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Pass pre-opened PCI device sysfs config file to QEMU

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This allows libvirt to open the PCI device sysfs config file prior
to dropping privileges so qemu can access the full config space.
Without this, a de-privileged qemu can only access the first 64
bytes of config space.

* src/qemu/qemu_conf.c, src/qemu/qemu_conf.h: Detect support
  for pci-assign.configfd option. Use this option when formatting
  PCI device string if possible
* src/qemu/qemu_driver.c: Pre-open PCI sysfs config file and pass
  to QEMU
This commit is contained in:
Alex Williamson 2010-05-26 13:32:38 +01:00 committed by Daniel P. Berrange
parent 7f44743c52
commit c444af1ac2
3 changed files with 134 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

98
src/qemu/qemu_conf.c
View File

@ -1354,6 +1354,48 @@ fail:
return -1;
}
static void qemudParsePCIDeviceStrs(const char *qemu, unsigned long long *flags)
{
const char *const qemuarg[] = { qemu, "-device", "pci-assign,?", NULL };
const char *const qemuenv[] = { "LC_ALL=C", NULL };
pid_t child;
int status;
int newstderr = -1;
if (virExec(qemuarg, qemuenv, NULL,
&child, -1, NULL, &newstderr, VIR_EXEC_CLEAR_CAPS) < 0)
return;
char *pciassign = NULL;
enum { MAX_PCI_OUTPUT_SIZE = 1024*4 };
int len = virFileReadLimFD(newstderr, MAX_PCI_OUTPUT_SIZE, &pciassign);
if (len < 0) {
virReportSystemError(errno,
_("Unable to read %s pci-assign device output"),
qemu);
goto cleanup;
}
if (strstr(pciassign, "pci-assign.configfd"))
*flags |= QEMUD_CMD_FLAG_PCI_CONFIGFD;
cleanup:
VIR_FREE(pciassign);
close(newstderr);
rewait:
if (waitpid(child, &status, 0) != child) {
if (errno == EINTR)
goto rewait;
VIR_ERROR(_("Unexpected exit status from qemu %d pid %lu"),
WEXITSTATUS(status), (unsigned long)child);
}
if (WEXITSTATUS(status) != 0) {
VIR_WARN("Unexpected exit status '%d', qemu probably failed",
WEXITSTATUS(status));
}
}
int qemudExtractVersionInfo(const char *qemu,
unsigned int *retversion,
unsigned long long *retflags) {
@ -1387,6 +1429,9 @@ int qemudExtractVersionInfo(const char *qemu,
&version, &is_kvm, &kvm_version) == -1)
goto cleanup2;
if (flags & QEMUD_CMD_FLAG_DEVICE)
qemudParsePCIDeviceStrs(qemu, &flags);
if (retversion)
*retversion = version;
if (retflags)
@ -2896,8 +2941,33 @@ error:
}
int
qemudOpenPCIConfig(virDomainHostdevDefPtr dev)
{
char *path = NULL;
int configfd = -1;
if (virAsprintf(&path, "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/config",
dev->source.subsys.u.pci.domain,
dev->source.subsys.u.pci.bus,
dev->source.subsys.u.pci.slot,
dev->source.subsys.u.pci.function) < 0) {
virReportOOMError();
return -1;
}
configfd = open(path, O_RDWR, 0);
if (configfd < 0)
virReportSystemError(errno, _("Failed opening %s"), path);
VIR_FREE(path);
return configfd;
}
char *
qemuBuildPCIHostdevDevStr(virDomainHostdevDefPtr dev)
qemuBuildPCIHostdevDevStr(virDomainHostdevDefPtr dev, const char *configfd)
{
virBuffer buf = VIR_BUFFER_INITIALIZER;
@ -2907,6 +2977,8 @@ qemuBuildPCIHostdevDevStr(virDomainHostdevDefPtr dev)
dev->source.subsys.u.pci.slot,
dev->source.subsys.u.pci.function);
virBufferVSprintf(&buf, ",id=%s", dev->info.alias);
if (configfd && *configfd)
virBufferVSprintf(&buf, ",configfd=%s", configfd);
if (qemuBuildDeviceAddressStr(&buf, &dev->info) < 0)
goto error;
@ -4611,8 +4683,30 @@ int qemudBuildCommandLine(virConnectPtr conn,
if (hostdev->mode == VIR_DOMAIN_HOSTDEV_MODE_SUBSYS &&
hostdev->source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI) {
if (qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE) {
char *configfd_name = NULL;
if (qemuCmdFlags & QEMUD_CMD_FLAG_PCI_CONFIGFD) {
int configfd = qemudOpenPCIConfig(hostdev);
if (configfd >= 0) {
if (virAsprintf(&configfd_name, "%d", configfd) < 0) {
close(configfd);
virReportOOMError();
goto no_memory;
}
if (VIR_REALLOC_N(*vmfds, (*nvmfds)+1) < 0) {
VIR_FREE(configfd_name);
close(configfd);
goto no_memory;
}
(*vmfds)[(*nvmfds)++] = configfd;
}
}
ADD_ARG_LIT("-device");
if (!(devstr = qemuBuildPCIHostdevDevStr(hostdev)))
devstr = qemuBuildPCIHostdevDevStr(hostdev, configfd_name);
VIR_FREE(configfd_name);
if (!devstr)
goto error;
ADD_ARG(devstr);
} else if (qemuCmdFlags & QEMUD_CMD_FLAG_PCIDEVICE) {

6
src/qemu/qemu_conf.h
View File

@ -89,6 +89,7 @@ enum qemud_cmd_flags {
QEMUD_CMD_FLAG_NO_HPET = (1LL << 33), /* -no-hpet flag is supported */
QEMUD_CMD_FLAG_NO_KVM_PIT = (1LL << 34), /* -no-kvm-pit-reinjection supported */
QEMUD_CMD_FLAG_TDF = (1LL << 35), /* -tdf flag (user-mode pit catchup) */
QEMUD_CMD_FLAG_PCI_CONFIGFD = (1LL << 36), /* pci-assign.configfd */
};
/* Main driver state */
@ -247,7 +248,10 @@ char * qemuBuildSoundDevStr(virDomainSoundDefPtr sound);
/* Legacy, pre device support */
char * qemuBuildPCIHostdevPCIDevStr(virDomainHostdevDefPtr dev);
/* Current, best practice */
char * qemuBuildPCIHostdevDevStr(virDomainHostdevDefPtr dev);
char * qemuBuildPCIHostdevDevStr(virDomainHostdevDefPtr dev,
const char *configfd);
int qemudOpenPCIConfig(virDomainHostdevDefPtr dev);
/* Current, best practice */
char * qemuBuildChrChardevStr(virDomainChrDefPtr dev);

34
src/qemu/qemu_driver.c
View File

@ -7658,6 +7658,8 @@ static int qemudDomainAttachHostPciDevice(struct qemud_driver *driver,
pciDevice *pci;
int ret;
char *devstr = NULL;
int configfd = -1;
char *configfd_name = NULL;
if (VIR_REALLOC_N(vm->def->hostdevs, vm->def->nhostdevs+1) < 0) {
virReportOOMError();
@ -7688,8 +7690,32 @@ static int qemudDomainAttachHostPciDevice(struct qemud_driver *driver,
goto error;
if (qemuDomainPCIAddressEnsureAddr(priv->pciaddrs, &hostdev->info) < 0)
goto error;
if (qemuCmdFlags & QEMUD_CMD_FLAG_PCI_CONFIGFD) {
configfd = qemudOpenPCIConfig(hostdev);
if (configfd >= 0) {
if (virAsprintf(&configfd_name, "fd-%s",
hostdev->info.alias) < 0) {
virReportOOMError();
goto error;
}
if (!(devstr = qemuBuildPCIHostdevDevStr(hostdev)))
qemuDomainObjEnterMonitorWithDriver(driver, vm);
if (qemuMonitorSendFileHandle(priv->mon, configfd_name,
configfd) < 0) {
qemuDomainObjExitMonitorWithDriver(driver, vm);
goto error;
}
qemuDomainObjExitMonitorWithDriver(driver, vm);
}
}
if (!virDomainObjIsActive(vm)) {
qemuReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("guest unexpectedly quit during hotplug"));
goto error;
}
if (!(devstr = qemuBuildPCIHostdevDevStr(hostdev, configfd_name)))
goto error;
qemuDomainObjEnterMonitorWithDriver(driver, vm);
@ -7713,6 +7739,9 @@ static int qemudDomainAttachHostPciDevice(struct qemud_driver *driver,
vm->def->hostdevs[vm->def->nhostdevs++] = hostdev;
VIR_FREE(devstr);
VIR_FREE(configfd_name);
if (configfd >= 0)
close(configfd);
return 0;
@ -7724,6 +7753,9 @@ error:
VIR_FREE(devstr);
pciDeviceListDel(driver->activePciHostdevs, pci);
VIR_FREE(configfd_name);
if (configfd >= 0)
close(configfd);
return -1;
}