@ void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_dev,
     uint8_t *exp_cap = hotplug_pdev->config + hotplug_pdev->exp.exp_cap;
     uint32_t sltcap = pci_get_word(exp_cap + PCI_EXP_SLTCAP);
     uint16_t sltctl = pci_get_word(exp_cap + PCI_EXP_SLTCTL);
+    PCIESlot *s = PCIE_SLOT(hotplug_pdev);
 
     /* Check if hot-unplug is disabled on the slot */
     if ((sltcap & PCI_EXP_SLTCAP_HPC) == 0) {
@@ -600,7 +601,17 @@ void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_dev,
         return;
     }
 
-    pcie_cap_slot_push_attention_button(hotplug_pdev);
+    if ((pci_dev->cap_present & QEMU_PCIE_LNKSTA_DLLLA) && s->fast_plug) {
+        pci_word_test_and_clear_mask(pci_dev->config + pci_dev->exp.exp_cap + PCI_EXP_LNKSTA,
+                                    PCI_EXP_LNKSTA_DLLLA);
+    }
+
+    if (s->fast_unplug) {
+        pcie_cap_slot_event(hotplug_pdev,
+                            PCI_EXP_HP_EV_PDC | PCI_EXP_HP_EV_ABP);
+    } else {
+        pcie_cap_slot_push_attention_button(hotplug_pdev);
+    }
 }
 
 /* pci express slot for pci express root/downstream port
diff --git a/include/hw/pci/pcie_port.h b/include/hw/pci/pcie_port.h
index 90e6cf45b8..7148a0959b 100644
--- a/include/hw/pci/pcie_port.h
+++ b/include/hw/pci/pcie_port.h
@@ -56,6 +56,9 @@ struct PCIESlot {
     uint8_t     chassis;
     uint16_t    slot;
 
+    uint8_t     fast_plug;
+    uint8_t     fast_unplug;
+
     PCIExpLinkSpeed speed;
     PCIExpLinkWidth width;
 
-- 
2.27.0