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qemu-kvm/SOURCES/kvm-vfio-pci-Make-vfio-cdev-pre-openable-by-passing-a-fi.patch

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From 965a44793806fef2094906947bd3b428638bf89a Mon Sep 17 00:00:00 2001
From: Zhenzhong Duan <zhenzhong.duan@intel.com>
Date: Tue, 21 Nov 2023 16:44:10 +0800
Subject: [PATCH 031/101] vfio/pci: Make vfio cdev pre-openable by passing a
file handle
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
RH-Author: Eric Auger <eric.auger@redhat.com>
RH-MergeRequest: 211: IOMMUFD backend backport
RH-Jira: RHEL-19302 RHEL-21057
RH-Acked-by: Cédric Le Goater <clg@redhat.com>
RH-Acked-by: Sebastian Ott <sebott@redhat.com>
RH-Commit: [30/67] a14b824b700e8fb36633cd159bcc422d992a316f (eauger1/centos-qemu-kvm)
Conflicts: contextual conflict in hw/vfio/pci.c due to
RHEL-only f73562144e492 vfio: cap number of devices that can be assigned
This gives management tools like libvirt a chance to open the vfio
cdev with privilege and pass FD to qemu. This way qemu never needs
to have privilege to open a VFIO or iommu cdev node.
Together with the earlier support of pre-opening /dev/iommu device,
now we have full support of passing a vfio device to unprivileged
qemu by management tool. This mode is no more considered for the
legacy backend. So let's remove the "TODO" comment.
Add helper functions vfio_device_set_fd() and vfio_device_get_name()
to set fd and get device name, they will also be used by other vfio
devices.
There is no easy way to check if a device is mdev with FD passing,
so fail the x-balloon-allowed check unconditionally in this case.
There is also no easy way to get BDF as name with FD passing, so
we fake a name by VFIO_FD[fd].
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
(cherry picked from commit da3e04b26fd8d15b344944504d5ffa9c5f20b54b)
Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
hw/vfio/helpers.c | 43 +++++++++++++++++++++++++++++++++++
hw/vfio/iommufd.c | 12 ++++++----
hw/vfio/pci.c | 28 +++++++++++++----------
include/hw/vfio/vfio-common.h | 4 ++++
4 files changed, 71 insertions(+), 16 deletions(-)
diff --git a/hw/vfio/helpers.c b/hw/vfio/helpers.c
index 168847e7c5..3592c3d54e 100644
--- a/hw/vfio/helpers.c
+++ b/hw/vfio/helpers.c
@@ -27,6 +27,7 @@
#include "trace.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
+#include "monitor/monitor.h"
/*
* Common VFIO interrupt disable
@@ -609,3 +610,45 @@ bool vfio_has_region_cap(VFIODevice *vbasedev, int region, uint16_t cap_type)
return ret;
}
+
+int vfio_device_get_name(VFIODevice *vbasedev, Error **errp)
+{
+ struct stat st;
+
+ if (vbasedev->fd < 0) {
+ if (stat(vbasedev->sysfsdev, &st) < 0) {
+ error_setg_errno(errp, errno, "no such host device");
+ error_prepend(errp, VFIO_MSG_PREFIX, vbasedev->sysfsdev);
+ return -errno;
+ }
+ /* User may specify a name, e.g: VFIO platform device */
+ if (!vbasedev->name) {
+ vbasedev->name = g_path_get_basename(vbasedev->sysfsdev);
+ }
+ } else {
+ if (!vbasedev->iommufd) {
+ error_setg(errp, "Use FD passing only with iommufd backend");
+ return -EINVAL;
+ }
+ /*
+ * Give a name with fd so any function printing out vbasedev->name
+ * will not break.
+ */
+ if (!vbasedev->name) {
+ vbasedev->name = g_strdup_printf("VFIO_FD%d", vbasedev->fd);
+ }
+ }
+
+ return 0;
+}
+
+void vfio_device_set_fd(VFIODevice *vbasedev, const char *str, Error **errp)
+{
+ int fd = monitor_fd_param(monitor_cur(), str, errp);
+
+ if (fd < 0) {
+ error_prepend(errp, "Could not parse remote object fd %s:", str);
+ return;
+ }
+ vbasedev->fd = fd;
+}
diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index 6e53e013ef..5accd26484 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -320,11 +320,15 @@ static int iommufd_cdev_attach(const char *name, VFIODevice *vbasedev,
uint32_t ioas_id;
Error *err = NULL;
- devfd = iommufd_cdev_getfd(vbasedev->sysfsdev, errp);
- if (devfd < 0) {
- return devfd;
+ if (vbasedev->fd < 0) {
+ devfd = iommufd_cdev_getfd(vbasedev->sysfsdev, errp);
+ if (devfd < 0) {
+ return devfd;
+ }
+ vbasedev->fd = devfd;
+ } else {
+ devfd = vbasedev->fd;
}
- vbasedev->fd = devfd;
ret = iommufd_cdev_connect_and_bind(vbasedev, errp);
if (ret) {
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 39e6a6678e..3412a63bb1 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2949,7 +2949,6 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
VFIOGroup *group;
char *tmp, *subsys;
Error *err = NULL;
- struct stat st;
int ret, i = 0;
bool is_mdev;
char uuid[UUID_STR_LEN];
@@ -2976,11 +2975,14 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
return;
}
- if (!vbasedev->sysfsdev) {
+ if (vbasedev->fd < 0 && !vbasedev->sysfsdev) {
if (!(~vdev->host.domain || ~vdev->host.bus ||
~vdev->host.slot || ~vdev->host.function)) {
error_setg(errp, "No provided host device");
error_append_hint(errp, "Use -device vfio-pci,host=DDDD:BB:DD.F "
+#ifdef CONFIG_IOMMUFD
+ "or -device vfio-pci,fd=DEVICE_FD "
+#endif
"or -device vfio-pci,sysfsdev=PATH_TO_DEVICE\n");
return;
}
@@ -2990,13 +2992,9 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
vdev->host.slot, vdev->host.function);
}
- if (stat(vbasedev->sysfsdev, &st) < 0) {
- error_setg_errno(errp, errno, "no such host device");
- error_prepend(errp, VFIO_MSG_PREFIX, vbasedev->sysfsdev);
+ if (vfio_device_get_name(vbasedev, errp) < 0) {
return;
}
-
- vbasedev->name = g_path_get_basename(vbasedev->sysfsdev);
vbasedev->ops = &vfio_pci_ops;
vbasedev->type = VFIO_DEVICE_TYPE_PCI;
vbasedev->dev = DEVICE(vdev);
@@ -3356,6 +3354,7 @@ static void vfio_instance_init(Object *obj)
vdev->host.bus = ~0U;
vdev->host.slot = ~0U;
vdev->host.function = ~0U;
+ vdev->vbasedev.fd = -1;
vdev->nv_gpudirect_clique = 0xFF;
@@ -3412,11 +3411,6 @@ static Property vfio_pci_dev_properties[] = {
qdev_prop_nv_gpudirect_clique, uint8_t),
DEFINE_PROP_OFF_AUTO_PCIBAR("x-msix-relocation", VFIOPCIDevice, msix_relo,
OFF_AUTOPCIBAR_OFF),
- /*
- * TODO - support passed fds... is this necessary?
- * DEFINE_PROP_STRING("vfiofd", VFIOPCIDevice, vfiofd_name),
- * DEFINE_PROP_STRING("vfiogroupfd, VFIOPCIDevice, vfiogroupfd_name),
- */
#ifdef CONFIG_IOMMUFD
DEFINE_PROP_LINK("iommufd", VFIOPCIDevice, vbasedev.iommufd,
TYPE_IOMMUFD_BACKEND, IOMMUFDBackend *),
@@ -3424,6 +3418,13 @@ static Property vfio_pci_dev_properties[] = {
DEFINE_PROP_END_OF_LIST(),
};
+#ifdef CONFIG_IOMMUFD
+static void vfio_pci_set_fd(Object *obj, const char *str, Error **errp)
+{
+ vfio_device_set_fd(&VFIO_PCI(obj)->vbasedev, str, errp);
+}
+#endif
+
static void vfio_pci_dev_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
@@ -3431,6 +3432,9 @@ static void vfio_pci_dev_class_init(ObjectClass *klass, void *data)
dc->reset = vfio_pci_reset;
device_class_set_props(dc, vfio_pci_dev_properties);
+#ifdef CONFIG_IOMMUFD
+ object_class_property_add_str(klass, "fd", NULL, vfio_pci_set_fd);
+#endif
dc->desc = "VFIO-based PCI device assignment";
set_bit(DEVICE_CATEGORY_MISC, dc->categories);
pdc->realize = vfio_realize;
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 3dac5c167e..697bf24a35 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -251,4 +251,8 @@ int vfio_devices_query_dirty_bitmap(VFIOContainerBase *bcontainer,
hwaddr size);
int vfio_get_dirty_bitmap(VFIOContainerBase *bcontainer, uint64_t iova,
uint64_t size, ram_addr_t ram_addr);
+
+/* Returns 0 on success, or a negative errno. */
+int vfio_device_get_name(VFIODevice *vbasedev, Error **errp);
+void vfio_device_set_fd(VFIODevice *vbasedev, const char *str, Error **errp);
#endif /* HW_VFIO_VFIO_COMMON_H */
--
2.39.3
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