Re: [RFC PATCH] vfio/common: Separate vfio-pci ranges

[Joao Martins]

On 08/09/2023 09:28, Cédric Le Goater wrote:
> On 9/8/23 10:16, Joao Martins wrote:
>> On 08/09/2023 08:14, Cédric Le Goater wrote:
>>> From: Joao Martins <joao.m.martins@oracle.com>
>>>
>>> QEMU computes the DMA logging ranges for two predefined ranges: 32-bit
>>> and 64-bit. In the OVMF case, when the dynamic MMIO window is enabled,
>>> QEMU includes in the 64-bit range the RAM regions at the lower part
>>> and vfio-pci device RAM regions which are at the top of the address
>>> space. This range contains a large gap and the size can be bigger than
>>> the dirty tracking HW limits of some devices (MLX5 has a 2^42 limit).
>>>
>>> To avoid such large ranges, introduce a new PCI range covering the
>>> vfio-pci device RAM regions, this only if the addresses are above 4GB
>>> to avoid breaking potential SeaBIOS guests.
>>>
>>> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
>>> [ clg: - wrote commit log
>>>         - fixed overlapping 32-bit and PCI ranges when using SeaBIOS ]
>>> Signed-off-by: Cédric Le Goater <clg@redhat.com>
>>> ---
>>>   hw/vfio/common.c     | 51 +++++++++++++++++++++++++++++++++++++++-----
>>>   hw/vfio/trace-events |  2 +-
>>>   2 files changed, 47 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>>> index
>>> 237101d03844273f653d98b6d053a1ae9c05a247..a5548e3bebf999e6d9cef08bdaf1fbc3b437e5eb
>>>  100644
>>> --- a/hw/vfio/common.c
>>> +++ b/hw/vfio/common.c
>>> @@ -27,6 +27,7 @@
>>>     #include "hw/vfio/vfio-common.h"
>>>   #include "hw/vfio/vfio.h"
>>> +#include "hw/vfio/pci.h"
>>>   #include "exec/address-spaces.h"
>>>   #include "exec/memory.h"
>>>   #include "exec/ram_addr.h"
>>> @@ -1400,6 +1401,8 @@ typedef struct VFIODirtyRanges {
>>>       hwaddr max32;
>>>       hwaddr min64;
>>>       hwaddr max64;
>>> +    hwaddr minpci;
>>> +    hwaddr maxpci;
>>
>> Considering this is about pci64 hole relocation, I wondered post-reading your
>> feedback, that maybe we should rename {min,max}pci to {min,max}pci64 (...)
> 
> yes.
> 
>>
>>>   } VFIODirtyRanges;
>>>     typedef struct VFIODirtyRangesListener {
>>> @@ -1408,6 +1411,31 @@ typedef struct VFIODirtyRangesListener {
>>>       MemoryListener listener;
>>>   } VFIODirtyRangesListener;
>>>   +static bool vfio_section_is_vfio_pci(MemoryRegionSection *section,
>>> +                                     VFIOContainer *container)
>>> +{
>>> +    VFIOPCIDevice *pcidev;
>>> +    VFIODevice *vbasedev;
>>> +    VFIOGroup *group;
>>> +    Object *owner;
>>> +
>>> +    owner = memory_region_owner(section->mr);
>>> +
>>> +    QLIST_FOREACH(group, &container->group_list, container_next) {
>>> +        QLIST_FOREACH(vbasedev, &group->device_list, next) {
>>> +            if (vbasedev->type != VFIO_DEVICE_TYPE_PCI) {
>>> +                continue;
>>> +            }
>>> +            pcidev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
>>> +            if (OBJECT(pcidev) == owner) {
>>> +                return true;
>>> +            }
>>> +        }
>>> +    }
>>> +
>>> +    return false;
>>> +}
>>> +
>>>   static void vfio_dirty_tracking_update(MemoryListener *listener,
>>>                                          MemoryRegionSection *section)
>>>   {
>>> @@ -1434,9 +1462,14 @@ static void vfio_dirty_tracking_update(MemoryListener
>>> *listener,
>>>        * would be an IOVATree but that has a much bigger runtime overhead 
>>> and
>>>        * unnecessary complexity.
>>>        */
>>> -    min = (end <= UINT32_MAX) ? &range->min32 : &range->min64;
>>> -    max = (end <= UINT32_MAX) ? &range->max32 : &range->max64;
>>> -
>>> +    if (vfio_section_is_vfio_pci(section, dirty->container) &&
>>> +        iova >= UINT32_MAX) {
>>> +        min = &range->minpci;
>>> +        max = &range->maxpci;
>>
>> (...) specially considering this check of making sure we skip the pci-hole32 
>> (as
>> that one is fixed)
> 
> yep. That check above might deserve a comment also.
> 
> Could you resend please ?
> 

yes. This is on top of your vfio-8.2 branch right?

> Thanks,
> 
> C.
> 
> 
>>
>>> +    } else {
>>> +        min = (end <= UINT32_MAX) ? &range->min32 : &range->min64;
>>> +        max = (end <= UINT32_MAX) ? &range->max32 : &range->max64;
>>> +    }
>>>       if (*min > iova) {
>>>           *min = iova;
>>>       }
>>> @@ -1461,6 +1494,7 @@ static void vfio_dirty_tracking_init(VFIOContainer
>>> *container,
>>>       memset(&dirty, 0, sizeof(dirty));
>>>       dirty.ranges.min32 = UINT32_MAX;
>>>       dirty.ranges.min64 = UINT64_MAX;
>>> +    dirty.ranges.minpci = UINT64_MAX;
>>>       dirty.listener = vfio_dirty_tracking_listener;
>>>       dirty.container = container;
>>>   @@ -1531,7 +1565,8 @@
>>> vfio_device_feature_dma_logging_start_create(VFIOContainer *container,
>>>        * DMA logging uAPI guarantees to support at least a number of ranges 
>>> that
>>>        * fits into a single host kernel base page.
>>>        */
>>> -    control->num_ranges = !!tracking->max32 + !!tracking->max64;
>>> +    control->num_ranges = !!tracking->max32 + !!tracking->max64 +
>>> +        !!tracking->maxpci;
>>>       ranges = g_try_new0(struct vfio_device_feature_dma_logging_range,
>>>                           control->num_ranges);
>>>       if (!ranges) {
>>> @@ -1550,11 +1585,17 @@
>>> vfio_device_feature_dma_logging_start_create(VFIOContainer *container,
>>>       if (tracking->max64) {
>>>           ranges->iova = tracking->min64;
>>>           ranges->length = (tracking->max64 - tracking->min64) + 1;
>>> +        ranges++;
>>> +    }
>>> +    if (tracking->maxpci) {
>>> +        ranges->iova = tracking->minpci;
>>> +        ranges->length = (tracking->maxpci - tracking->minpci) + 1;
>>>       }
>>>         trace_vfio_device_dirty_tracking_start(control->num_ranges,
>>>                                              tracking->min32, 
>>> tracking->max32,
>>> -                                           tracking->min64, 
>>> tracking->max64);
>>> +                                           tracking->min64, 
>>> tracking->max64,
>>> +                                           tracking->minpci, 
>>> tracking->maxpci);
>>>         return feature;
>>>   }
>>> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
>>> index
>>> ce61b10827b6a1203a5fe1a87a76d96f25c11345..ab52c6bb7f0c11e51fefef231c108d0c9381547e
>>>  100644
>>> --- a/hw/vfio/trace-events
>>> +++ b/hw/vfio/trace-events
>>> @@ -104,7 +104,7 @@ vfio_known_safe_misalignment(const char *name, uint64_t
>>> iova, uint64_t offset_wi
>>>   vfio_listener_region_add_no_dma_map(const char *name, uint64_t iova,
>>> uint64_t size, uint64_t page_size) "Region \"%s\" 0x%"PRIx64"
>>> size=0x%"PRIx64" is not aligned to 0x%"PRIx64" and cannot be mapped for DMA"
>>>   vfio_listener_region_del(uint64_t start, uint64_t end) "region_del
>>> 0x%"PRIx64" - 0x%"PRIx64
>>>   vfio_device_dirty_tracking_update(uint64_t start, uint64_t end, uint64_t
>>> min, uint64_t max) "section 0x%"PRIx64" - 0x%"PRIx64" -> update [0x%"PRIx64"
>>> - 0x%"PRIx64"]"
>>> -vfio_device_dirty_tracking_start(int nr_ranges, uint64_t min32, uint64_t
>>> max32, uint64_t min64, uint64_t max64) "nr_ranges %d 32:[0x%"PRIx64" -
>>> 0x%"PRIx64"], 64:[0x%"PRIx64" - 0x%"PRIx64"]"
>>> +vfio_device_dirty_tracking_start(int nr_ranges, uint64_t min32, uint64_t
>>> max32, uint64_t min64, uint64_t max64, uint64_t minpci, uint64_t maxpci)
>>> "nr_ranges %d 32:[0x%"PRIx64" - 0x%"PRIx64"], 64:[0x%"PRIx64" - 
>>> 0x%"PRIx64"],
>>> pci:[0x%"PRIx64" - 0x%"PRIx64"]"
>>>   vfio_disconnect_container(int fd) "close container->fd=%d"
>>>   vfio_put_group(int fd) "close group->fd=%d"
>>>   vfio_get_device(const char * name, unsigned int flags, unsigned int
>>> num_regions, unsigned int num_irqs) "Device %s flags: %u, regions: %u, 
>>> irqs: %u"
>>
>