Re: [PATCH 5/8] qemu: implement vsock hotplug

[Ján Tomko <jtomko@xxxxxxxxxx>]

On Wed, May 30, 2018 at 04:57:54PM +0200, Ján Tomko wrote:
> Allow hotplugging the vsock device.
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1291851
>
> Signed-off-by: Ján Tomko <jtomko@xxxxxxxxxx>
> ---
> src/qemu/qemu_driver.c  |  9 ++++++-
> src/qemu/qemu_hotplug.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++++
> src/qemu/qemu_hotplug.h |  4 +++
> 3 files changed, 82 insertions(+), 1 deletion(-)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 3aa694de12..fa94ae9e38 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -7690,6 +7690,14 @@ qemuDomainAttachDeviceLive(virDomainObjPtr vm,
>         }
>         break;
>
> +    case VIR_DOMAIN_DEVICE_VSOCK:
> +        ret = qemuDomainAttachVsockDevice(driver, vm, dev->data.vsock);
> +        if (ret == 0) {
> +            alias = dev->data.vsock->info.alias;
> +            dev->data.vsock = NULL;
> +        }
> +        break;
> +
>     case VIR_DOMAIN_DEVICE_NONE:
>     case VIR_DOMAIN_DEVICE_FS:
>     case VIR_DOMAIN_DEVICE_SOUND:
> @@ -7702,7 +7710,6 @@ qemuDomainAttachDeviceLive(virDomainObjPtr vm,
>     case VIR_DOMAIN_DEVICE_TPM:
>     case VIR_DOMAIN_DEVICE_PANIC:
>     case VIR_DOMAIN_DEVICE_IOMMU:
> -    case VIR_DOMAIN_DEVICE_VSOCK:
>     case VIR_DOMAIN_DEVICE_LAST:
>         virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
>                        _("live attach of device '%s' is not supported"),
> diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
> index b4bbe62c75..ada120bcfe 100644
> --- a/src/qemu/qemu_hotplug.c
> +++ b/src/qemu/qemu_hotplug.c
> @@ -3015,6 +3015,76 @@ qemuDomainAttachInputDevice(virQEMUDriverPtr driver,
> }
>
>
> +int
> +qemuDomainAttachVsockDevice(virQEMUDriverPtr driver,
> +                            virDomainObjPtr vm,
> +                            virDomainVsockDefPtr vsock)
> +{
> +    qemuDomainVsockPrivatePtr vsockPriv = (qemuDomainVsockPrivatePtr)vsock->privateData;
> +    qemuDomainObjPrivatePtr priv = vm->privateData;
> +    virDomainDeviceDef dev = { VIR_DOMAIN_DEVICE_VSOCK,
> +                               { .vsock = vsock } };
> +    virErrorPtr originalError = NULL;
> +    const char *fdprefix = "vsockfd";
> +    bool releaseaddr = false;
> +    char *fdname = NULL;
> +    char *devstr = NULL;
> +    int ret = -1;
> +
> +    if (vm->def->vsock) {
> +        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
> +                       _("the domain already has a vsock device"));
> +        return -1;
> +    }
> +
> +    if (qemuDomainEnsureVirtioAddress(&releaseaddr, vm, &dev, "vsock") < 0)
> +        return -1;
> +
> +    if (qemuAssignDeviceVsockAlias(vsock) < 0)
> +        goto cleanup;
> +
> +    if (qemuProcessOpenVhostVsock(vsock) < 0)
> +        goto cleanup;
> +
> +    if (virAsprintf(&fdname, "%s%u", fdprefix, vsockPriv->vhostfd) < 0)
> +        goto cleanup;
> +
> +    if (!(devstr = qemuBuildVsockDevStr(vm->def, vsock, priv->qemuCaps, fdprefix)))
> +        goto cleanup;
> +
> +    qemuDomainObjEnterMonitor(driver, vm);
> +    if (qemuMonitorAddDeviceWithFd(priv->mon, devstr, vsockPriv->vhostfd, fdname) < 0)
> +        goto exit_monitor;
> +
> +    if (qemuDomainObjExitMonitor(driver, vm) < 0) {
> +        releaseaddr = false;
> +        goto cleanup;
> +    }
> +
> +    VIR_STEAL_PTR(vm->def->vsock, vsock);
> +
> +    ret = 0;
> +
> + cleanup:
> +    if (ret < 0) {
> +        virErrorPreserveLast(&originalError);
> +        if (releaseaddr)
> +            qemuDomainReleaseDeviceAddress(vm, &vsock->info, NULL);
> +        virErrorRestore(&originalError);
> +    }
> +
> +    virDomainVsockDefFree(vsock);

This free is bogus - on success we consume the pointer and on failure
the caller frees the device.

I'll remove it before pushing.

Jano

> +    VIR_FREE(devstr);
> +    VIR_FREE(fdname);
> +    return ret;
> +

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