From be42017f858b8227a7a2569eb80adbcb79342145 Mon Sep 17 00:00:00 2001

Message-Id: <be42017f858b8227a7a2569eb80adbcb79342145.1382534060.git.jdenemar@redhat.com>

From: Peter Krempa <pkrempa@redhat.com>

Date: Thu, 10 Oct 2013 13:56:37 +0200

Subject: [PATCH] qemu: Prefer VFIO for PCI device passthrough

https://bugzilla.redhat.com/show_bug.cgi?id=1001738

Prefer using VFIO (if available) to the legacy KVM device passthrough.

With this patch a PCI passthrough device without the driver configured

will be started with VFIO if it's available on the host. If not legacy

KVM passthrough is checked and error is reported if it's not available.

(cherry picked from commit f094aaac48a6bbeef87a4df0345dfe2964297298)

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>

---

 docs/formatdomain.html.in |  9 ++++-----

 src/conf/domain_conf.h    |  2 +-

 src/libvirt_private.syms  |  1 +

 src/qemu/qemu_command.c   | 12 +++++++-----

 src/qemu/qemu_hostdev.c   | 30 +++++++++++++++++++++++++-----

 src/qemu/qemu_hostdev.h   |  4 +++-

 src/qemu/qemu_hotplug.c   |  2 +-

 src/qemu/qemu_process.c   | 15 ++++++++-------

 tests/qemuxml2argvtest.c  | 11 +++++++++++

 9 files changed, 61 insertions(+), 25 deletions(-)

diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in

index 4fecdee..512e0df 100644

--- a/docs/formatdomain.html.in

+++ b/docs/formatdomain.html.in

@@ -2704,11 +2704,10 @@

         backend, which is compatible with UEFI SecureBoot) or "kvm"

         (for the legacy device assignment handled directly by the KVM

         kernel module)Since 1.0.5 (QEMU and KVM

-        only, requires kernel 3.6 or newer). Currently, "kvm"

-        is the default used by libvirt when not explicitly provided,

-        but since the two are functionally equivalent, this default

-        could be changed in the future with no impact to domains that

-        don't specify anything.

+        only, requires kernel 3.6 or newer). The default, when

+        the driver name is not explicitly specified, is to check wether

+        VFIO is available and use it if it's the case. If VFIO is not

+        available, the legacy "kvm" assignment is attempted.

       
readonly

       
Indicates that the device is readonly, only supported by SCSI host

diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h

index 5a21576..5ad0318 100644

--- a/src/conf/domain_conf.h

+++ b/src/conf/domain_conf.h

@@ -398,7 +398,7 @@ enum virDomainHostdevSubsysType {

 /* the backend driver used for PCI hostdev devices */

 typedef enum {

-    VIR_DOMAIN_HOSTDEV_PCI_BACKEND_DEFAULT, /* currently kvm, could change */

+    VIR_DOMAIN_HOSTDEV_PCI_BACKEND_DEFAULT, /* detect automaticaly, prefer VFIO */

     VIR_DOMAIN_HOSTDEV_PCI_BACKEND_KVM,    /* force legacy kvm style */

     VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO,   /* force vfio */

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms

index 5e4de67..9a00dfe 100644

--- a/src/libvirt_private.syms

+++ b/src/libvirt_private.syms

@@ -261,6 +261,7 @@ virDomainHostdevFind;

 virDomainHostdevInsert;

 virDomainHostdevModeTypeToString;

 virDomainHostdevRemove;

+virDomainHostdevSubsysPciBackendTypeToString;

 virDomainHostdevSubsysTypeToString;

 virDomainHubTypeFromString;

 virDomainHubTypeToString;

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c

index 9c9b956..78f07c8 100644

--- a/src/qemu/qemu_command.c

+++ b/src/qemu/qemu_command.c

@@ -5347,10 +5347,10 @@ qemuBuildPCIHostdevDevStr(virDomainDefPtr def,

                           virQEMUCapsPtr qemuCaps)

 {

     virBuffer buf = VIR_BUFFER_INITIALIZER;

+    int backend = dev->source.subsys.u.pci.backend;

-    switch ((virDomainHostdevSubsysPciBackendType)

-            dev->source.subsys.u.pci.backend) {

-    case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_DEFAULT:

+    /* caller has to assign proper passthrough backend type */

+    switch ((virDomainHostdevSubsysPciBackendType) backend) {

     case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_KVM:

         virBufferAddLit(&buf, "pci-assign");

         if (configfd && *configfd)

@@ -5361,9 +5361,11 @@ qemuBuildPCIHostdevDevStr(virDomainDefPtr def,

         virBufferAddLit(&buf, "vfio-pci");

         break;

+    case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_DEFAULT:

     case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_TYPE_LAST:

-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",

-                       _("PCI passhthrough type needs to be specified"));

+        virReportError(VIR_ERR_INTERNAL_ERROR,

+                       _("invalid PCI passthrough type '%s'"),

+                       virDomainHostdevSubsysPciBackendTypeToString(backend));

         break;

     }

diff --git a/src/qemu/qemu_hostdev.c b/src/qemu/qemu_hostdev.c

index 7f3170d..81e0e88 100644

--- a/src/qemu/qemu_hostdev.c

+++ b/src/qemu/qemu_hostdev.c

@@ -564,7 +564,8 @@ qemuHostdevHostSupportsPassthroughLegacy(void)

 static bool

 qemuPrepareHostdevPCICheckSupport(virDomainHostdevDefPtr *hostdevs,

-                                  size_t nhostdevs)

+                                  size_t nhostdevs,

+                                  virQEMUCapsPtr qemuCaps)

 {

     bool supportsPassthroughKVM = qemuHostdevHostSupportsPassthroughLegacy();

     bool supportsPassthroughVFIO = qemuHostdevHostSupportsPassthroughVFIO();

@@ -581,6 +582,23 @@ qemuPrepareHostdevPCICheckSupport(virDomainHostdevDefPtr *hostdevs,

             continue;

         switch ((virDomainHostdevSubsysPciBackendType) *backend) {

+        case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_DEFAULT:

+            if (supportsPassthroughVFIO &&

+                virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_VFIO_PCI)) {

+                *backend = VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO;

+            } else if (supportsPassthroughKVM &&

+                       (virQEMUCapsGet(qemuCaps, QEMU_CAPS_PCIDEVICE) ||

+                        virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE))) {

+                *backend = VIR_DOMAIN_HOSTDEV_PCI_BACKEND_KVM;

+            } else {

+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",

+                               _("host doesn't support passthrough of "

+                                 "host PCI devices"));

+                return false;

+            }

+

+            break;

+

         case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO:

             if (!supportsPassthroughVFIO) {

                 virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",

@@ -589,7 +607,6 @@ qemuPrepareHostdevPCICheckSupport(virDomainHostdevDefPtr *hostdevs,

             }

             break;

-        case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_DEFAULT:

         case VIR_DOMAIN_HOSTDEV_PCI_BACKEND_KVM:

             if (!supportsPassthroughKVM) {

                 virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",

@@ -613,7 +630,8 @@ qemuPrepareHostdevPCIDevices(virQEMUDriverPtr driver,

                              const char *name,

                              const unsigned char *uuid,

                              virDomainHostdevDefPtr *hostdevs,

-                             int nhostdevs)

+                             int nhostdevs,

+                             virQEMUCapsPtr qemuCaps)

 {

     virPCIDeviceListPtr pcidevs;

     int last_processed_hostdev_vf = -1;

@@ -621,7 +639,7 @@ qemuPrepareHostdevPCIDevices(virQEMUDriverPtr driver,

     int ret = -1;

     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);

-    if (!qemuPrepareHostdevPCICheckSupport(hostdevs, nhostdevs))

+    if (!qemuPrepareHostdevPCICheckSupport(hostdevs, nhostdevs, qemuCaps))

         goto cleanup;

     virObjectLock(driver->activePciHostdevs);

@@ -1142,13 +1160,15 @@ cleanup:

 int

 qemuPrepareHostDevices(virQEMUDriverPtr driver,

                        virDomainDefPtr def,

+                       virQEMUCapsPtr qemuCaps,

                        bool coldBoot)

 {

     if (!def->nhostdevs)

         return 0;

     if (qemuPrepareHostdevPCIDevices(driver, def->name, def->uuid,

-                                     def->hostdevs, def->nhostdevs) < 0)

+                                     def->hostdevs, def->nhostdevs,

+                                     qemuCaps) < 0)

         return -1;

     if (qemuPrepareHostUSBDevices(driver, def, coldBoot) < 0)

diff --git a/src/qemu/qemu_hostdev.h b/src/qemu/qemu_hostdev.h

index 327d4d5..272086e 100644

--- a/src/qemu/qemu_hostdev.h

+++ b/src/qemu/qemu_hostdev.h

@@ -37,7 +37,8 @@ int qemuPrepareHostdevPCIDevices(virQEMUDriverPtr driver,

                                  const char *name,

                                  const unsigned char *uuid,

                                  virDomainHostdevDefPtr *hostdevs,

-                                 int nhostdevs);

+                                 int nhostdevs,

+                                 virQEMUCapsPtr qemuCaps);

 int qemuFindHostdevUSBDevice(virDomainHostdevDefPtr hostdev,

                              bool mandatory,

                              virUSBDevicePtr *usb);

@@ -50,6 +51,7 @@ int qemuPrepareHostdevSCSIDevices(virQEMUDriverPtr driver,

                                   int nhostdevs);

 int qemuPrepareHostDevices(virQEMUDriverPtr driver,

                            virDomainDefPtr def,

+                           virQEMUCapsPtr qemuCaps,

                            bool coldBoot);

 void qemuDomainReAttachHostScsiDevices(virQEMUDriverPtr driver,

                                        const char *name,

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c

index 0c42b0a..cdbafa7 100644

--- a/src/qemu/qemu_hotplug.c

+++ b/src/qemu/qemu_hotplug.c

@@ -1018,7 +1018,7 @@ int qemuDomainAttachHostPciDevice(virQEMUDriverPtr driver,

         return -1;

     if (qemuPrepareHostdevPCIDevices(driver, vm->def->name, vm->def->uuid,

-                                     &hostdev, 1) < 0)

+                                     &hostdev, 1, priv->qemuCaps) < 0)

         return -1;

     switch ((virDomainHostdevSubsysPciBackendType) backend) {

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c

index f979877..b9f291d 100644

--- a/src/qemu/qemu_process.c

+++ b/src/qemu/qemu_process.c

@@ -3540,6 +3540,12 @@ int qemuProcessStart(virConnectPtr conn,

             goto cleanup;

     }

+    VIR_DEBUG("Determining emulator version");

+    virObjectUnref(priv->qemuCaps);

+    if (!(priv->qemuCaps = virQEMUCapsCacheLookupCopy(driver->qemuCapsCache,

+                                                      vm->def->emulator)))

+        goto cleanup;

+

     /* network devices must be "prepared" before hostdevs, because

      * setting up a network device might create a new hostdev that

      * will need to be setup.

@@ -3550,7 +3556,8 @@ int qemuProcessStart(virConnectPtr conn,

     /* Must be run before security labelling */

     VIR_DEBUG("Preparing host devices");

-    if (qemuPrepareHostDevices(driver, vm->def, !migrateFrom) < 0)

+    if (qemuPrepareHostDevices(driver, vm->def, priv->qemuCaps,

+                               !migrateFrom) < 0)

         goto cleanup;

     VIR_DEBUG("Preparing chr devices");

@@ -3632,12 +3639,6 @@ int qemuProcessStart(virConnectPtr conn,

         }

     }

-    VIR_DEBUG("Determining emulator version");

-    virObjectUnref(priv->qemuCaps);

-    if (!(priv->qemuCaps = virQEMUCapsCacheLookupCopy(driver->qemuCapsCache,

-                                                      vm->def->emulator)))

-        goto cleanup;

-

     if (!qemuValidateCpuMax(vm->def, priv->qemuCaps))

         goto cleanup;

diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c

index 23ea2ee..1d964ce 100644

--- a/tests/qemuxml2argvtest.c

+++ b/tests/qemuxml2argvtest.c

@@ -98,6 +98,7 @@ static int testCompareXMLToArgvFiles(const char *xml,

     virConnectPtr conn;

     char *log = NULL;

     virCommandPtr cmd = NULL;

+    size_t i;

     if (!(conn = virGetConnect()))

         goto out;

@@ -154,6 +155,16 @@ static int testCompareXMLToArgvFiles(const char *xml,

     if (qemuAssignDeviceAliases(vmdef, extraFlags) < 0)

         goto out;

+    for (i = 0; i < vmdef->nhostdevs; i++) {

+        virDomainHostdevDefPtr hostdev = vmdef->hostdevs[i];

+

+        if (hostdev->mode == VIR_DOMAIN_HOSTDEV_MODE_SUBSYS &&

+            hostdev->source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI &&

+            hostdev->source.subsys.u.pci.backend == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_DEFAULT) {

+            hostdev->source.subsys.u.pci.backend = VIR_DOMAIN_HOSTDEV_PCI_BACKEND_KVM;

+        }

+    }

+

     if (!(cmd = qemuBuildCommandLine(conn, &driver, vmdef, &monitor_chr,

                                      (flags & FLAG_JSON), extraFlags,

                                      migrateFrom, migrateFd, NULL,

-- 

1.8.4