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Subject[RFC KERNEL PATCH v3 2/3] xen/pvh: Setup gsi and map pirq for passthrough device
Date
When dom0 is PVH, the gsi isn't be unmasked, that causes two
problems.

First, 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.

Second, for hvm guest, it allocates a pirq and irq for a
passthrough device by using gsi, before that, the gsi must first
have a mapping in dom0, see Xen code
pci_add_dm_done->xc_domain_irq_permission, it calls into Xen and
check whether dom0 has the mapping. But currently PVH dom0 uses
the kernel local interrupt mechanism instead of the pirq. So if
passthrough a device to guest on PVH dom0, it will fail at the
permission checking.

When assign a device to passthrough, proactively map priq for the
gsi of the device during that process.

Co-developed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Jiqian Chen <Jiqian.Chen@amd.com>
---
arch/x86/xen/enlighten_pvh.c | 116 +++++++++++++++++++++++++++++
drivers/acpi/pci_irq.c | 2 +-
drivers/xen/xen-pciback/pci_stub.c | 8 ++
include/linux/acpi.h | 1 +
include/xen/acpi.h | 1 +
5 files changed, 127 insertions(+), 1 deletion(-)

diff --git a/arch/x86/xen/enlighten_pvh.c b/arch/x86/xen/enlighten_pvh.c
index ada3868c02c2..d74a221bfb81 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 +26,121 @@
bool __ro_after_init xen_pvh;
EXPORT_SYMBOL_GPL(xen_pvh);

+typedef struct gsi_info {
+ u32 gsi;
+ int trigger;
+ int polarity;
+ int pirq;
+} 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
+ return -EINVAL;
+
+ 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);
+}
+
+static int xen_pvh_map_pirq(gsi_info_t *gsi_info)
+{
+ struct physdev_map_pirq map_irq;
+ int ret;
+
+ if (!gsi_info)
+ return -EINVAL;
+
+ map_irq.domid = DOMID_SELF;
+ map_irq.type = MAP_PIRQ_TYPE_GSI;
+ map_irq.index = gsi_info->gsi;
+ map_irq.pirq = gsi_info->gsi;
+
+ ret = HYPERVISOR_physdev_op(PHYSDEVOP_map_pirq, &map_irq);
+ gsi_info->pirq = map_irq.pirq;
+
+ return ret;
+}
+
+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) {
+ ret = 0;
+ xen_raw_printk("Already setup the GSI :%u\n", gsi_info.gsi);
+ } else if (ret) {
+ xen_raw_printk("Fail to setup gsi (%d)!\n", gsi_info.gsi);
+ return ret;
+ }
+
+ ret = xen_pvh_map_pirq(&gsi_info);
+ if (ret)
+ xen_raw_printk("Fail to map pirq for 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 24f599eaec14..c3aeefbf4ba1 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>
@@ -427,6 +428,13 @@ 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 54189e0e5f41..a211bdcdd6ff 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..ce7f5554f88e 100644
--- a/include/xen/acpi.h
+++ b/include/xen/acpi.h
@@ -67,6 +67,7 @@ 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)
{
--
2.34.1
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