[PATCH] qemu: modprobe vhost-vsock module

[Nikolay Shirokovskiy]

On 28.07.2020 13:12, Stefano Garzarella wrote:
> On Tue, Jul 28, 2020 at 12:58:07PM +0300, Nikolay Shirokovskiy wrote:
>> /dev/vhost-vsock is usable only if the module is loaded.  Let's load the module
>> just like in other places where kernel module is required (nbd, pci stub
>> driver).
> 
> Just a note, starting from Linux 4.13 (f4660cc994e1 ("vhost/vsock: use static
> minor number")) the kernel module should be automatically loaded when an
> application try to open /dev/vhost-vsock.
> 
> Did you find a case where that doesn't happen?
> 

Nope, it is just older kernel.

Nikolay

> 
>>
>> Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy at virtuozzo.com>
>> ---
>>  src/qemu/qemu_process.c | 18 ++++++++++++++++++
>>  1 file changed, 18 insertions(+)
>>
>> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
>> index ec6ca14..5aaa77c 100644
>> --- a/src/qemu/qemu_process.c
>> +++ b/src/qemu/qemu_process.c
>> @@ -92,6 +92,7 @@
>>  #include "viridentity.h"
>>  #include "virthreadjob.h"
>>  #include "virutil.h"
>> +#include "virkmod.h"
>>  
>>  #define VIR_FROM_THIS VIR_FROM_QEMU
>>  
>> @@ -6414,6 +6415,7 @@ qemuProcessPrepareHostStorage(virQEMUDriverPtr driver,
>>      return 0;
>>  }
>>  
>> +#define VHOST_VSOCK_MODULE "vhost-vsock"
>>  
>>  int
>>  qemuProcessOpenVhostVsock(virDomainVsockDefPtr vsock)
>> @@ -6422,6 +6424,22 @@ qemuProcessOpenVhostVsock(virDomainVsockDefPtr vsock)
>>      const char *vsock_path = "/dev/vhost-vsock";
>>      int fd;
>>  
>> +    if (virKModIsProhibited(VHOST_VSOCK_MODULE)) {
>> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>> +                       _("Failed to load vhost-vsock module: "
>> +                         "administratively prohibited"));
>> +        return -1;
>> +    } else {
>> +        g_autofree char *errbuf = NULL;
>> +
>> +        if ((errbuf = virKModLoad(VHOST_VSOCK_MODULE))) {
>> +            virReportError(VIR_ERR_INTERNAL_ERROR,
>> +                           _("Failed to load vhost-vsock module: %s"),
>> +                           errbuf);
>> +            return -1;
>> +        }
>> +    }
>> +
>>      if ((fd = open(vsock_path, O_RDWR)) < 0) {
>>          virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
>>                         "%s", _("unable to open vhost-vsock device"));
>> -- 
>> 1.8.3.1
>>
>