diff mbox series

[RFC,5/5] xen/privcmd: add IOCTL_PRIVCMD_GSI_FROM_IRQ

Message ID 20230312120157.452859-6-ray.huang@amd.com (mailing list archive)
State New, archived
Headers show
Series Add Xen PVH dom0 support for GPU | expand

Commit Message

Huang Rui March 12, 2023, 12:01 p.m. UTC 
From: Chen Jiqian <Jiqian.Chen@amd.com>

When hypervisor get an interrupt, it needs interrupt's
gsi number instead of irq number. Gsi number is unique
in xen, but irq number is only unique in one domain.
So, we need to record the relationship between irq and
gsi when dom0 initialized pci devices, and provide syscall
IOCTL_PRIVCMD_GSI_FROM_IRQ to translate irq to gsi. So
that, we can map pirq successfully in hypervisor side.

Signed-off-by: Chen Jiqian <Jiqian.Chen@amd.com>
Signed-off-by: Huang Rui <ray.huang@amd.com>
---
 arch/x86/pci/xen.c               |  4 ++++
 drivers/xen/events/events_base.c | 37 ++++++++++++++++++++++++++++++++
 drivers/xen/privcmd.c            | 20 +++++++++++++++++
 include/uapi/xen/privcmd.h       |  7 ++++++
 include/xen/events.h             |  5 +++++
 5 files changed, 73 insertions(+)

Comments

Roger Pau Monné March 15, 2023, 2:26 p.m. UTC | #1 
On Sun, Mar 12, 2023 at 08:01:57PM +0800, Huang Rui wrote:
> From: Chen Jiqian <Jiqian.Chen@amd.com>
> 
> When hypervisor get an interrupt, it needs interrupt's
> gsi number instead of irq number. Gsi number is unique
> in xen, but irq number is only unique in one domain.
> So, we need to record the relationship between irq and
> gsi when dom0 initialized pci devices, and provide syscall
> IOCTL_PRIVCMD_GSI_FROM_IRQ to translate irq to gsi. So
> that, we can map pirq successfully in hypervisor side.

GSI is not only unique in Xen, it's an ACPI provided value that's
unique in the platform.  The text above make it look like GSI is some
kind of internal Xen reference to an interrupt, but it's not.

How does a PV domain deal with this? I would assume there Linux will
also end up with IRQ != GSI, and hence will need some kind of
translation?

Thanks, Roger.
diff mbox series

Patch

diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 43b8b6d7147b..3237961c7640 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -143,6 +143,10 @@  static int acpi_register_gsi_xen_pvh(struct device *dev, u32 gsi,
 	else if (rc)
 		printk(KERN_ERR "Failed to setup GSI :%u, err_code:%d\n", gsi, rc);
 
+	rc = xen_pvh_add_gsi_irq_map(gsi, irq);
+	if (rc == -EEXIST)
+		printk(KERN_INFO "Already map the GSI :%u and IRQ: %d\n", gsi, irq);
+
 	return irq;
 }
 
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 48dff0ed9acd..39a57fed2de3 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -967,6 +967,43 @@  int xen_irq_from_gsi(unsigned gsi)
 }
 EXPORT_SYMBOL_GPL(xen_irq_from_gsi);
 
+int xen_gsi_from_irq(unsigned irq)
+{
+	struct irq_info *info;
+
+	list_for_each_entry(info, &xen_irq_list_head, list) {
+		if (info->type != IRQT_PIRQ)
+			continue;
+
+		if (info->irq == irq)
+			return info->u.pirq.gsi;
+	}
+
+	return -1;
+}
+EXPORT_SYMBOL_GPL(xen_gsi_from_irq);
+
+int xen_pvh_add_gsi_irq_map(unsigned gsi, unsigned irq)
+{
+	int tmp_irq;
+	struct irq_info *info;
+
+	tmp_irq = xen_irq_from_gsi(gsi);
+	if (tmp_irq != -1)
+		return -EEXIST;
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (info == NULL)
+		panic("Unable to allocate metadata for GSI%d\n", gsi);
+
+	info->type = IRQT_PIRQ;
+	info->irq = irq;
+	info->u.pirq.gsi = gsi;
+	list_add_tail(&info->list, &xen_irq_list_head);
+
+	return 0;
+}
+
 static void __unbind_from_irq(unsigned int irq)
 {
 	evtchn_port_t evtchn = evtchn_from_irq(irq);
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index e88e8f6f0a33..830e84451731 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -37,6 +37,7 @@ 
 #include <xen/page.h>
 #include <xen/xen-ops.h>
 #include <xen/balloon.h>
+#include <xen/events.h>
 
 #include "privcmd.h"
 
@@ -833,6 +834,21 @@  static long privcmd_ioctl_mmap_resource(struct file *file,
 	return rc;
 }
 
+static long privcmd_ioctl_gsi_from_irq(struct file *file, void __user *udata)
+{
+	struct privcmd_gsi_from_irq kdata;
+
+	if (copy_from_user(&kdata, udata, sizeof(kdata)))
+		return -EFAULT;
+
+	kdata.gsi = xen_gsi_from_irq(kdata.irq);
+
+	if (copy_to_user(udata, &kdata, sizeof(kdata)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static long privcmd_ioctl(struct file *file,
 			  unsigned int cmd, unsigned long data)
 {
@@ -868,6 +884,10 @@  static long privcmd_ioctl(struct file *file,
 		ret = privcmd_ioctl_mmap_resource(file, udata);
 		break;
 
+	case IOCTL_PRIVCMD_GSI_FROM_IRQ:
+		ret = privcmd_ioctl_gsi_from_irq(file, udata);
+		break;
+
 	default:
 		break;
 	}
diff --git a/include/uapi/xen/privcmd.h b/include/uapi/xen/privcmd.h
index d2029556083e..55fe748bbfd7 100644
--- a/include/uapi/xen/privcmd.h
+++ b/include/uapi/xen/privcmd.h
@@ -98,6 +98,11 @@  struct privcmd_mmap_resource {
 	__u64 addr;
 };
 
+struct privcmd_gsi_from_irq {
+	__u32 irq;
+	__u32 gsi;
+};
+
 /*
  * @cmd: IOCTL_PRIVCMD_HYPERCALL
  * @arg: &privcmd_hypercall_t
@@ -125,5 +130,7 @@  struct privcmd_mmap_resource {
 	_IOC(_IOC_NONE, 'P', 6, sizeof(domid_t))
 #define IOCTL_PRIVCMD_MMAP_RESOURCE				\
 	_IOC(_IOC_NONE, 'P', 7, sizeof(struct privcmd_mmap_resource))
+#define IOCTL_PRIVCMD_GSI_FROM_IRQ				\
+	_IOC(_IOC_NONE, 'P', 8, sizeof(struct privcmd_gsi_from_irq))
 
 #endif /* __LINUX_PUBLIC_PRIVCMD_H__ */
diff --git a/include/xen/events.h b/include/xen/events.h
index 344081e71584..8377d8dfaa71 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -133,6 +133,11 @@  int xen_pirq_from_irq(unsigned irq);
 /* Return the irq allocated to the gsi */
 int xen_irq_from_gsi(unsigned gsi);
 
+/* Return the gsi from irq */
+int xen_gsi_from_irq(unsigned irq);
+
+int xen_pvh_add_gsi_irq_map(unsigned gsi, unsigned irq);
+
 /* Determine whether to ignore this IRQ if it is passed to a guest. */
 int xen_test_irq_shared(int irq);