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From: John Johnson <john.g.johnson@oracle.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Elena Ufimtseva <elena.ufimtseva@oracle.com>,
	Jag Raman <jag.raman@oracle.com>,
	Swapnil Ingle <swapnil.ingle@nutanix.com>,
	John Levon <john.levon@nutanix.com>,
	QEMU Devel Mailing List <qemu-devel@nongnu.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	"thanos.makatos@nutanix.com" <thanos.makatos@nutanix.com>
Subject: Re: [PATCH RFC v2 08/16] vfio-user: get region info
Date: Thu, 9 Sep 2021 05:35:40 +0000	[thread overview]
Message-ID: <59C70EB8-E4D5-4F54-B0E8-A5A10334C0EC@oracle.com> (raw)
In-Reply-To: <YTd3zRAjg51tzzfd@stefanha-x1.localdomain>



> On Sep 7, 2021, at 7:31 AM, Stefan Hajnoczi <stefanha@redhat.com> wrote:
> 
> On Mon, Aug 16, 2021 at 09:42:41AM -0700, Elena Ufimtseva wrote:
>> @@ -1514,6 +1515,16 @@ bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
>>     return true;
>> }
>> 
>> +static int vfio_get_region_info_remfd(VFIODevice *vbasedev, int index)
>> +{
>> +    struct vfio_region_info *info;
>> +
>> +    if (vbasedev->regions == NULL || vbasedev->regions[index] == NULL) {
>> +        vfio_get_region_info(vbasedev, index, &info);
>> +    }
> 
> Maybe this will be called from other places in the future, but the
> vfio_region_setup() caller below already invoked vfio_get_region_info()
> so I'm not sure it's necessary to do this again?
> 
> Perhaps add an int *remfd argument to vfio_get_region_info(). That way
> vfio_get_region_info_remfd() isn't necessary.
> 

	I think they could be combined, but the region capabilities are
retrieved with separate calls to vfio_get_region_info_cap(), so I followed
that precedent.


>> @@ -2410,6 +2442,24 @@ int vfio_get_region_info(VFIODevice *vbasedev, int index,
>>                          struct vfio_region_info **info)
>> {
>>     size_t argsz = sizeof(struct vfio_region_info);
>> +    int fd = -1;
>> +    int ret;
>> +
>> +    /* create region cache */
>> +    if (vbasedev->regions == NULL) {
>> +        vbasedev->regions = g_new0(struct vfio_region_info *,
>> +                                   vbasedev->num_regions);
>> +        if (vbasedev->proxy != NULL) {
>> +            vbasedev->regfds = g_new0(int, vbasedev->num_regions);
>> +        }
>> +    }
>> +    /* check cache */
>> +    if (vbasedev->regions[index] != NULL) {
>> +        *info = g_malloc0(vbasedev->regions[index]->argsz);
>> +        memcpy(*info, vbasedev->regions[index],
>> +               vbasedev->regions[index]->argsz);
>> +        return 0;
>> +    }
> 
> Why is it necessary to introduce a cache? Is it to avoid passing the
> same fd multiple times?
> 

	Yes.  For polled regions, the server returns an FD with each
message, so there would be an FD leak if I didn’t check that the region
hadn’t already returned one.  Since I had to cache the FD anyway, I
cached the whole struct.


>> 
>>     *info = g_malloc0(argsz);
>> 
>> @@ -2417,7 +2467,17 @@ int vfio_get_region_info(VFIODevice *vbasedev, int index,
>> retry:
>>     (*info)->argsz = argsz;
>> 
>> -    if (ioctl(vbasedev->fd, VFIO_DEVICE_GET_REGION_INFO, *info)) {
>> +    if (vbasedev->proxy != NULL) {
>> +        VFIOUserFDs fds = { 0, 1, &fd};
>> +
>> +        ret = vfio_user_get_region_info(vbasedev, index, *info, &fds);
>> +    } else {
>> +        ret = ioctl(vbasedev->fd, VFIO_DEVICE_GET_REGION_INFO, *info);
>> +        if (ret < 0) {
>> +            ret = -errno;
>> +        }
>> +    }
>> +    if (ret != 0) {
>>         g_free(*info);
>>         *info = NULL;
>>         return -errno;
>> @@ -2426,10 +2486,22 @@ retry:
>>     if ((*info)->argsz > argsz) {
>>         argsz = (*info)->argsz;
>>         *info = g_realloc(*info, argsz);
>> +        if (fd != -1) {
>> +            close(fd);
>> +            fd = -1;
>> +        }
>> 
>>         goto retry;
>>     }
>> 
>> +    /* fill cache */
>> +    vbasedev->regions[index] = g_malloc0(argsz);
>> +    memcpy(vbasedev->regions[index], *info, argsz);
>> +    *vbasedev->regions[index] = **info;
> 
> The previous line already copied the contents of *info. What is the
> purpose of this assignment?
> 

	That might be a mis-merge.  The struct assignment was a bug
fixed several revs ago with the memcpy() call.


>> +    if (vbasedev->regfds != NULL) {
>> +        vbasedev->regfds[index] = fd;
>> +    }
>> +
>>     return 0;
>> }
>> 
>> diff --git a/hw/vfio/user.c b/hw/vfio/user.c
>> index b584b8e0f2..91b51f37df 100644
>> --- a/hw/vfio/user.c
>> +++ b/hw/vfio/user.c
>> @@ -734,3 +734,36 @@ int vfio_user_get_info(VFIODevice *vbasedev)
>>     vbasedev->reset_works = !!(msg.flags & VFIO_DEVICE_FLAGS_RESET);
>>     return 0;
>> }
>> +
>> +int vfio_user_get_region_info(VFIODevice *vbasedev, int index,
>> +                              struct vfio_region_info *info, VFIOUserFDs *fds)
>> +{
>> +    g_autofree VFIOUserRegionInfo *msgp = NULL;
>> +    int size;
> 
> Please use uint32_t size instead of int size to prevent possible
> signedness issues:
> - VFIOUserRegionInfo->argsz is uint32_t.
> - sizeof(VFIOUserHdr) is size_t.
> - The vfio_user_request_msg() size argument is uint32_t.

	OK

		JJ



  reply	other threads:[~2021-09-09  5:37 UTC|newest]

Thread overview: 108+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-16 16:42 [PATCH RFC v2 00/16] vfio-user implementation Elena Ufimtseva
2021-08-16 16:42 ` [PATCH RFC v2 01/16] vfio-user: introduce vfio-user protocol specification Elena Ufimtseva
2021-08-17 23:04   ` Alex Williamson
2021-08-19  9:28     ` Swapnil Ingle
2021-08-19 15:32     ` John Johnson
2021-08-19 16:26       ` Alex Williamson
2021-08-16 16:42 ` [PATCH RFC v2 02/16] vfio-user: add VFIO base abstract class Elena Ufimtseva
2021-08-16 16:42 ` [PATCH RFC v2 03/16] vfio-user: Define type vfio_user_pci_dev_info Elena Ufimtseva
2021-08-24 13:52   ` Stefan Hajnoczi
2021-08-16 16:42 ` [PATCH RFC v2 04/16] vfio-user: connect vfio proxy to remote server Elena Ufimtseva
2021-08-18 18:47   ` Alex Williamson
2021-08-19 14:10     ` John Johnson
2021-08-24 14:15   ` Stefan Hajnoczi
2021-08-30  3:00     ` John Johnson
2021-09-07 13:21       ` Stefan Hajnoczi
2021-09-09  5:11         ` John Johnson
2021-09-09  6:29           ` Stefan Hajnoczi
2021-09-10  5:25             ` John Johnson
2021-09-13 12:35               ` Stefan Hajnoczi
2021-09-13 17:23               ` John Johnson
2021-09-14 13:06                 ` Stefan Hajnoczi
2021-09-15  0:21                   ` John Johnson
2021-09-15 13:04                     ` Stefan Hajnoczi
2021-09-15 19:14                       ` John Johnson
2021-09-16 11:49                         ` Stefan Hajnoczi
2021-08-16 16:42 ` [PATCH RFC v2 05/16] vfio-user: define VFIO Proxy and communication functions Elena Ufimtseva
2021-08-24 15:14   ` Stefan Hajnoczi
2021-08-30  3:04     ` John Johnson
2021-09-07 13:35       ` Stefan Hajnoczi
2021-08-16 16:42 ` [PATCH RFC v2 06/16] vfio-user: negotiate version with remote server Elena Ufimtseva
2021-08-24 15:59   ` Stefan Hajnoczi
2021-08-30  3:08     ` John Johnson
2021-09-07 13:52       ` Stefan Hajnoczi
2021-08-16 16:42 ` [PATCH RFC v2 07/16] vfio-user: get device info Elena Ufimtseva
2021-08-24 16:04   ` Stefan Hajnoczi
2021-08-30  3:11     ` John Johnson
2021-09-07 13:54       ` Stefan Hajnoczi
2021-08-16 16:42 ` [PATCH RFC v2 08/16] vfio-user: get region info Elena Ufimtseva
2021-09-07 14:31   ` Stefan Hajnoczi
2021-09-09  5:35     ` John Johnson [this message]
2021-09-09  5:59       ` Stefan Hajnoczi
2021-08-16 16:42 ` [PATCH RFC v2 09/16] vfio-user: region read/write Elena Ufimtseva
2021-09-07 14:41   ` Stefan Hajnoczi
2021-09-07 17:24   ` John Levon
2021-09-09  6:00     ` John Johnson
2021-09-09 12:05       ` John Levon
2021-09-10  6:07         ` John Johnson
2021-09-10 12:16           ` John Levon
2021-08-16 16:42 ` [PATCH RFC v2 10/16] vfio-user: pci_user_realize PCI setup Elena Ufimtseva
2021-09-07 15:00   ` Stefan Hajnoczi
2021-08-16 16:42 ` [PATCH RFC v2 11/16] vfio-user: get and set IRQs Elena Ufimtseva
2021-09-07 15:14   ` Stefan Hajnoczi
2021-09-09  5:50     ` John Johnson
2021-09-09 13:50       ` Stefan Hajnoczi
2021-08-16 16:42 ` [PATCH RFC v2 12/16] vfio-user: proxy container connect/disconnect Elena Ufimtseva
2021-09-08  8:30   ` Stefan Hajnoczi
2021-08-16 16:42 ` [PATCH RFC v2 13/16] vfio-user: dma map/unmap operations Elena Ufimtseva
2021-09-08  9:16   ` Stefan Hajnoczi
2021-08-16 16:42 ` [PATCH RFC v2 14/16] vfio-user: dma read/write operations Elena Ufimtseva
2021-09-08  9:51   ` Stefan Hajnoczi
2021-09-08 11:03     ` John Levon
2021-08-16 16:42 ` [PATCH RFC v2 15/16] vfio-user: pci reset Elena Ufimtseva
2021-09-08  9:56   ` Stefan Hajnoczi
2021-08-16 16:42 ` [PATCH RFC v2 16/16] vfio-user: migration support Elena Ufimtseva
2021-09-08 10:04   ` Stefan Hajnoczi
2021-08-27 17:53 ` [PATCH RFC server v2 00/11] vfio-user server in QEMU Jagannathan Raman
2021-08-27 17:53   ` [PATCH RFC server v2 01/11] vfio-user: build library Jagannathan Raman
2021-08-27 18:05     ` Jag Raman
2021-09-08 12:25     ` Stefan Hajnoczi
2021-09-10 15:21       ` Philippe Mathieu-Daudé
2021-09-13 12:15         ` Stefan Hajnoczi
2021-09-10 15:20     ` Philippe Mathieu-Daudé
2021-09-10 17:08       ` Jag Raman
2021-09-11 22:29       ` John Levon
2021-09-13 10:19         ` Philippe Mathieu-Daudé
2021-08-27 17:53   ` [PATCH RFC server v2 02/11] vfio-user: define vfio-user object Jagannathan Raman
2021-09-08 12:37     ` Stefan Hajnoczi
2021-09-10 14:04       ` Jag Raman
2021-08-27 17:53   ` [PATCH RFC server v2 03/11] vfio-user: instantiate vfio-user context Jagannathan Raman
2021-09-08 12:40     ` Stefan Hajnoczi
2021-09-10 14:58       ` Jag Raman
2021-08-27 17:53   ` [PATCH RFC server v2 04/11] vfio-user: find and init PCI device Jagannathan Raman
2021-09-08 12:43     ` Stefan Hajnoczi
2021-09-10 15:02       ` Jag Raman
2021-08-27 17:53   ` [PATCH RFC server v2 05/11] vfio-user: run vfio-user context Jagannathan Raman
2021-09-08 12:58     ` Stefan Hajnoczi
2021-09-08 13:37       ` John Levon
2021-09-08 15:02         ` Stefan Hajnoczi
2021-09-08 15:21           ` John Levon
2021-09-08 15:46             ` Stefan Hajnoczi
2021-08-27 17:53   ` [PATCH RFC server v2 06/11] vfio-user: handle PCI config space accesses Jagannathan Raman
2021-09-09  7:27     ` Stefan Hajnoczi
2021-09-10 16:22       ` Jag Raman
2021-09-13 12:13         ` Stefan Hajnoczi
2021-08-27 17:53   ` [PATCH RFC server v2 07/11] vfio-user: handle DMA mappings Jagannathan Raman
2021-09-09  7:29     ` Stefan Hajnoczi
2021-08-27 17:53   ` [PATCH RFC server v2 08/11] vfio-user: handle PCI BAR accesses Jagannathan Raman
2021-09-09  7:37     ` Stefan Hajnoczi
2021-09-10 16:36       ` Jag Raman
2021-08-27 17:53   ` [PATCH RFC server v2 09/11] vfio-user: handle device interrupts Jagannathan Raman
2021-09-09  7:40     ` Stefan Hajnoczi
2021-08-27 17:53   ` [PATCH RFC server v2 10/11] vfio-user: register handlers to facilitate migration Jagannathan Raman
2021-09-09  8:14     ` Stefan Hajnoczi
2021-08-27 17:53   ` [PATCH RFC server v2 11/11] vfio-user: acceptance test Jagannathan Raman
2021-09-08 10:08   ` [PATCH RFC server v2 00/11] vfio-user server in QEMU Stefan Hajnoczi
2021-09-08 12:06     ` Jag Raman
2021-09-09  8:17   ` Stefan Hajnoczi
2021-09-10 14:02     ` Jag Raman

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