[RFC KERNEL PATCH v4 2/3] xen/pvh: Setup gsi for passthrough device

[Jiqian Chen <Jiqian.Chen@xxxxxxx>]

In PVH dom0, the gsis don't get registered, but the gsi of
a passthrough device must be configured for it to be able to be
mapped into a domU.

When assign a device to passthrough, proactively setup the gsi
of the device during that process.

Co-developed-by: Huang Rui <ray.huang@xxxxxxx>
Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
---
 arch/x86/xen/enlighten_pvh.c       | 90 ++++++++++++++++++++++++++++++
 drivers/acpi/pci_irq.c             |  2 +-
 drivers/xen/xen-pciback/pci_stub.c |  8 +++
 include/linux/acpi.h               |  1 +
 include/xen/acpi.h                 |  6 ++
 5 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/arch/x86/xen/enlighten_pvh.c b/arch/x86/xen/enlighten_pvh.c
index ada3868c02c2..ecadd966c684 100644
--- a/arch/x86/xen/enlighten_pvh.c
+++ b/arch/x86/xen/enlighten_pvh.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/acpi.h>
 #include <linux/export.h>
+#include <linux/pci.h>
 
 #include <xen/hvc-console.h>
 
@@ -25,6 +26,95 @@
 bool __ro_after_init xen_pvh;
 EXPORT_SYMBOL_GPL(xen_pvh);
 
+typedef struct gsi_info {
+       int gsi;
+       int trigger;
+       int polarity;
+} gsi_info_t;
+
+struct acpi_prt_entry {
+       struct acpi_pci_id      id;
+       u8                      pin;
+       acpi_handle             link;
+       u32                     index;          /* GSI, or link _CRS index */
+};
+
+static int xen_pvh_get_gsi_info(struct pci_dev *dev,
+                                                               gsi_info_t 
*gsi_info)
+{
+       int gsi;
+       u8 pin = 0;
+       struct acpi_prt_entry *entry;
+       int trigger = ACPI_LEVEL_SENSITIVE;
+       int polarity = acpi_irq_model == ACPI_IRQ_MODEL_GIC ?
+                                     ACPI_ACTIVE_HIGH : ACPI_ACTIVE_LOW;
+
+       if (dev)
+               pin = dev->pin;
+       if (!dev || !pin || !gsi_info)
+               return -EINVAL;
+
+       entry = acpi_pci_irq_lookup(dev, pin);
+       if (entry) {
+               if (entry->link)
+                       gsi = acpi_pci_link_allocate_irq(entry->link,
+                                                        entry->index,
+                                                        &trigger, &polarity,
+                                                        NULL);
+               else
+                       gsi = entry->index;
+       } else
+               gsi = -1;
+
+       if (gsi < 0)
+               return -EINVAL;
+
+       gsi_info->gsi = gsi;
+       gsi_info->trigger = trigger;
+       gsi_info->polarity = polarity;
+
+       return 0;
+}
+
+static int xen_pvh_setup_gsi(gsi_info_t *gsi_info)
+{
+       struct physdev_setup_gsi setup_gsi;
+
+       if (!gsi_info)
+               return -EINVAL;
+
+       setup_gsi.gsi = gsi_info->gsi;
+       setup_gsi.triggering = (gsi_info->trigger == ACPI_EDGE_SENSITIVE ? 0 : 
1);
+       setup_gsi.polarity = (gsi_info->polarity == ACPI_ACTIVE_HIGH ? 0 : 1);
+
+       return HYPERVISOR_physdev_op(PHYSDEVOP_setup_gsi, &setup_gsi);
+}
+
+int xen_pvh_passthrough_gsi(struct pci_dev *dev)
+{
+       int ret;
+       gsi_info_t gsi_info;
+
+       if (!dev)
+               return -EINVAL;
+
+       ret = xen_pvh_get_gsi_info(dev, &gsi_info);
+       if (ret) {
+               xen_raw_printk("Fail to get gsi info!\n");
+               return ret;
+       }
+
+       ret = xen_pvh_setup_gsi(&gsi_info);
+       if (ret == -EEXIST) {
+               xen_raw_printk("Already setup the GSI :%d\n", gsi_info.gsi);
+               ret = 0;
+       } else if (ret)
+               xen_raw_printk("Fail to setup GSI (%d)!\n", gsi_info.gsi);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(xen_pvh_passthrough_gsi);
+
 void __init xen_pvh_init(struct boot_params *boot_params)
 {
        u32 msr;
diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
index ff30ceca2203..630fe0a34bc6 100644
--- a/drivers/acpi/pci_irq.c
+++ b/drivers/acpi/pci_irq.c
@@ -288,7 +288,7 @@ static int acpi_reroute_boot_interrupt(struct pci_dev *dev,
 }
 #endif /* CONFIG_X86_IO_APIC */
 
-static struct acpi_prt_entry *acpi_pci_irq_lookup(struct pci_dev *dev, int pin)
+struct acpi_prt_entry *acpi_pci_irq_lookup(struct pci_dev *dev, int pin)
 {
        struct acpi_prt_entry *entry = NULL;
        struct pci_dev *bridge;
diff --git a/drivers/xen/xen-pciback/pci_stub.c 
b/drivers/xen/xen-pciback/pci_stub.c
index 46c40ec8a18e..22d4380d2b04 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -20,6 +20,7 @@
 #include <linux/atomic.h>
 #include <xen/events.h>
 #include <xen/pci.h>
+#include <xen/acpi.h>
 #include <xen/xen.h>
 #include <asm/xen/hypervisor.h>
 #include <xen/interface/physdev.h>
@@ -435,6 +436,13 @@ static int pcistub_init_device(struct pci_dev *dev)
                        goto config_release;
                pci_restore_state(dev);
        }
+
+       if (xen_initial_domain() && xen_pvh_domain()) {
+               err = xen_pvh_passthrough_gsi(dev);
+               if (err)
+                       goto config_release;
+       }
+
        /* Now disable the device (this also ensures some private device
         * data is setup before we export)
         */
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 4db54e928b36..7ea3be981cc3 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -360,6 +360,7 @@ void acpi_unregister_gsi (u32 gsi);
 
 struct pci_dev;
 
+struct acpi_prt_entry *acpi_pci_irq_lookup(struct pci_dev *dev, int pin);
 int acpi_pci_irq_enable (struct pci_dev *dev);
 void acpi_penalize_isa_irq(int irq, int active);
 bool acpi_isa_irq_available(int irq);
diff --git a/include/xen/acpi.h b/include/xen/acpi.h
index b1e11863144d..17c4d37f1e60 100644
--- a/include/xen/acpi.h
+++ b/include/xen/acpi.h
@@ -67,10 +67,16 @@ static inline void xen_acpi_sleep_register(void)
                acpi_suspend_lowlevel = xen_acpi_suspend_lowlevel;
        }
 }
+int xen_pvh_passthrough_gsi(struct pci_dev *dev);
 #else
 static inline void xen_acpi_sleep_register(void)
 {
 }
+
+static inline int xen_pvh_passthrough_gsi(struct pci_dev *dev)
+{
+       return -1;
+}
 #endif
 
 #endif /* _XEN_ACPI_H */
-- 
2.34.1