[RFC XEN PATCH v15 3/4] tools: Add new function to get gsi from dev

[Jiqian Chen <Jiqian.Chen@xxxxxxx>]

On PVH dom0, when passthrough a device to domU, QEMU and xl tools
want to use gsi number to do pirq mapping, see QEMU code
xen_pt_realize->xc_physdev_map_pirq, and xl code
pci_add_dm_done->xc_physdev_map_pirq, but in current codes, the gsi
number is got from file /sys/bus/pci/devices/<sbdf>/irq, that is
wrong, because irq is not equal with gsi, they are in different
spaces, so pirq mapping fails.

And in current codes, there is no method to get gsi for userspace.
For above purpose, add new function to get gsi, and the
corresponding ioctl is implemented on linux kernel side.

Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
Signed-off-by: Huang Rui <ray.huang@xxxxxxx>
Signed-off-by: Chen Jiqian <Jiqian.Chen@xxxxxxx>
Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
RFC: it needs to wait for the corresponding third patch on linux kernel side to 
be merged.
https://lore.kernel.org/xen-devel/20240607075109.126277-4-Jiqian.Chen@xxxxxxx/
---
v13->v15 changes:
Add "Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>"

v12->v13 changes:
Rename the function xc_physdev_gsi_from_pcidev to xc_pcidev_get_gsi to avoid 
confusion with physdev namesapce.
Move the implementation of xc_pcidev_get_gsi into xc_linux.c.
Directly use xencall_fd(xch->xcall) in the function xc_pcidev_get_gsi instead 
of opening "privcmd".

v11->v12 changes:
Nothing.

v10->v11 changes:
Patch#4 of v10, directly open "/dev/xen/privcmd" in the function 
xc_physdev_gsi_from_dev instead of adding unnecessary functions to libxencall.
Change the type of gsi in the structure privcmd_gsi_from_dev from int to u32.

v9->v10 changes:
Extract the implementation of xc_physdev_gsi_from_dev to be a new patch.
---
 tools/include/xen-sys/Linux/privcmd.h |  7 +++++++
 tools/include/xenctrl.h               |  2 ++
 tools/libs/ctrl/xc_freebsd.c          |  6 ++++++
 tools/libs/ctrl/xc_linux.c            | 20 ++++++++++++++++++++
 tools/libs/ctrl/xc_minios.c           |  6 ++++++
 tools/libs/ctrl/xc_netbsd.c           |  6 ++++++
 tools/libs/ctrl/xc_solaris.c          |  6 ++++++
 7 files changed, 53 insertions(+)

diff --git a/tools/include/xen-sys/Linux/privcmd.h 
b/tools/include/xen-sys/Linux/privcmd.h
index bc60e8fd55eb..607dfa2287bc 100644
--- a/tools/include/xen-sys/Linux/privcmd.h
+++ b/tools/include/xen-sys/Linux/privcmd.h
@@ -95,6 +95,11 @@ typedef struct privcmd_mmap_resource {
        __u64 addr;
 } privcmd_mmap_resource_t;
 
+typedef struct privcmd_pcidev_get_gsi {
+       __u32 sbdf;
+       __u32 gsi;
+} privcmd_pcidev_get_gsi_t;
+
 /*
  * @cmd: IOCTL_PRIVCMD_HYPERCALL
  * @arg: &privcmd_hypercall_t
@@ -114,6 +119,8 @@ typedef struct privcmd_mmap_resource {
        _IOC(_IOC_NONE, 'P', 6, sizeof(domid_t))
 #define IOCTL_PRIVCMD_MMAP_RESOURCE                            \
        _IOC(_IOC_NONE, 'P', 7, sizeof(privcmd_mmap_resource_t))
+#define IOCTL_PRIVCMD_PCIDEV_GET_GSI                   \
+       _IOC(_IOC_NONE, 'P', 10, sizeof(privcmd_pcidev_get_gsi_t))
 #define IOCTL_PRIVCMD_UNIMPLEMENTED                            \
        _IOC(_IOC_NONE, 'P', 0xFF, 0)
 
diff --git a/tools/include/xenctrl.h b/tools/include/xenctrl.h
index 2c4608c09ab0..924f9a35f790 100644
--- a/tools/include/xenctrl.h
+++ b/tools/include/xenctrl.h
@@ -1642,6 +1642,8 @@ int xc_physdev_unmap_pirq(xc_interface *xch,
                           uint32_t domid,
                           int pirq);
 
+int xc_pcidev_get_gsi(xc_interface *xch, uint32_t sbdf);
+
 /*
  *  LOGGING AND ERROR REPORTING
  */
diff --git a/tools/libs/ctrl/xc_freebsd.c b/tools/libs/ctrl/xc_freebsd.c
index 9dd48a3a08bb..9019fc663361 100644
--- a/tools/libs/ctrl/xc_freebsd.c
+++ b/tools/libs/ctrl/xc_freebsd.c
@@ -60,6 +60,12 @@ void *xc_memalign(xc_interface *xch, size_t alignment, 
size_t size)
     return ptr;
 }
 
+int xc_pcidev_get_gsi(xc_interface *xch, uint32_t sbdf)
+{
+    errno = ENOSYS;
+    return -1;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libs/ctrl/xc_linux.c b/tools/libs/ctrl/xc_linux.c
index c67c71c08be3..92591e49a1c8 100644
--- a/tools/libs/ctrl/xc_linux.c
+++ b/tools/libs/ctrl/xc_linux.c
@@ -66,6 +66,26 @@ void *xc_memalign(xc_interface *xch, size_t alignment, 
size_t size)
     return ptr;
 }
 
+int xc_pcidev_get_gsi(xc_interface *xch, uint32_t sbdf)
+{
+    int ret;
+    privcmd_pcidev_get_gsi_t dev_gsi = {
+        .sbdf = sbdf,
+        .gsi = 0,
+    };
+
+    ret = ioctl(xencall_fd(xch->xcall),
+                IOCTL_PRIVCMD_PCIDEV_GET_GSI, &dev_gsi);
+
+    if (ret < 0) {
+        PERROR("Failed to get gsi from dev");
+    } else {
+        ret = dev_gsi.gsi;
+    }
+
+    return ret;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libs/ctrl/xc_minios.c b/tools/libs/ctrl/xc_minios.c
index 3dea7a78a576..462af827b33c 100644
--- a/tools/libs/ctrl/xc_minios.c
+++ b/tools/libs/ctrl/xc_minios.c
@@ -47,6 +47,12 @@ void *xc_memalign(xc_interface *xch, size_t alignment, 
size_t size)
     return memalign(alignment, size);
 }
 
+int xc_pcidev_get_gsi(xc_interface *xch, uint32_t sbdf)
+{
+    errno = ENOSYS;
+    return -1;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libs/ctrl/xc_netbsd.c b/tools/libs/ctrl/xc_netbsd.c
index 31979937621e..1318d4d90608 100644
--- a/tools/libs/ctrl/xc_netbsd.c
+++ b/tools/libs/ctrl/xc_netbsd.c
@@ -63,6 +63,12 @@ void *xc_memalign(xc_interface *xch, size_t alignment, 
size_t size)
     return valloc(size);
 }
 
+int xc_pcidev_get_gsi(xc_interface *xch, uint32_t sbdf)
+{
+    errno = ENOSYS;
+    return -1;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libs/ctrl/xc_solaris.c b/tools/libs/ctrl/xc_solaris.c
index 5128f3f0f490..049e28d55ccd 100644
--- a/tools/libs/ctrl/xc_solaris.c
+++ b/tools/libs/ctrl/xc_solaris.c
@@ -32,6 +32,12 @@ void *xc_memalign(xc_interface *xch, size_t alignment, 
size_t size)
     return memalign(alignment, size);
 }
 
+int xc_pcidev_get_gsi(xc_interface *xch, uint32_t sbdf)
+{
+    errno = ENOSYS;
+    return -1;
+}
+
 /*
  * Local variables:
  * mode: C
-- 
2.34.1