In PVH dom0, when passthrough a device to domU, QEMU code
xen_pt_realize->xc_physdev_map_pirq wants to use gsi, 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.
To solve above problem, use new interface of Xen, xc_pcidev_get_gsi to get
gsi and use xc_physdev_map_pirq_gsi to map pirq when dom0 is PVH.
Signed-off-by: Jiqian Chen <jiqian.c...@amd.com>
Signed-off-by: Huang Rui <ray.hu...@amd.com>
Signed-off-by: Jiqian Chen <jiqian.c...@amd.com>
---
Hi All,
This is v8 to support passthrough on Xen when dom0 is PVH.
v7->v8 change:
* Since xc_physdev_gsi_from_dev was renamed to xc_pcidev_get_gsi, changed it.
* Added xen_run_qemu_on_hvm to check if Qemu run on PV dom0, if not use
xc_physdev_map_pirq_gsi to map pirq.
* Used CONFIG_XEN_CTRL_INTERFACE_VERSION to wrap the new part for compatibility.
* Added "#define DOMID_RUN_QEMU 0" to represent the id of domain that Qemu run
on.
Best regards,
Jiqian Chen
v6->v7 changes:
* Because the function of obtaining gsi was changed on the kernel and Xen side.
Changed to use
xc_physdev_gsi_from_dev, that requires passing in sbdf instead of irq.
v5->v6 changes:
* Because the function of obtaining gsi was changed on the kernel and Xen side.
Changed to use
xc_physdev_gsi_from_irq, instead of gsi sysfs.
* Since function changed, removed the Review-by of Stefano.
v4->v5 changes:
* Added Review-by Stefano.
v3->v4 changes:
* Added gsi into struct XenHostPCIDevice and used gsi number that read from gsi
sysfs
if it exists, if there is no gsi sysfs, still use irq.
v2->v3 changes:
* Due to changes in the implementation of the second patch on kernel side(that
adds
a new sysfs for gsi instead of a new syscall), so read gsi number from the
sysfs of gsi.
v1 and v2:
We can record the relation between gsi and irq, then when userspace(qemu) want
to use gsi, we can do a translation. The third patch of kernel(xen/privcmd: Add
new syscall
to get gsi from irq) records all the relations in acpi_register_gsi_xen_pvh()
when dom0
initialize pci devices, and provide a syscall for userspace to get the gsi from
irq. The
third patch of xen(tools: Add new function to get gsi from irq) add a new
function
xc_physdev_gsi_from_irq() to call the new syscall added on kernel side.
And then userspace can use that function to get gsi. Then xc_physdev_map_pirq()
will success.
Issues we encountered:
1. failed to map pirq for gsi
Problem: qemu will call xc_physdev_map_pirq() to map a passthrough device's gsi
to pirq in
function xen_pt_realize(). But failed.
Reason: According to the implement of xc_physdev_map_pirq(), it needs gsi
instead of irq,
but qemu pass irq to it and treat irq as gsi, it is got from file
/sys/bus/pci/devices/xxxx:xx:xx.x/irq in function xen_host_pci_device_get().
But actually
the gsi number is not equal with irq. They are in different space.
---
hw/xen/xen_pt.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
hw/xen/xen_pt.h | 1 +
2 files changed, 45 insertions(+)
diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
index 3635d1b39f79..7f8139d20915 100644
--- a/hw/xen/xen_pt.c
+++ b/hw/xen/xen_pt.c
@@ -766,6 +766,41 @@ static void xen_pt_destroy(PCIDevice *d) {
}
/* init */
+#define PCI_SBDF(seg, bus, dev, func) \
+ ((((uint32_t)(seg)) << 16) | \
+ (PCI_BUILD_BDF(bus, PCI_DEVFN(dev, func))))
+
+#if CONFIG_XEN_CTRL_INTERFACE_VERSION >= 42000
+static bool xen_run_qemu_on_hvm(void)
+{
+ xc_domaininfo_t info;
+
+ if (!xc_domain_getinfo_single(xen_xc, DOMID_RUN_QEMU, &info) &&
+ (info.flags & XEN_DOMINF_hvm_guest)) {
+ return true;
+ }
+
+ return false;
+}
+
+static int xen_map_pirq_for_gsi(PCIDevice *d, int *pirq)
+{
+ int gsi;
+ XenPCIPassthroughState *s = XEN_PT_DEVICE(d);
+
+ gsi = xc_pcidev_get_gsi(xen_xc,
+ PCI_SBDF(s->real_device.domain,
+ s->real_device.bus,
+ s->real_device.dev,
+ s->real_device.func));
+ if (gsi >= 0) {
+ return xc_physdev_map_pirq_gsi(xen_xc, xen_domid, gsi, pirq);
+ }
+
+ return gsi;
+}
+#endif
+
static void xen_pt_realize(PCIDevice *d, Error **errp)
{
ERRP_GUARD();
@@ -847,7 +882,16 @@ static void xen_pt_realize(PCIDevice *d, Error **errp)
goto out;
}
+#if CONFIG_XEN_CTRL_INTERFACE_VERSION >= 42000
+ if (xen_run_qemu_on_hvm()) {
+ rc = xen_map_pirq_for_gsi(d, &pirq);
+ } else {
+ rc = xc_physdev_map_pirq(xen_xc, xen_domid, machine_irq, &pirq);
+ }
+#else
rc = xc_physdev_map_pirq(xen_xc, xen_domid, machine_irq, &pirq);
+#endif
+
if (rc < 0) {
XEN_PT_ERR(d, "Mapping machine irq %u to pirq %i failed, (err: %d)\n",
machine_irq, pirq, errno);
diff --git a/hw/xen/xen_pt.h b/hw/xen/xen_pt.h
index 095a0f0365d4..a08b45b7fbae 100644
--- a/hw/xen/xen_pt.h
+++ b/hw/xen/xen_pt.h
@@ -36,6 +36,7 @@ void xen_pt_log(const PCIDevice *d, const char *f, ...)
G_GNUC_PRINTF(2, 3);
# define XEN_PT_LOG_CONFIG(d, addr, val, len)
#endif
+#define DOMID_RUN_QEMU 0
/* Helper */
#define XEN_PFN(x) ((x) >> XC_PAGE_SHIFT)
--
2.34.1
